The Project Gutenberg eBook of A handbook of systematic botany This ebook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this ebook or online at www.gutenberg.org. If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook. Title: A handbook of systematic botany Author: Eugenius Warming Contributor: Emil Knoblauch Translator: Michael Cresse Potter Release date: July 21, 2022 [eBook #68580] Language: English Original publication: United Kingdom: Swan Sonnenschein, 1895 Credits: Peter Becker, Karin Spence and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive) *** START OF THE PROJECT GUTENBERG EBOOK A HANDBOOK OF SYSTEMATIC BOTANY *** A HANDBOOK OF SYSTEMATIC BOTANY BY DR. E. WARMING _Professor of Botany in the University of Copenhagen_ WITH A REVISION OF THE FUNGI BY DR. E. KNOBLAUCH, _Karlsruhe_ TRANSLATED AND EDITED BY M. C. POTTER, M.A. F.L.S. _Professor of Botany in the University of Durham College of Science, Newcastle-upon-Tyne Author of “An Elementary Text-book of Agricultural Botany”_ WITH 610 ILLUSTRATIONS [Illustration] London SWAN SONNENSCHEIN & CO NEW YORK: MACMILLAN & CO 1895 BUTLER & TANNER, THE SELWOOD PRINTING WORKS, FROME, AND LONDON. PREFACE. The present translation of Dr. E. Warming’s _Haandbog i den Systematiske Botanik_ is taken from the text of the 3rd Danish Edition (1892), and from Dr. Knoblauch’s German Edition (1890), and the book has been further enriched by numerous additional notes which have been kindly sent to me by the author. Dr. Warming’s work has long been recognised as an original and important contribution to Systematic Botanical Literature, and I have only to regret that the pressure of other scientific duties has delayed its presentation to English readers. Dr. Warming desires me to record his high appreciation of the careful translation of Dr. Knoblauch, and his obligation to him for a number of corrections and improvements of which he has made use in the 3rd Danish Edition. In a few instances I have made slight additions to the text; these, however, appear as footnotes, or are enclosed in square brackets. In the present Edition the Thallophytes have been revised and rearranged from notes supplied to me by Dr. Knoblauch, to whom I am indebted for the Classification of the Fungi, according to the more recent investigations of Brefeld. The Bacteria have been revised by Dr. Migula, the Florideæ rearranged after Schmitz, and the Taphrinaceæ after Sadebeck. The main body of the text of the Algæ and Fungi remains as it was originally written by Dr. Wille and Dr. Rostrup in the Danish Edition, though in many places considerable alterations and additions have been made. For the sake of comparison a tabular key to the Classification adopted in the Danish Edition is given in the Appendix. In the Angiosperms I have retained the sequence of orders in the Danish original, and have not rearranged them according to the systems more familiar to English students. In any rearrangement much of the significance of Dr. Warming’s valuable and original observations would have been lost, and also from a teacher’s point of view I have found this system of great value. Although at present it may not be completely satisfactory, yet as an attempt to explain the mutual relationships, development and retrogression of many of the orders, it may be considered to have a distinct advantage over the more artificial systems founded upon Jussieu’s Divisions of Polypetalæ, Gamopetalæ, and Apetalæ. With reference to the principles of the systematic arrangement adopted, I may here insert the following brief communication from the author (dated March, 1890), which he has requested me to quote from the preface of Dr. Knoblauch’s edition:--“Each form which, on comparative morphological considerations, is clearly less simple, or can be shown to have arisen by reduction or through abortion of another type having the same fundamental structure, or in which a further differentiation and division of labour is found, will be regarded as younger, and as far as possible, and so far as other considerations will admit, will be reviewed later than the ‘simpler,’ more complete, or richer forms. For instance, to serve as an illustration: EPIGYNY and PERIGYNY are less simple than HYPOGNY; the Epigynous _Sympetalæ_, _Choripetalæ_, _Monocotyledones_ are, therefore, treated last, the _Hydrocharitaceæ_ are considered last under the _Helobieæ_, etc. ZYGOMORPHY is younger than ACTINOMORPHY; the _Scitamineæ_ and _Gynandræ_ therefore follow after the _Liliifloræ_, the _Scrophulariaceæ_ after the _Solanaceæ_, _Linaria_ after _Verbascum_, etc. FORMS WITH UNITED LEAVES indicate younger types than those with free leaves; hence the _Sympetalæ_ come after the _Choripetalæ_, the _Sileneæ_ after the _Alsineæ_, the _Malcaceæ_ after the _Sterculiaceæ_ and _Tiliaceæ_, etc. “ACYCLIC (spiral-leaved) flowers are older than cyclic (verticillate-leaved) with a definite number, comparing, of course, only those with the same fundamental structure. The _Veronica_-type must be considered as younger, for example, than _Digitalis_ and _Antirrhinum_, these again as younger than _Scrophularia_; _Verbascum_, on the contrary, is the least reduced, and therefore considered as the oldest form. Similarly the one-seeded, nut-fruited _Ranunculaceæ_ are considered as a later type (with evident abortion) than the many-seeded, folicular forms of the Order; the _Paronychieæ_ and _Chenopodiaceæ_ as reduced forms of the _Alsineæ_ type; and the occurrence of few seeds in an ovary as generally arising through reduction of the many-seeded forms. The _Cyperaceæ_ are regarded as a form derived from the _Juncaceæ_ through reduction, and associated with this, as is so often the case, there is a complication of the inflorescence; the _Dipsacaceæ_ are again regarded as a form proceeding from the _Valerianaceæ_ by a similar reduction, and these in their turn as an offshoot from the _Caprifoliaceæ_, etc. Of course these principles of systematic arrangement could only be applied very generally; for teaching purposes they have often required modification.” In preparing the translation considerable difficulty has been experienced in finding a satisfactory rendering of several terms which have no exact equivalent in English. I may here especially mention the term Vorblatt (Forblad) which I have translated by the term bracteole, when it clearly applied to the first leaf (or leaves) on a pedicel; but in discussing questions of general morphology a term was much needed to include both vegetative and floral shoots, and for this I have employed the term “Fore-leaf.” Also, the term “Floral-leaf” has been adopted as an equivalent of “Hochblatt,” and the term “bract” has been limited to a leaf subtending a flower. I have followed Dr. E. L. Mark in translating the word “Anlage” by “Fundament.” At the end of the book will be found a short appendix giving an outline of some of the earlier systems of Classification, with a more complete account of that of Hooker and Bentham. In a book of this character it is almost impossible to avoid some errors, but it is hoped that these will be comparatively few. In correcting the proof-sheets I have received invaluable assistance from Dr. Warming and Dr. Knoblauch, who have kindly read through every sheet, and to whom I am greatly indebted for many criticisms and suggestions. I have also to thank Mr. I. H. Burkill for his kind assistance in looking over the proofs of the Monocotyledons and Dicotyledons, and Mr. Harold Wager for kindly reading through the proofs of the Algæ and Fungi. My thanks are also especially due to Mr. E. L. Danielsen, and I wish to take this opportunity of acknowledging the very considerable help which I have received from him in translating from the Original Danish. M. C. POTTER. _January, 1895._ TABLE OF CONTENTS. BEING THE SYSTEM OF CLASSIFICATION ADOPTED IN THE PRESENT VOLUME. (_The Algæ and Fungi rearranged in co-operation with Dr. E. Knoblauch, the other Divisions as in the 3rd Danish Edition._) PAGE DIVISION I. THALLOPHYTA 4 A. Sub-Division. Myxomycetes, Slime-Fungi 5 B. Sub-Division. Algæ 8 Class 1. SYNGENETICÆ 14 „ 2. DINOFLAGELLATA 16 „ 3. DIATOMEÆ 18 „ 4. SCHIZOPHYTA 22 Family 1. Schizophyceæ 22 „ 2. Bacteria 26 Class 5. CONJUGATÆ 41 „ 6. CHLOROPHYCEÆ 46 Family 1. Protococcoideæ 47 „ 2. Confervoideæ 53 „ 3. Siphoneæ 59 Class 7. CHARACEÆ 64 „ 8. PHÆOPHYCEÆ (OLIVE-BROWN SEAWEEDS) 68 Family 1. Phæosporeæ 68 „ 2. Cyclosporeæ 73 Class 9. DICTYOTALES 76 „ 10. RHODOPHYCEÆ (RED SEAWEEDS) 77 Family 1. Bangioideæ 77 „ 2. Florideæ 78 C. Sub-Division. Fungi 84 Class 1. PHYCOMYCETES 96 Sub-Class 1. _Zygomycetes_ 96 „ 2. _Oomycetes_ 100 Family 1. Entomophthorales 102 „ 2. Chytridiales 102 „ 3. Mycosiphonales 104 Class 2. MESOMYCETES 108 Sub-Class 1. _Hemiasci_ 108 „ 2. _Hemibasidii_ 109 Class 3. MYCOMYCETES (HIGHER FUNGI) 114 Sub-Class 1. _Ascomycetes_ 114 Series 1. Exoasci 116 „ 2. Carpoasci 118 Family 1. Gymnoascales 118 „ 2. Perisporiales 119 „ 3. Pyrenomycetes 125 „ 4. Hysteriales 132 „ 5. Discomycetes 132 „ 6. Helvellales 136 Ascolichenes 136 Sub-Class 2. _Basidiomycetes_ 144 Series 1. Protobasidomycetes 145 „ 2. Autobasidiomycetes 157 Family 1. Dacryomycetes 159 „ 2. Hymenomycetes 159 „ 3. Phalloideæ 172 „ 4. Gasteromycetes 173 Basidiolichenes 176 Fungi Imperfecti 176 DIVISION II. MUSCINEÆ (MOSSES) 181 Class 1. HEPATICÆ 188 Family 1. Marchantieæ 190 „ 2. Anthoceroteæ 191 „ 3. Jungermannieæ 191 Class 2. MUSCI FRONDOSI 192 Family 1. Sphagneæ 193 „ 2. Schizocarpeæ 195 „ 3. Cleistocarpeæ 195 „ 4. Stegocarpeæ 195 DIVISION III. PTERIDOPHYTA 198 Class 1. FILICINÆ 205 Sub-Class 1. _Filices_ 205 Family 1. Eusporangiatæ 210 „ 2. Leptosporangiatæ 212 Sub-Class 2. _Hydropterideæ_ 215 Class 2. EQUISETINÆ (HORSETAILS) 221 Sub-Class 1. _Isosporous Equisetinæ_ 221 „ 2. _Heterosporous Equisetinæ_ 225 Class 3. LYCOPODINÆ (CLUB MOSSES) 226 Sub-Class 1. _Lycopodieæ_ 226 „ 2. _Selaginelleæ_ 228 TRANSITION FROM THE CRYPTOGAMS TO THE PHANEROGAMS 234 Asexual Generation of the Cormophytes 234 Sexual Generation; Fertilisation 243 DIVISION IV. GYMNOSPERMÆ 251 Class 1. CYCADEÆ (CYCADS) 252 „ 2. CONIFERÆ (PINE-TREES) 255 Family 1. Taxoideæ 259 „ 2. Pinoideæ 262 Class 3. GNETEÆ 270 Fossil Gymnosperms 271 DIVISION V. ANGIOSPERMÆ 273 Class 1. MONOCOTYLEDONES 274 Family 1. Helobieæ 278 „ 2. Glumifloræ 283 „ 3. Spadicifloræ 297 „ 4. Enantioblastæ 308 „ 5. Liliifloræ 309 „ 6. Scitamineæ 323 „ 7. Gynandræ 328 Class 2. DICOTYLEDONES 334 Sub-Class 1. _Choripetalæ_ 337 Family 1. Salicifloræ 337 „ 2. Casuarinifloræ 339 „ 3. Quercifloræ 340 „ 4. Juglandifloræ 349 „ 5. Urticifloræ 351 „ 6. Polygonifloræ 358 „ 7. Curvembryæ 363 „ 8. Cactifloræ 375 „ 9. Polycarpicæ 377 „ 10. Rhœadinæ 393 „ 11. Cistifloræ 406 „ 12. Gruinales 416 „ 13. Columniferæ 421 „ 14. Tricoccæ 430 „ 15. Terebinthinæ 435 „ 16. Aesculinæ 439 „ 17. Frangulinæ 443 „ 18. Thymelæinæ 448 „ 19. Saxifraginæ 451 „ 20. Rosifloræ 456 „ 21. Leguminosæ 466 „ 22. Passiflorinæ 475 „ 23. Myrtifloræ 482 „ 24. Umbellifloræ 490 „ 25. Hysterophyta 498 Sub-Class 2. _Sympetalæ_ 504 _A. Pentacyclicæ_ 506 Family 26. Bicornes 506 „ 27. Diospyrinæ 510 „ 28. Primulinæ 511 _B. Tetracyclicæ_ 514 Family 29. Tubifloræ 514 „ 30. Personatæ 517 „ 31. Nuculiferæ 531 „ 32. Contortæ 541 „ 33. Rubiales 548 „ 34. Dipsacales 556 „ 35. Campanulinæ 560 „ 36. Aggregatæ 564 APPENDIX 574 INDEX 593 CORRIGENDA. Page 9, line 12 from top, for _Hydrodicton_ read _Hydrodictyon_. „ 14, lines 1 and 2 from top, for _as in the preceding case_ read _in this case_. „ 14, „ 2 and 15 from top, for _zygote_ read _oospore_. „ 88, line 15 from bottom, for _Periphyses_ read _periphyses_. „ 124, „ 7 „ „ for _Chæromyces_ read _Choiromyces_. „ 142, „ 2 „ „ and in Fig. 137, for _Bœomyces_ read _Bæomyces_. „ 152, „ 2 „ top, for _Pirus_ read _Pyrus_. „ 152, „ 5 „ „ for _Crategus_ read _Cratægus_. „ 216, Fig. 215, for _Salvina_ read _Salvinia_. „ 306, line 6 from top, for _Pista_ read _Pistia_. „ 316, „ 26 „ „ after Dracæna insert a comma. „ 337, „ 13 „ „ for _end_ read _beginning_. „ 483, „ 11 „ bottom, for _Lagerstrœmia_ read _Lagerstrœmeria_. For ä, ö and ü read æ, œ and ue throughout. The following are not officinal in the British Pharmacopœia:--page 316, _Dracæna_ (Dragon’s-blood), _Smilax glabra_; p. 321, “Orris-root”; p. 326, species of _Curcuma_, _Alpinia officinarum_; p. 333, _Orchis_-species (“Salep”). On page 296, par. 4, only Pearl Barley is offic. in the Brit. Phar. CLASSIFICATION OF THE VEGETABLE KINGDOM. The Vegetable Kingdom is arranged in 5 Divisions. Division I.--=Thallophyta=, =Stemless Plants=, or those which are composed of a “thallus,” _i.e._ organs of nourishment which are not differentiated into root (in the sense in which this term is used among the higher plants), stem, or leaf. Vascular bundles are wanting. Conjugation and fertilisation in various ways; among most of the Fungi only vegetative multiplication. In contradistinction to the Thallophytes all other plants are called “Stem-plants” (“Cormophyta”), because their shoots are leaf-bearing stems. The name Thallophyta (Stemless-plants) is to some extent unsuitable, since many of the higher Algæ are differentiated into stem and leaf. The Thallophytes are again separated into 3 sub-divisions, namely: Sub-Division =A.=--=Myxomycetes, Slime-Fungi=, with only 1 class. Sub-Division =B.=--=Algæ=, with 10 classes: Class 1. Syngeneticæ. „ 2. Dinoflagellata, Peridinea. „ 3. Diatomeæ, Diatoms. „ 4. Schizophyta, Fission Algæ. „ 5. Conjugatæ. „ 6. Chlorophyceæ, Green Algæ. „ 7. Characeæ, Stone-worts. „ 8. Phæophyceæ, Brown Algæ. „ 9. Dictyotales. „ 10. Rhodophyceæ, Red Algæ. Sub-Division =C.=--=Fungi=, with 3 classes: Class 1. Phycomycetes. „ 2. Mesomycetes. „ 3. Mycomycetes, Higher Fungi. Division II.--=Bryophyta or Muscineæ, Mosses.= These have leaf-bearing shoots, but neither true roots nor vascular bundles. The lowest Mosses have, however, a thallus. Fertilisation is accomplished by means of self-motile, spirally coiled spermatozoids, through the agency of water. From the fertilised oosphere a “fruit-body” (capsule) with unicellular organs of reproduction (spores) is produced. The spore on germination gives rise to the vegetative system, which bears the organs of sexual reproduction; and this system is divided into two stages--the protonema, and the leaf-bearing plant produced on it. Alternation of generations: I. The protonema and the entire nutritive system which bears the organs of sexual reproduction. II. The capsule-like sporangium, with spores. 2 Classes: 1. Hepaticæ, Liverworts. 2. Musci, Leafy Mosses. Division III.--=Pteridophyta or Vascular Cryptogams=, =Fern-like Plants= having leaf-bearing shoots, true roots, and vascular bundles with tracheides and sieve-tubes. Fertilisation as in the Mosses. From the fertilised oosphere the leaf-bearing shoot arises, which bears on its leaves the reproductive organs, the spores, in capsule-like sporangia. From the germination of the spore a small prothallium is formed, which bears the sexual reproductive organs. Alternation of generations: I. Prothallium with organs of sexual reproduction. II. Leaf-bearing shoot with capsule-like sporangia. 3 Classes: 1. Filicinæ, True Ferns. 2. Equisetinæ, Horsetails. 3. Lycopodinæ, Club-mosses. Division IV.--=Gymnospermæ.= The vegetative organs are in the main similar to those in the 3rd Division; special shoots are modified into flowers for the service of reproduction. From the oosphere, which is fertilised by means of the pollen-tube, the leaf-bearing plant is derived; this passes the first period of its life as an embryo in the seed, and continues its development when the germination of the seed takes place. The organs corresponding to the spores of the two preceding Divisions, are called respectively the pollen-grain and embryo-sac. The pollen-grains are multicellular; i.e. they contain an indistinct prothallium. In the embryo-sac a prothallium, rich in reserve material (endosperm), with female organs of reproduction, is developed BEFORE FERTILISATION. The pollen-grains are carried by means of the wind to the ovules; these enclose the embryo-sac, and are situated on the open fruit-leaf (carpel), which has no stigma. Alternation of generations: I. Prothallium = Endosperm in ovule. II. Leaf-bearing plant, with flowers which produce the pollen-sac and ovule. 3 Classes: 1. Cycadeæ. 2. Coniferæ. 3. Gnetaceæ. Division V.--=Angiospermæ=. The members of this group are very similar to those of Division IV. The ovules are, however, encased in closed fruit-leaves (ovary), which have a special portion (stigma) adapted for the reception and germination of the pollen-grains. The pollen-grains are bicellular, but with only a membrane separating the two nuclei; they are carried to the stigma by animals (chiefly insects), by the wind, or by some other means. Endosperm is not formed till AFTER FERTILISATION. Alternation of generations in the main as in the Gymnosperms, but less distinct; while the sexual generation, the prothallium, with the organs of fertilisation, is also strongly reduced. 2 Classes:[1] 1. Monocotyledones. Embryo with one seed-leaf. 2. Dicotyledones. Embryo with two seed-leaves. For a long time the vegetable kingdom has been divided into. CRYPTOGAMS (so called because their organs of reproduction remained for some time undiscovered), and PHANEROGAMS or Flowering-plants which have evident sexual organs. The first three divisions belong to the Cryptogams, and the third and fourth divisions to the Phanerogams. This arrangement has no systematic value, but is very convenient in many ways. The Cryptogams are also known as Spore-plants, since they multiply by unicellular organs (spores), and the Phanerogams in contradistinction are called Seed-plants (Spermaphyta), since they multiply by seeds, multicellular bodies, the most important part of which is the embryo (a plant in its infancy). Mosses, Ferns, and Gymnosperms are together known as Archegoniatæ, since they possess in common a female organ of distinct structure, the Archegonium. DIVISION I. THALLOPHYTA. The thallus in the simplest forms is unicellular; in the majority, however, it is built up of many cells, which in a few instances are exactly similar; but generally there is a division of labour, so that certain cells undertake certain functions and are constructed accordingly, while others have different work and corresponding structure. Vessels or similar high anatomical structures are seldom formed, and the markings on the cell-wall are with few exceptions very simple. The Myxomycetes occupy quite an isolated position; their organs of nourishment are naked masses of protoplasm (plasmodia). As regards the external form, the thallus may be entirely without special prominences (such as branches, members), but when such are present they are all essentially alike in their origin and growth, that is, disregarding the hair-structures which may be developed. A shoot of a Seaweed or of a Lichen, etc., is essentially the same as any other part of the plant; only among the highest Algæ (Characeæ, certain Siphoneæ, _Sargassum_, and certain Red Seaweeds) do we find the same differences between the various external organs of the plant body as between stem and leaf, so that they must be distinguished by these names. _Roots_ of the same structure and development as in the Seed-plants are not found, but _organs of attachment_ (rhizoids and haptera) serve partly the biological functions of the root. SYSTEMATIC DIVISION OF THE THALLOPHYTES. To the Thallophytes belong three sub-divisions--Slime-Fungi, Algæ, and Fungi. Formerly the Thallophytes were divided into Algæ, Fungi, and Lichens. But this last group must be placed among the Fungi, since they are really Fungi, which live symbiotically with Algæ. The _Slime-Fungi_ must be separated from the true Fungi as a distinct subdivision. The _Algæ_ possess a colouring substance, which is generally green, brown, or red, and by means of which they are able to build up organic compounds from carbonic acid and water. The Bacteria, especially, form an exception to the Algæ in this respect; like the Fungi and Slime-Fungi they have as a rule no such colouring material, but must have organic carbonaceous food; these plants form no starch, and need no light for their vegetation (most Fungi require light for fructification). The Myxomycetes, Bacteria, and Fungi derive their nourishment either as _saprophytes_ from dead animal or vegetable matter, or as _parasites_ from living animals or plants (hosts), in which they very often cause disease. A remark, however, must be made with regard to this division. Among the higher plants so much stress is not laid upon the biological relations as to divide them into “green” and “non-green”; _Cuscuta_ (Dodder), a parasite, is placed among the Convolvulaceæ, _Neottia_ and _Corallorhiza_, saprophytes, belong to the Orchidacere, although they live like Fungi, yet their relations live as Algæ. In the same manner there are some colourless parasitic or saprophytic forms among the Algæ, and stress must be laid upon the fact that not only the Blue-green Algæ, but also the Bacteria, which cannot assimilate carbonic-acid, belong to the Algæ group, Schizophyceæ. The reason for this is that systematic classifications must be based upon the relationship of form, development, and reproduction, and from this point of view we must regard the Bacteria as being the nearer relatives of the Blue-green Algæ. All the Thallophytes, which are designated Fungi (when the entire group of Slime-Fungi is left out), form in some measure a connected series of development which only in the lower forms (Phycomycetes) is related to the Algæ, and probably through them has taken its origin from the Algæ; the higher Fungi have then developed independently from this beginning. The distinction of colour referred to is therefore not the only one which separates the Algæ from the Fungi, but it is almost the only characteristic mark by which we can at once distinguish the two great sub-divisions of the Thallophytes. The first forms of life on earth were probably “Protistæ,” which had assimilating colour material, or in other words, they were Algæ because they could assimilate purely inorganic food substances, and there are some among these which belong to the simplest forms of all plants. Fungi and Slime-Fungi must have appeared later, because they are dependent on other plants which assimilate carbon.[2] _Sub-Division I._--=MYXOMYCETES, SLIME-FUNGI.= The Slime-Fungi occupy quite an isolated position in the Vegetable Kingdom, and are perhaps the most nearly related to the group of Rhizopods in the Animal Kingdom. They live in and on organic remains, especially rotten wood or leaves, etc., on the surface of which their sporangia may be found. They are organisms without chlorophyll, and in their vegetative condition are masses of protoplasm without cell-wall (_plasmodia_). They multiply by means of _spores_, which in the true Slime-Fungi[3] are produced in sporangia, but in some others[4] free. The spores are round cells (Fig. 1 _a_) which in all the true Slime-Fungi are surrounded by a cell-wall. The wall bursts on germination, and the contents float out in the water which is necessary for germination. They move about with swimming and hopping motions like swarmspores (_e_, _f_), having a cilia at the front end and provided with a cell-nucleus and a pulsating vacuole. Later on they become a little less active, and creep about more slowly, while they continue to alter their form, shooting out arms in various places and drawing them in again (_g_, _h_, _i_, _k_, _l_, _m_); in this stage they are called _Myxamœbæ_. [Illustration: FIG. 1.--_a-l_ Development of “_Fuligo_” from spore to Myxamœba; _a-m_ are magnified 300 times; _m_ is a Myxamœba of _Lycogala epidendron_; _l´_ three Myxamœbæ of _Physarum album_ about to unite; _o_, a small portion of plasmodium, magnified 90 times.] [Illustration: FIG. 2.--The plasmodium (_a_) of _Stemonitis fusca_, commencing to form into sporangia (_b_); drawn on July 9. The dark-brown sporangia were completely formed by the next morning; _c-e_ shows the development of their external form.] [Illustration: FIG. 3.--Four sporangia of _Stemonitis fusca_, fixed on a branch. _a_ The plasmodium.] [Illustration: FIG. 4.--Sporangium of _Arcyria incarnata_. _B_ closed; _C_ open; _p_ wall of sporangium; _cp_ capilitium.] The Myxamœba grows whilst taking up nourishment from the material in which it lives, and multiplies by division. At a later stage a larger or smaller number of Myxamœbæ may be seen to coalesce and form large masses of protoplasm, _plasmodia_, which in the “Flowers of Tan” may attain the size of the palm of a hand, or even larger, but in most others are smaller. The plasmodia are independent, cream-like masses of protoplasm, often containing grains of carbonate of lime and colouring matter (the latter yellow in the Flowers of Tan). They creep about in the decaying matter in which they live, by means of amœboid movements, internal streamings of the protoplasm continually taking place; finally they creep out to the surface, and very often attach themselves to other objects, such as Mosses, and form sporangia (Fig. 2). These are stalked or sessile and are generally cylindrical (Fig. 3), spherical or pear-shaped (Fig. 4); they rarely attain a larger size than that of a pin’s head, and are red, brown, white, blue, yellow, etc., with a very delicate wall. In some genera may be found a “Capillitium” (Fig. 4 _cp_), or network of branched fine strands between the spores. Flowers of Tan (_Fuligo septica_) has a fruit-body composed of many sporangia (an Æthalium), which has the appearance of flat, irregular, brown cakes, inside the fragile external layer of which a loose powder, the spores, is found. It generally occurs on heaps of tanners’ bark, and appears sometimes in hot-beds in which that material is used, and is destructive by spreading itself over the young plants and choking them. All the motile stages may pass into _resting stages_, the small forms only surrounding themselves with a wall, but the large ones at the same time divide in addition into polyhedral cells. When favourable conditions arise, the walls dissolve and the whole appears again as a naked (free-moving) mass of protoplasm. To the genuine Slime-Fungi belong: _Arcyria_, _Trichia_, _Didymium_, _Physarum_, _Stemonitis_, _Lycogala_, _Fuligo_, _Spumaria_, _Reticularia_. Some genera wanting a sporangium-wall belong to the Slime-Fungi: _Ceratiomyxa_, whose fruit-body consists of polygonal plates, each bearing stalked spores; _Dictyostelium_, in which the swarm-stage is wanting and which has stalked spores. _Plasmodiophora brassicæ_ preys upon the roots of cabbages and other cruciferous plants, causing large swellings. _Pl. alni_ causes coral-shaped outgrowths on the roots of the Alder (_Alnus_). _Phytomyxa leguminosarum_ may be found in small knobs (tubercles) on the roots of leguminous plants. It is still uncertain whether it is this Fungus or Bacteria which is the cause of the formation of these tubercles. _Sub-Division_ II.--=ALGÆ=. =Mode of Life.= The Algæ (except most of the Bacteria) are themselves able to form their organic material by the splitting up of the carbonic acid contained in the water, or air in some cases, and for this purpose need light. The majority live in water, fresh or salt, but many are present on damp soil, stones, bark of trees, etc. With the exception of the Bacteria, no saprophytes have actually been determined to belong to this group, and only very few true parasites (for instance, _Phyllosiphon arisari_, _Mycoidea_, etc.), but a good many are found epiphytic or endophytic on other Algæ, or water plants, and on animals (for instance, certain _Schizophyceæ_ and _Protococcoideæ_; _Trichophilus welckeri_ in the hairs of _Bradypus_, the Sloth), and several species in symbiotic relation to various Fungi (species of Lichen), to Sponges (_e.g. Trentepohlia spongiophila_, _Struvea delicatula_), and to sundry Infusoria and other lower animals as Radiolarias, _Hydra_, etc. (the so-called _Zoochlorella_ and _Zooxantella_, which are perhaps partly stages in development of various Green and Brown Algæ). =Vegetative Organs.= The cells in all the Algæ (excepting certain reproductive cells) are surrounded by a membrane which (with the exception of the Bacteria) consists of pure or altered cellulose, sometimes forming a gelatinous covering, at other times a harder one, with deposits of chalk or silica formed in it. The cell-nucleus, which in the Schizophyta is less differentiated, may be one or more (_e.g. Hydrodictyon_, _Siphoneæ_) in each cell. Excepting in the majority of the Bacteria, _colour materials_ (of which _chlorophyll_, or modifications of it, always seems to be found) occur, which either permeate the whole cytoplasm surrounding the cell-nucleus, as in most of the coloured Schizophyta, or are contained in certain specially formed small portions of protoplasm (chromatophores). The individual at a certain stage of development consists nearly always of only one cell; by its division multicellular individuals may arise, or, if the daughter-cells separate immediately after the division, as in many of the simplest forms, the individual will, during the whole course of its existence, consist of only a single cell (unicellular Algæ). In multicellular individuals the cells may be more or less firmly connected, and all the cells of the individual may be exactly alike, or a division of labour may take place, so that certain cells undertake certain functions, and are constructed accordingly; this may also occur in parts of the cell in the large unicellular and multinuclear Algæ (Siphoneæ, p. 62). The cells in most of the Algæ belong to the _parenchymatous_ form; these, however, in the course of their growth, may very often become somewhat oblong; in many Algæ (particularly Fucoideæ and Florideæ) occur, moreover, _hyphæ-like threads_, which are very long, often branched, and are either formed of a single cell, or, more frequently, of a row of cells, having a well-pronounced apical growth. The parenchymatous as well as the hyphæ-like cells may, in the higher Algæ (especially in certain Fucoideæ and Florideæ), be further differentiated, so that they form well-defined anatomico-physiological systems of tissue, _i.e._ assimilating, conducting, storing, and mechanical. With regard to _the external form_, the thallus may present no differentiation, as in many unicellular Algæ, or in multicellular Algæ of the lower order, which are then either equally developed in all directions (_e.g. Pleurococcus_, Fig. 47), or form flat cell-plates (_Merismopedium_) or threads (_Oscillaria_, Fig. 21). The first step in the way of differentiation appears as a difference between apex and base (_Rivularia_, _Porphyra_); but the division of labour may proceed so that differences may arise between vegetative and reproductive cells (_Œdogonium_, Fig. 54); hairs and organs of attachment (rhizoids and haptera), which biologically serve as roots, are developed, and even leaves in certain forms of high order, belonging to different classes (_e.g. Caulerpa_, Fig. 59; _Characeæ_, Fig. 61; _Sargassum_, Fig. 72; and many Florideæ). =The non-sexual reproduction= takes place _vegetatively_, in many instances, simply by division into two, and more or less complete separation of the divisional products (Diatomaceæ, Desmidiaceæ (Fig. 36), many Fission-plants, etc.), or by detached portions of the thallus (_e.g. Caulerpa_, _Ulva lactuca_, etc.; among many Schizophyceæ, small filaments known as _hormogonia_ are set free), or _asexually_ by special reproductive cells (_spores_) set free from the thallus; these may be either _stationary_ or _motile_. The stationary reproductive cells (spores) may either be devoid of cell-wall (tetraspores of the Florideæ), or may possess a cell-wall; in the latter case they may be formed directly from the vegetative cells, generally by the thickening of the walls (_akinetes_), or only after a process of re-juvenescence (_aplanospores_). Aplanospores, as well as akinetes, may either germinate immediately or may become resting-cells, which germinate only after a period of rest. THE MOTILE ASEXUAL REPRODUCTIVE CELLS are spherical, egg- or pear-shaped, naked, _swarmspores_ (_zoospores_), which have arisen in other cells (_zoosporangia_), and propel themselves through the water by means of cilia; or they are _Phyto-Amœbæ_, which have no cilia and creep on a substratum by means of pseudopodia. The cilia, which are formed from the protoplasm (in the Bacteria, however, from the membrane), are mostly situated at the pointed and colourless end, which is directed forwards when in motion, and are 1, 2 (Fig. 5 _B_), 4 or more. Both the cilia in the Brown Algæ are attached to one side (Fig. 65); they are occasionally situated in a circle round the front end (_Œdogonium_, Fig. 6 _a_, and _Derbesia_), or are very numerous and situated in pairs distributed over a large part or nearly the whole of the zoospore (_Vaucheria_). Besides being provided with one or more nuclei (_Vaucheria_), they may also have a red “eye spot” and vacuoles, which are sometimes pulsating, _i.e._ they appear and reappear at certain intervals. The swarmspores move about in the water in irregular paths, and apparently quite voluntarily, revolving round their longer axes; but they come to the surface of the water in great numbers either because of their dependence on light, or driven by warm currents in the water, or attracted by some passing mass of food material. The swarmspores germinate, each forming a new plant, as their movement ceases they surround themselves with a cell-wall, grow, and then divide; in Fig. 6 _b_, two may be seen in the condition of germination, and about to attach themselves by means of the front end, which has been developed into haptera (see also Fig. 5 _B_, lowest figure). =The sexual reproduction= here, probably in all cases, consists in the coalescence of two masses of protoplasm, that is, in the fusion of their nuclei. [Illustration: FIG. 5.--_Cladophora glomerata. A_ The lower cells are full of swarmspores, whilst from the upper one the greater part have escaped through the aperture _m_. _B_ Free and germinating swarmspores.] [Illustration: FIG. 6.--_Œdogonium_: _a_ (free), _b_ germinating swarmspores.] [Illustration: FIG. 7.--_Zanardinia collaris. A_ Male gametangia (the small-celled) and female gametangia (large-celled). _C_ Female gamete. _D_ Male gamete. _B E_ Fertilisation. _F_ Zygote. _G_ Germinating zygote.] The simplest and lowest form is termed =conjugation=, or =isogamous= fertilisation, and is characterized by the fact that the two coalescing cells (termed gametes) are equal, or almost equal, in shape and size (the female gamete in the _Cutleriaceæ_, _e.g. Zanardinia collaris_, Fig. 7, is considerably larger than the male gamete). The cell in which the _gametes_ are developed is called a _gametaugium_, and the reproductive cell formed by their union--which generally has a thick wall and only germinates after a short period of rest--is termed a _zygote_ or _zygospore_. The conjugation takes place in two ways:-- (_a_) In the one way the gametes are motile cells (_planogametes_, _zoogametes_, Fig. 8), which unite in pairs during their swarming hither and thither in the water; during this process they lie side by side (Fig. 8 _d_), generally at first touching at the clear anterior end, and after a time they coalesce and become a motionless _zygote_, which surrounds itself with a cell-wall (Fig. 8 _e_). This form of conjugation is found in _Ulothrix_ (Fig. 8 _d_), _Acetabularia_, and other Algæ (Figs. 45, 56, 66). [Illustration: FIG. 8.--_Ulothrix zonata_: a portion of a thread with zoospores, of which two are formed in each cell (zoosporangium), the dark spots upon them are the “red eye-spots”; 1, 2, 3, 4 depict successive stages in the development of the zoospores; _b_ a single zoospore, at _v_ the pulsating vacuole; _c_ portion of a thread with gametes, of which sixteen are formed in each gametangium; _d_ gametes free and in conjugation; _e_ conjugation has been effected, and the formed zygotes are in the resting condition.] (_b_) Among other Algæ (_e.g. Diatomaceæ_ and _Conjugatæ_), the conjugating cells continue to be surrounded by the cell-wall of the mother-cell (_aplanogametes_ in an _aplanogametangium_); the aplanogametangia generally grow out into short branches, which lie close together and touch one another, the wall at the point of contact is then dissolved (Fig. 39). Through the aperture thus formed, the aplanogametes unite, as in the first instance, and form a rounded zygote, which immediately surrounds itself with a cell-wall. Various modifications occur; compare Figs. 37, 39, 41, 43. [Illustration: FIG. 9.--Fertilisation in the Bladder-wrack (_Fucus vesiculosus_).] [Illustration: FIG. 10.--_Sphæroplea annulina._] The highest form of the sexual reproduction is the =Egg- or Oogamous= fertilisation. The two coalescing cells are in the main unlike each other in form as well as size. The one which is considered as the male, and is known as the _spermatozoid_ (_antherozoid_), developes as a rule in large numbers in each mother-cell (_antheridium_); they are often self-motile (except in the Florideæ, where they are named _spermatia_), and are many times smaller than the other kind, the female, which is known as the _egg-cell_, (_oosphere_). The egg-cell is always a motionless, spherical, primordial cell which can either float about freely in the water, as in the Fucaceæ (Fig. 9), or is surrounded by a cell-wall (_oogonium_); generally only one oosphere is to be found in each oogonium, but several occur in _Sphæroplea_ (Fig. 10). The result of the spermatozoid coalescing with the egg-cell is, as in this case, the formation of a oospore, which generally undergoes a period of rest before germination (the Florideæ are an exception, a fruit-body, _cystocarp_, being produced as the result of coalescence). An example of fertilisation is afforded by the Alga, _Sphæroplea annulina_ (Fig. 10). The filamentous thallus is formed of cylindrical cells with many vacuoles (_r_ in _A_); some cells develope egg-cells (_B_), others spermatozoids (_C_), the latter in a particularly large number. The egg-cells are spherical, the spermatozoids of a club- or elongated pear-shape with two cilia at the front end (_G_; _E_ is however a swarmspore). The spermatozoids escape from their cells through apertures in the wall (_o_ in _C_) and enter through similar apertures (_o_ in _B_) to the egg-cells. The colourless front end of the spermatozoid is united at first with the “receptive spot” of the egg-cell (see _F_), and afterwards completely coalesces with it. The result is the formation of a oospore with wart-like excrescences (_D_). The female (_parthenogenesis_) or male (_androgenesis_) sexual cell may, sometimes without any preceding fertilisation, form a new individual (_e.g. Ulothrix zonata_, _Cylindrocapsa_, etc.). =Systematic division of the Algæ.= The Algæ are divided into the following ten classes: 1. SYNGENETICÆ; 2. DINOFLAGELLATA, or PERIDINEA; 3. DIATOMACEÆ; 4. SCHIZOPHYTA, FISSION-ALGÆ; 5. CONJUGATÆ; 6. CHLOROPHYCEÆ, GREEN-ALGÆ; 7. CHARACEÆ, STONE-WORTS; 8. PHÆOPHYCEÆ; 9. DICTYOTALES; 10. RHODOPHYCEÆ. Among the lowest forms of the Algæ, the Syngeneticæ, the Dinoflagellata, and the unicellular Volvocaceæ (Chlamydomoneæ), distinct transitional forms are found approaching the animal kingdom, which can be grouped as animals or plants according to their method of taking food or other characteristics. Only an artificial boundary can therefore be drawn between the animal and vegetable kingdoms. In the following pages only those forms which possess _chromatophores_, and have _no mouth_, will be considered as Algæ. Class 1. =Syngeneticæ.= The individuals are uni- or multicellular, free-swimming or motionless. The cells (which in the multicellular forms are loosely connected together, often only by mucilaginous envelopes) are naked or surrounded by a mucilaginous cell-wall, in which silica is never embedded. They contain one cell-nucleus, one or more pulsating vacuoles, and one to two band- or plate-like chromatophores with a brown or yellow colour, and sometimes a pyrenoid. Reproduction takes place by vegetative division, or asexually by zoospores, akinetes (or aplanospores?). Sexual reproduction is unknown. They are all fresh water forms. To this class may perhaps be assigned the recently arranged and very little known orders of _Calcocytaceæ_, _Murracytaceæ_, _Xanthellaceæ_, and _Dictyochaceæ_, which partly occur in the free condition in the sea, in the so-called “Plankton,” and partly symbiotic in various lower marine animals. The _Syngeneticæ_ are closely related to certain forms in the animal kingdom, as the Flagellatæ. Order 1. =Chrysomonadinaceæ.= Individuals, uni- or multicellular, swimming in free condition, naked or surrounded by a mucilaginous covering. The cells are generally oval or elongated, with 2 (rarely only 1) cilia, almost of the same length, and generally with a red “eye-spot” at their base, and with 2 (rarely 1 only) band-shaped chromatophores. Reproduction by the longitudinal division of the individual cells either during the swarming, or during a resting stage; in the multicellular forms also by the liberation of one or more cells, which in the latter case are connected together. A. Unicellular: _Chromulina_, _Cryptoglena_, _Microglena_, _Nephroselmis_. B. Multicellular: _Uroglena_, _Syncrypta_ (Fig. 11), _Synura_. [Illustration: FIG. 11.--_Syncrypta volvox_: the multicellular individual is surrounded by a mucilaginous granular envelope.] Among the unicellular Chrysomonadinaceæ are probably classed some forms which are only stages in the development of the multicellular, or of other _Syngeneticæ_. Order 2. =Chrysopyxaceæ= are unicellular, and differ mainly from the preceding in being attached either on a slime-thread (_Stylochrysalis_), or enclosed in an envelope (_Chrysopyxis_, Fig. 12). They have two cilia, and multiply by longitudinal (_Chrysopyxis_) or transverse division, and the swarming of one of the daughter-individuals (zoospore). Division may also take place in a motionless stage (_palmella-stage_). [Illustration: FIG. 12.--_Chrsopyxis bipes_: _m_ envelope, _Ec_ chromatophore, _cv_ contractile vacuole.] Order 3. =Dinobryinaceæ.= The individuals are originally attached, uni- or multicellular; each individual cell is distinctly contractile, and fixed at the bottom of a cup-shaped, open envelope. Cilia 2, but of unequal length. Asexual reproduction by zoospores, which are formed by straight or oblique longitudinal division of the mother-cell, during a palmella-stage which is produced in the winter aplanospores. _Epipyxis_, _Dinobryon_. Order 4. =Hydruraceæ.= The individuals are attached, without cilia, multicellular, branched, and with apical growth. The cells are spherical, but in the final stage almost spindle-shaped, and embedded in large masses of mucilage. Asexual reproduction by zoospores which are tetrahedric, with 1 cilia, and by resting akinetes. _Hydrurus_ is most common in mountain brooks. Class 2. =Dinoflagellata.= The individuals are of a very variable form, but always unicellular, and floating about in free condition. The cell is _dorsiventral_, _bilateral_, _asymmetric_ and generally surrounded by a colourless membrane, which has _no silica_ embedded in it, but is formed of a substance allied to _cellulose_. The membrane, which externally is provided with pores and raised borders, easily breaks up into irregularly-shaped pieces. In the forms which have longitudinal and cross furrows, _two cilia_ are fixed where these cross each other, and project through a cleft in the membrane; one of these cilia _projects freely_ and is directed longitudinally to the front or to the rear, the other one _stretches crosswise_ and lies close to the cell, often in a furrow (cross furrow). The chromatophores are coloured brown or green and may either be two parallel (_Exuviella_), or several radially placed, discs, which sometimes may coalesce and become a star-shaped chromatophore. The coloring material (pyrrophyl) consists, in addition to a modification of chlorophyl, also of _phycopyrrin_ and _peridinin_; this colour is sometimes more or less masked by the products of assimilation which consist of yellow, red or colourless oil (?) and starch. Cell-nucleus one: in _Polydinida_ several nuclei are found; contractile vacuoles many, which partly open in the cilia-cleft (Fig. 13 _gs_). In some an eye-spot, coloured red by hæmatochrome, is found. Pyrenoids occur perhaps in _Exuviella_ and _Amphidinium_. THE REPRODUCTION takes place as far as is known at present, only by division. This, in many salt water forms, may take place in the swarming condition, and, in that case, is always parallel to the longitudinal axis. The daughter-individuals, each of which retains half of the original shell, sometimes do not separate at once from each other, and thus chains (_e.g._ in _Ceratium_) of several connected individuals may be formed. In others, the division occurs after the cilia have been thrown off and the cell-contents rounded. The daughter-cells then adopt entirely new cell-walls. A palmella-stage (motionless division-stage) sometimes appears to take place, and also aplanospores (?) with one or two horn-like elongations (_e.g._ in _Peridinium cinctum_ and _P. tabulatum_); at germination one, or after division, two or more, new individuals may be formed. Sexual reproduction has not been observed with certainty. The Dinoflagellata move forward or backward, turning round their longitudinal axes; in their motion they are influenced by the action of light. The motion possibly may be produced only by the transverse cilium, which vibrates rapidly; whilst the longitudinal cilium moves slowly, and is supposed to serve mainly as a steering apparatus. They live principally in salt water, but also in fresh. Besides the coloured forms, which are able to make their own organic compounds by the splitting up of the carbonic acid contained in the water, there are a few colourless forms (_e.g. Gymnodinium spirale_), or such as do not possess chromatophores (_Polykrikos_); these appear to live saprophytically, and may be able to absorb solid bodies with which they come in contact. Dinoflagellata occur in the “Plankton” of the open sea, where they form together with Diatomaceæ the basis for the animal life. It is known with certainty that some salt water forms (like the _Noctiluca_, which belongs to the animal kingdom and to which they are perhaps related) produce light, known as phosphorescence. [Illustration: FIG. 13.--_A_ and _B Glenodinium cinctum_. _A_ seen from the ventral side, _B_ from behind; _fg_ transverse cilium; _g_ longitudinal cilium; _ch_ chromatophores; _a_ starch; _n_ cell-nucleus; _v_ vacuole; _oc_ eye-spot; _C Ceratium tetraceros_ from the ventral side; _r_ the right, _b_ the posterior horn; _lf_ longitudinal furrow; _gs_ cilium-cleft; _v_ vacuole; _g_ longitudinal cilium. (_A_ and _B_ mag. 450 times, _C_ 337 times.)] _Dinoflagellata_ (_Peridinea_, _Cilioflagellata_) are allied through their lowest form (_Exuviella_) to the Syngeneticæ and especially to the order Chrysomonadinaceæ. They may be divided into three orders. Order 1. =Adinida.= Without transverse or longitudinal furrows, but enclosed in two shells, and with two parallel chromatophores in each cell. _Exuviella_, _Prorocentrum_. Order 2. =Dinifera.= With tranverse and generally longitudinal furrow. Many radially-placed, disc-formed chromatophores. The most common genera are--_Ceratium_ (Fig. 13), _Peridinium_, _Glenodinium_ (Fig. 13), _Gymnodinium_, _Dinophysis_. Order 3. =Polydinida.= With several transverse furrows, no chromatophores, and several cell-nuclei. Only one genus--_Polykrikos_. The order _Polydinida_ deviates in a high degree from the other Dinoflagellata, not only by its many tranverse furrows, each with its own transverse cilium, and by the absence of chromatophores, but also in having several cell-nuclei and a kind of stinging capsule, which otherwise does not occur within the whole class. It may therefore be questionable whether this order should really be placed in the vegetable kingdom. Class 3. =Diatomeæ.= The individuals--each known as a _frustule_--assume very various forms and may be unicellular or multicellular, but present no differentiation; many similar cells may be connected in chains, embedded in mucilaginous masses, or attached to mucilaginous stalks. The cells are bilateral or centric, often asymmetrical, slightly dorsiventral and have no cilia; those living in the free condition have the power of sliding upon a firm substratum. The cell contains 1 cell-nucleus and 1–2 plate-shaped or several disc-shaped chromatophores. The colouring material “_Melinophyl_” contains, in addition to a modification of chlorophyl, a brown colouring matter, _diatomin_. 1 or 2 pyrenoids sometimes occur. Starch is wanting and the first product of assimilation appears to be a kind of oil (?). [Illustration: FIG. 14.--_Pinnularia_: _B_, from the edge, shows the valves fitting together; _A_, a valve.] [Illustration: FIG. 15.--Various Diatomaceæ. A _Diatoma vulgare_. B _Tabellaria flocculosa_. C _Navicula tumida_ (lateral views). D _Gomphonema constrictum_ (lateral views). E _Navicula west[=i][=i]_ (lateral views).] The cell-walls are _impregnated with silica_ to such a degree that they are imperishable and are therefore able to contribute in a great measure to the formation of the earth’s crust. The structure of their cell-wall is most peculiar and _differs from all other plants_ (except certain Desmidiaceæ); it does not consist of a single piece but is made up of two--the “shells”--(compare _Exuviella_ and _Prorocentrum_ among the Dinoflagellata) which are fitted into each other, one being a little larger than the other and embracing its edge, like a box with its lid (Fig. 14 _B_). The two parts which correspond to the bottom and lid of the box are known as _valves_. Along the central line of the valves a longitudinal _rib_ may often be found, interrupted at its centre by a small cleft (perhaps homologous with the cilia-cleft of the Dinoflagellata), through which the protoplasm is enabled to communicate with the exterior (Fig. 14 _A_). It is principally by reason of the valves, which bear numerous fine, transverse ribs, striæ or warts, etc. (Figs. 14, 15, 17), that the Diatomeæ have become so well known and employed as test objects in microscopical science. When the division takes place, the two shells are separated a little from each other, and after the cell-contents have divided into two masses, two new shells are formed, one fitting into the larger valve, the other one into the smaller valve of the original frustule. The latter cell (frustule) is thus, upon the whole, smaller than the mother-cell, and as the cells do not increase in size, some frustules are smaller than the ones from which they are derived, and thus, by repeated divisions, it follows that smaller and smaller frustules are produced. This continued diminution in size is, however, compensated for by the formation, when the cells have been reduced to a certain minimum, of _auxospores_, 2–3 times larger. These may either be formed _asexually_ by the protoplasm of a cell increasing, rounding off and surrounding itself with a new wall (_e.g. Melosira_) or after _conjugation_, which may take place with various modifications: 1. Two individuals unite after the secretion of a quantity of mucilage, and the valves then commence to separate from each other, on the side which the two individuals turn towards each other. The protoplasmic bodies now release themselves from their cell-wall, and each rounds off to form an ellipsoidal mass; these two protoplasmic masses (gametes) coalesce to form a zygote, the cell-nuclei and chromatophores also fusing together. The zygote increases in size, and surrounds itself with a firm, smooth, siliceous wall--the _perizonium_. The auxospores, whichever way they arise, are not resting stages. The germination of the zygote commences by the protoplasm withdrawing itself slightly from the cell-wall and constructing first the larger valve, and later on the smaller one; finally the membrane of the zygote bursts (_e.g. Himantidium_). 2. The conjugation occurs in a similar manner, but the protoplasm of the cells divides transversely before conjugation into two daughter-cells. Those lying opposite one another conjugate (Fig. 16) and form two zygotes. The formation of the perizonium, and germination take place as in the preceding instance (_e.g. Epithemia_). 3. Two cells place themselves parallel to each other, and each of the two cell-contents, without coalescing, becomes an auxospore. The formation of the wall takes place as in the preceding case. This is found in the Naviculeæ, Cymbelleæ, the Gomphonemeæ (_e.g. Frustulia_, _Cocconema_). [Illustration: FIG. 16.--Conjugation of _Cymbella variabilis_. _A_, The protoplasm in the two cells has divided into two masses; _B_ these masses coalesce in pairs; the cells (_B C_) enclosed in a mucilaginous matrix. _C D_ Auxospores and their formation.] The Diatomaceæ may be found in salt as well as in fresh water (often in such masses that the colour of the water or mud becomes yellow or brown; in the same manner the genera _Chætoceros_, _Rhizosolenia_, _Coscinodiscus_, and several others, form large slime-masses, “Plankton” on the surface of the sea), on damp soil and in dust blown by the wind. They occur as fossils in the recent formations, often in large deposits (siliceous earth, mountain meal), as in the cement lime in Jutland, the alluvial deposits beneath Berlin, in clay strata beneath peat bogs, in guano, etc. These accumulations of fossilized diatoms are used in the manufacture of dynamite and in various manufactures. The Diatomaceæ appear nearest to, and must be placed as a group co-ordinate with the Dinoflagellata, as they doubtless may be supposed to derive their origin from forms resembling _Exuviella_, and to have lost the cilia. The resemblances to the Desmidiaceæ which are striking in many respects, can only be conceived as analogies, and cannot be founded upon homologies, and it is therefore impossible to regard them as proof of genetic relationship. The family contains only one order. [Illustration: FIG. 17.--Various Diatomeæ. _A Synedra radians._ _B Epithemia turgida_ (from the two different sides). _C Cymbella cuspidata. D Cocconeis pediculus_ (on the right several situated on a portion of a plant, on the left a single one more highly magnified).] Order 1. =Diatomaceæ.= This order may be divided into two sub-orders, viz.-- Sub-Order 1. =Placochromaticæ.= The chromatophores are discoid, large, 1 or 2 in each cell; the structure of the valves is bilateral and always without reticulate markings. The following groups belong to this sub-order: _Gomphonemeæ_, _Cymbelleæ_, _Amphoreæ_, _Achnantheæ_, _Cocconeideæ_, _Naviculeæ_, _Amphipleureæ_, _Plagiotropideæ_, _Amphitropideæ_, _Nitzchieæ_, _Surirayeæ_, and _Eunotieæ_. Sub-Order 2. =Coccochromaticæ.= The chromatophores are granular, small and many in each cell. The structure of the cells is zygomorphic or centric, often with reticulate markings. The following groups belong to this sub-order: _Fragilarieæ_, _Meridieæ_, _Tabellarieæ_, _Licmophoreæ_, _Biddulphieæ_, _Anguliferæ_, _Eupodisceæ_, _Coscinodisceæ_, and _Melosireæ_. Class 4. =Schizophyta, Fission-Algæ.= The individuals are 1--many celled; the thallus consists in many of a single cell, in others of chains of cells, the cells dividing in only one definite direction (Figs. 18, 21). In certain Fission-Algæ the cell-chain branches (Fig. 30) and a difference between the anterior and the posterior ends of the chain is marked; in some, the cells may be united into the form of flat plates by the cell-division taking place in two directions; and in others into somewhat cubical masses, or rounded lumps of a less decided form, by the divisions taking place in three directions; or less defined masses may be formed by the divisions taking place in all possible directions. The cell-walls rarely contain cellulose, they often swell considerably (Figs. 20, 22), and show distinct stratifications, or they are almost completely changed into a mucilaginous mass in which the protoplasts are embedded, _e.g._ in _Nostoc_ (Fig. 22), and in the “Zooglœa” stage of the Bacteria (Fig. 27). Sexual reproduction is wanting. Vegetative reproduction by division and the separation of the divisional products by the splitting of the cell-wall or its becoming mucilaginous; among the Nostocaceæ, Lyngbyaceæ, Scytonemaceæ, etc., “Hormogonia” are found; in _Chamæsiphon_ and others single reproductive akinetes are formed. Many Fission-Algæ conclude the growing period by the formation of resting akinetes or aplanospores. The Schizophyta may be divided into 2 families: 1. SCHIZOPHYCEÆ. 2. BACTERIA. Family 1. =Schizophyceæ,[5] Blue-Green Algæ.= All the Blue-green Algæ are able to assimilate carbon by means of a colouring material containing chlorophyll (cyanophyll); but the chlorophyll in this substance is masked by a blue (phycocyan), or red (phycoerythrin, _e.g._ in _Trichodesmium erythræum_ in the Red Sea) colouring matter which may be extracted from them in cold water after death. The colouring matter, in most of them, permeates the whole of the protoplasm (excepting the cell-nucleus), but in a few (_e.g._ _Glaucocystis_, _Phragmonema_), slightly developed chromatophores are to be found. Where the cells are united into filaments (cell-chains) a differentiation into apex and base (_Rivulariaceæ_) may take place, and also between ordinary vegetative cells and heterocysts; these latter cannot divide, and are distinguished from the ordinary vegetative cells (Fig. 22 _h_) by their larger size, yellow colour, and poverty of contents. Branching sometimes occurs and is either true or spurious. [Illustration: FIG. 18.--_Microcoleus lyngbyanus_: _a_ portion of a filament, the thick sheath encloses only one cell-chain; in one place a cell is drawn out by the movement of the cell-chain; _b_ the cell-chain has divided into two parts (“hormongonia”) which commence to separate from each other.] The cell-chain in the spurious branching divides into two parts, of which either one or both grow beyond the place of division (Fig. 18) and often out to both sides (_e.g. Scytonema_), the divisions however, always take place transversely to the longitudinal direction of the cell-chain. In the true branching a cell elongates in the direction transverse to the cell-chain, and the division then takes place nearly at right angles to the former direction (_Sirosiphoniaceæ_). [Illustration: FIG. 19.--_Cylindrospermum majus_: _a_ resting akinete with heterocyst; _b-d_ germinating stages of a resting akinete; _e_ filament with two heterocysts and the formation of new akinetes; _f_ part of a filament with a heterocyst, and mature resting akinete.] Cilia are wanting, but the filaments are sometimes self-motile (_e.g._ hormogonia in _Nostoc_) and many partly turn round their axes, partly slide forward or backward (_Oscillaria_). Reproduction takes place by spores and hormogonia in addition to simple cell-division. Hormogonia are peculiar fragments of a cell-chain capable of motion, and often exhibit a vigorous motion in the sheath, until at last they escape and grow into a new individual (Fig. 18). The spores are reproductive akinetes (_Chamæsiphon_, etc.) or resting akinetes; these latter arise by the vegetative cells enlarging and constructing a thick cell-wall (Fig. 19 _e f_). On germination, this cell-wall bursts and the new cell-chain elongates in the same longitudinal direction as before (Fig. 19 _b c_). Many (_e.g._ _Oscillaria_) may however winter in their ordinary vegetative stage. Aplanospores are wanting. The Fission-Algæ are very prevalent in fresh water and on damp soil, less so in salt water; they also often occur in water which abounds in decaying matter. Some are found in warm springs with a temperature as high as 50° C. The Family may be divided into 2 sub-families: 1. HOMOCYSTEÆ (heterocysts are wanting): _Chroococcaceæ_, _Lyngbyaceæ_ and _Chamœsiphonaceæ_. 2. HETEROCYSTEÆ (heterocysts present): _Nostocaceæ_, _Rivulariaceæ_, _Scytonemaceæ_ and _Sirosiphoniaceæ_. Order 1. =Chroococcaceæ.= The individuals are 1--many-celled, but all the cells are uniform, united to form plates or irregular masses, often surrounded by a mucilaginous cell-wall, but never forming cell-chains. Multiplication by division and sometimes by resting akinetes, but reproductive akinetes are wanting. _Chroococcus_, _Aphanocapsa_, _Glœocapsa_ (Fig. 20), _Cœlosphærium_, _Merismopedium_, _Glaucocystis_, _Oncobyrsa_, _Polycystis_, _Gomphosphæria_. [Illustration: FIG. 20.--_Glœocapsa atrata_: _A_, _B_, _C_, _D_, _E_ various stages of development.] [Illustration: FIG. 21.--_Oscillaria_; =a= terminal, =b= central portion of a filament.] Order 2. =Lyngbyaceæ (Oscillariaceæ).= The cells are discoid (Fig. 21), united to straight or spirally twisted, free filaments, which are unbranched, or with spurious branching. The ends of the cell-chains are similar. Heterocysts absent. Reproduction by synakinetes, resting akinetes are wanting. _Oscillaria_ (Fig. 21), _Spirulina_, _Lyngbya_, _Microcoleus_, _Symploca_, _Plectonema_. Order 3. =Chamæsiphonaceæ.= The individuals are 1--many-celled, attached, unbranched filaments with differentiation into apex and base, without heterocysts. Multiplication by reproductive akinetes; resting akinetes are wanting. _Dermocarpa_, _Clastidium_, _Chamæsiphon_, _Godlewskia_, _Phragmonema_. Order 4. =Nostocaceæ.= The individuals are formed of multicellular, unbranched filaments, without differentiation into apex and base; heterocysts present. Reproduction by synakinetes and resting akinetes. [Illustration: FIG. 22.--_Nostoc verrucosum. A_ The plant in its natural size; an irregularly folded jelly-like mass. _B_ One of the cell-chains enlarged, with its heterocysts (_h_), embedded in its mucilaginous sheath.] Some genera are not mucilaginous, _e.g. Cylindrospermum_ (Fig. 19). The cell-chains in others, _e.g. Nostoc_, wind in between one another and are embedded in large structureless jelly-like masses, which may attain the size of a plum or even larger (Fig. 22); sometimes they are found floating in the water, sometimes attached to other bodies. Other genera as follows: _Aphanizomenon_ and _Anabæna_ (in lakes and smaller pieces of water); _Nodularia_ is partly pelagic. Some occur in the intercellular spaces of higher plants, thus _Nostoc_-forms are found in _Anthoceros_, _Blasia_, _Sphagnum_, _Lemna_, and in the roots of _Cycas_ and _Gunnera_; _Anabæna_ in _Azolla_. Order 5. =Rivulariaceæ.= The individuals are multicellular filaments, with differentiation into apex and base; spurious branching, and a heterocyst at the base of each filament, reproduction by synakinetes and resting akinetes, rarely by simple reproductive akinetes. _Rivularia_, _Glœotrichia_, _Isactis_, _Calothrix_. Order 6. =Scytonemaceæ.= The individuals are formed of multicellular filaments with no longitudinal division; differentiation into apex and base very slight or altogether absent; branching spurious; heterocysts present. Reproduction by synakinetes, rarely by resting akinetes and ordinary reproductive akinetes. _Tolypothrix_, _Scytonema_, _Hassalia_, _Microchæte_. Order 7. =Sirosiphoniaceæ.= The individuals are formed of multicellular threads with longitudinal divisions; true branching and heterocysts, and often distinct differentiation into apex and base. Reproduction by synakinetes, rarely by resting akinetes and ordinary reproductive akinetes. _Hapalosiphon_, _Stigonema_, _Capsosira_, _Nostocopsis_, _Mastigocoleus_. Family 2. =Bacteria.=[6] The Bacteria (also known as Schizomycetes, and Fission-Fungi) are the smallest known organisms, and form a parallel group to the Blue-green Algæ, but separated from these Algæ by the absence of their colouring material; chlorophyll is only found in a few Bacteria. The various forms under which the vegetative condition of the Bacteria appear, are termed as follows: 1. GLOBULAR FORMS, COCCI (Figs. 27, 30 _c_): spherical or ellipsoidal, single cells, which, however, are usually loosely massed together and generally termed “_Micrococci_.” 2. ROD-LIKE FORMS: more or less elongated bodies; the shorter forms have been styled “_Bacterium_” (in the narrower sense of the word), and the term “_Bacillus_” has been applied to longer forms which are straight and cylindrical (Figs. 28, 29, 30 _E_). [Illustration: FIG. 23.--_Spirillum sanguineum._ Four specimens. One has two cilia at the same end, the sulphur grains are seen internally.] 3. THREAD-LIKE FORMS: unbranched, long, round filaments, resembling those of _Oscillaria_, are possessed by _Leptothrix_ (very thin, non-granular filaments; Fig. 30 _A_, the small filaments) and _Beggiatoa_ (thicker filaments, with strong, refractile grains or drops of sulphur (Fig. 31); often self-motile). Branched filaments, with false branching like many _Scytonemaceæ_, are found in _Cladothrix_ (Fig. 30 _B_, _G_). 4. SPIRAL FORMS: Rod-like or filamentous bodies, which more or less strongly resemble a corkscrew with a spiral rising to the left. In general these are termed _Spirilla_ (Fig. 23); very attenuated spirals, _Vibriones_ (standing next to Fig. 30 _M_); if the filaments are slender and flexible with a closely wound spiral, _Spirochætæ_ (Fig. 24). 5. The MERISMOPEDIUM-FORM, consisting of rounded cells arranged in one plane, generally in groups of four, and produced by divisions perpendicular to each other. 6. The SARCINA-FORM, consisting of roundish cells which are produced by cellular division in all the three directions of space, united into globular or ovoid masses (“parcels”) _e.g. Sarcina ventriculi_ (Figs. 25, 26). [Illustration: FIG. 24.--_Spirochæte obermeieri_, in active motion (_b_) and shortly before the termination of the fever (_c_); a blood corpuscles.] All Bacteria are unicellular. In the case of the micrococci this is self-evident, but in the “rod,” “thread,” and “spiral” Bacteria, very often numerous cells remain united together and their individual elements can only be recognised by the use of special reagents. [Illustration: FIG. 25.--_Sarcina ventriculi._ One surface only is generally seen. Those cells which are drawn with double contour are seen with the correct focus, and more distinctly than those cells lying deeper drawn with single contour.] [Illustration: FIG. 26.--_Sarcina minuta_: _a-d_ successive stages of one individual (from 4–10 p.m.); _f_ an individual of 32 cells.] The condition termed “Zooglœa,” which reminds us of _Nostoc_, is produced by the cells becoming strongly mucilaginous. A number of individuals in active division are found embedded in a mass of mucilage, which either contains only one, or sometimes more, of the above-named forms. The individuals may eventually swarm out and continue their development in an isolated condition. Such mucilaginous masses occur especially upon moist vegetables (potatoes, etc.), on the surface of fluids with decaying raw or cooked materials, etc. The mucilaginous envelope is thrown into folds when the Bacteria, with their mucilaginous cell-walls, multiply so rapidly that there is no more room on the surface of the fluid. The cells of the Bacteria are constructed like other plant-cells in so far as their diminutive size has allowed us to observe them. The cell-wall only exceptionally shows the reactions of cellulose (in _Sarcina_, _Leuconostoc_; also in a Vinegar-bacterium, _Bacterium xylinum_); a mucilaginous external layer is always present. The body of the cell mostly appears to be an uniform or finely granulated protoplasm. Very few species (_e.g. Bacillus virens_) contain chlorophyll; others are coloured red (purple sulphur Bacteria); the majority are colourless. _Bacillus amylobacter_ shows a reaction of a starch-like material when treated with iodine before the spore-formation. Some Bacteria contain sulphur (see p. 37). The body, which has been described as a _cell-nucleus_, is still of a doubtful nature. Artificial colourings with aniline dyes (especially methyl-violet, gentian-violet, methylene-blue, fuchsin, Bismarck-brown and Vesuvin) play an important part in the investigations of Bacteria. MOVEMENT. Many Bacteria are self-motile; the long filaments of _Beggiatoa_ exhibit movements resembling those of _Oscillaria_. In many motile forms the presence of cilia or flagella has been proved by the use of stains; many forms have one, others several cilia attached at one or both ends (Fig. 23) or distributed irregularly over the whole body; the cilia are apparently elongations of the mucilaginous covering and not, as in the other Algæ of the protoplasm. In _Spirochæte_ the movement is produced by the flexibility of the cell itself. Generally speaking, the motion resembles that of swarm-cells (_i.e._ rotation round the long axis and movement in irregular paths); but either end has an equal power of proceeding forwards. The swarming motion must not be confounded with the hopping motion of the very minute particles under the microscope (Brownian movement). VEGETATIVE REPRODUCTION takes place by continued transverse division; hence the name “Fission-Fungi” or “Fission-Algæ,” has been applied to the Bacteria. SPORES. The spores are probably developed in two ways. In the ENDOSPOROUS species (Figs. 28, 29), the spore arises as a new cell inside the mother-cell. The spores are strongly refractile, smaller than the mother-cell, and may be compared to the aplanospores of other Algæ. In addition to these there are the ARTHROSPOROUS species in which the cells, just as in _Nostoc_ and other Blue-green Algæ, assume the properties of spores without previously undergoing an endogenous new construction, and are able to germinate and form new vegetative generations (Fig. 27). The formation of spores very often commences when the vegetative development begins to be restricted. [Illustration: FIG. 27.--_Leuconostoc mesenterioides_: _a_ a zooglœa, natural size; _b_ cross section of zooglœa; _c_ filaments with spores; _d_ mature spores; _e-i_ successive stages of germination; in _e_ portions of the ruptured spore-wall are seen on the external side of the mucilaginous covering. (_b-i_ magnified 520.)] The spores germinate as in _Nostoc_ by the bursting of the external layer of the cell-wall, either by a transverse or longitudinal cleft, but always in the same way, in the same species (Fig. 28, example of transverse cleft). DISTRIBUTION. Bacteria and their germs capable of development, are found everywhere, in the air (dust), in surface water, and in the superficial layers of the soil. The number varies very much in accordance with the nature of the place, season, etc. They enter, together with air and food, into healthy animals and occur always in their alimentary tract. GROWTH AND REPRODUCTION depend upon the conditions of temperature. There is a certain minimum, optimum and maximum for each species; for instance (in degrees Centigrade)-- Minim. Opt. Maxim. _Bacillus subtilis_ + 6 c. 30 + 50 _B. anthracis_ 15 20–25 43 _Spirillum choleræ asiaticæ_ 8 37 40 (but grows only feebly if under 16°). _Bacterium tuberculosis_ 28 37–38 42 [Illustration: FIG. 28.--_Bacillus megaterium_: _a_ outline of a living, vegetative cell-rod; _b_ a living, motile, pair of rods; _p_ a similar 4-celled rod after the effects of iodine alcohol; _c_ a 5-celled rod in the first stages of spore-formation; _d-f_ successive stages of spore-formation in one and the same pair of rods (in the course of an afternoon); _r_ a rod with mature spores; _g^1–g^3_ three stages of a 5-celled rod, with spores sown in nutritive solution; _h^1–h^2_, _i_, _k_, _l_ stages of germination; _m_ a rod in the act of transverse division, grown out from a spore which had been sown eight hours previously. (After de Bary; _a_ mag. 250, the other figures 600 times).] [Illustration: FIG. 29.--_Bacillus amylobacter._ Motile rods, partly cylindrical and without spores, partly swollen into various special shapes and with spore-formation in the swelling. _s_ Mature spore, with thick mucilaginous envelope. (After de Bary; mag. 600 times, with the exception of _s_, which is more highly magnified.)] The functions of life cease on a slight excess of the maximum or minimum temperature, numbness setting in when either of these limits is passed. _Crenothrix_-threads provided with mucilaginous envelopes may, according to Zopf, sustain a temperature of-10°. Some Bacteria are said to be able to resist the exposure to as low a temperature as-110° for a short time. It is not known at what degree of cold the death of the Bacteria occurs: the greatest degree of heat which the vegetative cells can withstand is about the same as that for other vegetative plant-cells, namely, about 50–60° C. Certain Bacteria, _e.g. B. thermophilus_, grow and thrive vigorously at 70° C. Many spores, on the contrary, are able to bear far higher temperatures (in several species a temperature for some duration of above 100°, those of _Bacillus subtilis_, for instance, can withstand for hours a temperature of 100° in nutrient solutions; the spores remain capable of development after exposure to a dry heat of 123° C.). The _Desiccation_ of the air, if prolonged, kills many forms when in the vegetative condition. The spores however can bear a much longer period of dryness, some even several years. OXYGEN. Some species cannot live without a supply of free oxygen (_Aerobic_), _e.g._ the Vinegar-bacteria, the Hay-bacilli, the Anthrax-bacilli, the Cholera-_Microspira_. Other species again thrive vigorously without supply of free oxygen, and are even checked in their development by the admission of air (_Anaerobic_), _e.g._ the butyric acid Bacterium (_Clostridium butyricium_ = _Bacillus amylobacter_). A distinction may be drawn between obligate and facultative aerobics and obligate and facultative anaerobics. Several Bacteria, producing fermentation, may grow without the aid of oxygen when they are living in a solution in which they can produce fermentation; but, if this is not the case, they can only grow when a supply of oxygen is available. A great number of the pathogenic Bacteria belong to the facultative anaerobics. A luminous Bacterium (_Bacillus phosphorescens_) which in the presence of a supply of oxygen gives a bluish-white light, has been found in sea-water. Phosphorescent Bacteria have frequently been observed upon decaying sea-fish, as well as on the flesh of other animals; by transferring the Bacteria from cod fish to beef, etc., the latter may be made luminous. _Organic carbon compounds_ are indispensable for all Bacteria, (except, as it appears, for the nitrifying organisms), as they can only obtain the necessary supplies of _carbon_ from this source. The supplies of _nitrogen_, which also they cannot do without, can be obtained equally as well from organic compounds as from inorganic salts, such as saltpetre or ammonia-compounds. The various “ash-constituents” are also essential for their nourishment. While Moulds and Yeast-Fungi grow best in an acid substratum, the _Bacteria_, on the other hand, generally thrive _best_ in a _neutral_ or slightly _alkaline_ one. In _sterilization_, _disinfection_, and _antisepsis_, means are employed by which the Bacteria are killed, or checked in their development, for instance, by heat (ignition, cooking, hot vapours, hot air, etc.), or poisons (acids, corrosive sublimate). The process of preserving articles of food, in which they are boiled and then hermetically sealed, aims at destroying the Bacteria, or the spores of those which already may be present in them, and excluding all others. As the Bacteria are unable to assimilate carbon from the carbonic acid of the air, but must obtain it from the carbon-compounds already in existence in the organic world, they are either _saprophytes_ or _parasites_. Some are exclusively either the one or the other, _obligate_ saprophytes or parasites. But there are transitional forms among them, some of which are at ordinary times saprophytes, but may, when occasion offers, complete their development wholly or partly as parasites--_facultative parasites_; others are generally parasitic, but may also pass certain stages of development as saprophytes--_facultative saprophytes_. All chlorophyll-free organisms act in a transforming and disturbing manner on the organic compounds from which they obtain their nourishment, and while they themselves grow and multiply, they produce, each after its kind, compounds of a less degree of complexity, _i.e._ they produce _fermentation_, _putrefaction_, sometimes the formation of _poisons_, and in living beings often _disease_. Those organisms which produce fermentation are called _ferments_; this word, however, is also employed for similar transformations in purely chemical materials (inorganic ferments or enzymes). Many organic (“living”) ferments, among which are Yeast-cells and Bacteria, give off during their development certain inorganic and soluble ferments (enzymes) which may produce other transformations without themselves being changed. Different organisms may produce in the same substratum different kinds of transformation; alcoholic fermentation may for instance be produced by different species of Fungi, but in different proportions, and the same species produces in different substrata, different transformations (_e.g._ the Vinegar-bacteria oxydize diluted alcohol to vinegar, and eventually to carbonic acid and water). In the study of Bacteria it is absolutely necessary to sterilize the vessels employed in cultivation, the apparatus, and nutrient solutions, _i.e._ to free them from Bacteria germs and also to preserve the cultures from the intrusion of any foreign germs (“pure-cultures”). A firm, transparent, nutritive medium is frequently employed. This may be prepared by adding to the nutrient solutions (broth) either gelatine, or--when the Bacteria are to be cultivated at blood-heat--serum of sheep’s or calf’s blood, agar-agar or carragen; serum alone may in itself serve as a nutrient medium. The so-called “plate-cultures” are frequently employed, _i.e._ the germs are isolated by shaking them with the melted liquid nutrient gelatine, which is then spread on a glass plate and allowed to coagulate; when later on the individual germs grow into colonies, these remain separate in the solid substratum and it is easy to pursue their further development. Similar plate-cultures may also be cultivated in test-tubes and on microscopic slides. The slides and glass plates must be placed in “moist chambers” free from Bacteria. By sowing a few cells (if possible one) using a fine platinum wire, pure cultures for further investigation may be obtained. In order to prove the relationship between pathogenic Bacteria and certain diseases, the experimental production of pathogenic Bacteria by the inoculation of Bacteria from pure cultures into healthy animals, is very important. It has not so far been possible to establish a _classification_ of the Bacteria, as the life-history of many species, has not yet been sufficiently investigated.[7] The opinions of botanists are at variance, in many cases, about the forms of growth of a particular kind. Some species are pleomorphic (many-formed) while others possess only one form. The following Bacteria are =Saprophytes=:-- _Cladothrix dichotoma_ is common in stagnant and running water which is impregnated with organic matter; the cell-chains have false branching. According to Zopf, _Leptothrix ochracea_ is one of the forms of this species which, in water containing ferrous iron (_e.g._ as FeCO_{3}), regularly embeds ferric-oxide in its sheath by means of the activity of the protoplasm. _Leptothrix ochracea_ and other Iron-bacteria, according to Winogradsky (1888), do not continue their growth in water free from protoxide of iron; while they multiply enormously in water which contains this salt of iron. The large masses of ochre-coloured slime, found in meadows, bogs, and lakes, are probably due to the activity of the Iron-bacteria. [Illustration: FIG. 30.--_Cladothrix dichotoma._] Those forms which, according to Zopf’s views, represent the forms of development of _Cladothrix dichotoma_ are placed together in Fig. 30. A represents a group of plants, seventy times magnified, attached to a Vaucheria. The largest one is branched like a tree, with branches of ordinary form; a specimen with spirally twisted branches is seen to the right of the figure, at the lower part some small _Leptothrix_-like forms. _B_ shows the manner of branching and an incipient _Coccus_-formation. _C_ a _Coccus_-mass whose exit from the sheath has been observed. _D_ the same mass as _C_ after the course of a day, the Cocci having turned into _rods_. _E_ a group of Cocci in which some have developed into shorter or longer rods. _F_ one of these rods before and after treatment with picric acid, which causes the chain-like structure to become apparent. _G_ a portion of a plant with conspicuous sheath, two lateral branches are being formed. _H_ part of a plant, whose cells have divided and form Cocci. The original form of the cells in which the Cocci are embedded may still be recognised. I. _Leptothrix_-filaments with conspicuous mucilaginous sheath, from which a series of rods is about to emerge; the rod near the bottom is dead, and has remained lying in the sheath. _K_ part of a plant which is forming Cocci, those at the top are in the zooglœa-stage, at the base they are elongating to form rods and _Leptothrix_-filaments. _L_ a portion of a branched _Cladothrix_, which divides into motile _Bacillus_-forms; the rays at the free ends indicate the currents which the cilia produce in the water. _M_ a spirally-twisted, swarming filament, before and after division into halves. _N_ part of a tree-like zooglœa with Cocci and short rods.--All of these spirilla, zooglœa, etc., which Zopf has connected with _Clad. dichotoma_, are according to Winogradsky, independent organisms. _Micrococcus ureæ_ produces _urinal fermentation_ (transformation of urinal matter into ammonium carbonate); aerobic; round cells generally united to form bent chains or a zooglœa.--Several other kinds of Bacteria have the same action as this one: in damp soil containing ammonia-compounds, _saltpetre-formations_ are produced by _M. nitrificans_ and several different kinds of Bacteria. _Micrococcus prodigiosus_ is found on articles of food containing starch; “bleeding bread” is caused by this Bacterium, which has the power of forming a red pigment; it also occurs in milk, and produces lactic acid. _Leuconostoc mesenterioides_ is the frog-spawn Bacterium (Fig. 27) which is found in sugar manufactories, and has the power of producing a viscous fermentation in saccharine solutions which have been derived from plants, _e.g._ in beetroot-sugar manufactories, where large accumulations of mucilage are formed at the expense of the sugar, with an evolution of carbonic acid. The cell-rows, resembling somewhat a pearl necklace, have thick mucilaginous cell-walls, and form white “Nostoc”-lumps. The mucilage eventually deliquesces and the cells separate from each other; arthrospores?--Similar viscous deteriorations occur in beer and wine, which may then be drawn out into long, string like filaments--“ropiness.” _Bacterium aceti_, the Vinegar-bacterium, oxidizes alcohol into acetic acid (acetous-fermentation) and forms a greyish covering of Bacteria (“Vinegar-mother”) on the surface of the liquid; the acetic acid formed, becomes by continued oxidization by _B. aceti_, again transformed into carbonic acid and water. Aerobic; short cylindrical cells, often united into chains, or to form a zooglœa; sometimes also rod-and spindle-shaped. The Vinegar-bacteria and other kinds with ball- or rod-forms sometimes become swollen, spindle-shaped, or oval links; they are supposed to be diseased forms[8] (“Involution-forms”). _Bacillus lacticus_ (_Bacterium acidi lactici_, Zopf) is always found in milk which has stood for some time, and in sour foods (cabbage, cucumbers, etc.); it turns the milk sour by producing lactic acid fermentation in the sugar contained in the milk; the lactic acid formed, eventually causes the coagulation of the casein. It resembles the Vinegar-bacteria, occurring as small cylindrical cells, rarely in short rows; not self-motile.--Several other Bacteria appear to act in the same way, some occurring in the mouth of human beings; some of these Bacteria give to butter its taste and flavour. The _kefir-grains_ which are added to milk for the preparation of kefir, contain in large numbers a Bacterium (_Dispora caucasica_) in the zooglœa-form, a Yeast-fungus, and _Bacillus lacticus_. Kefir is a somewhat alcoholic sour milk, rich in carbonic acid; it is a beverage manufactured by the inhabitants of the Caucasus, from the milk of cows, goats, or sheep, and is sometimes used as a medicine. In the production of kefir, lactic acid fermentation takes place in one part of the sugar contained in the milk, and alcoholic fermentation in another part, and the casein which had become curdled is partially liquefied (peptonised) by an enzyme of a Zooglœa-bacterium. _Bacillus amylobacter_ (_Bacillus butyricus_), the Butyric-acid-bacterium (Fig. 29), is a very common anaerobic which produces fermentation in sugar and lactic-acid salts, and whose principal product is _butyric acid_. It destroys articles of food and (together with other species) plays a part in the butyric acid fermentation which is necessary in the making of cheese; it is very active wherever portions of plants are decaying, in destroying the cellulose in the cell-walls of herbaceous plants, and is thus useful in the preparation of flax and hemp. The cells are self-motile, generally cylindrical, sometimes united into short rows; endosporous; the spore-forming cells swell, assume very different forms, and show granulose reaction. The germ-tube grows out in the direction of the long axis of the spore. _Bacillus subtilis_, the Hay-bacillus, is developed in all decoctions of hay; a slender, aerobic, self-motile Bacillus; endosporous (aplanospores); the spore-wall ruptures transversely on germination. _Crenothrix kuehniana_ occurs in the springs of many baths, in wells, in water or drain-pipes. [Illustration: FIG. 31.--_Beggiatoa alba_: _a_ from a fluid containing abundance of sulphuretted hydrogen; _b_ after lying 24 hours in a solution devoid of sulphuretted hydrogen; _c_ after lying an additional 48 hours in a solution devoid of sulphuretted hydrogen, by this means the transverse walls and vacuoles have become visible.] _Beggiatoa_ (parallel with the Blue-green Alga _Oscillaria_). Long filaments formed of cylindrical cells which are attached by one of the ends, but which are nearly always free when observed. The filaments, like those of _Oscillaria_, describe conical figures in their revolutions, the free filaments slide upwards and parallel with one another; sheaths are wanting; strongly refractive sulphur drops are found in the interior. The Beggiatoas are the most prevalent _Sulphur-bacteria_. They occur, very commonly in large numbers, wherever plant or animal remains are decaying in water in which sulphuretted hydrogen is being formed; thus, for example, _B. alba_ (Fig. 31) occurs frequently as a white covering or slimy film on mud containing organic remains. ~_B. mirabilis_ is remarkable for its size and its strong peristaltic movements.~ The Sulphur-bacteria oxidize the sulphuretted hydrogen, and accumulate sulphur in the shape of small granules of soft amorphic sulphur, which in the living cell never passes over into the crystalline state. They next oxidize this sulphur into sulphuric acid, which is immediately rendered neutral by absorbed salts of calcium, and is given off in the form of a sulphate, thus CaCO_{3} is principally changed into CaSO_{4}. In the absence of sulphur the nutritive processes are suspended, and consequently death occurs either sooner or later. The Sulphur-bacteria may exist and multiply in a fluid which only contains traces of organic matter, in which organisms devoid of chlorophyll are not able to exist. The Beggiatoas very frequently form white, bulky masses in sulphur wells and in salt water, the traces of organic material which the sulphur water contains proving sufficient for them. ~The cellulose-fermentation, to which the sulphur wells in all probability owe their origin, mainly procures them suitable conditions for existence. The CaCO_{3} and H_{2}S, formed during the cellulose fermentation by the reduction of CaSO_{4} is again changed into CaSO_{4} and CO_{2} by the Sulphur-bacteria (Winogradsky, 1887).--Other Sulphur-bacteria, the so-called purple Sulphur-bacteria, _e.g._ _B. roseo-persicina_, _Spirillum sanguineum_ (Fig. 23), _Bacterium sulfuratum_, etc., have their protoplasm mixed with a red colouring matter (bacterio-purpurin) which, like chlorophyll, has the power, in the presence of light, of giving off oxygen (as proved by T. W. Englemann, 1888, in oxygen-sensitive Bacteria). The three purple Sulphur-bacteria mentioned, are, according to Winogradsky, not pleomorphic kinds but embrace numerous species.~ Many _Spirilli_ (_Spirillum tenue_, _S. undula_, _S. plicatile_, and others) are found prevalent in decaying liquids. Bacteria (especially Bacilli) are the cause of many substances emitting a foul odour, and of various changes in milk. =Parasitic Bacteria= live in other living organisms; but the relation between “host” and parasite may vary in considerable degree. Some parasites do no injury to their host, others produce dangerous contagious diseases; some choose only a special kind as host, others again live equally well in many different ones. There are further specific and individual differences with regard to the _predisposition_ of the host, and every individual has not the same receptivity at all times. THE HARMLESS PARASITES OF HUMAN BEINGS. Several of the above mentioned saprophytes may also occur in the alimentary canal of human beings; _e.g._, the Hay-bacillus, the Butyric-acid-bacillus, etc.; but the gastric juice prevents the development of others, at all events in their vegetative condition. _Sarcina ventriculi_, “packet-bacterium,” is only known to occur in the stomach and intestines of human beings, and makes its appearance in certain diseases of the stomach (dilation of the stomach, etc.) in great numbers, without, however, being the cause of the disease. It occurs in somewhat cubical masses of roundish cells (Fig. 25). LESS DANGEROUS PARASITES. In the mouth, especially between and on the teeth, a great many Bacteria are to be found (more than fifty species are known), _e.g. Leptothrix buccalis_ (long, brittle, very thin filaments which are united into bundles), Micrococci in large lumps, _Spirochæte cohnii_, etc. Some of them are known to be injurious, as they contribute in various ways to the decay of the teeth (_caries dentium_); a _Micrococcus_, for instance, forms lactic acid in materials containing sugar and starch, and the acid dissolves the lime salts in the external layers of the teeth: those parts of the teeth thus deprived of lime are attacked by other Bacteria, and become dissolved. Inflammation in the tissues at the root of a tooth, is probably produced by septic materials which have been formed by Bacteria in the root-canal. DANGEROUS PARASITES. In a large number of the infectious diseases of human beings and animals, it has been possible to prove that parasitic Bacteria have been the cause of the disease. Various pathogenic Bacteria of this nature, belonging to the coccus, rod, and spiral Bacteria groups, are mentioned in the following:-- =Pathogenic Micrococci.= _Staphylococcus pyogenes aureus_ produces abscesses of various natures (boils, suppurative processes in internal organs). The same effects are produced by-- _Streptococcus pyogenes_, which is the most frequent cause of malignant puerperal fever; it is perhaps identical with-- _Streptococcus erysipelatis_, which is the cause of erysipelas in human beings. _Diplococcus pneumoniæ_ (A. Fränkel) is the cause of pneumonia, and of the epidemic cerebro-spinal meningitis. _Gonococcus_ (Neisser) is the cause of gonorrhea and inflammation of the eyes. =Pathogenic Rod-Bacteria.= _Bacterium choleræ gallinarum_, an aerobic, facultative parasite which produces fowl-cholera among poultry; it is easily cultivated on various substrata as a saprophyte. The disease may be conveyed both through wounds and by food, and may also be communicated to mammals. _Bacillus anthracis_, the _Anthrax bacillus_ (Fig. 32), chiefly attacks mammals, especially herbivorous animals (house mice, guinea-pigs, rabbits, sheep, cattle), in a less degree omnivorous animals (including human beings), and in a still less degree the Carnivores. Aerobic. Cylindrical cells, 3–4 times as long as broad, united into long rod-like bodies, which may elongate into long, bent, and twisted filaments. Not self-motile. Endosporous. Germination takes place without the throwing off of any spore-membrane (compare Hay-bacillus p. 37 which resembles it). Contagion may take place both by introduction into wounds, and from the mucous membrane of the intestines or lungs, both by vegetative cells and by spores; in intestinal anthrax, however, only by spores. The Bacillus multiplies as soon as it has entered the blood, and the anthrax disease commences. The Bacilli not only give off poison, but also deprive the blood of its oxygen. Vegetative cells only occur in living animals. This species is a _facultative parasite_ which in the first stage is a saprophyte, and only in this condition forms spores. [Illustration: FIG. 32.--_Anthrax bacillus_ (_Bacillus anthracis_) with red (_b_) and white (_a_) blood-corpuscles.] [Illustration: FIG. 33.--_Anthrax bacillus._ The formation of the spores; magnified 450 times.] _Bacillus tuberculosis_ produces tuberculosis in human beings, also in domestic animals (_perlsucht_). It is a distinct parasite, but may also live saprophytically. It is rod-formed, often slightly bent, and is recognised principally by its action with stains (when stained with an alkaline solution of methyl-blue or carbolic fuchsin, it retains the colour for a long time even in solutions of mineral acids, in contrast with the majority of well-known Bacteria): it probably forms spores which are able to resist heat, dryness, etc. _Bacillus lepræ_ produces leprosy; _Bacillus mallei_ produces glanders; _Bacillus tetani_, tetanus (the tetanus bacillus is very common in soil; anaerobic); _Bacillus diphtheriæ_, diphtheria; _Bacillus typhosus_, typhoid fever, etc. =Pathogenic Spiral Bacteria.= _Spirochæte obermeieri_ (Fig. 24) produces intermittent fever (febris recurrens); it makes its appearance in the blood during the attacks of fever, but it is not to be found during intervals when there is no fever. Obligate parasite. _Spirillum choleræ asiaticæ_ (_Microspira comma_) without doubt produces Asiatic cholera; an exceedingly motile spirillum, which is also found in short, bent rods (known as the “Comma-bacillus”), it lives in the intestines of those attacked by the disease, and gives off a strong poison which enters the body. It is easily cultivated as a saprophyte. A great many circumstances seem to show that a number of other infectious diseases (syphilis, small-pox, scarlet-fever, measles, yellow-fever, etc.) owe their origin to parasitic Bacteria, but this has not been proved with certainty in all cases. It has been possible by means of special cultivations (ample supply of oxygen, high temperature, antiseptic materials) to produce from the parasitic Bacteria described above (_e.g._ the fowl-cholera and the anthrax Bacteria) _physiological varieties_ which are distinct from those appearing in nature and possess a less degree of “virulence,” _i.e._ produce fever and less dangerous symptoms in those animals which are inoculated with them. The production of such physiological varieties has come to be of great practical importance from the fact that they are used as vaccines, _i.e._ these harmless species produce in the animals inoculated with them _immunity_ from the malignant infectious Bacteria from which they were derived. This immunity is effected by the change of the products of one or more of the Bacteria, but we do not yet know anything about the way in which they act on the animal organism. The white blood corpuscles, according to the Metschnikoff, play the part of “Phagocytes” by absorbing and destroying the less virulent Bacteria which have entered the blood, and by so doing they are gradually enabled to overcome those of a more virulent nature. [Illustration: FIG. 34.--_a_ and _b_ The same blood-cell of a Frog: _a_ in the act of engulfing an anthrax-bacillus; _b_ after an interval of a few minutes when the bacillus has been absorbed.] Class 5. =Conjugatæ.= The Algæ belonging to this class have chlorophyll, and pyrenoids round which starch is formed. The cells divide only in one direction, they live solitarily, or united to form filaments which generally float freely (seldom attached). Swarm-cells are wanting. _The fertilisation is isogamous (conjugation) and takes place by means of aplanogametes._ The zygote, after a period of rest, produces, immediately on germination, one or more new vegetative individuals; sometimes akinetes or aplanospores are formed in addition. They only occur in fresh or slightly brackish water. Order 1. =Desmidiaceæ.= The cells generally present markings on the outer wall, and are mostly divided into two symmetrical halves by a constriction in the middle, or there is at least a symmetrical division of the protoplasmic cell-contents. The cell-wall consists nearly always of two layers, the one overlapping the other (Fig. 35 _C_). The cells either live solitarily or are united into unbranched filaments. The mass of protoplasm formed by the fusion of the two conjugating cells becomes the zygote, which on germination produces one (or after division 2, 4 or 8) new vegetative individual. The chromatophores are either star-, plate-, or band-shaped, and regularly arranged round the long axis of the cell. [Illustration: FIG. 35.--A Cell of _Gymnozyga brebissonii_, external view showing the distribution of the pores. _B A_ portion of the membrane of _Staurastrum bicorne_ with pores containing protoplasmic projections. _C_ Cell-wall of _Hyalotheca mucosa_ during cell-division: the central part, being already formed, shows the connection with the divisional wall.] The Desmidiaceæ are not able to swim independently, many species, however, show movements of different kinds by rising and sliding forward on the substratum. These movements, which are partly dependent upon, and partly independent of light and the force of gravitation, are connected with the protrusion of a mucilaginous stalk. The mucilage, which sometimes surrounds the whole individual, may acquire a prismatic structure, it is secreted by the protoplasmic threads which project through certain pores definitely situated in the walls (Fig. 35 _A_, _B_). VEGETATIVE MULTIPLICATION takes places by division. A good example of this is found in _Cosmarium botrytis_ (Fig. 36 _A-D_). The nucleus and chromatophores divide, and simultaneously the central indentation becomes deeper, the outer wall is then ruptured making a circular aperture through which the inner wall protrudes forming a short, cylindrical canal between the two halves to which it is attached (Fig. 36 _C_). After elongation the canal is divided by a central transverse wall, which commences as a ring round its inner surface and gradually forms a complete septum. The dividing wall gradually splits, and the two individuals separate from each other, each one having an old and a new half. The two daughter-cells bulge out, receive a supply of contents from the parent-cells, and gradually attain their mature size and development (Fig. 36 _B-D_). Exceptions to this occur in some forms. [Illustration: FIG. 36.--_Cosmarium botrytis. A-D_ Different stages of cell-division.] [Illustration: FIG. 37.--_Cosmarium meneghinii_: _a-c_ same individual seen from the side, from the end, and from the edge; _d-f_ stages of conjugation; _g-i_ germination of the zygote.] CONJUGATION takes place in the simplest way in _Mesotænium_, where the two conjugating cells unite by a short tube (conjugation-canal), which is not developed at any particular point. The aplanogametes merge together after the dissolution of the dividing wall, like two drops of water, almost without any trace of preceding contraction, so that the cell-wall of the zygote generally lies in close contact with the conjugating cells. The conjugating cells in the others lie either transversely (_e.g. Cosmarium_, Fig. 37 _d_; _Staurastrum_, etc.), or parallel to one another (_e.g. Penium_, _Closterium_, etc.), and emit a short conjugation-canal (Fig. 37 _d_) from the centre of that side of each cell which is turned towards the other one. These canals touch, become spherical, and on the absorption of the dividing wall the aplanogametes coalesce in the swollen conjugation-canal (Fig. 37 _e_), which is often surrounded by a mucilaginous envelope. The zygote, which is often spherical, is surrounded by a thick cell-wall, consisting of three layers; the outermost of these sometimes bears thorn-like projections, which in some species are simple (Fig. 37 _f_), in others branched or variously marked; in some, however, it remains always smooth (_e.g._ _Tetmemorus_, _Desmidium_). Deviation from this mode of conjugation may occur within certain genera (_e.g._ _Closterium_, _Penium_). Upon germination the contents of the zygote emerge, surrounded by the innermost layers of the wall (Fig. 37 _g_, _h_) and generally divide into two parts which develop into two new individuals, placed transversely to each other (Fig. 37 _i_); these may have a somewhat more simple marking than is generally possessed by the species. [Illustration: FIG. 38.--Desmidiaceæ. _A Closterium moniliferum_; _B Penium crassiusculum_; _C Micrasterias truncata_ (front and end view); _D Euastrum elegans_; _E_ _Staurastrum muticum_ (end view).] The most frequent genera are:-- _A._ Solitary cells: MESOTÆNIUM, PENIUM (Fig. 38 _B_), CYLINDROCYSTIS, EUASTRUM (Fig. 38 _D_), MICRASTERIAS (Fig. 38 _C_), COSMARIUM (Fig. 36, 37), XANTHIDIUM, STAURASTRUM (Fig. 38 _E_), PLEUROTÆNIUM, DOCIDIUM, TETMEMORUS, CLOSTERIUM (Fig. 38 _A_), SPIROTÆNIA. _B._ Cells united into filaments: SPHÆROZOSMA, DESMIDIUM, HYALOTHECA, GYMNOZYGA, ANCYLONEMA, GONATOZYGON. Order 2. =Zygnemaceæ.= Cell-wall without markings. The cells are cylindrical, not constricted in the centre, and (generally) united into simple, unbranched filaments. The whole contents of the conjugating cells take part in the formation of the zygote, which on germination grows out directly into a new filament. _Spirogyra_ is easily recognised by its spiral chlorophyll band; _Zygnema_ has two star-like chromatophores in each cell (Fig. 40); both these genera are very common Algæ in ponds and ditches. [Illustration: FIG. 39.--_Spirogyra longata. A_ At the commencement of conjugation, the conjugation-canals begin to protrude at _a_ and touch one another at _b_; the spiral chlorophyll band and cell-nuclei (_k_) are shown. _B_ A more advanced stage of conjugation; _a_, _a’_ the rounded female and male aplanogametes: in _b’_ the male aplanogamete is going over to and uniting with the female aplanogamete (_b_).] [Illustration: FIG. 40.--A cell of _Zygnema_. _S_ Pyrenoid.] [Illustration: FIG. 41.--_Zygnema insigne_, with zygote.] [Illustration: FIG. 42.--Germinating zygote of _Spirogyra jugalis_: the young plant is still unicellular; the end which is still in the wall of the zygote is elongated and root-like; the chromatophore divides and forms the spiral band.] The conjugation among the Zygnemaceæ takes place in the following manner: the cells of two filaments, lying side by side, or two cells, the one being situated above the other in the same filament (Fig. 41), push out small protuberances opposite each other (Fig. 39 _A_, _a_, _b_); these finally meet, and the dividing wall is absorbed so that a tube is formed connecting one cell with the other; the protoplasmic contents round off, and the whole of these contents of one of the cells glides through the conjugation-tube and coalesces with that of the other (Fig. 39 _B_), the aggregate mass then rounds off, surrounds itself with a cell-wall, and becomes a zygote. A distinct difference may be found between the cells in the two filaments, those in the one whose protoplasmic contents pass over being cylindrical, while those of the recipient one are more barrel-shaped, and of a larger diameter. The former may be regarded as a male, the latter as a female plant. The zygote germinates after a period of rest, and grows out into a new filament (Fig. 42). Order 3. =Mesocarpaceæ.= The cell-walls are glabrous, unconstricted in the centre, and united into simple unbranched filaments. The chromatophore consists of an axial chlorophyll-plate, with several pyrenoids. The zygote is formed by the coalescence of two cells (Fig. 43) (sometimes three or four), but the whole protoplasmic contents of the cells do not take part in this process, a portion always remaining behind; the aplanogametes coalesce in the conjugation-canal. The zygote thus formed appears incapable of germination until after 3–5 divisions. Of the cells so formed, only one is fertile, the sterile cells, according to Pringsheim, constituting a rudimentary sporocarp. The germinating cells grow out into a new filament. In this order, conjugation has been observed between two cells of the same filament. The Mesocarpaceæ thrive best in water which contains lime. [Illustration: FIG. 43.--Mougeotia calcarea. Cells showing various modes of conjugation: at _m_ tripartition; _pg_ quadripartition; _s_ quinquipartilion of the zygote.] Class 6. =Chlorophyceæ (Green Algæ).= These Algæ are coloured green by chlorophyll, seldom in combination with other colouring matter, and then especially with red. The product of assimilation is frequently starch, which generally accumulates round certain specially formed portions of protoplasm termed pyrenoids. The thallus is uni- or multicellular; in the higher forms (certain Siphoneæ) the organs of vegetation attain differentiation into stem and leaf. The asexual reproduction takes place in various ways; the sexual reproduction is effected by conjugation of motile gametes, or by oogamous fertilisation. The swarm-cells (zoospores, gametes, and spermatozoids) are constructed symetrically, and have true protoplasmic cilia, these generally being attached to the front end of the swarm-cells. Most of these Algæ live in water (fresh or salt); some are found upon damp soil, stones, or tree-stems, and some live enclosed in other plants. The Class is divided into three families:-- 1. PROTOCOCCOIDEÆ: Volvocaceæ, Tetrasporaceæ, Chlorosphæraceæ, Pleurococcaceæ, Protococcaceæ, Hydrodictyaceæ. 2. CONFERVOIDEÆ: Ulvaceæ, Ulothricaceæ, Chætophoraceæ, Mycoideaceæ, Cylindrocapsaceæ, Œdogoniaceæ, Coleochætaceæ, Cladophoraceæ, Gomontiaceæ, Sphæropleaceæ. 3. SIPHONEÆ: Botrydiaceæ, Bryopsidaceæ, Derbesiaceæ, Vaucheriaceæ, Phyllosiphonaceæ, Caulerpaceæ, Codiaceæ, Valoniaceæ, Dasycladaceæ. Family 1. =Protococcoideæ.= The Algæ which belong to this group are uni- or multicellular with the cells more or less firmly connected, sometimes in a definite, sometimes in an indefinite form (Fig. 47). Colonies are formed either by division or by small unicellular individuals becoming united in a definite manner; the colonies formed in this latter way are termed _Cœnobia_. Apical cells and branching are absent. Multiplication by division; asexual reproduction by zoospores, rarely by akinetes. Sexual reproduction may be wanting, or it takes place by isogamous, rarely by oogamous fertilisation. Some are attached by means of a stalk to other objects (_Characium_, Fig. 49), others occur as “Endophytes” in the tissues of certain Mosses or Phanerogams, _e.g. Chlorochytrium lemnæ_, in _Lemna trisulca_; _Endosphæra_, in the leaves of _Potamogeton_, _Mentha aquatica_, and _Peplis portula_; _Phyllobium_, in the leaves of _Lysimachia nummularia_, _Ajuga_, _Chlora_, and species of Grasses; _Scotinosphæra_ in the leaves of _Hypnum_ and _Lemna trisulca_; the majority, however, live free in water and in damp places. Many species which were formerly considered to belong to this family have been proved to be higher Algæ in stages of development. Order 1. =Volvocaceæ.= The individuals in this order are either uni- or multicellular, and during the essential part of their life are free-swimming organisms. They are generally encased in a mucilaginous envelope, through which 2–6 cilia project from every cell. The vegetative reproduction takes place by the division of all, or a few, of the cells of the individual; in some a palmella-stage is found in addition. The sexual reproduction takes place by isogamous or oogamous fertilisation. The Volvocaceæ may be considered to include the original forms of the Chlorophyceæ, because, among other reasons, the motile stage is here the most prominent; they also form the connecting link between the animal Flagellata, and forms intermediate to the _Syngeneticæ_ may perhaps be found amongst them. Three series of green Algæ may be supposed to have taken their origin from the Volvocaceæ: CONJUGATEÆ (_Desmidiaceæ_) which have lost the swarming stage, but whose conjugation is the nearest to the fertilisation in _Chlamydomonas pulvisculus_: the PROTOCOCCACEÆ in which the vegetative divisions have disappeared, while the swarming stage continues to be present, though of shorter duration; and TETRASPORACEÆ, in which the vegetative divisions are more prominent, whilst the swarming stage is less so. A. UNICELLULAR INDIVIDUALS. The principle genera are: _Chlamydomonas_, _Sphærella_, _Phacotus_.--_Sphærella nivalis_ is the Alga which produces the phenomenon of “Red Snow,” well known on high mountains and on ice and snow fields in the polar regions. The red colouring matter which appears in this and other green Algæ, especially in the resting cells, is produced by the alteration of the chlorophyll. _Phacotus lenticularis_ has an outer covering incrusted with lime, which, at death, or after division, opens out into two halves. Species may be found among _Chlamydomonas_, in which conjugation takes place between gametes of similar size without cell-wall, but in _C. pulvisculus_ conjugation takes place between male and female aplanogametes which are surrounded by a mucilaginous envelope. [Illustration: FIG. 44--_Gonium pectorale._] [Illustration: FIG. 45.--_Pandorina morum._] B. MULTICELLULAR INDIVIDUALS. The most important genera are _Gonium_, _Stephanosphæra_, _Pandorina_, _Eudorina_, _Volvox_.--_Gonium_ has 4 or 16 cells arranged in a definite pattern in a flat plate (Fig. 44). _Pandorina_ (Fig. 45), has 16 cells arranged in a sphere (Fig. 45 _A_). The vegetative reproduction takes place in this way: each cell, after having rounded off, and after the withdrawal of the cilia, divides itself into 16 new ones (Fig. 45 _B_), each forming a new individual, which soon grows to the size of the mother-individual. It was in this Alga that the conjugation of self-motile gametes was first discovered by Pringsheim, 1869. When conjugation is about to take place, each cell divides into sixteen, as in vegetative reproduction, but the 16 × 16 cells all separate from one another (Fig. 45 _C_, female gametes, and _D_, male gametes), and swarm solitarily in the water. The male are, most frequently, smaller than the female, but otherwise they are exactly alike; they are more or less pear-shaped, with a colourless anterior end, 2 cilia, a red “eye-spot,” etc. After swarming for some time they approach each other, two and two, generally a large and a smaller one, and come into contact at their colourless end; in a few moments they coalesce and become one cell (Fig. 45 _E_, _F_), this has at first a large colourless anterior end, 4 cilia, and 2 “eye-spots” (Fig. 45 _G_), but these soon disappear and the cell becomes uniformly dark-green and spherical, and surrounds itself with a thick cell-wall, losing at the same time its power of motion: the zygote (Fig. 45 _H_) is formed, and becomes later on a deep red colour. On the germination of the zygote, the protoplasmic cell-contents burst open the wall (Fig. 45 _J_), and emerge as a large swarmspore (Fig. 45 _K_) which divides into 16 cells, and the first small individual is formed (Fig. 45 _L_, _M_). _Eudorina_ is like _Pandorina_ in structure, but stands somewhat higher, since the contrast between the conjugating sexual cells is greater, the female one being a motionless oosphere. [Illustration: FIG. 46.--_Volvox globator_, sexual individual: _a_ antheridia which have formed spermatozoids; _b_ oogonia.] The highest stage of development is found in _Volvox_ (Fig. 46). The cells are here arranged on the circumference of a sphere, and enclose a cavity filled with mucilage. The number of these cells may vary from 200–22,000, of which the majority are vegetative and not reproductive, but some become large, motionless oospheres (Fig. 46 _b_); others, which may appear as solitary individuals, divide and form disc-shaped masses of from 8–256 small spermatozoids (Fig. 46 _a_). After the oosphere has been fertilised by these, the oospore surrounds itself by a thick, sometimes thorny cell-wall, and on germination becomes a new individual of few cells. A few cells conspicuous by their larger size may be found (1–9, but generally 8) in certain individuals, and these provide the vegetative reproduction, each forming by division a new individual. Order 2. =Tetrasporaceæ= reproduce both by vegetative divisions and swarmspores, some have also gamete-conjugation. The principal genera are: _Tetraspora_, _Apiocystis_, _Dactylococcus_, _Dictyosphærium_, _Chlorangium_. Order 3. =Chlorosphæraceæ.= _Chlorosphæra._ Order 4. =Pleurococcaceæ.= In this order the swarm-stages and sexual reproduction are entirely absent. Vegetative reproduction by division. The principal genera are: _Pleurococcus_ (Fig. 47), _Scenedesmus_ (Fig. 48), _Raphidium_, _Oocystis_, _Schizochlamys_, _Crucigenia_, _Selenastrum_.--_Pleurococcus vulgaris_ (Fig. 47) is one of the most common Algæ throughout the world, occurring as green coverings on tree-stems, and damp walls, and it is one of the most common lichen-gonidia. [Illustration: FIG. 47.--_Pleurococcus vulgaris._] [Illustration: FIG. 48.--_Scenedesmus quadricauda._] Order 5. =Protococcaceæ.= The cells are motionless, free or affixed on a stalk (_e.g. Characium_, Fig. 49), either separate or loosely bound to one another; they never form multicellular individuals. Multiplication by division is nearly always wanting. Reproduction takes place by swarmspores, which have 1 or 2 cilia, and sexual reproduction in some by gamete-conjugation. The principal genera are: _Chlorococcum_, _Chlorochytrium_, _Chlorocystis_, _Scotinosphæra_, _Endosphæra_, _Phyllobium_, _Characium_, _Ophiocytium_, _Sciadium_. [Illustration: FIG. 49.--_Characium strictum._ _A_ The cell-contents have divided into many swarmspores. _B_ Swarmspores escaping.] Order 6. =Hydrodictyaceæ.= The individuals are unicellular but several unite after the zoospore-stage into definitely formed families (cœnobia). Ordinary vegetative division is wanting, but asexual reproduction takes place by zoospores (or by motionless cells without cilia), which unite and form a family similar to the mother-family, inside the mother-cell, or in a mucilaginous envelope. Where sexual reproduction is found it takes place by gamete-conjugation. The principal genera are: _Pediastrum_ (Fig. 50), _Cœlastrum_, _Hydrodictyon_ (Fig. 51). [Illustration: FIG. 5O.--_Pediastrum asperum._] [Illustration: FIG. 51.--_Hydrodictyou reticulatum. A_ A cell where the zoospores are on the point of arranging themselves to form a net. _B_ A cell with gametes swarming out.] The cœnobium of _Hydrodictyon reticulatum_ (Water-net) is formed of a large number of cells which are cylindrical, and attached to one another by the ends (Fig. 51). The asexual reproduction takes place by zoospores, which are formed in large numbers (7,000–20,000) in each mother-cell, within which they move about for a time, and then come to rest and arrange themselves into a new net (Fig. 51 _A_) which is set free by the dissolution of the wall of the mother-cell, grows, and becomes a new cœnobium. The sexual reproduction takes place by gamete-conjugation. The gametes are formed in the same manner as the zoospores, but in larger numbers (30,000–100,000), and swarm out of the mother-cell (Fig. 51 _B_). The zygote forms, on germination, 2–5 large zoospores, each with one or two cilia, these generally swarm about for a time, and after a period of rest become irregular thorny bodies (polyhedra); their contents again divide into zoospores, the thorny external coating of the polyhedra is cast off, and the zoospores, surrounded by the dilated internal coating, unite to form a small family, which produces several others in the manner described. Family 2. =Confervoideæ.= The individuals are always multicellular, the cells firmly bound together and united into unbranched or branched filaments, expansions, or masses of cells which grow by intercallary divisions or have apical growth. In the first seven orders the cells are uninuclear, but the cells of the remaining three orders contain several nuclei. Asexual reproduction by zoospores, akinetes or aplanospores. Sexual reproduction by isogamous or oogamous fertilisation. The Confervoideæ, through the Ulvaceæ, are connected with the Tetrasporaceæ, and from the _Coleochætaceæ_, which is the most highly developed order, there are the best reasons for supposing that the Mosses have taken their origin. The _Cladophoraceæ_ show the nearest approach to the _Siphoneæ_. Order 1. =Ulvaceæ.= The thallus consists of one or two layers of parenchymatous cells, connected together to form either a flat membrane (_Monostroma_, _Ulva_) or a hollow tube (_Enteromorpha_), and may be either simple, lobed, or branched. Reproduction takes place by detached portions of the thallus; or asexually by zoospores or akinetes. Gamete-conjugation is known to take place in some members of this order, the zygote germinating without any resting-stage. The majority are found in salt or brackish water. [Illustration: FIG. 52.--_Ulothrix zonata_: a portion of a filament with zoospores, which are formed two in each cell (zoosporangium); the dark spots are the red “eye-spots”; 1, 2, 3, 4, denote successive stages in the development of the zoospores; _b_ a single zoospore, _v_ the pulsating vacuole; _c_ portion of a filament with gametes, sixteen are produced in each gametangium; _d_ free gametes, solitary or in the act of conjugation; _e_ the conjugation is completed, and the formed zygote has assumed the resting-stage.] Order 2. =Ulothricaceæ.= The thallus consists normally of a simple unbranched filament (sometimes a small expansion consisting of one layer of cells is formed, as in _Schizomeris_ and _Prasiola_ which were formerly described as separate genera). Asexual reproduction takes place by means of zoospores (with 1, 2, or 4 cilia), akinetes or aplanospores; the last named may germinate immediately, or only after a period of rest. Sexual reproduction takes place by the conjugation of gametes of about the same size, each having two cilia (Fig. 52 _d_). The zygote of _Ulothrix_, on germination, produces a brood of zoospores which swarm for a time and then elongate to become _Ulothrix_-filaments (alternation of generations). The gametes may also germinate without conjugation in the same manner as the zoospores. The principal genera are: _Ulothrix_, _Hormidium_, _Conferva_, _Microspora_.--_Ulothrix zonata_ is very common in running fresh water. Nearly all the species of _Hormidium_ occur on damp soil, tree-stems and stones. Order 3. =Chætophoraceæ.= The thallus consists of a single, branched, erect or creeping filament of cells, often surrounded by mucilage. The cells have only one nucleus. Asexual reproduction by zoospores with 2 or 4 cilia, by akinetes, or aplanospores. In many, conjugation between gametes with 2 cilia may be found. They approach on one side, Ulothricaceæ, and on the other, Mycoideaceæ. The principal genera are: _Stigeoclonium_, _Draparnaldia_, _Chætophora_, _Entoderma_, _Aphanochæte_, _Herposteiron_, _Phæothamnion_, _Chlorotylium_, _Trichophilus_, _Gongrosira_, _Trentepohlia_. Most of the species of _Trentepohlia_ are coloured red by the presence of a red colouring material, which occurs in addition to the chlorophyll. They are aerial Algæ which live on stones (_T. jolithus_, “violet stone,” so named on account of its violet-like odour in rainy weather), on bark and old wood (_T. umbrina_), or on damp rocks (_T. aurea_). _Trichophilus welckeri_ lives in the hair of Bradypus. Order 4. =Mycoideaceæ.= The thallus is discoid, consisting of one or more cell-layers, and is always attached. Asexual reproduction by zoospores with 2 or 4 cilia. Sexual reproduction in some species by the conjugation of gametes with 2 cilia. This order forms the connecting link between _Chætophoraceæ_ and _Coleochætaceæ_. The species occur in fresh water (_Chætopeltis_) as well as in salt (_Pringsheimia_), on the carapace of tortoises (_Dermatophyton_ = _Epiclemmydia_), or endophytic between the cuticle and the epidermal cells of the leaves of tropical plants, destroying the leaf-tissue (_Mycoidea_). Order 5. =Cylindrocapsaceæ.= The thallus consists of a simple (rarely, in parts, formed of many rows) unbranched filament, attached in the young condition, which has short cells with a single nucleus, and is enveloped in a thick envelope with a laminated structure. Asexual reproduction by zoospores with 2 cilia, which are formed 1, 2, or 4 in each vegetative cell. The antheridia are produced by a single cell, or a group of cells, in a filament, dividing several times without increasing in size. Two egg-shaped spermatozoids, each with 2 cilia (Fig. 53 _D_), are formed in each antheridium, and escape through an aperture in the side; in the first stages they are enclosed in a bladder-like membrane (Fig. 53 _B_, _C_). Other cells of the filament swell out and form oogonia (Fig. 53 _A_), which resemble those of _Œdogonium_. After fertilisation, the oospore surrounds itself with a thick wall, and assumes a reddish colour. The germination is unknown. The unfertilised oospheres remain green, divide often into 2–4 daughter-cells, and grow into new filaments. [Illustration: FIG. 53.--_Cylindrocopsa involuta. A_ Oogonium with oosphere (_o_) surrounded by spermatozoids (_s_). _B_ Two antheridia, each with two spermatozoids. _C_ Spermatozoids surrounded by their bladder-like membrane. _D_ Free spermatozoid.] This order, which only includes one genus, _Cylindrocapsa_, forms the connecting link between _Ulothricaceæ_ and _Œdogoniaceæ_. The few species (4) occur only in fresh water. Order 6. =Œdogoniaceæ.= The thallus consists of branched (_Bulbochæte_) or unbranched (_Œdogonium_) filaments, attached in the early stages. The cells may be longer or shorter, and have one nucleus. Asexual reproduction by zoospores, which have a chaplet of cilia round the base of the colourless end (Fig. 6 _a_). Sexual reproduction takes place by oogamous fertilisation. On the germination of the oospore, 4 zoospores are formed (Fig. 54 _F_). They occur only in fresh or slightly brackish water. The division of the cells takes place in quite a peculiar and unusual manner. At the upper end of the cell which is about to divide, a ring-shaped thickening of soft cellulose is formed transversely round the wall; the cell-nucleus of the mother-cell and the protoplasm then divide by a transverse wall into two portions of similar size, and the cell-wall bursts transversely along the central line of the thickened ring. The cell-wall thus divides into two parts--the upper one short, the “cap,” and the lower one much longer, the “sheath.” The portions of the original cell-wall now separate from each other, the cellulose ring extending, and supplying an additional length of cell-wall between them. The cap and sheath will project a little in front of the piece thus inserted. The dividing wall between the two new cells is formed near to the uppermost edge of the sheath, and gradually becomes thicker and firmer. The inserted piece of wall forms the larger part of the wall of the upper cell: the remainder is formed by the cap. This mode of division is repeated exactly in the same way, and new caps are formed close below the first one, one for every division. [Illustration: FIG. 54.--_A Œdogonium ciliatum. A_ Female plant with three oogonia (_og_) and dwarf-males (_m_). _B_ An oogonium with spermatozoid (_z_) seen entering the oosphere (_o_) having passed through an aperture near the summit of the oogonium; _m_ dwarf-male. _C_ Ripe oospore. _D Œdogonium gemelliparum. F_ Portion of a male filament from which spermatozoids (_z_) are emerging. _E_ Portion of filament of _Bulbochæte_; the upper oogonium still encloses the oospore, in the central one the oospore is escaping while the lower one is empty. _F_ Four zoospores developed from an oospore. _G_ Zoospore germinating.] Fertilisation takes place in the following way. The oogonium is a large ellipsoidal, swollen cell (_og_, in Fig. 54 _A_), whose contents are rounded off into an oosphere with a colourless receptive-spot (see _B_); an aperture is formed in the wall of the oogonium, through which the spermatozoids are enabled to enter (_B_). The spermatozoids are produced either directly, as in _D_ (in pairs), in basal cells of the filament, or indirectly. In the latter case a swarmspore (_androspore_) is formed which comes to rest, attaches itself to an oogonium, germinates, and gives rise to a filament of a very few cells--_dwarf-male_ (_A_, _B_, _m_). The spermatozoids are formed in the upper cell of the dwarf-male (_m_), and are set free by the summit of the antheridium lifting off like a lid. On the germination of the oospore (_C_), which takes place in the following spring, 4 zoospores are produced (_F_) (_i.e._ the sexual generation); these swarm about for a time, and ultimately grow into new filaments. [Illustration: FIG. 55.--_Coleochæte pulvinata. A_ A portion of a thallus with organs of reproduction; _a_ oogonium before, _b_ after fertilisation; _c_ an antheridium, closed; _d_ open, with emerging spermatozoid. _B_ Ripe oogonium, with envelope. _C_ Germination of the oospore. _D_ Zoospore. _E_ Spermatozoid.] Order 7. =Coleochætaceæ.= The thallus is always attached, and of a disc- or cushion-shape, formed by the dichotomous branching of filaments of cells united in a pseudo-parenchymatous manner. Each cell has only one nucleus. Asexual reproduction by zoospores with 2 cilia (Fig. 55 _D_), which may arise in all the cells. Sexual reproduction by oogamous fertilisation. The spermatozoids resemble the swarmspores, but are smaller (_E_), and originate singly (in the species figured) in small conical cells (_c_, _d_ in _A_). The oogonia are developed at the extremities of certain branches: they are bottle-shaped cells with very long and thin necks (_trichogyne_), open at the end (_a_ in _A_); at the base of each oogonium is a spherical oosphere. The spermatozoids reach the oosphere through the trichogyne, or through an aperture in the wall when the trichogyne is absent, and fertilisation having taken place, the oogonium becomes surrounded by a cell-layer (envelope), which grows out from the cells near its base (_b_ in _A_), and in this way a kind of fruit is formed (_B_) (_spermocarp_, _cystocarp_). The oospore, next spring, divides and forms a parenchymatous tissue (homologous with the Moss-sporophyte); this bursts open the envelope (_C_), and a zoospore (homologous with the spores of the Moss-capsule) arises in each of the cells, and produces a new _Coleochæte_. We have then, in this case, a still more distinct alternation of generations than in _Œdogonium_. Only one genus, _Coleochæte_, is known, but it contains several species, all living in fresh water. Order 8. =Cladophoraceæ.= This order is probably derived from the Ulothricaceæ. The thallus consists of a single, unbranched or branched filament, generally with an apical cell. The cells have each 2 or more nuclei. Asexual reproduction by zoospores with 2 or 4 cilia, and by akinetes. Conjugation of gametes with 2 cilia is found in some genera. They occur in salt as well as in fresh water. The principal genera are: _Urospora_, _Chætomorpha_, _Rhizoclonium_, _Cladophora_; of the last named genus the species _C. lanosa_ and _C. rupestris_ are common in salt water; _C. fracta_ and _C. glomerata_ in fresh water. Order 9. =Gomontiaceæ.= _Gomontia polyrrhiza_, the only species hitherto known, is found on old calcareous shells of certain salt water Molluscs. Order 10. =Sphæropleaceæ.= The thallus consists of free, unbranched filaments, with very elongated multinuclear cells. The vegetative cells form no zoospores. Sexual reproduction by oogamous fertilisation (see page 13, Fig. 10 _B_). The oospore has a thick wall (Fig. 10 _D_) studded with warts, and assumes a colour resembling red lead. It germinates only in the following spring, and produces 1–8 zoospores, each with 2 cilia (Fig. 10 _E_), which grow into new filaments. Only one species, _Sphæroplea annulina_, is known. Family 3. Siphoneæ. The thallus has apical growth, and in the vegetative condition consists generally of one single (in the Valoniaceæ most frequently of more) multinuclear cell, which may be much branched, and whose separate parts in the higher forms (_e.g. Bryopsis_, Fig. 57; _Caulerpa_, Fig. 59, etc.) may be differentiated to perform the various physiological functions (as root, stem and leaf). Vegetative multiplication by detached portions of the thallus (gemmæ); asexual reproduction by zoospores, akinetes, or aplanospores. Sexual reproduction by gamete-conjugation, rarely by oogamous fertilisation. The zygote or oospore germinates as a rule without any resting-stage. [Illustration: FIG. 56.--_Botrydium granulatum_: _a_ an entire plant forming swarmspores; _b_ swamspores; _c_ an individual with gametangia; _d_, gamete; _e_, _f_, _g_ conjugation; _h_ zygote seen from above; _i_ the same in a lateral view.] Most of the Siphoneæ occur in salt water or on damp soil. Many (_e.g._ _Dasycladaceæ_) are very much incrusted with lime, and occur, in the fossilized condition, in the deposits from the Cretaceous period to the present time. The Siphoneæ are connected by their lowest forms (_Botrydiaceæ_ or _Valonia_) with the Protococcaceæ, but show also, through the Valoniaceæ, points of relationship to the _Cladophoraceæ_. Order 1. =Botrydiaceæ.= The thallus in the vegetative condition is unicellular, club-shaped, with a small single (_Codiolum_) or repeatedly dichotomously branched system of colourless rhizoids (_Botrydium_, Fig. 56 _a_), by which it is attached to objects immersed in salt water (_Codiolum_) or to damp clay soil (_Botrydium_). Asexual reproduction by zoospores with one (_Botrydium_) or two cilia, and by aplanospores. The sexual reproduction is only known in _Botrydium_, and takes place in the following manner: in the part of the thallus which is above ground and in an active vegetative condition, several round cells (Fig. 56 _c_) are formed, which may be green or red according as they grow under water, or exposed to the strong light of the sun. These cells must be considered as “gametangia” as they produce many gametes (_d_) provided with two cilia. The zygote (_h_, _i_) formed by the conjugation (_e_, _f_, _g_) may either germinate immediately, or become a thick-walled resting-cell of an irregular, angular form. Order 2. =Bryopsidaceæ.= The thallus in the vegetative condition is unicellular, and consists at the lower extremity of branched rhizoids, while the upper portion is prolonged into a stem-like structure of unlimited growth, producing, acropetally, branches and leaf-like structures. The latter have limited growth, and are separated by a cross wall from the stem, and become gametangia, or drop off. The gametes have two cilia, and are of two kinds: the female, which are green and large and the male, which are of brownish colour and smaller. Zoospores or any other method of asexual reproduction are unknown. Only one genus, _Bryopsis_, living in salt water. [Illustration: FIG. 57.--_Bryopsis plumosa_. A the plant, natural size. B A portion (enlarged) which shows the growing point (v), and the leaves derived from it in acropetal succession.] Order 3. =Derbesiaceæ.= Only one genus, _Derbesia_, living in saltwater. The zoospores, which are formed in a few lateral, swollen zoosporangia, possess one nucleus which has arisen through the coalescence of several, and they resemble the zoospores of _Œdogonium_ by having a circle of cilia attached at the base of the colourless spot. Order 4. =Vaucheriaceæ.= The thallus consists, in the vegetative condition, of a single irregularly or dichotomously branched cell, without differentiation into stem or leaf; root-like organs of attachment may however occur. Asexual reproduction by zoospores, which are formed singly in the extremity of a branch cut off by a transverse wall. They contain many nuclei, and bear small cilia situated in pairs, which give the appearance of a fine “pile” covering the whole or a great part of the surface. Akinetes, aplanospores, and phytoamœbæ (naked masses of protoplasm, without cilia, which creep like an amœba on a substratum) may occur under certain conditions. The sexual reproductive organs are formed on short lateral branches, and are separated from the vegetative cell (Fig. 58 _A_) by cell-walls. Numerous spermatozoids, each with two cilia, are developed in the coiled antheridium (_A_, _b_). The oogonium is a thick, egg-shaped, often oblique cell, with its protoplasm rounded into an oosphere, which has a hyaline “receptive-spot” (_A_, _a_) immediately beneath the aperture formed in the wall of the oogonium. A slimy mass, which serves to receive the spermatozoids, is formed in some species in this aperture. The spermatozoids when liberated swim towards and enter the oosphere, which then immediately surrounds itself with a thick cell-wall. The mature oospore (_B_) contains a large quantity of oil. At germination the outer cell-wall bursts and a new plant is formed. There is only one genus, _Vaucheria_, with species living in salt as well as in fresh water and on damp soil. [Illustration: FIG. 58.--_Vaucheria sessilis_. _A_ Fertilisation; _b_ the antheridia; _a_ the oogonia; _a_ the receptive spot. _B_ Oospore.] Order 5. =Phyllosiphonaceæ= are parasites in the leaves and stalks of Flowering-plants. Order 6. =Caulerpaceæ.= The thallus has distinct differentiation into root, stem and leaf-like members (Fig. 59); it is unicellular. Within the cell, strong, branched threads of cellulose extend from one side to the other serving as stays to support the thallus. Reproduction takes place by detached portions of the thallus; no other modes of reproduction are known. This order may most approximately be classed with the _Bryopsidaceæ_. The genus _Caulerpa_ consists of more than seventy species which inhabit the tropical seas. Order 7. =Codiaceæ.= The thallus has various forms, but without distinct differentiation in stem- or leaf-structures, sometimes (_e.g._ _Halimeda_) it is very much incrusted with lime. In the early stages it is unicellular (later, often multicellular), very much branched, with the branches, at any rate partly, so united or grown in amongst one another (Fig. 60) that an apparently parenchymatous cellular body is formed. Akinetes or aplanospores are wanting; zoospores (or gametes?) may be developed in some species, however, in special swollen sporangia. Fertilisation similar to that in _Bryopsis_ occurs perhaps in _Codium_. They are all salt water forms. Order 8. =Valoniaceæ.= The thallus is generally multicellular, without differentation into stem- or leaf-structures, but the cells are sometimes united together and form a leaf-like reticulate expansion (_e.g. Anadyomene_). Zoospores are known in some, and they are then formed directly in the vegetative cells. In others (_e.g. Valonia_), a mass of protoplasm, which maybe separated through the damaging of a cell, can surround itself with a cell-wall, and grow into a new plant. No other modes of reproduction are known. The most important genera are: _Valonia_, _Siphonocladus_, _Chamædoris_, _Struvea_, _Microdictyon_, _Anadyomene_. They are all salt water forms. [Illustration: FIG. 59.--_Caulerpa prolifera_ (natural size).] As already pointed out, the _Valoniaceæ_ occupy a somewhat central position among the Siphoneæ, and present points of similarity and contrast with the _Botrydiaceæ_ and the _Bryopsidaceæ_ through _Valonia_, with the _Dasycladaceæ_ through _Chamædoris_, and also with the _Cladophoraceæ_ through _Siphonocladus_, and _Struvea_. Order 9. =Dasycladaceæ.= The thallus consists of an axile longitudinal cell, destitute of transverse walls, attached at the base by root-like organs of attachment, and producing acropetally whorls of united, single or branched, leaf-like structures with limited growth. Asexual reproduction is wanting. Sexual reproduction by conjugation of gametes which arise in separate, fertile leaves, either directly or from aplanospores, which develope into gametangia. The principal genera are: _Acetabularia_, _Dasycladus_, _Neomeris_, _Cymopolia_. All marine. [Illustration: FIG. 60.--_Halimeda opuntia._ Plant (natural size). _B_ Part of a longitudinal section.] The curiously shaped _Acetabularia mediterranea_ grows gregariously on limestone rocks, and shells of mussels in the Mediterranean; it resembles a minute umbrella with a small stem, sometimes as much as nine centimetres in height, and a shade which may be more than one centimetre in diameter. The cell-membrane is thick, and incrusted with carbonate and oxalate of lime. Only the lower, root-like part of the thallus, which penetrates the calcareous substratum survives the winter, and may grow up into a new plant. The sterile leaves, which drop off early, are dichotomously branched and formed of cylindrical cells separated from each other by cross-walls, but they are not grown together. The shade is formed by a circle of 70–100 club-shaped rays (fertile leaves) grown together, in each ray 40–80 aplanospores are formed, which become liberated at the breaking of the shade, and later on are changed to gametangia (compare _Botrydium_) which open by a lid and allow a large number of egg-shaped gametes with two cilia to escape. Gametes from various gametangia conjugate with one another; the product of the conjugation swarms about for some time, rounds off, and then surrounds itself with a cell-wall. The zygote germinates after a period of rest and then produces a sexual plant. The aplanospores (gametangia) thus represent the sexual generation. Class 7. =Characeæ.= The thallus has a stem with nodes and internodes; and whorls of leaves, on which may be developed the antheridia and oogonia, are borne at the nodes. Vegetative reproduction by bulbils and accessory shoots. Zoospores are wanting. The antheridia are spherical, and contain a number of filaments in which the spirally coiled spermatozoids, each with two cilia, are formed. The oogonium is situated terminally, and is at first naked, but becomes later on surrounded by an investment, and forms after fertilisation the so-called “fruit.” The oospore, after a period of rest, germinates by producing a “proembryo,” from which the young sexual plant arises as a lateral branch. The Characeæ are distinguished by the structure of their vegetative system as well as by the spirally-coiled spermatozoids, and stand as an isolated group among the Thallophytes, of which, however, the Siphoneæ appear to be their nearest relations. They were formerly, but wrongly, placed near the Mosses. The class contains only one order, the Characeæ. Order 1. =Characeæ.= Algæ with a peculiar odour, often incrusted with lime, and of a brittle nature. They generally grow gregariously in large masses at the bottom of fresh and brackish water, and are from a few inches to more than a foot in height. The stem has long internodes which in _Nitella_ are formed of one cylindrical cell; in _Chara_ of a similar cell, but closely surrounded by a cortical layer of smaller ones. The protoplasm in contact with the cell-wall exhibits in a well-marked degree the movement of rotation (cyclosis), carrying the chlorophyll corpuscles along with it. The internodes are separated from each other by a layer of small cells (nodal cells) from which the leaves are produced. The leaves are borne in whorls of from 5–12 which regularly alternate with one another as in the higher verticillate plants; a branch is borne in the axil of the first formed leaf of each whorl (Fig. 61 _A_, _n_). [Illustration: FIG. 61.--_Chara fragilis. A_ Portion of a plant, natural size. _B_ Portion of a leaf _b_, with leaflets β′-β′′; _a_ antheridium; _c_ oogonium. _C_ A shield.--_Nitella flexilis. D_ Filament from antheridium with spermatozoids. _E_ Free spermatozoids.] The leaves are constructed in the same manner as the stem; they are divided into a series of joints, but have only a limited power of growth; their terminal cell, too, is not enclosed by a cortex. Leaflets are borne at their nodes. The growth of the stem is unlimited, and proceeds by means of an apical cell (Fig. 62 _s_). The apical cell divides into a segment-cell and a new apical cell. The segment-cell then divides by a transverse wall into two cells, one lying above the other; the lower one, without any further division, becomes one of the long, cylindrical, internodal cells (Fig. 62 _in_), and the upper one (Fig. 62 _n_) divides by vertical walls to form the nodal cells. The cortical cells (Fig. 62 _r_) which surround the long internodal cells of _Chara_, are derived from the divisions of the nodal cells; the cells covering the upper portion of an internodal cell being derived from the node immediately above it, and those in the lower part of the internode from the node below it. [Illustration: FIG. 62.--_Chara fragilis_: _s_ apical cell; _n_, _n_ nodal cells; _in_ internodal cells; _bl_, _bl_ leaves; _r_, _r_ the cortical cells.] [Illustration: FIG. 63.--Oogonium of _Chara_: _k_ “crown”; _u_ receptive spot; _s_ spermatozoids.] The organs of reproduction are very conspicuous by their colour and form. They are always situated on the leaves, the plants being very frequently monœcious. The antheridia (Fig. 61 _B_, _a_) are modified leaflets or the terminal cell of a leaf; they are spherical and become red when mature. Their wall consists of 8 “shields,” _i.e._ of plate-like cells, 4 of which cover the upper half, and are triangular; the 4 round the lower half, to which the stalk of the antheridia is attached, being quadrilateral, with sides of unequal length. The shields (Fig. 61 _C_) have dentated edges, with the teeth fitting into one another, and their faces ornamented with ridges. From the centre of the internal face of each shield (_C_) a cylindrical cell, the _manubrium_, projects nearly as far as the centre of the antheridium; at the inner end of each of the manubria a spherical cell, the _capitulum_, is situated. Each capitulum bears six secondary capitula, from each of which four long coiled filaments (_C_, _D_) project into the cavity of the antheridium. These filaments are divided by transverse walls into from 100–200 discoid cells, in each of which a biciliated, coiled spermatozoid is developed (_D_, _E_) from the nucleus. The spermatozoids escape from their mother-cell and are set free by the shields separating from one other. The female organ of reproduction (Fig. 61 _B_, 63) is a small modified shoot, whose apical cell functions as an oogonium, its protoplasm forming the oosphere, which has a colourless receptive-spot at the summit (Fig. 63 _u_). The oogonium is situated on a nodal cell, from which 5 cells grow out in a circle and coil round the oogonium, covering it with a close investment. These cells divide once or twice at the top, so that 5 or 10 small cells are cut off, which project above the oogonium and form the so-called “crown” (Fig. 63 _k_). The crown either drops off at fertilisation, or its cells separate to form a central canal for the passage of the spermatozoids. The wall of the oosphere[9] above the receptive spot becomes mucilaginous, and allows the spermatozoid to fuse with the oosphere. The oospore, on germination (Fig. 64 _sp_), becomes a small filamentous plant of limited growth (Fig. 64 _i_, _d_, _q_, _pl_)--the proembryo--and from this, as a lateral outgrowth, the sexual generation is produced. The order is divided into two sub-orders:-- A. NITELLEÆ. The crown consists of 10 cells; cortex absent: _Nitella_, _Tolypella_. B. CHAREÆ. The crown consists of 5 cells; cortex present: _Tolypellopsis_, _Lamprothamnus_, _Lychnothamnus_, _Chara_. _Chara crinita_ is parthenogenetic; in large districts of Europe only female plants are found, yet oospheres are formed capable of germination. [Illustration: FIG. 64.--_Chara fragilis._ Germinating oospore (_sp_); _i_, _d_, _g_, _pl_, form together the proembryo rhizoids (_w′_) are formed at _d_; _w′_ the so-called tap-root; at _g_ are the first leaves of the sexual plant, which appears as a lateral bud.] About 40 species of fossilized _Chara_, determined by their carpogonia, are known in the geological formations from the Trias up to the present day. Class 8. =Phæophyceæ (Olive-Brown Seaweeds).= The Phæophyceæ are Algæ, with chromatophores in which the chlorophyll is masked by a brown colour (phycophæin). The product of assimilation is a carbohydrate (fucosan), _never true starch_. In the highest forms (_Fucaceæ_), the thallus presents differentiation into stem, leaf, and root-like structures. The asexual reproduction takes place by means of zoospores. The sexual reproduction is effected by the coalescence of motile gametes, or by oogamous fertilisation. The swarm-cells are _monosymmetric_, each moved by two cilia which are true protoplasmic structures, and generally _attached laterally_ (Fig. 65). The Phæophyceæ are almost entirely saltwater forms; a few species of _Lithoderma_ live in fresh water. The class is divided into two families:-- 1. PHÆOSPOREÆ: 1 Sub-Family, Zoogonicæ; 2 Sub-Family, Acinetæ. 2. CYCLOSPOREÆ: Fucaceæ. Family 1. =Phæosporeæ.= The family consists of multicellular plants, whose cells are firmly united together to form a thallus; this, in the simplest cases, may be a branched filament of cells (_Ectocarpus_), or, in the highest, may resemble a stem with leaves (_Laminariaceæ_), while all transitional forms may be found between these two. The thallus grows by intercalary divisions (_e.g. Ectocarpus_), or by an apical cell (_e.g._ _Sphacelaria_); pseudo-parenchymatous tissue may sometimes be formed by cells, which were originally distinct, becoming united together. The size of the thallus varies; in some species it is quite small--almost microscopical,--while in the largest it is many metres in length. The vegetative cells in the lower forms are nearly uniform, but in those which are more highly developed (_Laminariaceæ_ and _Fucaceæ_), they are sometimes so highly differentiated that mechanical, assimilating, storing and conducting systems may be found; the last named systems are formed of long cells with perforated, transverse walls, which bear a strong resemblance to the sieve-tubes in the higher plants. [Illustration: FIG. 65.--Swarmspore of _Cutleria multifida_.] The colouring matter in the living cells (“phæophyl”) contains chlorophyll; but this is concealed by a brown (“phycophæin”), and a yellow (“phycoxanthin”) colouring material, and hence all these Algæ are a lighter or darker _yellow-brown_. Starch is not formed. Asexual reproduction takes place, (1) by zoospores which arise in unilocular zoosporangia, and are monosymmetric, with two cilia attached laterally at the base of the colourless anterior end (Fig. 65), the longer one being directed forwards and the shorter backwards; or (2) by aplanospores (?). [Illustration: FIG. 66.--_Ectocarpus siliculosus_. _I a-f_ A female gamete in the various stages of coming to rest. _II_ A motionless female gamete surrounded by male gametes. _III a-e_ Stages in the coalescence of male and female gametes.] [Illustration: FIG. 67.--_Zanardinia collaris_. _A_ Male gametangia (the smaller celled) and female gametangia (the larger celled). _C_ Female gamete. _D_ Male gamete. _B_, _E_ Fertilisation. _F_ Zygote. _G_ Germinating zygote.] Sexual reproduction has only been discovered in a few cases, and takes place by means of gametes (oogamous fertilisation perhaps occurs in the Tilopteridæ). The gametes have the same structure as the zoospores, and arise in multilocular gametangia; these, like the zoosporangia, are outgrowths from the external surface, or arise as modifications from it. The conjugating gametes may be similar (_e.g. Ectocarpus pusillus_), or there may be a more or less pronounced difference of sex, an indication of which is found in _Ectocarpus siliculosus_ (Fig. 66). When the gametes in this species have swarmed for a time, some, which are generally larger, are seen to attach themselves by one of the cilia, which by degrees is shortened to form a kind of stalk (compare the upper gamete in Fig. 66 _II_); these are the female gametes, which now become surrounded by a number of males endeavouring to conjugate with them, but only one succeeds in effecting fertilisation. The protoplasm of the two gametes coalesces (Fig. 66 _III_), and a zygote (_e_) is formed. The male gametes which do not conjugate may germinate, but the plants derived from them are much weaker than those produced by the zygotes. Strongly pronounced sexual differences are found in the Cutleriaceæ, in which order the male and female gametes arise in separate gametangia (Fig. 67 _A_). The male gametes (Fig. 67 _D_) are much smaller than the female gamete (Fig. 67 _C_); the latter, after swarming for a short time, withdraws the cilia, and is then ready to become fertilised (Fig. 67 _B_, _E_), thus we have here a distinct transition to the oogamous fertilisation which is found in the Fucaceæ. Alternation of generations is rarely found. 1. Sub-Family. =Zoogonicæ.= Reproduction by means of gametes and zoospores. Order 1. =Ectocarpaceæ.= The thallus consists of single or branched filaments with intercalary growth, extending vertically from a horizontal, branched filament or a disc, but sometimes it is reduced to this basal portion only. Zoosporangia and gametangia (for fertilisation see Fig. 66) are either outgrowths or arise by the transformation of one or several of the ordinary cells. The most common genera are: _Ectocarpus_ and _Pylaiella_. Order 2. =Choristocarpaceæ.= _Choristocarpus_, _Discosporangium_. Order 3. =Sphacelariaceæ.= The thallus consists of small, parenchymatous, more or less ramified shoots, presenting a feather-like appearance. In the shoots, which grow by means of an apical cell (Fig. 68 _S_), a cortical layer, surrounding a row of central cells, is present. Sporangia and gametangia are outgrowths from the main stem or its branches. _Sphacelaria_, _Chætopteris_ are common forms. [Illustration: FIG. 68.--Apex of the thallus of _Chætopteris plumosa_. _S_ Apical cell.] Order 4. =Encoeliaceæ.= _Punctaria_, _Asperococcus_, _Phyllitis fascia_. Order 5. =Striariaceæ.= _Striaria_, _Phlœospora_. Order 6. =Dictyosiphonaceæ.= _Dictyosiphon._ Order 7. =Desmarestiaceæ.= _Desmarestia aculeata_ is common. Order 8. =Myriotrichiaceæ.= _Myriotrichia._ Order 9. =Elachistaceæ.= _Elachista fucicola_ is a common epiphyte on species of _Fucus_. Order 10. =Chordariaceæ.= The shoot-systems are often surrounded by mucilage. _Chordaria_; _Leathesia difformis_ occurs as rounded, brown-green masses of the size of a nut, generally attached to other Seaweeds. Order 11. =Stilophoraceæ.= _Stilophora rhizodes_ is common. Order 12. =Spermatochnaceæ.= _Spermatochnus paradoxus_ is common. Order 13. =Sporochnaceæ.= _Sporochnus._ Order 14. =Ralfsiaceæ.= _Ralfsia verrucosa_ is common as a red-brown incrustation on stones and rocks at the water’s edge. Order 15. =Lithodermataceæ.= Some species of the genus _Lithoderma_ occur in fresh water. [Illustration: FIG. 69.--_Laminaria digitata_ (much reduced in size).] Order 16. =Laminariaceæ.= The thallus is more or less leathery, and has generally a root-like lower part (Fig. 69) which serves to attach it, and a stalk or stem-like part, terminated by a large leaf-like expansion. Meristematic cells are situated at the base of the leaf, and from these the new leaves are derived. The older leaf thus pushed away by the intercalary formation of the younger ones, soon withers (Fig. 69). Gametes are wanting. Zoosporangia are developed from the lower part of a simple, few-celled sporangiophore, which is an outgrowth from a surface-cell and has a large club-formed apical cell. The sporangia are aggregated into closely packed sori, which cover the lower part of the terminal leaf, or occur on special, smaller, lateral, fertile fronds (_Alaria_). Most of the species belonging to this order live in seas of moderate or cold temperature and occur in the most northern regions that have yet been explored, forming their organs of reproduction during the cold and darkness of the arctic night. _Laminaria_ is destitute of a midrib and has only one terminal leaf. _L. digitata_ has a broad leaf, which, by the violence of the waves, is torn into a number of palmate strips (Fig. 69). _L. saccharina_ has a small, undivided leaf. _Alaria_ has a midrib and special fertile fronds. _A. esculenta_ occurs plentifully on the west coast of Norway and on the shores of Great Britain. _Chorda filum_, a common seaweed, is thick, unbranched, and attains a length of several metres, without any strong demarcation between stalk and leaf. Some attain quite a gigantic size, _e.g. Macrocystis pyrifera_, whose thallus is said sometimes to be more than 300 metres in length. The _Lessonia_-species, like the above, form submarine forests of seaweed on the south and south-west coasts of South America, the Cape, and other localities in the Southern Hemisphere. USES. The large Laminarias, where they occur in great numbers, are, like the Fuci, used for various purposes, for example, in the production of iodine and soda, and as an article of food (_Laminaria saccharina_, _Alaria esculenta_, etc.). _Laminaria saccharina_ contains a large quantity of sugar (mannit) and is in some districts used in the preparation of a kind of syrup; in surgical operations it is employed for the distension of apertures and passages, as for instance the ear-passage. It is by reason of the anatomical peculiarities and structure of the cell-walls, that they are employed for this purpose. The cell-walls are divided into two layers, an inner one which has very little power of swelling, and an outer one, well developed and almost gelatinous--the so-called “intercellular substance”--which shrivels up when dried, but can absorb water and swell to about five times its size. The stalks of _Laminaria clustoni_ are officinal. Order 17. =Cutleriaceæ.= The thallus is formed by the union of the originally free, band-shaped shoots. The growth is intercalary. Sexual reproduction by the conjugation of male and female gametes. An asexual generation of different appearance, which produces zoospores, arises from the germination of the zygote. _Cutleria_, _Zanardinia_. Sub-Family 2. =Acinetæ.= Branched, simple cell-rows with intercalary growth. The organs of reproduction are partly uni-and partly multicellular; in the unicellular ones a cell without cilia is formed, which may be destitute of a cell-wall, but has one nucleus (oosphere?), or which has a cell-wall and contains several (generally four) nuclei (aplanospores?); in the multicellular, monosymmetric swarm-cells with two cilia (spermatozoids?) are formed. The fertilisation has not been observed. Order 1. =Tilopteridaceæ.= _Haplospora_, _Tilopteris_. Family 2. =Cyclosporeæ.= The individuals are multicellular, with growth by an apical cell. The thallus--often bilateral--is differentiated into a root-like structure (attachment-disc), and stem, sometimes also into leaves (_Sargassum_). Sometimes a differentiation occurs into various tissue-systems, viz. an external assimilating tissue, a storing tissue, a mechanical tissue of thickened, longitudinal, parenchymatous, strengthening cells, and a conducting tissue of sieve-cells, or of short sieve-tubes with perforated walls. Colouring material, as in Phæosporeæ. Vegetative reproduction can only take place by means of detached portions of the thallus (_Sargassum_), which are kept floating by means of bladders (Fig. 70 _A_, _a_, Fig. 72). Zoospores are wanting. The sexual reproduction takes place by oogamous fertilisation. The oogonia and antheridia are formed inside special organs (conceptacles), and are surrounded by paraphyses. The conceptacles (Fig. 70 _B_, Fig. 71 _b_) are small, pear-shaped or spherical depressions, produced by a special ingrowth of the surface cells of the thallus, and their mouths (_ostioles_) project like small warts; they are either situated near the end of the ordinary branches of the thallus (_Fucus serratus_, Fig. 71 _a_) which may be swollen on this account (_Fucus vesiculosus_, Fig. 70 _A_, _b_), or on special short branches (_Ascophyllum_, _Sargassum_). The vertical section of a conceptacle is seen in Fig. 70 _B_ (see also Fig. 71 _b_) where, in addition to the paraphyses, oogonia only are seen (_F. vesiculosus_ is diœcious--male plant, yellow-brown; female plant, olive-brown); but in some species antheridia, together with oogonia, are produced in the same conceptacle. The oogonia are large, almost spherical cells, situated on a short stalk, in each of which are formed from 1–8 (in _Fucus_, 8; in _Ascophyllum_, 4; in _Halidrys_, 1; in _Pelvetia_, 2) rounded, immotile oospheres. The wall of the oogonium ruptures, and the oospheres, still enclosed in the inner membrane, are ejected through the mouth of the conceptacle, and float about in the water, being finally set free by the bursting of the inner membrane. The antheridia are oblong cells (Fig. 70 _C_, _a_), many of which are produced on the same branched antheridiophore (Fig. 70 _C_); the numerous spermatozoids are provided with 2 cilia and are very small (Fig. 70 _D_, two antheridia surrounded by spermatozoids, one being open). The spermatozoids, still enclosed by the inner membrane of the antheridium, are similarly set free, and fertilisation takes place in the water, numerous spermatozoids collecting round the oosphere (Fig. 70 _E_), which is many times larger, and by their own motion causing it to rotate. After fertilisation, the oospore surrounds itself with a cell-wall and germinates immediately, attaching itself (Fig. 70 _F_) to some object, and by cell-division grows into a new plant. [Illustration: FIG. 70.--_Fucus vesiculosus. A_ Portion of thallus with swimming bladders (_a_) and conceptacles (_b_). _B_ Section of a female conceptacle; _h_ the mouth; _p_ the inner cavity; _s_ oogonia. _C_ Antheridiophore; _a_ antheridium; _p_ sterile cells. _D_ Antheridia out of which the spermatozoids are escaping. _E_ Fertilisation. _F_ Germinating oospore.] [Illustration: FIG. 71.--_Fucus serratus_. _a_ Portion of a male plant which has been exposed to the action of the open air for some time; small orange-yellow masses, formed by the antheridia, are seen outside the mouths of the male conceptacles (nat. size). _b_ Cross section through the end of a branch of a female plant, showing the female conceptacles (× 4).] [Illustration: FIG. 72.--_Sargassum bacciferum_. A portion of the thallus, natural size.] Order 1. =Fucaceæ.= The following species are common on our coasts: _Fucus vesiculosus_ (Fig. 70) has a thallus with an entire margin, and with bladders arranged in pairs; _F. serratus_ (Fig. 71) without bladders, but with serrated margin; _Ascophyllum nodosum_ has strap-like shoots, which here and there are swollen to form bladders; _Halidrys siliquosa_ has its swimming bladders divided by transverse walls; _Himanthalia lorea_, which is found on the west coast of Norway, and the south coast of England, has a small perennial, button-shaped part, from the centre of which proceeds the long and sparsely branched, strap-like, annual shoot, which bears the conceptacles. The Gulf-weed (_Sargassum bacciferum_, Fig. 72) is well known historically from the voyage of Columbus; it is met with in large, floating, detached masses in all oceans, and is found most abundantly in the Atlantic, off the Canary Islands and the Azores, and towards the Bermudas. The stalked, spherical air-bladders are the characteristic feature of this genus. The thallus is more highly developed than in _Fucus_, and there is a contrast between the stem and leaf-like parts. The portions which are found floating are always barren, only those attached are fertile. USES. The Fucaceæ, like the Laminariaceæ, are used as manure (the best kinds being _Fucus vesiculosus_ and _Ascophyllum nodosum_), for burning to produce kelp, and as food for domestic animals (_Ascophyllum nodosum_ is especially used for this purpose). Class 9. =Dictyotales.= The plants in this class are multicellular, and brown, with apical growth, new cells being derived either from a flat apical cell, or from a border of apical cells. The thallus is flat, leaf- or strap-shaped, attached by haptera, which are either found only at the base, or on the whole of the lower expansion of the thallus. The cells are differentiated into the following systems of tissues: an external, small-celled layer of assimilating cells, generally one cell in thickness, and an internal, large-celled layer of one or only a few cells in thickness, forming the mechanical and conducting tissues. All the reproductive cells are motionless. Asexual reproduction by naked, motionless spores (tetraspores) which are formed 1–4 in each tetrasporangium, the latter being outgrowths from the surface cells of special, sexless individuals. Zoospores are wanting. The sexual organs are of two kinds, oogonia and antheridia, which are formed from the surface cells, either on the same or different individuals. The oogonia are spherical or oval, and are generally placed close together; each contains one oosphere, which on maturity is ejected into the surrounding water, and is then naked and motionless. The antheridia are formed of longitudinal cells, united in groups, whose contents by repeated divisions--transverse and longitudinal--are divided into a large number of small, colourless, motionless spermatia--round or elongated--which are set free by the dissolution of the wall of the antheridium. The process of fertilisation has not yet been observed. The Dictyotales, in having tetraspores and spermatia, deviate considerably from the Phæophyceæ, but may be classed near to the Tilopteridæ, in which there are asexual spores with 4 cell-nuclei, which may be considered as an indication of the formation of tetraspores. Order 1. =Dictyotaceæ.= _Dictyota dichotoma_ which has a thin, regularly dichotomously divided thallus, occurs on the coasts of the British Isles. _Padina_ is found on the south coast. Class 10. =Rhodophyceæ (Red Seaweeds).= The plants comprised in this class are multicellular; they are simple or branched filaments, or expansions consisting of 1 to several layers of cells; the thallus may be differentiated (as in many _Florideæ_), to resemble stem, root, and leaf. The cells contain a distinctly differentiated nucleus (sometimes several), and distinct chromatophores, coloured by rhodophyll. The chlorophyll of the chromatophores is generally masked by a red colouring matter (phycoerythrin), which may be extracted in cold, fresh water; or rarely by phycocyan. Pyrenoids occur in some. Starch is never formed in the chromatophores themselves, but a modification--Florideæ starch--may be found in the colourless protoplasm. Asexual reproduction by motile or motionless spores (tetraspores) which are devoid of cilia and of cell-wall. Swarmspores are never found. Sexual reproduction is wanting, or takes place by the coalescence of a spermatium and a more or less developed female cell. The spermatia are naked masses of protoplasm, devoid of cilia and chromatophores. The female cell (carpogonium) is enclosed by a cell-wall, and after fertilisation forms a number of spores, either with or without cell-walls (carpospores), which grow into new individuals. The Rhodophyceæ may be divided into two families: 1. BANGIOIDEÆ. 2. FLORIDEÆ. Family 1. =Bangioideæ.= The thallus consists of a branched or unbranched cell-filament, formed of a single row or of many rows of cells, or of an expansion, one or two layers of cells in thickness, but without conspicuous pores for the intercommunication of the cells. The growth of the thallus is chiefly intercalary. The star-like chromatophores contain chlorophyll and are coloured blue-green with phycocyan, or reddish with phycoerythrin; all these colouring matters are occasionally found in the same cell (_Bangia_-species). Asexual reproduction by tetraspores, without cilia, but capable of amœboid movements. Sexual reproduction is wanting, or takes place by the coalescence of a spermatium with a carpogonium, which is only slightly differentiated from the vegetative cells, and is devoid of a trichogyne. The carpospores are destitute of cell-wall and arise directly by the division of the fertilised oosphere. The Bangioideæ occur chiefly in salt water. Order 1. =Goniotrichaceæ.=--The thallus consists of a branched cell-filament without rhizoids. Tetraspores are formed directly from the entire contents of the mother-cell, without any preceding division. Fertilisation unknown. _Asterocystis_, _Goniotrichum_. The _Goniotrichaceæ_, through the blue-green _Asterocystis_, are allied to the Myxophyceæ, and through _Goniotrichum_ to the _Porphyraceæ_. Order 2. =Porphyraceæ.=--The thallus is formed of an expansion consisting of a layer of 1–2 cells, which, at the base, are attached to the substratum by means of a special form of haptera (_Porphyra_, _Diploderma_); or of unbranched (very rarely slightly branched) filaments, attached at the base by haptera (_Bangia_): or it extends from a prostrate cell-disc (various species of _Erythrotrichia_). Tetraspores are formed after one or more divisions of the mother-cell, either from the whole or only a part of its contents; they possess amœboid movements, or have a jerky, sliding-forward motion. The antheridia have the same appearance as the vegetative cells, but divide several times, and several spermatia are formed, either simultaneously from the whole contents (_Porphyra_, _Bangia_), or the spermatia are successively formed from a part of the contents of the antheridium (_Erythrotrichia_). The carpogonium is without a trichogyne, but the oosphere has a colourless spot which may sometimes rise a little above the surface of the thallus, and may be considered as an early stage in the development of the trichogyne. The spermatia form a canal through the membrane of the carpogonium, and their contents coalesce with the oosphere at its colourless spot. The fertilised oosphere divides on germination into a number of carpospores, which are set free as naked, motionless masses of protoplasm, which grow and give rise to new individuals (alternation of generations). Family 2. =Florideæ.= The thallus has one or more apical cells, grows principally by apical growth, and may be differentiated into root, stem, and leaf. The chromatophores vary in form, but have a red or brownish colour, due to chlorophyll and phycoerythrin. Asexual reproduction by motionless tetraspores, which generally arise by the division into four of the contents of the tetrasporangium. The carpogonium has a trichogyne, and the carpospores, which are formed indirectly from the fertilised oosphere, possess a cell-wall. [Illustration: FIG. 73.--_Callithamnion elegans_: _a_ a plant with tetraspores (× 20); _b_ apex of a branch with tetraspores(× 250).] [Illustration: FIG. 74.--_Polysiphonia variegata_: _a_ a portion of a male plant with antheridia; _b_ spermatia; _c_ transverse section of thallus.] The thallus may assume very different forms. In the simplest species it is filamentous and formed of single, branched rows of cells (_Callithamnion_, etc., Fig. 73). _Ceramium_ has a filamentous thallus, generally dichotomously forked (Fig. 75), or sometimes pinnately branched, which, at the nodes, or throughout its entire length, is covered by a layer of small cortical cells. _Polysiphonia_ (Fig. 74) has a filamentous, much branched thallus, made up of a central cylindrical cell, surrounded by a layer of other cells, cortical cells, which in length and position correspond to the central ones. In many of the Red Algæ the vegetative organs are differentiated into stems and leaves, the former having, as in _Chara_, unlimited growth in length, whilst the latter soon attain their full development. _Chondrus_ has a fleshy, gelatinous thallus, without nodes; it is repeatedly forked into flat branches of varying thickness. _Furcellaria_ has a forked thallus with thick branches and without nodes. The thallus of _Delesseria_ (Fig. 76) consists of branches, often bearing leaf-like structures, with a midrib and lateral ribs springing from it. These ribs persist through the winter, and at the commencement of the succeeding period of vegetation the lateral ribs become the starting points for new leaves. In _Corallina_ the thallus is pinnately branched, and divided into nodes and internodes. The name has been given to this genus from the fact that the thallus is incrusted with carbonate of lime to such a degree that it becomes very hard, and the whole plant adopts a coral-like appearance. Other genera which are similarly incrusted, and have a leaf-like or even crustaceous thallus (such as _Melobesia_, _Lithothamnion_), are included in this family. In some instances the cells of the thallus may be found _differentiated_ into more or less well defined tissues, so that it is possible to find special assimilating, mechanical, and conducting tissues, the last named in some cases having the double function of conducting and of serving as a reservoir in which starch is found as a reserve material. The cells of the Florideæ, which are formed by the division of a mother-cell into two daughter-cells of unequal size, have always larger or smaller pits in the cell-walls, and the thin cell-wall separating two pits from each other is perforated by a number of small holes. These pits are particularly developed in the conducting tissues, but sieve-tubes are very rarely to be found. [Illustration: FIG. 75.--_Ceramium diaphanum_ (nat. size).] [Illustration: FIG. 76.--_Delesseria sanguinea_ (about ⅓).] _Tetraspores_ may be wanting (_e.g. Lemanea_) or may often arise on special, non-sexual individuals. In some (_e.g. Batrachospermum_) only one tetraspore is formed in each tetrasporangium, but the number is generally four, which may be formed tetrahedrally (Fig. 73) or by divisional walls perpendicular to each other, or even in a single row. The tetrasporangia in some species are free (Fig. 73), but in the majority they are embedded in the thallus. [Illustration: FIG. 77.--_A Lejolisia mediterranea_: _r_ haptera; _s_ longitudinal section through a cystocarp; _p_ the empty space left by the liberated spore (_t_). _B-E Nemalion multifidum_: _a_ antheridia; _b_ procarpium with trichogyne, to which two spermatia are adhering.] The sexual reproduction (discovered by Thuret and Bornet, 1867) differs in the essential points from that of all other plants, and approaches most nearly to the sexual reproduction of the _Bangioideæ_. The sexual cells are developed from the terminal cells (never nodal cells) of the branched cell-filaments, which constitute the thallus. The mother-cells of the spermatia (_spermatangia_) are generally arranged in a group, in the so-called _antheridia_ (Figs. 74, 77 _A_, _a_). On becoming ripe the membrane of the spermatangium ruptures and the _spermatia_ emerge as spherical or ovoid, naked (a little later they may possess a cell-wall) masses of protoplasm which are not endowed with the power of motion, and hence are carried passively by the current of the water in which they may happen to be, to the female cell. This latter is analogous with the oogonium of the Green Algæ. The female reproductive organ is termed the _procarpium_, and consists of two parts, a lower swollen portion--the _carpogonium_ (Fig. 77 _b_ in _A_ and _B_)--which contains the cell-nucleus, and an upper filamentous prolongation--the _trichogyne_ (Fig. 77 _B_)--which is homologous with the colourless receptive spot of the oosphere of the Green Algæ, and the _Porphyraceæ_. In the sexual reproduction of the majority of the Florideæ, a very important part is played by certain special cells, rich in cell-contents--the _auxiliary cells_. These are either dispersed in the interior of the thallus, or are arranged together in pairs with the cell-filament which bears the carpogonium, and are generally united with this to form an independent multicellular _procarpium_. The spermatia attach themselves firmly to the trichogyne and surround themselves with a cell-wall. The dividing wall at the point of contact is perforated, and the nucleus of the spermatium probably travels through the trichogyne to the swollen part of the procarpium--the _carpogonium_--and fuses with its nucleus. After fertilisation the trichogyne withers (Fig. 77 _C_), but the lower portion of the procarpium, constituting the _fertilised oosphere_, grows out and forms in various ways, first a tuft of spore-forming filaments known as _gonimoblasts_, and finally the _carpospores_. These latter form a new asexual generation (compare the germination of the oospore of _Œdogonium_ and _Coleochæte_). The gonimoblasts may arise in three ways:-- 1. In the _Nemalionales_, branched filaments grow out from the oosphere and form an upright, compressed or expanded tuft of spore-forming filaments. 2. In the _Cryptonemiales_, several branched or unbranched filaments (_ooblastema-filaments_) grow out from the oosphere, and conjugate in various ways with the auxiliary cells. The gonimoblasts are then formed from the single cells produced by the conjugation. 3. In the _Gigartinales_ and _Rhodymeniales_ the oosphere conjugates with an auxiliary cell by means of a short ooblastema-filament, and from this auxiliary cell a gonimoblast is produced. The motionless _carpospores_, which sometimes in the early stages are naked, and afterwards invested with a cell-wall, are developed from the terminal cells (and perhaps also from some of the other cells) of the branches of the gonimoblast. The gonimoblasts constitute sharply defined parts of the plant in which the carpospores arise. These parts are called _cystocarps_ and are either naked (Fig. 77 _E_), or surrounded by a covering (pericarp or involucre, Fig. 77 _A_) formed in different ways. On this account the Florideæ were formerly divided into GYMNOSPOREÆ (_Batrachospermum_, _Nemalion_, _Ceramium_, etc.) and ANGIOSPOREÆ (_Farcellaria_, _Lejolisia_, _Delesseria_, _Melobesia_, etc.). The Florideæ are divided into four sub-families:-- Sub-Family 1. =Nemalionales.= The fertilised oosphere produces directly the gonimoblast. Order 1. =Lemaneaceæ.= Algæ of brownish colour and living in fresh water. They lack tetraspores, and the very sparingly branched fertile filaments, composed of many rows of cells, grow out from a proembryo, which consists of a single row of cells bearing branches. _Lemanea fluviatilis_, often found on rocks and stones in quickly flowing streams. Order 2. =Helminthocladiaceæ.= Tetraspores are generally wanting (_e.g._ in _Nemalion_) or arise one in each tetrasporangium (_e.g. Batrachospermum_) and it is only in _Liagora_ that four cruciate tetraspores are formed. _Chantransia corymbifera_ consists of simple, branched cell-rows, and is an independent species. Several other _Chantransia-forms_, living in fresh water, are “proembryos” of species of the genus _Batrachospermum_. The germinating carpospore grows out into filaments and forms a so-called proembryo which, if not shaded, attains only a small size, but when growing in shady situations presents a much greater development. These highly developed proembryos have been described as species of _Chantransia_. The proembryo can reproduce by division, or by tetraspores which are developed singly in the sporangia; in _B. vagum_ and _B. sporulans_ which do not possess fully developed female reproductive organs, the proembryos serve almost entirely to reproduce the species. The young _Batrachospermum_-plant arises from the end of an upright filament of the proembryo. The proembryo is generally persistent, and continually produces new _Batrachospermums_. These latter bear the sexual reproductive organs and also whorls of branches: the central row of cells is enclosed by cells growing from the base of the whorls of branches, and from these cortical cells secondary proembryos are developed. In this alternation of shoots there is really no alternation of generations, since the proembryo and the shoots with the sexual reproductive organs are parts of the same thallus. Several species of _Batrachospermum_ have a bluish green or verdigris colour. _Nemalion multifidum_ has a brown-red thallus, slightly branched, which is attached to rocks near the water’s edge. Order 3. =Chætangiaceæ.= _Galaxaura_ has a thallus thickly incrusted with lime. Order 4. =Gelidiaceæ.= _Naccaria, Gelidium._ Sub-Family 2. =Gigartinales.= The fertilised auxiliary cell grows towards the thallus, to produce the gonimoblasts. Procarpia generally present. Order 5. =Acrotylaceæ.= _Acrotylus._ Order 6. =Gigartinaceæ.= _Gigartina_, _Phyllophora_, _Ahnfeltia_; _Chondrus crispus_, with dark red, dichotomously branched thallus, is common on the coasts of Scandinavia and Great Britain. Order 7. =Rhodophyllidaceæ.= _Rhodophyllis_, _Euthora_; _Cystoclonium purpurascens_ is common, and sometimes the ends of its branches may be modified into tendril-like haptera. Sub-Family 3. =Rhodymeniales.= The fertilised auxiliary cell forms the gonimoblast on the side away from the thallus. Procarpia are abundantly produced. Order 8. =Sphærococcaceæ.= _Gracilaria._ Order 9. =Rhodymeniaceæ.= _Rhodymenia palmata_ is a common species. _Lomentaria_, _Chylocladia_, _Plocamium_. Order 10. =Delesseriaceæ.= _Delesseria sanguinea_; _D. alata_ and _D. sinuosa_ are handsome forms which are not uncommon. Order 11. =Bonnemaisoniaceæ.= _Bonnemaisonia._ Order 12. =Rhodomelaceæ.= _Rhodomela_, _Odonthalia_; _Polysiphonia_, of which many species are to be found on the coasts of Great Britain, has a filamentous, richly branched thallus consisting of a central row of cells surrounded by a varying number of cortical cells of similar size--the so-called “siphons.” Order 13. =Ceramiaceæ.= Pretty Algæ, often branched dichotomously, or unilaterally pinnate. _Spermothamnion, Griffithsia, Callithamnion, Ceramium, Ptilota._ Sub-Family 4. =Cryptonemiales.= The cells formed by the coalescence of the auxiliary cells and the ooblastema-filaments, produce the gonimoblasts. The _carpogonium-filaments_ and the auxiliary cells are scattered singly in the thallus. Order 14. =Gloiosiphoniaceæ.= _Gloiopeltis._ Order 15. =Grateloupiaceæ.= _Halymenia, Cryptonemia._ Order 16. =Dumontiaceæ.= _Dumontia, Dudresnaya._ Order 17. =Nemastomaceæ.= _Furcellaria_, which has dichotomously branched, round shoots, is common on the coasts of Great Britain. Order 18. =Rhizophyllidaceæ.= _Polyides, Rhizophyllis._ Order 19. =Squamariaceæ.= The Algæ belonging to this order form crust-like coverings on stones, mussel-shells, and on other Algæ, but are not themselves incrustated: _Petrocelis_, _Cruoria_, _Peyssonellia_. Order 20. =Corallinaceæ.= Partly crustaceous, partly erect, branched Algæ, thickly incrusted with lime, so that a few species (_Lithothamnia_, also called _Nullipora_) occur in fossilized condition from Jurassic to Tertiary periods. _Melobesia, Lithophyllum, Lithothamnion, Corallina._ USES. “Carragen” is the thallus of _Chondrus crispus_ (Irish Moss) and _Gigartina mamillosa_. It is a common article of food on the coasts of Ireland, and swells to a jelly when cooked. It is officinal. _Rhodymenia palmata_ is generally eaten as food in Ireland and in some places on the west coast of Norway; it is also used as food for sheep and hence is termed “Sheep-seaweed.” Agar-Agar is the jelly obtained from species of _Gelidium_ and _Gigartina_ growing in China and Japan. Sub-Division III. =FUNGI.= =Mode of Life.= The Fungi have no chlorophyll, and are thus unable in any stage of their existence to assimilate carbon; they must therefore live as _saprophytes_ or _parasites_. There is, however, no strong line of demarcation between these; many Fungi commence as true parasites, but only attain their full development upon or in dead plants or animals (_Rhytisma_, _Empusa_). Many saprophytes may occasionally appear as parasites, and are then designated “_facultative parasites_” (_Nectria cinnabarina_, _Lophodermium pinastri_), in contradistinction to those which only appear as parasites, “_obligate parasites_” (Mildew, Brand-and Rust-Fungi, _Cordyceps_). The parasites which live on the surface of the host-plant are termed _epiphytic_ (Mildew, _Fusicladium_); and those living in its tissues are termed _endophytic_ (_Ustilago_, _Peronospora_). _Epizoic_ (_Oidium tonsurans_, _Laboulbenia_) and _endozoic_ Fungi (_Cordyceps_, _Entomophthora_), are distinguished, in the same manner, as those which live on the surface or in the interior of animals. The Fungi designated _pathogenic_ are especially those which produce disease in human beings and in animals. Most of the diseases of plants are attributed to the parasitic Fungi. These force their way into the host-plant by piercing the outer wall of the epidermis, as in the Potato-disease; or by growing in through the stomata, _e.g._ the summer generations of the Rust of Wheat; or they can only penetrate through a wound, _e.g. Nectria_. Some effect an entrance into the host-plant by the secretion of a poisonous matter or ferment, which softens and destroys the cell-walls (_Sclerotinia_). Some Yeast and Mould Fungi secrete ferments (enzymes), which, for example, convert cane-sugar into a sugar capable of fermentation. The relation of the parasitic Fungus to the host-plant is mainly of two kinds. In the one case, the cell-contents are destroyed, the protoplasm is killed, and the cellular tissue becomes discoloured and dies (_Peronospora_, _Armillaria mellea_, _Polyporus_); in the other case, the parasite has an irritating effect on the cellular tissue, whereby the affected organ grows more rapidly and becomes larger than normal, producing _hypertrophy_. Such malformations are termed _Fungi-galls_ (Mycocecidia); in this manner “witches’ brooms” are produced by _Æcidium_, “pocket-plum” by _Taphrina_, and other deformities by _Exobasidium_ and _Cystopus candidus_. This hypertrophy may either be produced by a vigorous cell-multiplication, which is most frequently the case, or by the enlargement of the individual cells (_Synchytrium_, _Calyptospora_). The relation between host and Fungus among the Lichens is of a very peculiar nature, termed “_symbiosis_.” =Vegetative Organs.= The vegetative parts of a Fungus are termed its _mycelium_.[10] This is formed of a mass of long, cylindrical, branched cells resembling threads (and hence termed _hyphæ_), which have a continued apical growth. The mycelium, in its early development, shows a well-marked difference between the two main groups of true Fungi: in the _Phycomycetes_, or Algal Fungi, the mycelium has no transverse walls, and is therefore unicellular, while in the _Mesomycetes_ and _Mycomycetes_ it is provided with dividing walls, which gradually arise during growth, in the youngest hyphæ; intercalary transverse walls may also be formed at a later period. In the hyphæ of some of the Higher Fungi (_Hymenomycetes_), connections may be formed between two contiguous cells of the same hypha, by a protuberance growing out from an upper cell just above the transverse wall, and forming a junction with the cell below. These are known as _clamp-connections_; they appear to be of use in affording communication between the two cells. The hyphæ of Fungi, where they come in contact with one another, often grow together, so that =H=-formed combinations (fusions) are produced, which give rise to very compact felted tissue. When the hyphæ are not only closely interwoven, but also united and provided with many transverse walls, the mycelium assumes the appearance of a tissue with isodiametric cells, and is then termed _pseudo-parenchyma_. The hyphæ-walls are sometimes very much thickened, and composed of several layers, and the external layers, by the absorption of water, may often swell very much and become mucilaginous. In some instances the walls are colourless, in others coloured, the most frequent colour being brown. The cell-contents may also be coloured, and in that case are generally yellow; this colour is chiefly connected with the fat (oil) which may be found in abundance in the Fungi, whilst starch is invariably absent in all the true Fungi. The mycelium assumes many different forms; sometimes it appears as a thread-like, cobwebby, loose tissue, less frequently as firm strands, thin or thick membranes, horn-like plates or tuber-like bodies. The _thread-like_ mycelium may, in the parasitic Fungi, be intercellular or intracellular, according as it only extends into the interstices between the cells or enters into the cells proper. In the first case there are generally found haustoria, or organs of suction (_e.g._ among the _Peronosporaceæ_; _Taphrina_, on the contrary, has no haustoria); but haustoria are also found among the epiphytic Fungi (_e.g._ Erysiphaceæ). Intracellular mycelia are found in the Rust-Fungi, in _Claviceps purpurea_, _Entomophthora_, etc. In spite of its delicate structure, this mycelium may live a long time, owing to the circumstance that it continues to grow peripherally, while the older parts gradually die off (“fairy rings”). _String-like_ mycelia may be found, for example, in _Phallus_, _Coprinus_, and are formed of hyphæ, which run more or less parallel to each other. _Membrane-like_ mycelia are chiefly to be found in Fungi growing on tree-stems (Polyporaceæ and Agaricaceæ); they may have a thickness varying from that of the finest tissue-paper to that of thick leather, and may extend for several feet. The peculiar horny or leather-like strands and plates which, for instance, appear in _Armillaria mellea_, are known as _Rhizomorpha_; they may attain a length of more than fifty feet. The _tuber-like_ mycelia or _sclerotia_ play the part of resting mycelia, since a store of nourishment is accumulated in them, and after a period of rest they develope organs of reproduction. The sclerotia are hard, spherical, or irregular bodies, from the size of a cabbage seed to that of a hand, internally white or greyish, with a brown or black, pseudo-parenchymatous, external layer. Sclerotia only occur in the higher Fungi, and are found both in saprophytes, _e.g. Coprinus_, and in parasites, _e.g. Claviceps_ (Ergot), _Sclerotinia_. =Reproduction.= SEXUAL REPRODUCTION is found only among the lower Fungi which stand near to the Algæ, the Algal-Fungi, and takes place by the same two methods as in the Algæ, namely by _conjugation_ and by the _fertilisation_ of the egg-cell in the oogonium. The majority of Fungi have only ASEXUAL reproduction. The most important methods of this kind of reproduction are the _sporangio-fructification_ and the _conidio-fructification_. In the SPORANGIO-FRUCTIFICATION the _spores_ (endospores) _arise inside_ a mother-cell, the sporangium (Fig. 80). Spores without a cell-wall, which move in water by means of cilia and hence are known as _swarmspores_ or _zoospores_, are found among the Oomycetes, the sporangia in which these are produced being called swarm-sporangia or zoosporangia (Figs. 86, 87, 91, 94). In the CONIDIO-FRUCTIFICATION the _conidia_ (exospores) arise on special hyphæ (conidiophores), or directly from the mycelium. When conidiophores are present, the conidia are developed upon them terminally or laterally, either in a basipetal succession (in many Fungi, for example in _Penicillium_, Fig. 111, _Erysiphe_, _Cystopus_), or acropetally (in which method the chains of conidia are often branched; examples, _Pleospora vulgaris_, _Hormodendron cladosporioides_). All conidia are at first unicellular, sometimes at a later stage they become two-celled or multicellular through the formation of partition-walls (_Piptocephalis_). The conidia with thick, brown cell-walls, and contents rich in fats (_resting conidia_), can withstand unfavourable external conditions for a much longer period than conidia with thin walls and poor in contents. The SPORANGIA arise either from the ordinary cells of the mycelium (_Protomyces_), or are borne on special hyphæ. They are generally spherical (_Mucor_, Fig. 80; Saprolegniaceæ), egg-, pear-, or club-shaped (Ascomycetes), more rarely they are cylindrical or spindle-shaped. While among the Phycomycetes the size, form, and number of spores are indefinite in each species, in the Ascomycetes the sporangia (_asci_) have a definite size, form, and number of spores. The spores of the Ascomycetes are known as ascospores. The sporangio-fructification is found under three main forms. 1. FREE SPORANGIOPHORES which are either single (_Mucor_, Fig. 78), or branched (_Thamnidium_). 2. SPORANGIAL-LAYERS. These are produced by a number of sessile or shortly-stalked sporangia, being formed close together like a palisade (_Taphrina_, Fig. 105). 3. SPORANGIOCARPS. These consist usually of many sporangia enclosed in a covering, they are found only in the Carpoasci, and are also known as _ascocarps_. The parts of an ascocarp are the _covering_ (_peridium_), and the _hymenium_, which is in contact with the inner wall of the peridium, and is generally made up of asci, and sterile, slender hyphæ. The latter either penetrate between the asci and are branched and multicellular (_paraphyses_, Figs. 103 _d_, 123, 125, 129), or clothe those parts of the inner wall which bear no asci (_periphyses_; among many peronocarpic Ascomycetes, _e.g. Chætomium_, _Sordaria_, _Stictosphæra hoffmanni_). The ascocarps are produced directly from the mycelium, or from a _stroma_, that is a vegetative body of various forms, in which they may be embedded (Figs. 116 _B_, _C_). Among the conidio-fructifications there are, in the same way, three divisions. 1. FREE CONIDIOPHORES (Fig. 109). The form of the conidiophores, the shape, and number of its spores are various. In the most highly developed Fungi, the Basidiomycetes, there are, however, special more highly developed conidiophores, the _basidia_, which have a definite form and spores of a definite shape and number. The conidia borne on basidia are called _basidiospores_. 2. CONIDIAL-LAYERS. (_a_) The SIMPLEST case of this is found when the conidiophores arise directly from the mycelium, parallel to one another, and form a flat body (_e.g. Exobasidium vaccinii_, _Hypochnus_; among the Phycomycetes, _Empusa muscæ_ and _Cystopus_). (_b_) In a HIGHER form the conidial-layers are thick, felted threads (_stroma_) inserted between the mycelium and the _hymenium_ (_i.e._ the region of the conidiophores). Examples are found in a section of the Pyrenomycetes (Fig. 122). (_c_) The HIGHEST form has the _basidial-layer_, that is a conidial-layer with more highly developed conidiophores (basidia). The basidial-layer, with stroma, and the hymenium (region of the basidia), forms the basidio-fructification, which is branched in the Clavariaceæ, and hat-shaped in other Hymenomycetes (in these groups the hymenium is confined to the lower side of the pileus). The hymenium of the conidial-layer and basidial-layer is composed entirely of conidiophores, or of conidiophores and sterile hyphæ (_paraphyses_) which are probably always unicellular. Paraphyses are found in _Entomophthora radicans_, and in certain Basidiomycetes (_e.g. Corticium_). 3. CONIDIOCARPS (_pycnidia_). A special covering surrounds the conidia-forming elements. The inner side of this covering (_peridium_) bears the hymenium, _i.e._ those elements from which the conidia are abstricted. The conidiocarps arise either immediately from the hyphæ or from a _stroma_ in which they are generally embedded. Conidiocarps are entirely wanting in the Phycomycetes. On the other hand they are found among the Ascomycetes and Basidiomycetes, and in the latter group the conidiocarps contain more highly differentiated conidiophores (basidia) and are known as _basidiocarps_. Conidiocarps with simple conidiophores, are found only among the Basidiomycetes, in the Uredinaceæ, and in _Craterocolla cerasi_. In the Ascomycetes (Figs. 120 _d_, _e_; 117 _a_, _b_; 123 _a_; 124 _b_) the conidiocarps are visible, as points, to the naked eye, while the basidiocarps of the Basidiomycetes (Figs. 170, 171, 173–176, 178–180) vary from the size of a pea to that of a child’s head. The “spermogonia” of the Ascomycetes and Lichenes, are conidiocarps with small conidia (_microconidia_) which germinate sometimes more slowly than other conidia, and formerly were erroneously considered as male reproductive cells, and called spermatia. The conidia of the Fungi are not primitive structures. The comparison of the sporangia and conidia among the Zygomycetes, and among the species of the genus _Peronospora_ shows, that the conidia are aberrant formations, and that they have arisen through the degeneration of the sporangium, which, by the reduction of its spores to one, has itself become a spore. In the genera _Thamnidium_ and _Chætocladium_ the gradual diminution of the sporangia, and the reduction of the number of spores can be distinctly followed. In _Thamnidium_ the number of spores is often reduced to one, which is _free_ in the sporangium. In _Chætocladium_ however the sporangia are typically _one-spored_, the spore is always united with the sporangium, and the two become a single body, the so-called _conidium_, which is in reality a closed sporangium. How close is the connection between the sporangia and conidia of _Thamnidium_ and _Chætocladium_, is seen from the fact that, in the conidial stage of _Chætocladium_ the same whorl-form of branching appears as in the sporangial stages of _Thamnidium chætocladioides_, and also, that the conidia of _Ch. fresenianum_ throw off the former sporangium-wall (exosporium), while _Ch. jonesii_ germinates without shedding its exosporium. The Phycomycetes have doubtless sprung from Water-Algæ and inherit the sporangia from them. On this supposition, as the Phycomycetes assumed a terrestrial mode of life, the sporangia would become adapted to the distribution of the spores by means of the air, the sporangia would become small, contain dust-like spores, and would eventually become closed-sporangia, _i.e._ conidia. The conidia are a terrestrial method for the multiplication of Fungi. In the Hemiasci and the Ascomycetes the sporangia are still preserved, but in every instance they are adapted to terrestrial spore-distribution, their spores being set free on the destruction of the sporangium-wall (generally shot out) and distributed through the air. For further examples of spore-distribution see below, p. 91–93. The reproduction of Fungi is accomplished not only by spores and conidia, but also sometimes by _chlamydospores_. These are fundaments[11] of sporangiophores and conidiophores, which have taken on a resting condition in the form of a spore, and are able to germinate and produce carpophores. In the formation of the chlamydospores the hyphæ accumulate reserve materials at the expense of the neighbouring cells; in the undivided hyphæ of the Phycomycetes transverse walls are formed, and finally the chlamydospores are set free by the decay of the empty cells connecting them with the mycelium. One must distinguish between _oidia_ and _true chlamydospores_. The former are more simple, the latter are a somewhat more differentiated form of carpophore fundaments, which serve for propagation in the same manner as spores. In _Chlamydomucor racemosus_ the chlamydospores grow out into the air and form differentiated carpophores. In the Autobasidiomycetes they only germinate vegetatively, and not with the formation of fructifications. From _Chlamydomucor_ up to the Autobasidiomycetes the successive development of the fructification, which is interrupted by the formation of the chlamydospores, degenerates more and more. Among certain Ustilagineæ the chlamydospores (brand-spores) no longer germinate with the production of fructifications. In the Uredinaceæ, only one of the three chlamydospore-forms has the property of producing fructifications on germination; the other forms only germinate vegetatively, like ordinary spores, and in the same manner as the chlamydospores of the Autobasidiomycetes. In the Hemibasidii, and the Uredinaceæ, in _Protomyces_, the chlamydospores are the chief means of reproduction. They are found also among the Ascomycetes. The sporangia and the conidia of the Fungi have their common origin in the sporangia of the Phycomycetes. The asci (and the Ascomycetes which are characterised by these bodies) are descended from the sporangia-forming, lower Fungi; the basidia (and the Basidiomycetes) from those which bear conidia. _The sporangia of the Phycomycetes are the primitive form and the starting point for all the reproductive forms of the Fungi._ The chlamydospores appear besides in all classes of Fungi as supplementary forms of reproduction, and are of no importance in determining relationships. Although the expression “fruit” must essentially be applied to true Phanerogams, yet, through usage, the term “_fruit-forms_,” is employed to designate the forms or means of reproduction of Fungi, and the organs of reproduction are known as _organs of fructification_, the sporangiophores and conidiophores as _fruit-bearers_ (_carpophores_), and the sporangiocarps, conidiocarps, and basidiocarps as “_fruit-bodies_.” The majority of Fungi have more than one method of reproduction, often on various hosts (Uredinaceæ). Species with one, two, or more than two methods of reproduction are spoken of as having monomorphic, dimorphic, or pleomorphic fructification. Monomorphic, _e.g._ the Tuberaceæ; dimorphic, _Mucor_, _Piptocephalis_, Saprolegniaceæ, _Penicillium crustaceum_; pleomorphic, _Puccinia graminis_, _Capnodium salicinum_ (in the last species there are five methods of reproduction: yeast-like conidia, free conidiophores, conidiocarps with small and large conidia, and ascocarps). =The liberation and distribution of the spores and conidia.= The spores and conidia, on account of their small size and lightness, are spread far and wide by currents in the air, but in addition to this method, insects and other animals frequently assist in disseminating them. The liberation of the conidia is occasionally effected by the complete shrinking away of the conidiophore, but more frequently by abstriction from the conidiophores, either by their gradually tapering to a point, or by the dissolution of a cross-wall (generally of a mucilaginous nature). The individual links of conidia-chains are detached from one another in the same way, or often by means of small, intercalary cells, which are formed at the base of the individual links, and becoming slimy, dissolve upon the maturity of the spores. Special contrivances for ejecting the spores and conidia may often be found. In _Peronospora_ the cylindrical fruit-hyphæ in the dry condition become strap-shaped and also twisted. These are very hygroscopic, and the changes of form take place so suddenly, that the spores are violently detached and shot away. In _Empusa_ a peculiar squirting mechanism may be found (Fig. 85). Each club-shaped hypha which projects from the body of the fly, bears a conidium at its apex; a vacuole, which grows gradually larger, is formed in the slimy contents of the hypha, and the pressure thereby eventually becomes so great that the hypha bursts at its apex, and the conidium is shot into the air. By a similar mechanism, the spores of many of the Agaricaceæ are cast away from the parent-plants. In the case of _Pilobolus_ (Fig. 84) the entire sporangium is thrown for some distance into the air by a similar contrivance, the basal region of the sporangium having, by the absorption of water, been transformed into a slimy layer which is readily detached. _Sphærobolus_, a Gasteromycete, has a small, spherical fruit-body (basidiocarp), the covering of which, when ripe, suddenly bursts, and the basidiospores contained in it are forcibly ejected. _The spores which are enclosed in asci_ are, in some instances, set free from the mother-cell (ascus) prior to their complete development (_Elaphomyces_, _Eurotium_). In the case of the majority of the Pyrenomycetes and Truffles, the asci swell by the absorption of water into a slimy mass, which gradually disappears, so that the spores lie free in the fruit-body; they either remain there till the fruit-body decays, as in those which have no aperture (Perisporiaceæ, Tuberaceæ), or the slimy mass, by its growth, is forced out through the aperture of the sporocarp, taking the spores with it (_Nectria_). The ejection of the spores by mechanical means takes place in a number of Ascomycetes, and should many spores be simultaneously ejected, a dust-cloud may be seen with the naked eye to arise in the air from the fruit-body. This is the case in the larger species of _Peziza_, _Helvella_, _Rhytisma_, when suddenly exposed to a damp current of air. A distinction is drawn between a simultaneous ejection of all the spores contained in the ascus, and an ejection at intervals (successive), when only one spore at a time is thrown out. The first of these methods is the most frequent, and is brought about by the ascus being lined with a layer of protoplasm, which absorbs water to such a degree that the elastic walls are extended at times to double their original size. The spores are forced up against the free end of the ascus, a circular rupture is made at this point, and the elastic walls contract, so that the fluid with the spores is ejected. Special means may in some instances be found to keep the spores together, and compel their simultaneous ejection. Thus, a tough slime may surround all the spores (_Saccobolus_), or a chain-apparatus, similarly formed of tough slime; or there may be a hooked appendage from each end of the spores which hooks into the appendage of the next spore (_Sordaria_). The paraphyses occurring between the asci in many Ascomycetes, also play a part in the distribution of the spores, by reason of the pressure they exercise. The asci in some of the Pyrenomycetes, which are provided with jar-shaped fruit-bodies, elongate to such an extent that, without becoming detached from their bases, they reach the mouth of the fruit-body one at a time, burst and disperse their spores, and so make room for those succeeding. An ejection of the spores at intervals from the ascus is rarer. It takes place, for instance, in _Pleospora_, whose asci have a double wall. The external wall, by absorption of water, at last becomes ruptured, and the internal and more elastic membrane forces itself out in the course of a few seconds to one of two or three times greater length and thickness, so that one spore after another is forcibly ejected from a narrow aperture at the end of the ascus. =Germination of spores= (conidia and chlamydospores). In many spores may be found one or more _germ-pores_, _i.e._ thinner places, either in the inner membrane (uredospores, _Sordaria_) or in the external membrane (teleutospores in Rust-Fungi), through which the germination takes place. Generally this does not occur till the spores have been set free: in some Ascomycetes germination commences inside the ascus (_Taphrina_, _Sclerotinia_). The different ways in which the spores germinate may be classified into three groups. I. THE ORDINARY GERMINATION occurs by the spore emitting a germ-tube, which immediately developes into a mycelium. In spores with a double wall it is only the inner membrane which forms the germ-tube. In swarmspores a single wall is formed after the withdrawal of the cilia, and this, by direct elongation, becomes the germ-tube. The protoplasm accumulated in the spore enters the hypha, which, in pure water, can only grow as long as the reserve nourishment lasts. =2.= GERMINATION WITH PROMYCELIUM differs only by the circumstance that the hypha developed from the germ-tube has a very limited growth, and hence it does not immediately develope into a mycelium, but produces conidia (Rust-and Brand-Fungi). This promycelium must only be regarded as an advanced development of a conidiophore or basidium. =3.= THE YEAST-FORMATION of conidia consists in the production of outgrowths, very much constricted at their bases, from one or more places. Each of the conidia formed in this manner may again germinate in the same way. When sufficient nourishment is present, a branched chain of such conidia is formed, and these are finally detached from one another. Yeast-like buddings from the conidia are produced in various Fungi, _e.g. Ascoidea_, _Protomyces_, Ustilagineæ, Ascomycetes, Tremellaceæ, etc. In the Ustilagineæ these conidia are an important element in the development. The budding conidia of _Exobasidium_ forms a “mould” on the nutritive solution. The yeast-like conidia are not to be confounded with the “Mucor-yeast” (comp. Mucoraceæ). For _Saccharomyces_ see Appendix to the Fungi, page 176. In a compound spore (_i.e._ when a mass of spores are associated together) each spore germinates on its own account. There are sometimes, however, certain among them which do not germinate, but yield their contents to those which do. The _length of time_ for which conidia can retain their power of germination is shortest (being only a few weeks) in those having thin walls and containing a large supply of water (Peronosporaceæ, Uredinaceæ). In many spores a resting period is absolutely necessary before they are able to germinate (resting spores). It has been observed in some spores and conidia, that the faculty of germinating may be preserved for several years if the conditions necessary for germination remain absent (Ustilagineæ, _Eurotium_, _Penicillium_). The optimum, minimum and maximum temperatures required for the germination of the spores has been decided in the case of a good many Fungi. A large portion of the most common Fungi have their optimum at 20°C., minimum at 1–2°C, maximum at 40°C. In the case of pathogenic Fungi the optimum is adapted to the temperature of the blood. Fungi living in manure, whose spores are often adapted to germinate in the alimentary canals of warm-blooded animals, have an optimum corresponding to the temperature of these animals, but with a little margin. =Systematic Division.=--The lowest class of the Fungi is that of the PHYCOMYCETES, which have an unicellular mycelium, sexual and asexual reproduction, and have doubtless sprung from sporangia-bearing, lower Green Algæ. From the Phycomycetes (and certainly from the Zygomycetes) spring two well defined branches, each with numerous distinct species; to the one branch belong the HEMIASCI and the ASCOMYCETES, to the other the HEMIBASIDII and the BASIDIOMYCETES. Ascomycetes and Basidiomycetes may be united under the title of MYCOMYCETES or HIGHER FUNGI. The Hemiasci and the Hemibasidii constitute the class of MESOMYCETES. The Hemiasci are an intermediate form between Zygomycetes and Ascomycetes; the Hemibasidii a similar group between the Zygomycetes and Basidiomycetes. Mesomycetes and Mycomycetes have only asexual reproduction; sexual reproduction is wanting. Their mycelium is multicellular. Up to the present time about 39,000 species have been described. Review of the divisions of the Fungi:-- Class I.--=Phycomycetes (Algal-Fungi).= Sub-Class 1. =Zygomycetes.= Sub-Class 2. =Oomycetes.= Family 1. ENTOMOPHTHORALES. Family 2. CHYTRIDIALES. Family 3. MYCOSIPHONALES. Class II. =Mesomycetes.= Sub-Class 1. =Hemiasci.= Sub-Class 2. =Hemibasidii (Brand-Fungi).= Class III.--=Mycomycetes (Higher Fungi).= Sub-Class 1. =Ascomycetes.= Series 1. =Exoasci.= Series 2. =Carpoasci.= Family 1. GYMNOASCALES. } Family 2. PERISPORIALES. } Angiocarpic Exoasci. Family 3. PYRENOMYCETES. } Family 4. HYSTERIALES. } Hemiangiocarpic Exoasci. Family 5. DISCOMYCETES.} Family 6. HELVELLALES. Gymnocarpic (?) Exoasci. Additional: ASCOLICHENES. Lichen-forming Ascomycetes. Sub-Class 2. =Basidiomycetes.= Series 1.--Protobasidiomycetes. Partly gymnocarpic, partly angiocarpic. Series 2. Autobasidiomycetes. Family 1. DACRYOMYCETES. Gymnocarpic. Family 2. HYMENOMYCETES. Partly gymnocarpic, partly hemiangiocarpic. Family 3. PHALLOIDEÆ. Hemiangiocarpic. Family 4. GASTEROMYCETES. Angiocarpic. Additional: BASIDIOLICHENES. Lichen-forming Basidiomycetes. Additional to the Fungi: FUNGI IMPERFECTI. Incompletely known (_Saccharomyces_, _Oidium_-forms, etc.). Class 1. =Phycomycetes (Algal-Fungi).=[12] This group resembles _Vaucheria_ and the other Siphoneæ among the Algæ. ORGANS OF NUTRITION. The mycelium is formed of a single cell, often thread-like and abundantly branched (Fig. 78). Vegetative propagation by chlamydospores and oidia. Asexual reproduction by endospores (sometimes _swarmspores_) and conidia. Sexual reproduction by conjugation of two hyphæ as in the Conjugatæ, or by fertilisation of an egg-cell in an oogonium. On this account the class of the Phycomycetes is divided into two sub-classes: ZYGOMYCETES and OOMYCETES. Sub-Class I. =Zygomycetes.= Sexual reproduction takes place by zygospores, which function as resting-spores, and arise in consequence of _conjugation_ (Fig. 81); in the majority of species these are rarely found, and only under special conditions. The most common method of reproduction is by endospores, by acrogenous conidia, by chlamydospores, or by oidia. _Swarmspores are wanting._ Parasites and saprophytes (order 6 and 7). The zygospores are generally produced when the formation of sporangia has ceased; _e.g._ by the suppression of the sporangial-hyphæ (_Mucor mucedo_), or by the diminution of oxygen; _Pilobolus crystallinus_ forms zygospores, when the sporangia are infected with saprophytic _Piptocephalis_ or _Pleotrachelus_. =A.= Asexual reproduction only by sporangia. Order 1. =Mucoraceæ.= The spherical sporangia contain many spores. The zygospore is formed between two unicellular branches (gametes). The unicellular mycelium (Fig. 78) of the Mucoraceæ branches abundantly, and lives, generally, as a saprophyte on all sorts of dead organic remains. Some of these Fungi are known to be capable of producing _alcoholic fermentation_, in common with the Saccharomyces. This applies especially to _Chlamydomucor racemosus_ (_Mucor racemosus_), when grown in a saccharine solution, and deprived of oxygen; the mycelium, under such conditions, becomes divided by transverse walls into a large number of small cells. Many of these swell out into spherical or club-shaped cells, and when detached from one another become chlamydospores, which abstrict new cells of similar nature (Fig. 79). These chlamydospores were formerly erroneously termed “mucor-yeast,” but they must not be confounded with the yeast-conidia (page 94). They are shortened hyphæ, and are not conidia of definite size, shape, and point of budding. Oidia are also found in _Chlamydomucor_. [Illustration: FIG. 78.--_Mucor mucedo._ A mycelium which has sprung from one spore, whose position is marked by the *: _a_, _b_, _c_ are three sporangia in different stages of development; _a_ is the youngest one, as yet only a short, thick, erect branch; _b_ is commencing to form a sporangium which is larger in _c_, but not yet separated from its stalk.] The Mucoraceæ, in addition to the chlamydospores and oidia, have a more normal and ordinary method of reproduction; viz., by _spores_ which are formed without any sexual act. _Mucor_ has round sporangia; from the mycelium one or more long branches, sometimes several centimetres in length, grow vertically into the air; the apex swells (Figs. 78, 80) into a sphere which soon becomes separated from its stalk by a transverse wall; in the interior of this sphere (sporangium) a number of spores are formed which eventually are set free by the rupture of the wall. The transverse wall protrudes into the sporangium and forms the well-known columella (Fig. 80 _d_, _e_). The formation of spores takes place in various ways among the different genera. [Illustration: FIG. 79.--Chlamydospores of _Chlamydomucor racemosus_ (× 375 times.)] [Illustration: FIG. 80.--_Mucor mucedo_: _a_ a spore commencing to germinate (× 300 times); _b_ a germinating spore which has formed a germ-tube from each end (× 300 times); _c_ the apex of a young sporangium before the formation of spores has commenced; the stalk is protruded in the sporangium in the form of a column: on the wall of the sporangium is found a very fine incrustation of lime in the form of thorn-like projections; _d_ a sporangium in which the formation of spores has commenced; _e_ a sporangium, the wall of which is ruptured, leaving a remnant attached to the base of the columella as a small collar. A few spores are seen still adhering to the columella.] SEXUAL REPRODUCTION by conjugation takes place in the following manner. The ends of two hyphæ meet (Fig. 81) and become more or less club-shaped; the ends of each of these are cut off by a cell-wall, and two new small cells (Fig. 81 _A_) are thus formed, these coalesce and give rise to a new cell which becomes the very thick-walled zygote (zygospore), and germinates after period of rest, producing a new hypha, which bears a sporangium (Fig. 81 _E_). _Mucor mucedo_, Pin-mould, resembles somewhat in appearance _Penicillium crustaceum_ and is found growing upon various organic materials (bread, jam, dung, etc.). _Pilobolus_ (Figs. 83, 84) grows on manure. Its sporangium (Fig. 84 _a″_) is formed during the night and by a peculiar mechanism (page 92) is shot away from the plant in the course of the day. This generally takes place in the summer, between eight and ten a.m. The sporangium is shot away to a height which may be 300 times greater than that of the plant itself, and by its stickiness it becomes attached to portions of plants, etc., which are in the vicinity. If these are eaten by animals, the spores pass into the alimentary canal and are later on, sometimes even in a germinating condition, passed out with the excrement, in which they form new mycelia. _Phycomyces nitens_ (“Oil-mould”) is the largest of the Mould Fungi; its sporangiophores may attain the height of 10–30 c.m. Order 2. =Rhizopaceæ.= _Rhizopus nigricans_ (_Mucor stolonifer_) which lives on decaying fruits containing sugar, on bread, etc., has, at the base of the sporangiophores, tufts of rhizoids, _i.e._ hyphæ, which function as organs of attachment. From these, “runners” are produced which in a similar manner develope sporangiophores and rhizoids. [Illustration: FIGS. 81, 82.--_Mucor mucedo_: _A-C_ stages in the formation of the zygote; D zygote; E germination of zygote: the exospore has burst, and the endospore grown into a hypha bearing a sporangium.] Order 3. =Thamnidiaceæ.= On the same sporangiophore, in addition to a large, terminal, many-spored sporangium, many smaller, lateral sporangia are formed with a few spores. Thamnidium. =B.= Asexual reproduction by sporangia and conidia. Order 4. =Choanephoraceæ.= _Choanephora_ with creeping endophytic mycelium, and perpendicular sporangiophores. Order 5. =Mortierellaceæ.= _Mortierella polycephala_ produces on the same mycelium conidia and sporangiophores. _M. rostafinskii_ has a long stalked sporangiophore, which is surrounded at its base by a covering of numerous felted hyphæ. [Illustration: FIG. 83.--_Pilobolus._ Mycelium (_a_, _a_), with a sporangiophore (_A_) and the fundament of another (_B_).] [Illustration: FIG. 84.--_Pilobolus._ Sporangium (_a″_) with stalk (_a-c_), which is covered by many small drops of water pressed out by turgescence.] =C.= Asexual reproduction only by conidia. Order 6. =Chætocladiaceæ.= The conidia are abstricted singly and acrogenously. _Chætocladium_ is a parasite on the larger Mucoraceæ. Order 7. =Piptocephalidaceæ.= The conidia are formed acrogenously and in a series, by transverse divisions. The zygospore arises at the summit of the conjugating hyphæ, which are curved so as to resemble a pair of tongs. _Piptocephalis_ and _Syncephalis_ live parasitically on the larger Mucoraceæ. Sub-Class 2. =Oomycetes.= Sexual reproduction is oogamous with the formation of brown, thick-walled _oospores_ which germinate after a period of rest. Asexual reproduction by conidia and _swarmspores_. Parasites, seldom saprophytes. The oospores are large spores which are formed from the egg-cell (oosphere) of the _oogonium_ (oosporangium, Fig. 89, 95). A branch of the mycelium attaches itself to the oogonium and forms at its apex the so-called “_antheridium_” (pollinodium[13]): this sends one or more slender prolongations (fertilising tubes) through the wall of the oogonium to the egg-cell. [Illustration: FIG. 85.--_Empusa muscæ_ (Fly-mould). I. A fly killed by the fungus, surrounded by a white layer of conidia. II. The conidiophores (_t_) projecting from the body of the fly. Some of the conidia, a few of which have developed secondary conidia, are attached to the hairs (mag. 80 times). III. A perfect hypha. IV. A hypha in the act of ejecting a conidium (_c_), enveloped in a sticky slime (_g_). V. A conidium which has developed a secondary conidium (_sc_). VI. A branched hypha produced by cultivation. VII. A secondary conidium which has produced a small mycelium (_m_). VIII. A conidium germinating on the fly’s body. IX. Mycelium. X. Conidia germinating like yeast in the fatty tissue of the fly. (III.-VII. and IX. magnified 300 times; VIII. and X. magnified 500 times.)] A fertilisation, a passage of the contents of the antheridium to the egg-cell, has as yet only been observed in _Pythium_; in _Phytophthora_ only one small mass of protoplasm passes through the fertilising tube to the egg-cell; in _Peronospora_ and the Saprolegniaceæ no protoplasm can be observed to pass through the fertilising tube, so that in these instances _parthenogenesis_ takes place; _Saprolegnia thuretii_, etc., have generally even no antheridia, but nevertheless form normal oospores. Fertilisation of the egg-cell by means of self-motile _spermatozoids_ is only found in _Monoblepharis sphærica_. =A.= Asexual reproduction by conidia only. Family 1. =Entomophthorales.= The mycelium is richly branched. The family is a transitional step to the conidia-bearing Zygomycetes, since the oospores of many members of this family arise, and are formed, like zygospores. Order 1. =Entomophthoraceæ.= Mycelium abundantly developed. This most frequently lives parasitically in living insects, causing their death. The conidiophores forming the conidial-layer project from the skin, and abstrict a proportionately large conidium which is ejected with considerable force, and by this means transferred to other insects. These become infected by the entrance of the germ-tube into their bodies. The spherical, brown resting-spores develope inside the bodies of insects and germinate by emitting a germ-tube. GENERA: _Empusa_ has a good many species which are parasitic on flies, moths, grasshoppers, plant-lice. The conidia emit a germ-tube which pierces the skin of the insect; a number of secondary conidia are then produced inside its body, by division or by gemmation similar to that taking place in yeast, each of which grows and becomes a long unbranched hypha, and these eventually fill up the body of the animal, causing distension and death. Each of these hyphæ projects through the skin, and abstricts a conidium, which is ejected by a squirting contrivance. The best known species is _E. muscæ_ (Fig. 85), which makes its appearance epidemically towards autumn on the common house-fly, and shows itself by the dead flies which are found on the windows and walls attached by their probosces, distended wings, and legs. They have swollen abdomen, broad white belts of hyphæ between the abdominal rings, and are surrounded by a circle of whitish dust formed by the ejected conidia.--_Entomophthora_ sends out, at definite places, from the mycelium hidden in the insect’s body, bundles of hyphæ, which serve the purpose of holding fast the dead insects, the ramifications attaching themselves to the substratum: the conidiophores are branched, the conidia are ejected by the divisional walls between the hyphæ and the conidia dividing into two layers, those which terminate the hyphæ suddenly expanding and throwing the conidia into the air. _E. radicans_ makes its appearance epidemically on caterpillars. =B.= Asexual reproduction by zoospores or conidia. Family 2. =Chytridiales.= In this family the mycelium is very sparsely developed or is wanting. The entire plant consists principally or entirely of a single zoosporangium whose zoospores have generally one cilium. The resting-spores arise either directly from the zoosporangium, which, instead of forming zoospores, surrounds itself by a thick cell-wall; or they are formed by the conjugation of two cells (in which case they are spoken of as oospores). Microscopic Fungi, parasitic on water plants (especially Algæ) or small aquatic animals, seldom on land plants. Order 1. =Olpidiaceæ.= Without mycelium. Swarmspores and resting-spores. In the _Olpidieæ_, the swarmspores, probably, most frequently form themselves into a plasmodium (naked mass of protoplasm) which may become a single zoosporangium or a resting sporangium. _Olpidium trifolii_ occurs in _Trifolium repens_.--In the _Synchytrieæ_ the plasmodium emerging from the swarmspores breaks up either at once, or after a period of rest, into smaller plasmodia, each of which will become a zoosporangium. _Synchytrium anemones_ is found on _Anemone nemorosa_; _S. mercurialis_ on _Mercurialis perennis_; _S. aureum_ on many plants, particularly _Lysimachia nummularia_. [Illustration: FIG. 86.--_Chytridium lagenula._ Zoosporangium _a_ before, _b_ after the liberation of the swarmspores.] [Illustration: FIG. 87.--_Obelidium mucronatum_: _m_ mycelium; _s_ swarmspores.] Order 2. =Rhizidiaceæ.= Mycelium present. Zoospores and resting-spores. _Chytridium_ (Fig. 86). _Obelidium_ (Fig. 87) is bicellular; the one cell is the mycelium, the other the zoosporangium; found on insects. The species of _Cladochytrium_ are intercellular parasites on marsh plants. _Physoderma._ Order 3. =Zygochytriaceæ.= Mycelium present. Zoospores and oospores. The latter are the product of the conjugation of two cells (Fig. 88). _Polyphagus euglenæ_ on _Euglena viridis_. _Urophlyctis pulposa_ on species of _Chenopodium_. Family 3. =Mycosiphonales.= The mycelium is bladder-like or branched. Zoospores. Sexual reproduction by oospores, which are produced in oogonia. The latter are fertilised, in some forms, by the antheridium. Order 1. =Ancylistaceæ.= The entire bladder-like mycelium is used for the construction of zoosporangia, oogonia, or antheridia. _Lagenedium_ is parasitic on _Spirogyra_, etc. Order 2. =Peronosporaceæ.= Almost entirely _parasites_. The unicellular, often very long and abundantly branched mycelium lives in the intercellular spaces of living plants, especially in the green portions, and these are more or less destroyed and deformed in consequence. Special small branches (_suction-organs_, “_haustoria_”) are pushed into the cells in order to abstract nourishment from them. Both oospores and conidia germinate either immediately, or they develope into sporangia with swarmspores, having always two cilia. Only one oospore is formed in each oogonium; its contents (Fig. 89) divide into a centrally placed egg-cell and the “periplasm” surrounding it; this is of a paler colour and on the maturity of the oospore forms its thick, brown, external covering. [Illustration: FIG. 88.--_Polyphagus euglenæ. A_ with smooth, _B_ with thorny oospores; _m_ and _f_ the two conjugating cells.] [Illustration: FIG. 89.--_Peronospora alsinearum._ Mycelium with egg-cell and antheridium.] [Illustration: FIG. 90.--_Phytophthora infestans_ (strongly magnified). Cross section through a small portion of a Potato-leaf (the under side turned upwards): _a_ the mycelium; _b b_ two conidiophores projecting through a stoma; _c_ conidia; _e_ the spongy tissue of the leaf; _g_ the epidermis.] _The Potato-fungus_ (_Phytophthora infestans_) is of great interest. Its thallus winters in the Potato-tuber; other organs for passing the winter, such as oospores, are not known. When the tuber germinates, the Fungus-hyphæ penetrate the young shoot and keep pace with the aerial growth and development of the plant. The conidiophores emerge through the stomata, especially on the under side of the leaves; they branch like a tree (Fig. 90), and appear to the naked eye as a fine mould on the surface of the plant. The disease soon makes itself known by the brown colouring of those parts of the plant which are attacked, and by their withering. An ovoid conidium arises at first by the formation of a dividing wall at the apex of each branch of the conidiophore (Fig. 90 _c c_), and immediately underneath it another is formed, which pushes the first to one side, and so on. These conidia sometimes germinate directly, and form a mycelium, but most frequently their protoplasm divides into many small masses, each of which becomes a pear-shaped zoospore provided with two cilia (Fig. 91). Water is required for their germination, and when the ripe conidia are placed in a drop of water the swarm-cells are formed in the course of about five hours. They swarm about in rain and dewdrops in the Potato-fields, and are carried with the water to the Potato-plants and to the tubers in the soil. The wind also very easily conveys the conidia to healthy Potato-fields and infects them. The enormous quantity of conidia and swarm-cells that may be formed in the course of a summer explains the rapid spreading of the disease; and the preceding makes it clear why wet summers are favourable to its existence. When the swarm-cells germinate, they round off, and then surround themselves with a cell-wall which grows out into the germ-tube, and _pierces through the epidermis_ of the host-plant (Fig. 92). Having entered the host, a new mycelium is formed. The potato disease, since 1845, has been rampant in Europe; it has, no doubt, been introduced from America, which, it must be remembered, is the home of the Potato-plant. [Illustration: FIG. 91.--_Phytophthora infestans_: _a-c_ conidia detached; in _c_ the swarm-cells are leaving the mother-cell; _d_ two free-swimming swarm-cells.] [Illustration: FIG. 92.--_Phytophthora infestans._ Cross section through a portion of a Potato-stalk. Two germinating conidia (_a_, _b_) piercing the epidermis, and the mycelium penetrating the cells.] The conidia exhibit various characters which are employed for the separation of the genera. _Pythium_ is the most simple form. The contents of the terminally-formed conidia emerge as a spherical mass and divide into swarmspores. _P. de Baryanum_ lives in the seedlings of many different Flowering-plants, which it completely destroys.--_Phytophthora_ is distinguished by the circumstance that the sparsely-branched conidiophores bear, sympodially, chains of conidia. Besides the Potato-fungus (see above), _Ph. fagi_ belongs to this group; it developes oospores very abundantly, and does great harm to seedlings of the Beech, Sycamore, and Pine trees.--_Peronospora_ generally has conidiophores which are repeatedly forked, and bear a conidium on each of the most extreme ramifications. Many do great harm to their host-plants. _P. viticola_, on Vines, and _P. nivea_, on umbelliferous plants, have swarmspores, which are absent in the following species of this genus: _P. sparsa_, on Roses; _P. gangliformis_, on composites; _P. alsinearum_, on Stitchwort; _P. parasitica_, on cruciferous plants; _P. viciæ_, on Vetches and Peas; _P. schachtii_, on Beets; _P. violacea_, on the flowers of _Scabiosa_; _P. radii_, on the ray-florets of _Matricaria_.--_Cystopus_ (_Albugo_) has the conidia developed in chains, which form a cohesive white layer underneath the epidermis of the host-plant. _Cystopus candidus_, on cruciferous plants, especially Shepherd’s Purse and _Brassica_; the germination commences on the cotyledons, and from this point the mycelium developes together with the host-plant; _C. cubicus_, on the leaves of Compositæ. [Illustration: FIG. 93.--A fly overgrown with _Saprolegnia_.] [Illustration: FIG. 94.--Formation of swarmspores in a _Saprolegnia_: a germinating swarmspores.] Order 3. =Saprolegniaceæ=, _Water-Fungi_ which live as saprophytes on organic remains lying in water, for instance, on dead flies (Fig. 93), worms, remains of plants; but they may also make their appearance on living animals, being frequently found, for example, on the young trout in rearing establishments. [Illustration: FIG. 95.--Oogonium with two antheridia, _Achlya racemosa_.] The thallus is a single, long and branched cell. It has one portion which serves as root, and lives in the substratum, where it ramifies abundantly for the purpose of absorbing nourishment; and another portion projecting freely in the water, and sending out hyphæ on all sides (Fig. 93). The asexual reproduction takes place by swarmspores (Fig. 94), which are developed in large sporangia; these swarmspores generally possess two cilia, and on germination grow into new plants. The entire protoplasm in the oogonium is formed into one or more oospheres, without any surrounding “periplasm.” The oospheres may not be fertilised (p. 100), and then develope parthenogenetically. Genera: _Saprolegnia_, whose swarmspores disperse immediately after having left the sporangium. _S. ferax_ is the cause of a disease in fish (“Salmon disease”) and in the crayfish.--_Achlya_, whose swarmspores accumulate in a hollow ball before the mouth of the sporangium.--_Leptomitus_ has strongly indented hyphæ, causing a “linked” appearance. _L. lacteus_ is frequent in the waste matter from sugar factories.--_Monoblepharis_ deviates from the others by the greater development of its fertilising process; the oosphere, situated in an open oogonium, becoming fertilised by self-motile spermatozoids, which are provided with a cilium at the posterior end. Class 2. =Mesomycetes.= The Mesomycetes are intermediate forms between the Phycomycetes and the Higher Fungi. In the vegetative organs, and in the multicellular hyphæ, they resemble the Higher Fungi; the methods of reproduction, however, show the characters of the Phycomycetes, namely sporangia and conidiophores of varying size and with varying number of spores; definite and typically formed asci and basidia are not present. Sexual reproduction is wanting. The HEMIASCI are transitional between the Phycomycetes and the Ascomycetes, the HEMIBASIDII (Brand-Fungi) form the transition to the Basidiomycetes. Sub-Class 1. =Hemiasci.= The Hemiasci are Fungi with _sporangia_ which, _although resembling asci_, yet have _not_, however, _a definite form and a definite number of spores_. Besides endospores, conidia, chlamydospores and oidia are found. Order 1. =Ascoideaceæ.= _Ascoidea rubescens_ forms irregular, reddish-brown masses in the sap issuing from felled Beeches. It has _free sporangia_, which resemble asci in their structure, in the development and ejection, and in the definite shape and size of the spores. The formation of the sporangia takes place when the nutriment is nearly exhausted, and resembles that of the conidia, since they are developed from the end of a hypha which enlarges, and the swelling becomes separated by a transverse wall. Within the sporangia numerous spores of a cap-like form are developed, which are set free through an opening at the apex. Sporangia are formed successively at the apex of the same hypha, the second commencing to develope as the first is dehiscing. Conidia and sporangia are not formed simultaneously; the former may be considered as closed sporangia. Order 2. =Protomycetaceæ.= _Protomyces pachydermus_ causes hard swellings on the stems and leaf-stalks of the Cichorieæ (_Taraxacum_, etc.). These swellings consist of _chlamydospores_ (resting-spores), which germinate and become free, ascus-like sporangia, with numerous small spores. In nutritive solutions the chlamydospores form conidia with yeast-like buddings. _P. macrosporus_ on _Ægopodium_, and other Umbelliferæ. Order 3. =Thelebolaceæ.= _Thelebolus stercoreus_, is found on the dung of deer, hares, and rabbits, and has _closed sporangia_, which resemble asci in their shape and regular construction, and in the ejection of spores. The covering encloses only one sporangium, even where the sporangia arise close together. This order, by reason of the covering of the sporangia, forms the transition from the Hemiasci to the Carpoasci, while the two first supply an intermediate step to the Exoasci. Sub-Class 2. =Hemibasidii, Brand-Fungi.= The Brand-Fungi (also known as USTILAGINEÆ) are Fungi with _basidia-like conidiophores_, which, however, have not yet advanced to a definite form or number of conidia. They are true parasites, whose mycelium spreads itself in the intercellular spaces of Flowering plants. The mycelium is colourless, quickly perishable, has transverse walls at some distance from each other (Fig. 96), and sends out haustoria into the cells of the host-plant. [Illustration: FIG. 96.--_Entyloma ranunculi._ 1. Cross section of a portion of a leaf of _Ficaria_ permeated by the mycelium; a bundle of hyphæ with conidia emerging from a stoma; in one of the cells are found four brand-spores. 2. A brand-spore developed in the middle of a hypha.] It most frequently happens that the germ-tube enters the host-plant at its most tender age, that is, during the germination of the seed; the mycelium then wanders about in the tissues of the shoot during its growth, until it reaches that part of the plant where the spores are to be formed. The spore-formation takes place in the same way in all those species whose brand-spores are developed in the floral parts of the host-plant. Many Brand-Fungi have, however, a more local occurrence, and the mycelium is restricted to a smaller area of the leaf or stem. Those organs of the host-plant in which the brand-spores are developed often become strongly hypertrophied. In perennial plants the mycelium winters very often in the rhizome. [Illustration: FIG. 97.--_Doassansia alismatis._ 1. A fruit-body, formed by a covering of oblong hyphæ, which encloses a mass of brand-spores, and is embedded in the leaf-tissue of the host-plant; 20 times natural size. 2. A germinating brand-spore, 500 times natural size. 3. Three connected resting-spores, 400 times natural size. 4. Two conidia grown together, 600 times natural size.] The brand-spores are the winter resting-spores of the Brand-Fungi. They arise in the tissues of the host-plant, which is often destroyed, and become free through the rupture of the epidermis; they are thick-walled, generally brown or violet, and very often possess warts, spines, or reticulate markings. Fruit-bodies, that is enclosed organs of reproduction, are found in few genera (_Sphacelotheca_, _Graphiola_; _Doassansia_, Fig. 97). In _Tolyposporium_, _Tuburcinia_, _Thecaphora_ (Fig. 102), etc., the brand-spores are united into a _ball of spores_. On germination the brand-spores behave as _chlamydospores_, namely, as the fundament of conidiophores, by emitting a short germ-tube, _i.e._ a conidiophore (“promycelium”). The USTILAGINACEÆ (Fig. 99, 2) have a short _transversely divided_ conidiophore, with _laterally_ developed conidia (comp. the basidia of the Protobasidiomycetes). The conidiophores of the TILLETIACEÆ are undivided (unicellular promycelia), and bear the conidia terminally, and so resemble the basidia of the Autobasidiomycetes. [Illustration: FIG. 98.--_Tuburcinia._ 1. _T. trientalis._ Hyphæ, some of which bear conidia at the apex, forcing themselves out between the epidermal cells on the under side of the leaf; 320 times natural size. 2. _T. trientalis._ A ball of spores in which some of the individual brand-spores are about to germinate; 520 times natural size. 3. _T. primulicola_: various forms of conidia (500 times natural size).] In _Tilletia_, _Entyloma_, _Neovossia_, _Tuburcinia_, the brand-spores germinate and form basidia-like conidiophores with spindle-shaped conidia; their mycelium, on the other hand, produces later only single, sickle-shaped conidia, so that two kinds of conidia are found, as in a few Basidiomycetes. In some species, _e.g. Ustilago hordei_, the brand-spores only germinate vegetatively and form a mycelium. In nutritive solutions (solutions of dung, etc.) where they live as _saprophytes_, the brand-spores of many species emit germ-tubes, and on these, _yeast-like conidia_ are produced by repeated budding, which grow into mycelia only when the nutritive solution is exhausted. These conidia have not the power of producing alcoholic fermentation. The very numerous conidia, which are found in the dung of herbivorous animals, are probably the yeast-conidia of Brand-Fungi. The brand-spores, which are eaten by animals with the grain and hay, pass into the dung and without doubt give rise to a very rich multiplication of yeast-conidia. [Illustration: FIG. 99.--_Ustilago._ 1. Formation of brand-spores. 2. Germinating brand-spore of _U. perennans_. 3. Germinating brand-spore of _U. cardui_ (after Brefeld). 4. _U. filiformis. a_ A brand-spore with developed basidium; _b_ another, with a conidium; _c_ with two conidia; _d_ with two conidia placed diametrically opposite to each other; _e_, detached conidia which are growing into hyphæ.] [Illustration: FIG. 100.--_Tilletia tritici_: _a_ an ear of Wheat in which all the grains are attacked by Stinkbrand; _b_ a blighted corn surrounded by the chaff; _c_ a blighted corn grown together with a stamen; _d_ the same cut across; _e_ a brand-spore; _f_, _g_, _h_ germinating brand-spores; _i_ germinating conidia; _j_ the mycelium; _k_-_k_ brand-spore-forming mycelium-threads. (_c-h_ magnified 400 times; _i-k_ 300 times.)] The conidia (also called “sporidia”) of many species unite generally into an H-form (Figs. 97, 4; 100 h; 101, 4). This union in pairs does not, however, take place with a view to germination, there is no fusion of nuclei, and therefore in this “fusion” there is no sexual act. Order 1. =Ustilaginaceæ.= Conidiophores with transverse walls and lateral conidia.--_Ustilago_ (Fig. 99) generally developes its spores in the floral organs of its host-plant, the ovary or anthers, where they arise from hyphæ, and form a slimy mass which when mature becomes a black dust. To this order belong _U. avenæ_, parasitic on Oats, _U. hordei_ and _U. nuda_ (_U. jenseni_), on Barley; these are the usual cause of “Smut” on cereals. _U. hypodytes_ on straw of _Elymus_ and _Agropyrum_. _U. filiformis_ in the leaves of _Glyceria_. _U. caricis_ transforms the fruits of various species of _Carex_ into black, dusty balls. _U. violacea_ developes its violet spore-powder in the anthers of the Caryophyllaceæ. _U. tragopogonis_, transforms entire inflorescences of _Tragopogon_ into a black-violet mass. Among the largest are _U. grandis_, which causes the large swollen nodes in the stem of _Phragmites_, and the Maize Blight, _U. maydis_, which produces outgrowths about the size of a hand on the spadix of the Maize. Order 2. =Tilletiaceæ.= Conidiophores undivided, generally several conidia arise at their apices.--_Tilletia tritici_, the _Stinkbrand on Wheat_ (Fig. 100). The mycelium lives in Wheat-plants, producing its spores in the ovary after the whole interior of this body has been destroyed by the mycelium, with the exception of the external layer of the wall of the ovary, which remains essentially unaltered and encloses the closely packed, firm mass of spores (Fig. 100 _d_). The grains of Wheat thus attacked are shorter and thicker than the sound ones, and the ears show the presence of this Fungus by their erect position, and the wide separation of the chaff (Fig. 100 _a_). The unpleasant odour of the ovary prior to the ripening of the spores, has given the name “Stinkbrand,” and, in like manner, its hardness when it encloses the ripe spores, is the reason of its being also called “Stonebrand.” On account of this hardness, the diseased grains are readily harvested together with the healthy ones, which become infected by the spores at the threshing. _T. lævis_ (_T. fœtens_) also occurs on Wheat and has smooth brand-spores. [Illustration: FIG. 101.--_Urocystis._ 1, _U. covalloides_. A spore-ball, magnified 450 times. 2–4, _U. anemones_: 2–3, brand-spores which are about to germinate (magnified 450 times). 4, Conidia, the two in a state of fusion, a third with vacuoles and division-wall, magnified 500 times.] _Entyloma_ (Fig. 96), a genus with numerous species, which appear in spots on the leaves of the host-plant, and _Tuburcinia_ (Fig. 98), which makes its appearance on the Primulaceæ, produce white conidia-spots on the surface of the host-plant. The first-named has single spores, the latter has its spores closely massed together.--_Urocystis_ (Fig. 101) has its spores surrounded by a number of small and lighter coloured barren spores. _U. occulta_, Rye-stem Blight, forms its spores in long streaks in the stems and leaves of the Rye, and does considerable damage. _U. cepulæ_ on Onions. _U. violæ_ forms large dark-violet swellings in the leaf-stalk and stems of Violets.--_Thecaphora_ (Fig. 102) appears in seedlings of _Convolvulus_ and _Astragalus_. As a means of protection against the Smut-Fungi which make their appearance on the different cereals, a submersion of the grains in a solution of blue vitriol (½%) for twelve hours, or better still, submerging for five minutes in water heated to 53–55° _C_ (Jensen’s method) is employed. [Illustration: FIG. 102.--_Thecaphora._ 1, _T. convolvuli_, a ball of spores, one of the brand-spores has emitted a septate branched conidiophore (× 520). 2, _T. affinis_, a ball of spores (× 520).] Class 3. =Mycomycetes, Higher Fungi.= The MYCOMYCETES are not entirely aquatic in habit; they have hyphæ with _transverse walls_, but _no sexual reproductive organs_. The asexual reproduction takes place in very different ways; by endospores (in asci), conidia, basidiospores, chlamydospores, and oidia. Swarmspores are never found. Two chief methods of reproduction may be distinguished, and hence the class may be divided into two large sub-classes:--the ASCOMYCETES (with asci), and the BASIDIOMYCETES (with basidia). Sub-Class 1. =Ascomycetes.= The main characteristic which distinguishes the Ascomycetes is the _ascus_; a name given to a sporangium of a definite shape and size, and containing a definite number of spores. The shape is generally club-like or spherical, the number of spores 8 (in some 2, 4, 16 or more), see Figs. 103, 105, 108, 110, 113, 116, 120, 121, 123, 129. In the lowest forms, the EXOASCI, the ascus springs directly from the mycelium without the formation of a fruit-body (_i.e._ ascocarp). In the higher forms, which contain many species, the CARPOASCI, the asci are united and form ascocarps which may be more or less enclosed (angiocarpic, hemiangiocarpic, and probably gymnocarpic). [Illustration: FIG. 103.--Endogenous formation of spores in _Peziza confluens_. In the youngest asci there is only one nucleus (_b_, _e_); this divides into two (_f_); and the division is repeated so that there are 4 nuclei in _c_ and 8 in _g_. These surround themselves with protoplasm and a cell-wall (_h_, _i_). The protoplasm of the mother-cell is not entirely used up.] The hyphæ of the _Mycelium_ in some remain free, in others they are felted together and form thick strands or flat, cushion-like bodies (compare in particular the stromata of the Pyrenomycetes). Some species form _sclerotia_ (Figs. 116, 128). Asexual reproduction by means of _conidia_ is known in many species as the principal means of reproduction, and the one which affords the most rapid means of distribution. The conidia may be produced on conidiophores (Fig. 109), in conidial-layers (Fig. 122), and often in conidiocarps (pycnidia, Figs. 120 _d_, _e_; 123 _a_; 124 _b._). These last occur partly as the so-called “spermogonia” (that is, pycnidia with microconidia). The conidiophores never approach the basidia. In many species the ascospores germinate and form conidia immediately (_Nectria cinnabarina_, _Sclerotinia_, _Taphrina_, etc.), sometimes while they are still in the ascus and before their ejection (_Taphrina_, Fig. 105 _a_). In many instances the conidia by means of continued budding can, for a longer or shorter time, produce yeast-conidia, _e.g. Taphrina_. In many other cases the conidia arise from the germ-tubes of the ascospores, or at any part of the mycelium. The unripe asci of _Taphrina_, when placed in water, develop conidia at their apices. The _Sclerotinia_-species produce numerous conidia whose germination has never been observed. The formation of conidia and asci sometimes takes place on the same fruit-body. In _Heterosphæria patella_ the conidia and asci are developed successively in the same fruit-body; in the ascocarps of _Dermatea frangula_ and _Sclerotinia sclerotiorum_ the formation of conidia may take place. The ascocarps frequently arise from the conidial-layers (_Nectria cinnabarina_, etc.). This relationship of the two forms of reproduction to each other may be explained by considering that both have descended phylogenetically from sporangia. Sometimes _chlamydospores_ and _oidia_ also appear in the Ascomycetes; on germination, however, they do not, as in _Protomyces_, form sporangia, and on this account cannot be distinctly distinguished from conidia. The asci are morphologically the highest form of reproduction and are always found at the close of the development of these Fungi; the accessory forms of reproduction are first developed, but a well-defined alternation of generations does not occur. In the Ascomycetes there are more than 11,000 described species, which can be classed as follows:-- Series 1. EXOASCI. Only one order. „ 2. CARPOASCI. Family 1. _Gymnoascales_, } „ 2. _Perisporiales_, } Angiocarpic Carpoasci. „ 3. _Pyrenomycetes_, } „ 4. _Hysteriales_, } Hemiangiocarpic Carpoasci. „ 5. _Discomycetes_,} „ 6. _Helvellales_, Gymnocarpic (?) Carpoasci. Additional _Ascolichenes_: Lichen-forming Ascomycetes. Series 1. =Exoasci.= Ascomycetes with FREE ASCI; sometimes also conidia, chlamydospores and oidia. One order. Order. =Taphrinaceæ.= Of the genera belonging to this order, _Taphrina_, _Endomyces_, and _Ascocorticium_, the first is most important. _Endomyces decipiens_ is a parasite in the fruit-body of _Armillaria mellea_; _E. magnusii_ lives in the gelatinous, fermenting exudations of Oak-trees; _Ascocorticium albidum_ is found under the bark of the Fir-tree. _Endomyces_ has chlamydospores and oidia. The species of _Taphrina_ are parasites, whose free asci may be found in great numbers, generally closely pressed together, on the parts of plants which they have attacked. The asci are developed directly from the ascogenous cells of a fertile, generally sub-cuticular, hypha, which arises from the sterile mycelium. The latter arises from the germinating ascospore, and may hibernate in the tissues of its host, particularly in the winter buds, and then with the commencement of the next period of vegetation it continues its growth side by side with that of its host. The hyphæ ramify in the intercellular spaces or beneath the cuticle, but have no haustoria. The ascospores (Fig. 105 _A_) and unripe asci may produce conidia. [Illustration: FIG. 104.--_Taphrina_ (_Exoascus_) _pruni_. Yeast-like budding of a germinating spore (× 600).] [Illustration: FIG. 105.--_Taphrina betulina_: _a_ ascus filled with conidia; _b_ germinating spores (× 600).] Very remarkable appearances, and swellings of the attacked tissues, are produced when the mycelium is perennial; for example, the “Witches’-brooms” and “Pockets.” The hard, hollow, stoneless plums, known as “Pocket” or “Bladder” Plums, are produced by considerable changes in the tissues of the fruit; these are caused particularly by _T. pruni_ on several species of _Prunus_. The “Witches’-brooms,” on the contrary, are deformations of entire twigs or branches, and often attain a very large size. They occur on _Alnus incana_, caused by _T. epiphylla_; on _Carpinus betulus_, by _T. carpini_; on Cherry-trees, by _T. cerasi_; on Plum-trees, by _T. insititiæ_; on Birches, by _T. turgida_ and _T. betulina_. _T. deformans_ attacks the leaves of the Peach, and causes them to curl. When a perennial mycelium is wanting, the infection is confined as a rule to white or yellow spots on the leaves, _e.g._ the commonest, _T. sadebeckii_, on _Alnus glutinosa_, and _T. aurea_ on species of _Populus_. _T. alni incanæ_ (Fig. 106) causes considerable hypertrophies on the pistillate catkins of the Alder, which may be compared to the “pockets” of _Prunus_. [Illustration: FIG. 106.--_Taphrina alni incanæ_ on the Alder (nat. size).] Series 2. =Carpoasci.= The Carpoasci are Ascomycetes, whose asci are enclosed in fruit-bodies, _i.e. ascocarps_. The accessory means of reproduction are free conidiophores (Fig. 109), conidial-layers (Fig. 122), conidiocarps (Fig. 120 _D_, _E_, etc.), chlamydospores and oidia. For the different methods of distributing the ascospores, see p. 92. Of the six families of the Carpoasci, the first three--_Gymnoascales_, _Perisporiales_, and _Pyrenomycetes_--are ANGIOCARPIC (that is, the ascocarp remains closed throughout its existence, and does not dehisce when ripe); the fourth and fifth families (_Hysteriales_ and _Discomycetes_), on the other hand, are HEMIANGIOCARPIC (the ascocarp, here also called an _apothecium_, is closed in the early stages, but opens at the commencement of ripening and exposes a hymenium of crowded asci); the family of _Helvellales_ has probably GYMNOCARPIC (or hemiangiocarpic) fruit-bodies. Family 1. =Gymnoascales.= The ascocarps are surrounded by a _spongy and incomplete envelope_. One order, poor in species. Order =Gymnoascaceæ=.--The ascocarps are borne sometimes solitarily, or sometimes coiled together. _Gymnoascus reessii_ forms small bodies about 1 mm. in diameter on old horse-dung, which at first are white and afterwards orange-red.--_Ctenomyces serratus_ lives on the old feathers in birds’ nests. Family 2. =Perisporiales.= The ascocarps are surrounded by a _complete envelope_ without any opening: the fruit-bodies are cleistocarpic; the spores are only liberated after the disintegration of the fruit-bodies. Paraphyses are wanting. The two first orders have in addition the means of reproduction by conidia. Order 1. =Erysiphaceæ, Mildews.= The Fungi belonging to this order are epiphytic parasites, whose mycelium, somewhat resembling a cobweb, may be seen on the leaves and other green portions of plants (see Figs. 107, 108). The hyphæ ramify in all directions upon the surface of their host, and emit haustoria which penetrate the epidermal cells, and thus derive the necessary nutriment. The Mildew-Fungi thus belong to the obligate parasites, and during their growth dwarf and destroy the portions of their host on which they live. The reproduction takes place in the first instance by abstriction of conidio-chains from the end of special branches (Fig. 108 _c_, a hypha is seen in the act of detaching a conidium). The conidia may germinate immediately, and thus quickly reproduce their species. When present in large numbers they appear as a white meal covering the surface of the plant on which the fungus is found. Later on appear the dark brown, spheroid ascocarps (Fig. 108 _a_) which, although small, are generally just visible to the naked eye as black specks. [Illustration: FIG. 107.--_Erysiphe cichoracearum_: _a_ mycelium-threads; _b_ sterile hypha (“pollinodium”); _c_ fertile hypha (ascogone or archicarp); _d_ and _e_ young ascocarps.] A characteristic feature of the Mildew-Fungi is the thin, pseudo-parenchymatous covering of the ascocarp, enclosing _one_ (_Podosphæra_ and _Sphærotheca_; compare _Thelebolus_ among the Hemiasci) or _a few_ asci (Fig. 108 _c_), which do not form any hymenium, but are irregularly placed. The cells of the ascocarp-envelope are often prolonged into hair-like appendages. The ascocarps are developed from the mycelium at places where two hyphæ cross each other (Fig. 107). At these places two short and erect hyphæ are produced side by side. The one from the lower hypha (Fig. 107 _c_) assumes an ellipsoidal shape, and is known as the _archicarp_ or _ascogone_, while the other (“_pollinodium_”) arches over the ascogone. From the latter one ascus may be at once developed (_Sphærotheca_, etc.), or after its division several asci may be produced, each developed from one division. The sterile hypha (termed “pollinodium,” since it was formerly, but erroneously, supposed to fertilise the ascogone) produces a number of branches, and forms the pseudo-parenchymatous envelope of one cell in thickness, enclosing the asci. [Illustration: FIG. 108.--_Erysiphe communis._ A small portion of a leaf with this Fungus growing upon it (considerably magnified). The hyphæ b and d do not belong to this Fungus, but are reproductive organs of a pyrenomycetous Fungus parasitic upon it (_Cicinnobolus_).] Many plants, both cultivated and wild, are attacked by various species of Mildew. A common means of prevention against their attacks is to dust the diseased parts with sulphur. [Illustration: FIG. 109.--_Eurotium glaucum_: α portion of mycelium lying horizontally; β vertically-placed conidiophore; the mycelium gives rise to another branch near α; the conidia are abstricted from short flask-shaped cells; _b_ a ripe conidium; _c_, _d_ germinating conidia; _e_ spirally-twisted hypha, commencement of an ascocarp; _f_ a stage later; _g_ still later, the hypha at the base of the coil has given off branches which are applied to it; _h_, _i_ sections of young ascocarps.] _Sphærotheca pannosa_ occurs on the leaves of Roses, and on the fruit of Peaches and Apricots. _S. castagnei_ on _Humulus_, _Cucumis_, etc.--_Erysiphe tuckeri_ grows on the leaves and fruit of the Vine; it spins its hyphæ over the bunches of grapes, curtails their growth, and causes them to burst, and to become decayed and rotten (Grape-disease). The Fungus was first noticed in England in 1845, and later was found in all countries where grapes are grown. It is only known in the conidial form (“Oidium tuckeri”). Many other species of _Erysiphe_ are found on herbaceous plants.--_Microsphæra_ has appendages which are repeatedly forked at their extremities. _M. grossulariæ_ on _Ribes grossularia_.--_Uncinula_ has appendages with spirally-coiled extremities; on _Salix_ and _Acer_.--_Phyllactinia_ has a circle of bristle-like appendages with dilated bases. _P. guttata_ on _Corylus_, _Fraxinus_, _Fagus_, etc. Order 2. =Perisporiaceæ=, Moulds and Mildews. A group of Fungi widely distributed and found in all situations. Usually they have a well-developed surface mycelium, and small, round, seldom conspicuous ascocarps, containing ovoid, pulley-like spores. They are partly saprophytic, partly parasitic, in the latter condition having a brown mycelium. [Illustration: FIG. 110.--_Eurotium glaucum_: _a_ longitudinal section of a half-ripe ascocarp, bounded externally by a well-defined layer of cells, enclosing asci in various stages of development; _b_ a semi-ripe, _c_ an almost ripe ascus; _d_ and _e_ spores seen from the edge and side; _f_ germinating spore twenty-two hours after been sown in plum juice.] _Eurotium glaucum_ (= _E. herbariorum_, Figs. 109, 110) and _E. repens_ live on dead organic matter, preserved fruits, etc. The conidial forms of both species are known as “Moulds” (Fig. 109), and formerly were described under the name “_Aspergillus glaucus_.” The conidia for some time remain attached to each other in chains (Fig. 109 _a_); they are abstricted from sterigmata arranged radially on the spherical, swollen end of the conidiophore. The small yellow or brownish ascocarps are frequently found in herbaria, especially when the specimens have been insufficiently dried. _Aspergillus fumigatus_ and others are pathogenic, causing mycosis in warm-blooded animals. [Illustration: FIG. 111.--_Penicillium crustaceum_: _a_ conidia (× 300); _b_ germination of conidia; _c_ small portion of mycelium, produced from a conidium at *, with five conidiophores; _d_ young conidiophore (× 630), a flask-shaped cell is abstricting a conidium; _e_ the same conidiophore after 9–10 hours.] [Illustration: FIG. 112.--_Penicillium crustaceum_: _a_ two spirally-coiled hyphæ arise from the mycelium, from one of which (archicarp) the asci are produced; _b_ a further step in the development of the ascocarp; the branching archicarp is surrounded by sterile hyphæ; _c_ section of young ascocarp; the larger hyphæ in the centre are the ascogenous hyphæ; these are enclosed by a pseudo-parenchyma of sterile hyphæ (× 300); _d_ series of ripe asci with spores; _e_ four ascopores seen laterally; _f_ germinating ascospores (× 800).] _Penicillium crustaceum_ (_P. glaucum_, Figs. 111, 112) is an exceedingly common “Mould.” Its mycelium appears very frequently on any organic matter which is permitted to remain untouched, and soon covers it with a dense mass of blue-green conidiophores. These branch at their summits and bear flask-shaped cells from which the conidia are abstricted. The ascocarps which, both in size and colour, resemble grains of sand, have only been obtained in luxuriant cultivation with a limited supply of oxygen. _Capnodium salicinum_ (_Fumago salicina_, _Cladosporium fumago_), a common Mildew, forms dark overgrowths on the leaves and branches of various shrubs (Poplars, Elms, Willows) and on Hops. The conidia appear in various forms, as on conidiophores, in conidiocarps with large multicellular conidia, and in conidiocarps with small unicellular conidia; in nutritive solutions yeast-like conidia are also developed.--_Apiosporium pinophilum_ produces mildew on the leaves of _Abies alba_ and _Picea excelsa_. (The conidial-forms were formerly described as “_Antennaria pinophila_”). Order 3. =Tuberaceæ, Truffles.= The Fungi belonging to this order are entirely subterranean. The mycelium is filamentous, and partly parasitic upon the roots of plants, especially trees, in its neighbourhood; it is then known as _Mycorhiza_. The fruit-body is relatively large, in some cases about the size of a hen’s egg. Internally it is traversed by a number of winding passages (Fig. 113 _a_), the walls of which are coated with the asci. The asci (_b_) contain only a small number of spores, and these are set free by the putrefaction of the fruit-body. Conidia are unknown. [Illustration: FIG. 113.--_Tuber melanosporum_: _a_ fruit-body (nat. size), a portion having been removed to show the internal structure; _b_ an ascus with ascospores.] _Tuber melanosporum_, _T. brumale_, _T. æstivum_, and other species are edible. _Terfezia leonis_ and _Choiromyces mæandriformis_ are also edible. The Truffles are always found in woods and under trees, and disappear when these are destroyed. France and Italy produce the best and the largest number of Truffles, which are hunted by specially trained dogs and pigs. In _Elaphomyces_ (Stag-Truffle) the fruit-body has a corky external layer, and is inedible. Some of the species are found in this country. _E. granulatus_ is parasitic on the roots of the Fir. Family 3. =Pyrenomycetes.= In this family the hymenium is enclosed in small fruit-bodies, _perithecia_ (Fig. 120 _b_), which appear to the naked eye as small dots. In shape they resemble a globe or a flask with a narrow mouth, through which the spores are ejected (peronocarpic ascocarps). Different kinds of reproduction--conidia, pycnidia (chiefly with microconidia), chlamydospores, and perithecia--are found in the same species. The various stages in the life-history of these Fungi are so dissimilar, that formally they were considered to be different genera. Ergot furnishes a very good example. [Illustration: FIG. 114.--A small portion of an ovary attacked with _Claviceps purpurea_ (_Sphacelia_).] [Illustration: FIG. 115.--An ovary with the conidial stage of _Claviceps purpurea_ (_Sphacelia_).] This family may be subdivided into 3 sub-families. Sub-Family 1. =Hypocreales.= The perithecia are _pale, fleshy, brightly coloured_, and generally aggregated on a stroma. Conidia and chlamydospores occur very frequently. Only one order. Order. =Hypocreaceæ.= In this order the majority are parasites upon Flowering-plants (_Nectria_, _Polystigma_, _Epichloë_, _Claviceps_); but some are parasites upon Fungi (_Hypomyces_, _Melanospora_), or upon insects (_Cordyceps_). [Illustration: FIG. 116.--_Claviceps purpurea. A_ Sclerotium with stromata (_cl_) (× by 2). _B_ Stroma divided longitudinally to show the perithecia (_cp_). _C_ A perithecium with the surrounding hyphæ (_hy_). _D_ An ascus ruptured, with the eight filamentous ascospores emerging.] The most important member of this order is the ERGOT (_Claviceps purpurea_, Figs. 114, 115, 116). This Fungus is found in the flowers of many species of Grasses, especially the Rye, attacking and destroying the ovaries. In the FIRST or CONIDIAL STAGE of the attack, the ovaries are found covered with a white, irregularly folded mycelium (Fig. 114 _m_, Fig. 115), formed of numerous hyphæ woven together and penetrating the wall of the ovary. From these a number of hyphæ (Fig. 114 _a_) project into the air and abstrict from their apices the conidia (_b_) which serve as reproductive organs. The mycelium also secretes a sticky, stinking fluid (honey-dew) in which the conidia are embedded in great numbers. The honey-dew exudes from the bases of the glumes, and is greedily sought by flies, which thus carry the conidia to other ovaries. In this manner fresh ears are infected, which might escape were the conidia only distributed by the wind. This stage formerly was regarded as an independent Fungus, known as _Sphacelia segetum_ (Fig. 115). On germination, the conidia produce either a new mycelium (Fig. 114 _d_, _c_), or new conidia. The SECOND or SCLEROTIUM STAGE is the one in which the Fungus passes the winter. The mycelium penetrates deeper and deeper into the attacked ovaries, their tissues are destroyed and replaced by the hyphæ, which gradually become more and more felted together. A firm, pseudo-parenchymatous mass of hyphæ is thus formed at the base of the loosely-woven _Sphacelia_, which is in part transformed into the hard sclerotium, and the remainder thrown off. A dark, hard, poisonous body, longer than the natural grain, is thus formed; these bodies are known as Ergots, and were formerly considered to be a distinct species,--_Sclerotium clavus_ (“Secale cornutum,” Ergot, Fig. 116 _A_, _c_). The THIRD STAGE, described as _Claviceps purpurea_, is developed in the following spring from the germinating sclerotium, which produces dark-red stromata with short stalks. In the stroma numerous perithecia with asci and ascospores are produced. The latter may infect young flowers of the cereals, in which the disease is then developed as before. [Illustration: FIG. 117.--_Nectria cinnabarina_: _a_ branch of _Acer pseudoplatanus_, with conidial-layers and perithecia (nat. size); _b_ a conidial-layer (_Tuberculoria vulgaris_); _c_, a mass of perithecia. (_b_ and _c_ × 8.)] Several species of the genus _Nectria_, with blood-red perithecia, are found as dangerous parasites, especially _N. ditissima_, which causes “Canker” in the Beech, Ash, and Apple, etc.; _N. cucurbitula_, which appears on Pine-trees, and _N. cinnabarina_ (Fig. 117), whose conidial form was formerly named _Tubercularia vulgaris_.--_Polystigma rubrum_ forms shining red spots on the green leaves of _Prunus_-species.--_Epichloë typhina_ is parasitic on the sheaths of Grasses, on which it first forms a white conidial-layer, later on a yellow layer of perithecia.--_Cordyceps_ (Chrysalis Fungus, Figs. 118, 119) lives in and destroys insects, and after compassing their death produces the club-formed, generally yellow, stromata, one part of which bears conidia (_Isaria_) and another perithecia. _C. militaris_ (Fig. 118) on the chrysalides and caterpillars of moths, is the most common. The so-called _Botrytis bassiana_, which produces the disease known by the name of “Muscardine,” in silkworms, is probably a conidial form belonging to _Cordyceps_. [Illustration: FIG. 118.--_Cordyceps militaris._ I Stromata with conidiophores (_Isaria farinosa_). II A larva, with stromata, bearing perithecia. III A spore.] [Illustration: FIG. 119.--_Cordyceps robertii_ on the larva of _Hepialus virescens_: _a_ stalk of stroma; _b_ perithecia.] Sub-Family 2. =Sphæriales.= To this sub-family belong the majority of the Pyrenomycetes. The perithecia are of a _firm consistence_ (tough, leathery, woody or carbonaceous), and of a _dark_ colour. Their _covering_ is _quite distinct from the stroma_ when this structure is present. The stromata are sometimes very large, and may be either cushion-like, crustaceous, upright and club-like, or branched bodies. In general, small, inconspicuous Fungi, living on dead vegetable matter, sometimes parasites. Free conidiophores and conidiocarps are known in many species, and in several, chlamydospore-like forms of reproduction. Orders 3–18 constitute the Sphæriaceæ of older systematists. [Illustration: FIG. 120.--_Strickeria obducens_: _a_ a portion of an Ash-branch with the bark partly thrown off; on the wood are numerous black perithecia (× 20); _b_ longitudinal section through a perithecium; _c_ a spore; _d_ longitudinal section through a pycnidium whose ascospores are being ejected; _e_ portion of the same, with hyphæ and spores.] Order 1. =Sordariaceæ.=--Fungi living on dung with fragile perithecia, either aerial or buried in the substratum. The dark brown or black spores have either a mucilaginous envelope (_Sordaria_, etc.) or mucilaginous appendages (_Podospora_), by means of which their expulsion and distribution are promoted. Order 2. =Chætomiaceæ.= Perithecia fragile, free, bearing on the summit a tuft of hairs. _Chætomium_, on decaying vegetable matter. Orders 3–7. _Perithecia scattered or aggregated, situated from the commencement on the surface of the substratum. Stroma wanting._ Order 3. =Trichosphæriaceæ.= _Trichosphæria parasitica_ (Fig. 121), on _Abies alba_; _Herpotrichia nigra_ on _Picea excelsa_ and _Pinus montana_. [Illustration: FIG. 121.--_Trichosphæria parasitica_: _a_ a twig of _Abies alba_, with epiphytic mycelium; _b_ a leaf with mycelium and sporangia (magnified); _c_ a sporangium (× 60); _d_ an ascus with spores (× 550).] Order 4. =Melanommaceæ.= _Rosellinia quercina_ lives in the roots of 1–3-year-old Oaks, and destroys the plants. Order 5. =Ceratostomaceæ.= Order 6. =Amphisphæriaceæ.= _Strickeria obducens_ (Fig. 120) has brick-like spores, and lives aggregated on the hard branches of _Fraxinus_. Order 7. =Lophiostomaceæ.= Order 8. =Cucurbitariaceæ.= Perithecia tufted, _at first embedded, then breaking through_, often situated upon an indistinct _stroma_. Orders 9–13. _The perithecia remain embedded, and are only liberated by the casting off of the covering layers of the substratum. Stroma wanting._ Order 9. =Sphærellaceæ.= The species of _Sphærella_ have colourless, bicellular spores. They live upon the leaves of many plants, and develope spherical perithecia upon the fallen leaves. Order 10. =Pleosporaceæ.= The conidial-forms of _Pleospora herbarum_ and _P. vulgaris_ form a black covering on various plants, known as “smuts.”--_Venturia ditricha_ occurs on the underside of dry Birch leaves, and perhaps to this belongs the conidial-form, _Fusicladium pirinum_, which causes the “Rust spots” on Apples and Pears. Order 11. =Massariaceæ.= Order 12. =Clypeosphæriaceæ.= Order 13. =Gnomoniaceæ.= Perithecia, with peak-like aperture. _Gnomonia erythrostoma_ in the leaves of _Prunus avium_, which turn brown and do not fall in autumn. Orders 14–18. _Stroma generally well developed. The perithecia are embedded in the stroma, but when this is rudimentary, in the substratum._ Order 14. =Valsaceæ.= _Valsa._ Order 15. =Diatrypaceæ.= _Diatrype._ Order 16. =Melanconidaceæ.= Order 17. =Melogrammataceæ.= Order 18. =Xylariaceæ.= This order is the most highly developed of the Sphæriales. The _stroma_ arises on the _surface of the substratum_, which is generally dead or decorticated wood; it is well-developed, crustaceous, hemispherical or upright. In the younger conditions it is covered with a layer of conidia, and later on it bears the _perithecia_, arranged in a layer immediately _beneath its surface_. The ascospores are of a dark colour. Often also there are free conidiophores. [Illustration: FIG. 122.--_Xylaria hypoxylon_ (nat. size) on a tree stump: _a_ younger, _b_ an older stroma, both of which, with the exception of the black lower portion, are covered with white conidia; _n_, spot where the perithecia are developed; _c_ an old stroma with upper part fallen off; _d_, _e_ large branched stromata; _k_ conidia.] _Hypoxylon_ and _Ustulina_ have a cushion-like or crustaceous stroma.--_Xylaria_ has a club-shaped or branched stroma, often several centimetres high. _X. hypoxylon_ (Fig. 122) and _X. polymorpha_ occur on old tree stumps.--_Poronia_ grows on old horse dung, and has a conical stroma. Sub-Family 3. =Dothideales.= The _perithecia_ are always embedded in a _black stroma_, and are _not distinctly separated_ from it. The accessory forms of reproduction are: conidiophores, conidiocarps, and yeast-like conidia. The majority are parasites. One order. Order =Dothideaceæ=. _Phyllachora graminis_ produces scab-like patches on the leaves of the Grasses.--_Scirrhia rimosa_ grows on the leaf-sheathes of _Phragmites_.--_Rhopographus pteridis_ on _Pteridium aquilinum_. Family 4. =Hysteriales.= This family, like the following, has hemiangiocarpic ascocarps (_apothecia_). These are closed in the early stages, but when ripe _open_ in a _valvular manner_ by a _longitudinal fissure_; they are black, oblong, and often twisted. Some species are parasites, especially upon the Coniferæ. [Illustration: FIG. 123.--_Lophodermium (Hypoderma) nervisequium_: _a_ two leaves of _Abies alba_ seen from above with pycnidia; _b_ a leaf seen from the underside with apothecia; _c_ an ascus with ascospores. (× 500.)] [Illustration: FIG. 124.--Three leaves of the Red-pine with _Lophodermium macrosporum_: _a_ under side of the leaves with apothecia; _b_ a leaf from upper side with pycnidia. (× about 2.)] [Illustration: FIG. 125.--_Lophodermium pinastri_: _a_ leaves of _Pinus sylvestris_ with apothecia (nat. size); _b_ two paraphyses and an ascus with filamentous spores.] Order 1. =Hysteriaceæ.= _Hysterium pulicare_ upon the ruptured bark of many trees. Order 2. =Hypodermaceæ.= The species of _Lophodermium_ live upon the leaves of Conifers, and are the cause of their falling off (_blight_). _L. pinastri_ (Fig. 125), on the leaves of _Pinus_ and _Picea_; the leaves become red-brown and fall off; at first conidiocarps are formed, and later apothecia; _L. nervisequium_ (Fig. 123), on _Abies alba_; _L. macrosporum_ (Fig. 124), on _Picea excelsa_; _L. brachysporum_, on _Pinus strobus_. Order 3. =Dichænaceæ.= Order 4. =Acrospermaceæ.= Family 5. =Discomycetes.= The ascocarps (_apothecia_) are at first closed, and _only open_ at the time of their ripening, not valvularly, but more or less like a _saucer_ or _cup_, so that the hymenium lies exposed on their upper surface. In the first three sub-families, and generally also in the fourth, the apothecia are formed inside the substratum. The apothecia are, in contrast to the Pyrenomycetes, light and brightly coloured, and their size varies very much, and may be several centimetres in diameter. Paraphyses are often present between the asci; they often contain colouring matter, and give to the disc its characteristic colour. The tissue on which the asci are borne is known as the _hypothecium_. The shape and colour of the spores is not so varied as in the Pyrenomycetes. The accessory forms of reproduction are conidia (sometimes of two forms), chlamydospores, and oidia. The family is divided into 5 sub-families. Sub-Family 1. =Phacidiales.= The apothecia are developed in the interior of the substratum, which they break through, and in general dehisce apically. The envelope is tough and black. Hypothecium inconspicuous; hymenium flat. Order 1. =Euphacidiaceæ.= _Phacidium abietinum_, on the leaves of _Abies alba_.--_Rhytisma_; the pycnidia are found in the summer on the green leaves, while the apothecia are developed on the fallen leaves and dehisce in the following spring. _R. acerinum_ causes black spots on the leaves of the Sycamore, and _R. salicinum_ on Willows. Order 2. =Pseudophacidiaceæ.= Sub-Family 2. =Stictidales.= The apothecia when ripe break through the substratum which forms a border round them. Hymenium generally saucer-shaped. Order 1. =Stictidaceæ.= _Stictis._ Order 2. =Ostropaceæ.= _Ostropa._ Sub-Family 3. =Tryblidiales.= The apothecia are embedded in the substratum in the early stages, and then are raised high above it. Hypothecium thick. Hymenium cup-shaped. Order 1. =Tryblidiaceæ.= _Tryblidium._ Order 2. =Heterosphæriaceæ.= _Heterosphæria patella_ on the dead stalks of Umbellifers. Sub-Family 4. =Dermateales.= The apothecia in the early stages are embedded in the substratum and then break through it, or are from the first situated on the surface of the substratum. Hypothecium thick. Order 1. =Cenangiaceæ.= _Cenangium._ Order 2. =Dermateaceæ.= _Dermatea._ Order 3. =Patellariaceæ.= _Patellea_, _Biatorella_, _Patellaria_. Order 4. =Caliciaceæ.= _Calicium_, _Coniocybe_, etc., on the bark of trees. Order 5. =Arthoniaceæ.= _Arthonia_ on the bark of several trees. _Celidium stictarum_ on the apothecia of _Sticta pulmonaria_. Order 6. =Bulgariaceæ.= Apothecia gelatinous under moist conditions, and horny when dried.--_Calloria fusarioides_; the red apothecia break out in the spring on the dried stalks of _Urtica dioica_; a gelatinous reproductive form of the Fungus is found before the apothecia, which consists of oidia (formerly described as “_Dacryomyces urticæ_”).--_Bulgaria inquinans_ on the living or fallen trucks of Oaks and Beeches. [Illustration: FIG. 126.--_Botrytis cinerea_: _a_ slightly magnified; _b_ more highly magnified; _c_ germinating conidium.] [Illustration: FIG. 127.--_Sclerotinia fuckeliania_: _a_ sclerotium with conidiophores; _b_ with apothecia; _c_ section through sclerotium and apothecium; _d_ ascus with eight ascospores. (× 390.)] Sub-Family 5. =Pezizales.= _The apothecia are developed on the surface of the substratum and are waxy or fleshy_; at the commencement closed, and covered with a saucer- or cup-shaped, seldom flat, hymenium. The _hypothecium_ is generally well developed. This sub-family is the richest in species of the Discomycetes and contains forms of very different habit. They grow upon dead wood, upon the ground, and upon dung. A few are parasites. Order 1. =Helotiaceæ.= Apothecia with waxy envelope of colourless, or yellowish prosenchymatous cells.--~_Chlorosplenium æruginosum_ is found on decaying wood (particularly Oak and Birch), to which it gives a green colour. _Sclerotinia_ has sclerotia which are developed upon the host-plant and from which, after a period of rest, the long, brown-stalked apothecia arise. _S. ciborioides_ (_S. trifoliorum_, Fig. 128) is parasitic on Clover; _S. sclerotiorum_, on _Daucus_-roots, _Phaseolus_, etc.; _S. baccarum_, on the berries of _Vaccinium myrtillus_; “_Botrytis cinerea_” is a common parasite and is probably the conidial form of _S. fuckeliania_ (Fig. 127).--_Helotium herbarum_ lives on dry plant stems.--_Dasyscypha willkommii_ (Fig. 129) produces Larch-canker on the bark of the Larch.~ [Illustration: FIG. 128.--_Sclerotinia ciborioides_: _a_ sclerotium with three apothecia slightly magnified; _b_ ascus with eight ascospores; _c_ germinating ascospore.] [Illustration: FIG. 129.--_Dasyscypha willkommii_: _a_ portion of bark of _Larix decidua_ with sessile, cup-shaped apothecia (nat. size); _b_ two paraphyses on either side of an ascus with eight ascospores.] Order 2. =Mollisiaceæ.= _Mollisia cinerea_, principally on decaying wood. Order 3. =Pezizaceæ.= This order contains the largest and morphologically the highest forms of the _Discomycetes_. Apothecia fleshy, and in the later conditions generally saucer-shaped. _Peziza_, with sessile apothecia, growing on the ground; _P. cochleata_ is brown, and coiled like a snail-shell; _P. coccinea_ is scarlet; _P. aurantia_ occurs as an orange-coloured expansion on the ground. Order 4. =Ascobolaceæ.= Apothecia fleshy; in the later stages flat or convex. The asci are, comparatively speaking, large, and often contain a great number of spores which escape by the casting off of a lid on the summit of the ascus. Generally living on dung.--_Ascobolus furfuraceus_, etc. Family 6. =Helvellales.= These Fungi have the appearance of clubs, bells, or mushrooms, consisting of an upright _stalk_ bearing a _large and fleshy_ head, on the _exterior surface_ of which the _hymenium_ is spread. The ascocarps are probably gymnocarpic from the beginning, and on this account these plants are placed in a separate family. The development of the ascocarps is unknown. The _Morchella_ (Morell) grows on the ground; some species are edible. 1 order. Order. =Helvellaceæ.= _Spathulea_ is yellow and club-shaped, and forms “fairy rings” in woods.--_Geoglossum_ (Earth-tongue) projects above the ground as a black tongue, or as a club-shaped body. Several species are found in meadows and on heaths.--_Helvella_ has a stalk, bearing an irregularly folded head, on the external surface of which is the hypothecium.--_Morchella_ (Morell, Fig. 130), the stalk bears on its summit the conical or spherical head, the external surface of which is reticulate and bears the asci.--_Mitrula. Verpa._ [Illustration: FIG. 130.--_Morchella esculenta_: _a_ an entire specimen, about one half natural size; _b_ longitudinal section through the head.] APPENDIX TO THE ASCOMYCETES: Family 7. =Ascolichenes (Lichen-forming Ascomycetes).= The Lichens were formerly classed among the Thallophyta as a group quite distinct from the Algæ and Fungi. Investigations during the last twenty-five years, however, have conclusively proved that the Lichens are Fungi which reproduce in the same manner as the Ascomycetes, or, more rarely, the Basidiomycetes, and have entered into a peculiar _symbiotic relation with Algæ_, especially the Cyanophyceæ and Protococcoideæ, with which they associate, and without which they would be unable to exist. The Fungus forms the largest portion of the Lichen, enclosing the Alga with which it may be said to be commensal. The Fungus especially produces reproductive bodies and absorbs the inorganic nourishment through the rhizoids, whilst the Alga supplies it with the organic materials. In consequence of this the Lichens, in contradistinction to other Fungi, need light for the development of their nutritive organs, and are therefore, in any case internally, of a more or less greenish colour. The form and condition of the thallus is unusual among the Fungi, and they can grow upon rocks and in other places where no dead organic matter, such as would be required by other Fungi, is obtainable. [Illustration: FIG. 131.--Transverse section through the thallus of _Sticta fuliginosa_ (× 500): _r-r_ rhizoid-strands, which arise from the under side; _g-g_ gonidial layer; _m_ medullary layer; _o_ upper, _u_ lower cortex.] Two cellular forms are therefore to be found in each Lichen: 1. The cells which belong to the Fungus. These are generally septate, branched _hyphæ_ without any trace of chlorophyll. In the thallus of the majority of Lichens there may be found a medullary layer (Fig. 131 _m_) of loosely-woven hyphæ, between which there are large air chambers; and an _external layer_ (cortex) (Fig. 131 _o_, _u_) formed of closely-woven hyphæ without any intercellular spaces. In some Lichens (Collemaceæ) the hyphæ wind about in the thallus, being equally distributed throughout, without forming any decided strata. These Lichens moreover become gelatinous when exposed to moisture (Fig. 132), on account of the swelling of the walls of the Algæ. The hyphæ contain protoplasm with drops of oil, but never starch; their walls easily swell when exposed to damp after having been dried, and in some (_e.g._ _Cetraria islandica_) they become gelatinous when cooked. Certain strata of hyphæ become blue on treatment with iodine alone, from which it is inferred that the wall is allied, in its chemical nature, to starch. 2. The enclosed Algæ, termed “gonidia.” Some belonging to the Cyanophyceæ, Protococcoideæ, (especially _Pleurococcus_) and Chroococcaceæ, are spherical and are found isolated, or in irregular _groups_ of cells (Fig. 131 _g_); some belonging to _Nostoc_ (Fig. 132 _g_), Lyngbyaceæ, etc., are placed in cell-rows. Each Lichen, as a rule, has only one definite Algal-form for its gonidium. The gonidia either lie together in a certain stratum between the cortex and the medullary layer (Fig. 131 _g_), or are scattered irregularly throughout the entire thallus (Fig. 132). The thallus is in the first instance termed “heteromerous,” in the second instance, “homoiomerous.” The Fungal-hyphæ embrace the gonidia and apply themselves closely to, or even penetrate them, and hence it has been difficult to decide whether the one cellular form does or does not develop from the other (Figs. 134, 135). This theory regarding the symbiosis of Fungi and Algæ to form a Lichen is termed the Schwendenerian theory, after the first scientist who advanced it with any weight. It had been already indicated by De Bary, and further arguments in its support have at a later time been adduced by Bornet, Stahl, Treub, Frank, Bonnier, Alfr. Möller and others. [Illustration: FIG. 132.--_Collema microphyllum._ Transverse section through the thallus; _g Nostoc_-chains; _h_ hyphæ.] [Illustration: FIG. 133.--_Ephebe pubescens._ The apex of a branch of the thallus with two lateral branches (_s_): _h_ its hyphæ; _g_ the apical gonidium of the main branch.] [Illustration: FIG. 134.--_Nostoc lichenoides_, which is attached by a germinating thread (_h_) of _Collema glaucescens_.] [Illustration: FIG. 135.--_A_ Germinating spore of _Physcia parietina_ with _Protococcus viridis_. _B Synalissa symphorea_ with _Glæocapsa_. _C Cladonia furcata_ with _Protococcus_.] The thallus of the Lichen appears mainly under three forms:-- 1. The CRUSTACEOUS, which adheres firmly to the substratum (bark, stone) throughout its entire surface, without being raised into any free patches or lobes. It has, in many instances, no definite outline, and hyphal-branches from it often penetrate deeply into the substratum. It grows at the circumference and sometimes dies away in the centre (Figs. 138, 139, 140). 2. The FOLIACEOUS. This also lies flat upon the substratum, but is not firmly attached to and has a definite outline. It grows at the margin, and raises itself a little by free outgrowths and lobes (Fig. 141). The rhizoid-strands spring out from its whitish under surface (Fig. 131, _r_). [Illustration: FIG. 136.--Portion of a hymenium: _d_ a thin stratum on which the asci (_s_) are situated.] [Illustration: FIG. 137.--Spores of, _a Cladonia_, _Lecanora_ and _Pertusaria_; _b Bæomyces_; _c Sphinctrina_; _d_, _e_, _f_ various species of _Parmelia_; _g_, _h Verrucaria_ in its younger and older condition; _i_, _k_ species of _Leptogium_.] 3. The FRUTICOSE, which is attached to its substratum at a small point from which it projects freely, either erect or pendulous. It is more or less tufted, in the form of a bush (Figs. 142, 143). These three thallus-forms gradually pass over by many intermediate forms into one another. [Illustration: FIG. 138.--_Lecanora subfusca_: _a_ the bark on which it is situated; _l_ the thallus; _s_ the ascocarp; _s’_ an ascocarp.] [Illustration: FIG. 139.--_Graphis_ (two species).] [Illustration: FIG. 140.--_Pertusaria communis._] The Lichens, like other Ascomycetes, have very variously constructed ascospores (Fig. 137), which are enclosed in asci (Fig. 136), usually surrounded by paraphyses attached together. Furthermore they possess pycnidia (Fig. 141) containing numerous microconidia. These were formerly considered as organs of fructification, and were termed “spermatia,” and the pycnidia, “spermogonia.” Alfr. Möller proved, in 1887, that the microconidia are able to germinate and produce a mycelium with new conidia, just as in other Ascomycetes. VEGETATIVE REPRODUCTION takes place by _soredia_, which to the naked eye appear as whitish powder on the surface of the thallus. They are small round bodies, formed by one or a group of gonidia, which are surrounded by a mass of felted hyphæ. After the rupture of the cortex they are set free, and readily carried by the wind to other places, where under favourable circumstances they establish a new thallus. [Illustration: FIG. 141.--_A_ A portion of the thallus of _Parmelia parietina_ with ascocarps (_a_) and pycnidia (_b_). _B_ A portion of the thallus of _Cetraria islandica_ with pycnidia at the end of small lobes. _C_ A lobe with pycnidia and ejected microconidia. (Magnified).] GEOGRAPHICAL DISTRIBUTION. The Lichens are the most hardy plants, and are the first to appear on hitherto bare rocks which they gradually disintegrate, and hence prepare the way for the growth of other plants. They are to be found from the Polar regions to the Equator; from the highest snow-free mountain-peaks down to the level of the sea; on the stems of trees; on rocks, soil, some even on inundated places; on stones in woodland streams, and on beaches; but they are never found upon rotten organic remains. Some grow gregariously in enormous masses, and form wide-stretching carpets, _e.g._ Reindeer Moss (_Cladonia rangiferina_), species of _Cetraria_ and other fruticose Lichens. USES. On account of the cell-wall being composed of Lichenstarch (Lichenin), the Iceland-Lichen and Manna-Lichen (_Lecanora esculenta_) are used as food; the latter grows on stones, in the deserts of Asia and North Africa, and is often torn loose in large masses and carried away by the wind. The Reindeer-Lichen is not only the principal food of the reindeer, but it is also used in the manufacture of Danish brandy. _Cetraria islandica_ (Lichen islandicus) is OFFICINAL. Colouring materials (lacmus, orseille, persio) are made from several species, especially from _Roccella tinctoria_ (from the rocky coasts of the Mediterranean). _Parmelia saxatilis_ and particularly _Lecanora tartarea_ are used for colouring purposes in the Northern countries. About 2,000 species of Lichens have been described. If we disregard the Basidiolichenes, which will be considered on page 176, the remaining Lichens (Ascolichenes) may be divided into the two following orders according to the structure of the fruit-bodies:-- Order 1. =Pyrenolichenes.= The ascocarps (apothecia) are spherical or flask-shaped, as in the Pyrenomycetes, more rarely linear (_Graphis_). According to the nature of the thallus, these Lichens may be divided into:-- _a._ Thallus homoiomerous, but not gelatinous, branching according to the mode of growth of the Algæ: _Ephebe_ (Fig. 133), with Algæ of the genus _Stigonema_. _b._ Thallus homoiomerous, gelatinous: _Lichina_. _c._ Thallus heteromerous, crustaceous: _Verrucaria_, _Pyrenula_; _Graphis_ (Fig. 139), which may be considered as Hysteriaceæ with gonidia; several species of _Graphis_ are common on bark. _d._ Thallus heteromerous, foliaceous: _Endocarpon_. _e._ Thallus heteromerous, fruticose: _Sphærophorus_. Order 2. =Discolichenes.= These, as in the Discomycetes, have open apothecia, which, as a rule, are cupular, more rarely hemispherical (_Cladonia_). According to the nature of the thallus, these Lichens may be divided into:-- _a._ Thallus homoiomerous, but not gelatinous, branching according to the mode of growth of the Algæ: _Cœnogonium_. _b._ Thallus homoiomerous, gelatinous: _Collema_ (Fig. 132), with Algæ of the genus _Nostoc_; _Leptogium_. _c._ Thallus heteromerous, crustaceous: _Pertusaria_ (Fig. 140), _Lecidea_, with apothecia open from the beginning; _Lecanora_, with apothecia, which in the beginning are closed, later on open, but with a rim formed by the thallus (Fig. 138); _Bæomyces_, whose apothecia are borne on a stem formed by the thallus. _d._ Thallus heteromerous, foliaceous: _Parmelia_ (_P. saxatilis_; _P. parietina_, Wall-Lichen, Fig. 141, is yellow, very frequent on tree-stems, stone-walls, tiles); _Physcia_ (_P. ciliaris_, frequent on tree-stems); _Sticta_ (_S. pulmonacea_, Lung-Lichen, on tree-stems); _Peltigera_, especially on the Moss among trees; _Umbilicaria_, on rocks. _e._ Thallus heteromerous, fruticose: _Cetraria_ (_C. islandica_), “Iceland Moss,” with an olive-brown, flat, furrowed, fringed thallus, on heaths; _C. nivalis_, white, in the Polar regions; _Evernia_, _Ramalina_, _Usnea_ (_U. barbata_, Beard-Lichen, Fig. 143); _Roccella_, _Stereocaulon_, _Cladonia_, of which the genus _C. rangiferina_, Reindeer-Moss (Fig. 142) is important; _Cladonia_ has two kinds of thallus, one scaly and leaf-like, the other erect, which bears the apothecia and may be fruticose (Fig. 142), or cupular (Fig. 144); they grow in soil in forests and on heaths. [Illustration: FIG. 142.--_Cladonia rangiferina_: _s_ ascocarp.] [Illustration: FIG. 143.--_Usnea barbata_: _s_ ascocarp. (Slightly magnified.)] [Illustration: FIG. 144.--_Cladonia pyxidata._] Sub-Class 2. =Basidiomycetes.= This sub-class embraces the most highly developed Fungi, with large “fruit-bodies,” which in ordinary language we shortly term Funguses, Toadstools, or Mushrooms. They have no sporangia, but reproduce only by means of basidiospores, conidia, chlamydospores and oidia. The chief characteristic of this sub-class is the _basidium_ (Fig. 145), _i.e._ the conidiophore, which has a distinctive form, and bears a definite number (generally 4) of characteristically shaped conidia (basidiospores, Fig. 145 _c_, _d_, _e_). [Illustration: FIG. 145.--Development of spores in _Corticium_.] The summit of each basidium is produced generally into four conical points (_sterigmata_, Fig. 145 _b_), from each of which a basidiospore is abstricted. The basidia may be classified into three principal groups, each of which accompanies a distinctive conidiophore: 1, the long, filamentous, _transversely divided_ basidia, with lateral sterigmata and spores, found in the Uredinaceæ (Figs. 146 _D_, 153), Auriculariaceæ (Fig. 160 _B_), and Pilacraceæ; 2, the spherical, _longitudinally divided_ basidia of the Tremellaceæ (Figs. 160 _C d_; 161 iii. iv.); and 3, the ovoid, or cylindrical, _undivided_ basidia of the Autobasidiomycetes (Figs. 145, 163, etc.); the two last have apical sterigmata and spores. The first two groups are the septate basidia (_protobasidia_), of the _Protobasidiomycetes_; while the unseptate basidia (autobasidia) of the _Autobasidiomycetes_ are the third group. On the formation of the basidiospores, the nucleus of the basidium divides into four nuclei, each of which is transferred to a spore. In addition to the basidia, _simple conidiophores_ are also found. In the Protobasidiomycetes, the simple conidia are very generally found as accessory methods of reproduction in conjunction with the basidiospores; but less frequently in the Autobasidiomycetes, _e.g._ among the Dacryomycetes, Tomentellaceæ, _Heterobasidion annosum_. The simple conidiophores vary in size, and in the number and shape of the conidia; they, however, resemble the basidia, and are doubtless an early stage in the development of the definitely formed basidia. Finally, well-defined _chlamydospores_, formed in various ways, appear in the Basidiomycetes as supplementary reproductive bodies (compare p. 90). Among the Protobasidiomycetes, chlamydospores are at present only found among the Uredinaceæ, but in various forms; in the majority of families of the Autobasidiomycetes _oidia_ frequently occur (Fig. 162), but genuine chlamydospores seldom. In the same species several of the known forms of reproduction may be distinguished. The _mycelium_ is generally composed of white, branched strands, consisting of numerous felted hyphæ; in some, sclerotia are found.--The great majority are saprophytes; some (particularly all the Uredinaceæ), are parasites. DIVISIONS OF THE BASIDIOMYCETES. Series 1. PROTOBASIDIOMYCETES: partly gymnocarpic, partly angiocarpic. „ 2. AUTOBASIDIOMYCETES. Family 1. DACRYOMYCETES: gymnocarpic. „ 2. HYMENOMYCETES: partly gymnocarpic, partly hemiangiocarpic. „ 3. PHALLOIDEÆ: hemiangiocarpic. „ 4. GASTEROMYCETES: angiocarpic. Appended. BASIDIOLICHENES: Lichen-forming basidiomycetes. Series I. =Protobasidiomycetes.= To this series belong the lowest of the Basidiomycetes. The _basidia_ appear in two principal forms (1 and 2 on page 144) and are _divided_ into four cells, either transversely or longitudinally, each division forming a sterigma which abstricts a basidiospore. The first three orders, Uredinaceæ, Auriculariaceæ, and Tremellaceæ have _gymnocarpic_ fruit-bodies, while those of the Pilacraceæ, on the contrary, are _angiocarpic_. Order 1. =Uredinaceæ (Rusts).= All the Rust-Fungi are parasites, their mycelium living in the interior of the stems and leaves of their hosts, causing red, brown, or black spots--hence their name--and malformations, sometimes of considerable size. The Rust-Fungi are gymnocarpic and destitute of a hymenium; for these reasons they are regarded as the simplest order of the Basidiomycetes. They are entirely parasitic, and their filamentous, branched mycelium ramifies in the intercellular spaces of its host, and often protrudes haustoria into the cells. The mycelium is perennial should it enter a woody tissue; it may also hibernate in the rhizomes of perennial herbs and permeate the shoots springing from them, but in the majority of the Rust-Fungi the mycelium has a very limited growth. The chief means of reproduction of the Rust-Fungi are the _chlamydospores_, which in the more highly developed species occur in three forms, namely, the teleuto-, æcidio-, and uredo-spores. The spores, in the host, are formed immediately beneath its epidermis, which is ruptured on the ripening of the spores, with the production of “rust,” brown, red, or black spots. Those chlamydospores which produce basidia are termed _teleutospores_. The spore on germination produces a _transversely divided basidium_, “promycelium,” on which basidiospores, “sporidia,” generally four in number, are produced on lateral sterigmata. This basidio-fructification is _gymnocarpic_; the basidia neither form a hymenium nor a fruit-body (only _Cronartium_ and _Gymnosporangium_ have a slight indication of a basidio-fructification). Many Rust-Fungi, in addition to basidiospores, have small, _unicellular conidia_, “spermatia,” which are borne in conidiocarps, “_spermogonia_.” The ~TELEUTOSPORES~ (_Winter-spores_) may be either unicellular or multicellular; in the majority of cases they are enclosed in a hard outer cell-wall, the exospore, which in some cases is very strongly developed; they have also a long or short stalk, the remains of the spore-bearing hypha. Each cell of the teleutospore has _one germ-pore_ (a thin portion of the wall, for the protrusion of the germ-tube; in _Phragmidium_ and _Gymnosporangium_ there are, however, several germ-pores). The colour of the teleutospores is generally much darker than that of the uredospores, and it is by these that the majority of the Rust-Fungi _hibernate_. In _Gymnosporangium_, two kinds of teleutospores are found (distinguished by their size and thickness of exospore). In many species of _Puccinia_, the form of the teleutospores varies very much, so that in the same layer spores have been observed with the characteristic form of other, allied genera.--The teleutospores of _Endophyllum_ resemble æcidiospores, since they are united in chains, whose cells are easily separated, and are produced in the interior of a “peridium.” The multicellular teleutospores of _Coleosporium_ function as basidia, and from each cell immediately produce basidiospores.--The teleutospores of _Coleosporium_ and _Chrysomyxa_, differ from other teleutospores in the absence of exospore and germ-pore. The ÆCIDOSPORES (_Spring-spores_) are produced in chains which are generally enclosed in an _envelope_ of hyphæ, the _peridium_; the _peridium_ enclosing the spores being termed the _æcidium_. The æcidiospores are unicellular, and generally of an orange colour; they are often separated by intermediate cells which wither and so assist in the distribution of the spores. The exospore is made up of minute, radially arranged rods. _Generally germination_ proceeds _immediately_, the æcidiospore producing a germ-tube, which developes into a mycelium bearing either uredo- or teleutospores. The æcidia of many Rust-Fungi were formerly considered as distinct genera. The æcidia of _Phragmidium_, _Triphragmium_, and _Melampsora_, in which the _peridium is wanting_, were in part considered as _Cæoma_. The æcidia with fimbriate edge, or those of _Gymnosporangium_ with longitudinal lattice-like splits, were considered as “_Rœstelia_” (Lattice-Rust); large, sac-shaped æcidia on the Coniferæ were known as _Peridermium_. The ~UREDOSPORES~ (_Summer-spores_) are unicellular and arise singly, seldom in chains (_Coleosporium_). Their colourless, warty exospore bears, _in the equatorial plane_, 2–8 _germ-pores_. In the majority, _germination_ proceeds _immediately_, and a mycelium is produced which at first gives rise to uredospores and afterwards to teleutospores. The uredospore-formations of _Melampsorella_ and _Cronartium_ are enclosed in an _envelope_, and hence resemble æcidia.--Between the uredospores sterile, unicellular hyphæ (paraphyses) may be found. The _spermogonia_ are spherical or pear-shaped _conidiocarps_, generally embedded in the substratum, and are produced before the æcidia, before or simultaneously with the uredospores, or before the teleutospores. The conidia, as far as observations go, do not generally germinate under ordinary conditions. Among the Rust-Fungi some species are found which only form basidiospores and teleutospores (_Puccinia malvacearum_, _Chrysomyxa abietis_). Other species have in addition uredospores; others spermogonia and uredospores; others spermogonia and æcidia; others spermogonia, uredospores and æcidia. Those species in which all the methods of reproduction are not developed must not be considered as incomplete forms. As a rule the mycelium, which is produced from the basidiospores, developes æcidia; in the species, however, without æcidia, it developes the uredo-form, and when the uredospores are also absent, the teleutospore-form. It has been established in some species of _Puccinia_ and _Uromyces_ that the formation of æcidia can be suppressed, and it is not a necessary part of the cycle of development of the species. The majority of Rust-Fungi hibernate in the teleutospore-form. Many species are able to hibernate in the uredospore-form (_Coleosporium senecionis_). Others pass the winter in the æcidio-form, and develope æcidia on new hosts (_Uromyces pisi_, on _Euphorbia cyparissias_; _Phragmidium subcorticium_, on _Rosa_; _Æcidium elatinum_, on _Abies alba_). In _Chrysomyxa abietis_, the mycelium, developed from the basidiospores, survives the winter. Among the Rust-Fungi, with several forms of reproduction, there are about sixty whose development can only be completed by an _alternation of hosts_, that is, on one host only uredo-and teleutospores are produced, while the further development of the germinating basidiospores, and the formation of the æcidia and spermogonia from its mycelium, can only take place on a second quite distinct and definite host (_heterœcious_ or _metoxenous_ Fungi). Those Fungi which have all their forms of reproduction on the same host are termed _autœcious_ or _autoxenous_. It is not, however, always necessary that the heterœcious Rust-Fungi should regularly change their hosts; for example, _Puccinia graminis_ can hibernate in the uredo-form on the wild Grasses, and in the spring can distribute itself again in the same form. As a consequence of the alternation of hosts the various forms of development were considered as independent genera (_Uredo_, _Æcidium_, _Rœstelia_, _Cæoma_, _Peridermium_), until De Bary and Oersted established, about the same time (1865), the mutual connection of some forms, and paved the way for the right conception of these Fungi. [Illustration: FIG. 146.--_Puccinia graminis_.] As an example of one of the most highly developed species, _Puccinia graminis_, the “Rust of Wheat,” holds a prominent position. Its uredospores and teleutospores are produced (Fig. 146) on Grasses (on cereals, especially Wheat, Rye, Oats, and many wild Grasses), while the æcidia and spermogonia are confined to the Berberidaceæ. The teleutospores, developed on the Grasses, hibernate on the dried portions of their host, and in the succeeding year each of the two cells of the teleutospore may develop a _basidium_ with four basidiospores (Fig. 146 _D_, _c_). The basidiospores are distributed by the wind, germinate quickly, and only proceed to further development on _Berberis_ or _Mahonia_. The germ-tube _bores through the epidermis_ of the Barberry-leaf, and forms a mycelium in its interior, its presence being indicated by reddish-yellow spots on the leaf. After 6–10 days the flask-shaped _spermogonia_ appear (Fig. 147 _B_; _C_, _a_; conidia in Fig. 147 _D_) and a few days later the cup-shaped _æcidia_ (Fig. 147 _A_; _C_, _c_, _d_, _e_). The former are generally on the _upper_, and the latter on the _under side_ of the leaf. The orange-coloured æcidiospores scatter like dust, and germinate only on Grasses; the germination takes place in about two days when placed on any green part of a Grass. The germ-tube enters the Grass-leaf through a stoma; a mycelium is developed in the leaf, giving rise to a small, oval, rust-coloured spot (Fig. 146 _A_); in about 6–9 days the epidermis is ruptured over the red spot, and numerous reddish-yellow _uredospores_, formed on the mycelium, are set free. The uredospores (Fig. 146 _B_) are scattered by the wind, and can germinate should they fall on the green portions of other Grasses: they then emit 2–4 germ-tubes through the equatorially-placed germ-pores. The germ-tubes enter a leaf through a stoma, a new mycelium is then developed, and in about eight days a fresh production of uredospores takes place, which germinate as before. The uredospore-mycelium very soon produces, in addition, the brown _teleutospores_, which give a brown colour to the rust-coloured spots, the familiar uredospores on the cereals being quite suppressed towards the close of the summer (Fig. 146 _C, D_). The “Rust of Wheat” hibernates on some wild Grasses in the uredospore-form. [Illustration: FIG. 147.--_Æcidium berberidis_. _A_ Portion of lower surface of leaf of Barberry, with cluster-cups (æcidia). _B_ A small portion of leaf, with spermogonia, from above. _C_ Transverse section of leaf on the upper side, in the palisade parenchyma are three spermogonia (_a b_); on the lower side an unripe æcidium (_c d_) and two ripe æcidia (_d, e, f_); _f_ chain of æcidiospores. _D_ Hyphæ, forming conidia.] GENERA. _Puccinia_ (Fig. 146, 147) has bicellular teleutospores, each having a germ-pore, and the æcidia when present have an indented peridium; some species, as exceptions, have 1–3-celled teleutospores. Many species are HETERŒCIOUS, for example, _P. graminis_, described above; _P. rubigo_, which also infests various Grasses, but whose æcidia appear on _Anchusa_; the masses of teleutospores are small; they contain paraphyses, and are for a long time covered by the epidermis. _P. coronata_, on Oats and Rye Grass; its æcidia on _Rhamnus_; the teleutospores are surmounted by a crown--“coronate processes.” _P. phragmitis_, on Reeds; æcidia on species of _Rumex_ and _Rheum_. _P. moliniæ_, on _Molinia cœrulea_; the æcidia on Orchids. _P. poarum_, on Meadow-Grass; æcidia on _Tussilago_. Various Puccinias growing on species of _Carex_ have their æcidia on _Urtica_, _Lysimachia_, _Cirsium_, _Pedicularis_, etc.--Of those AUTŒCIOUS species, which have all their generations on the same host, may be noted:--_P. galii_, _P. menthæ_, _P. violæ_, _P. epilobii_, _P. asparagi_, which grow on the hosts from which they have taken their specific names.--As representative of a group which have spermogonia, uredo-and teleutospores on the same host, but on different individuals, _P. suaveolens_, on the Field-Thistle, may be mentioned. The spermogonia have a strong odour.--A peculiar group (_Leptopuccinia_) has only teleutospores, which germinate immediately, and whilst still attached to their living host. To this group belong _P. arenariæ_, on a number of Caryophyllaceæ; and _P. malvacearum_, on various Malvaceæ, introduced in 1873 from South America to Europe, where it soon proved very destructive to Hollyhocks. _Uromyces_ (Fig. 149) differs only from _Puccinia_ in always having unicellular teleutospores. Among this genus both heterœcious and autœcious species are found. To the first group belong _U. pisi_, whose æcidia are found on _Euphorbia cyparissias_, and _U. dactylidis_, whose æcidia appear on _Ranunculus_; to the second group belong _U. betæ_, _U. phaseoli_, _U. trifolii_. _Triphragmium_ has teleutospores with three cells (one below and two above), on _Spiræa ulmaria_. _Phragmidium_ (Fig. 150) has teleutospores consisting of a row of cells (3–10) arranged in a straight line; the upper cell has one germ-pore and the others four germ-pores placed equatorially. Both this and the preceding genus have large, irregular æcidia without peridia, but often with bent, club-like paraphyses (150 _b_ and _c_); they are all autœcious, and are only found on the Rosaceæ. [Illustration: FIG. 148.--_Gymnosporangium sabinæ_. A small portion of the epidermis of a Pear-leaf (_a_) pierced at _b_ by the germinating basidiospore (_c_).] [Illustration: FIG. 149.--_Uromyces genisteæ_; _a_ uredospore; _b_ teleutospore.] _Endophyllum_ (see above, under teleutospores, p. 147) on species of _Sempervivum_. _Gymnosporangium_ (Figs. 152, 154) has bicellular teleutospores collected in large, gelatinous masses formed by the swelling of the long spore-stalks; in each cell 2–4 germ-pores are found. Uredospores are wanting. All the species are heterœcious; the teleutospores appear on _Juniperus_, the æcidia (_Rœstelia_) on the Pomaceæ. _G. sabinæ_, on _Juniperus sabina_, _J. virginiana_, etc., has the æcidia (“_Rœstelia cancellata_”) on _Pyrus communis_ (Figs. 152, 148); _G. juniperinum_, on _Juniperus communis_ with “_Rœstelia cornuta_” (Fig. 154 _a_) on _Sorbus aucuparia_, _Aria nivea_ (_S. aria_) and _Malus communis_; _G. clavariæforme_ on _Juniperus communis_, the æcidium belonging to it (“_Rœstelia lacerata_”) on _Cratægus oxyacantha_. _Melampsora_ has prismatic teleutospores placed parallel to each other and forming a crustaceous layer; in many species they are divided longitudinally into several cells (Fig. 151). The æcidia, without peridium, belonged to the old genus _Cæoma_. _M. caprearum_, on Willows, has the æcidia (_Cæoma euonymi_) on _Euonymus_. _M. hartigii_, on Osiers; the æcidium on _Ribes_. _M. mixta_, on _Salix repens_ and Orchids. _M. pinitorqua_, on leaves of the Aspen, æcidia on Pine branches (Pine shoot fungus); _M. populina_ on _Populus monilifera_ and _nigra_; _M. betulina_ (Fig. 153), on Birch leaves; _M. padi_ (Fig. 151), on leaves of _Prunus padus_, developes teleutospores in the epidermal cells; _M. lini_ is the cause of injury to the Flax; _M. agrimoniæ_. [Illustration: FIG. 150.--_Phragmidium gracile_: _a_ an uredospore; _b_ and _c_ two paraphyses; _d_ a young teleutospore; _e_ a teleutospore with a basidium and two basidiospores (_s_); _f_ two series of æcidiospores (_Ph. rosæ_).] _Calyptospora gœppertiana_; teleutospores on _Vaccinium vitis idæa_; spermogonia and æcidia on _Abies alba_ (Firneedle-Rust). _Coleosporium_ (Fig. 155) forms its uredospores in reddish-yellow chains; for the teleutospores, see page 147. _C. senecionis_, on the Groundsel; its æcidium (_Peridermium wolffii_) on Pine-leaves (Fig. 155 a). Other species on _Sonchus_, _Petasites_, _Campanula_, _Rhinanthaceæ_. _Chrysomyxa_ (Fig. 156) has bright red, branched teleutospore-chains; each spore developes a 4-celled basidium. _C. ledi_, on _Ledum palustre_; its æcidia on the leaves of the Fir. _C. abietis_ (Fig. 156), without uredo-and æcidiospores; teleutospores on the leaves of the Fir. In the first summer, yellow bands are formed on the leaves, and in the following spring the red cushions of spores. [Illustration: FIG. 151.--_Melampsora padi_: _a_ and _b_ uredospores; _c-f_ teleutospores, seen from different sides.] [Illustration: FIG. 152.--Pear-leaf, seen from the under side, with “_Rœstelia cancellata_”: in different ages (_a_ youngest, _d_ oldest).] [Illustration: FIG. 153.--_Melampsora betulina_: _a_ uredospores; _b_ three contiguous teleutospores, one of which has developed a basidium with three basidiospores. (× 400.)] [Illustration: FIG. 154.--_Gymnosporanginum juniperinum_: _a_ a small leaf with three clusters of æcidia (nat. size); _b_ three conidia; _c_ two æcidiospores on one of which are seen the germ-pores; _d_ a portion of the wall of an æcidium; _e_, _f_ two teleutospores.] [Illustration: FIG. 155.--_Coleosporium senecionis_: _a_ Pine-leaves with æcidia (_Peridermium wolffii_) nat. size; _b_ an æcidiospore; _c_ a germinating æcidiospore; _d_ a chain of uredospores; _e_ a chain of teleutospores of which the terminal one has germinated and produced a basidiospore (_s_).] _Cronartium_ (Figs. 157, 159) has unicellular teleutospores united in numbers to form erect threads or columns; the uredospores are enclosed in a “peridium”; _C. ribicola_ (Fig. 157), on leaves of Ribes (especially Black Currants); its æcidia (_Peridermium strobi_, or _P. klebahni_) on the stems and branches of _Pinus strobus_ (Fig. 159), on which it causes great damage; _C. asclepiadeum_, on _Vincetoxicum officinale_; its æcidia (_Peridermium cornui_) on the stems and branches of _Pinus silvestris_. [Illustration: FIG. 156.--_Chrysomyxa abietis_: _a_ leaf of the Fir, with 5 clusters of basidiospores (× 4); _b_ branched rows of teleutospores springing from the mycelium (_m_).] [Illustration: FIG. 157.--_Cronartium ribicola_: _a_ mass of uredospores (× 50); _b_ an uredospore; _c_ a column of teleutospores (× 60); _d_ a small portion of the same more highly magnified, with a basidium and two basidiospores (_s_).] To the Fungi of which the æcidium is known, whilst the remaining forms are still undetermined, but which are without doubt heterœcious, belong _Æcidium elatinum_, which produces the enormous “witches’ brooms” and barrel-shaped swellings on stems and branches of _Abies alba_; and _Æcidium strobilinum_ (Fig. 158), which attacks Fir-cones, causing all the scales to become covered with clusters of æcidia opening by a lid. _Hemileia vastatrix_ destroyed the coffee plantations in Asia. [Illustration: FIG. 158.--_Æcidium strobilinum_: _a_ scale of cone of _Picea excelsa_, with numerous æcidia; _b_ æcidiospores arranged in a series; _c_ a cell of the peridium.] Order 2. =Auriculariaceæ.= The _long, transversely divided_ basidia bear laterally 4 _long sterigmata_ with basidiospores (Fig. 160 _B_) and are united to form an _hymenium_ on the surface of the fruit-body. Parasites or saprophytes. _Auricularia sambucina_ (_Auricula judæ_), Judas’-ear, has large fruit-bodies, which may attain the size of several inches, resembling an ear or a mussel shell. In the moist condition they are flesh-coloured, tough and gelatinous, but when dried, become hard, grey and wrinkled; the exterior is covered with short hairs; while the internal surface bears the hymenium. Habitat: stems and branches of old Elder-trees (_Sambucus_). Order 3. =Tremellaceæ.= The _round, pear-shaped, longitudinally divided basidia_ bear 4 _elongated sterigmata_, situated apically, and 4 basidiospores (Fig. 160 _C_, _D_), and are united into the _hymenium_ on the surface of the fruit-body. The fruit-bodies are frequently gelatinous and quivering; similar fruit-bodies are also found in the Dacryomycetaceæ and Hydnaceæ. Simple conidiophores, which appear not infrequently in the basidiocarps, before the basidia, are known in many species. Saprophytes. [Illustration: FIG. 159.--_Peridermium strobi_: æcidia of _Cronartium ribicola_ (nat. size).] [Illustration: FIG. 160.--_B Auricularia sambucina_: _a-d_ basidia in various stages of development; _e_ a sterigma bearing a spore.--_C Tremella lutescens_: _a-d_ basidia seen from various sides (_b_ from above) and in various stages of development; _e_ sterigma with basidiospore (× 400). _D Exidia glandulosa_: _a-c_ various stages in the development of a basidium; _d_ sterigma with basidiospore (× 350).] _Exidia_ has kidney-shaped, oblong basidiospores, and small, hook-like conidia; _E. glandulosa_, _E. albida_, etc., on wood.--_Craterocolla_ has conidiocarps; _C. cerasi_ on Cherry-wood.--_Sebacina incrustans_; the yellow, fleshy, or cartilaginous fruit-bodies are found in autumn covering the ground in moist woods.--_Tremella_ has round basidiospores; _T. mesenterica_ has irregularly-folded, quivering, orange fruit-bodies, about one inch in breadth; _T. lutescens_ (Fig. 161) has orange-yellow conidial-and yellow basidial-layers; _T. frondosa_ has fruit-bodies upwards of a foot in breadth. Order 4. =Pilacraceæ.= The _transversely divided basidia_ have _no sterigmata_, but sessile basidiospores, and fill up the cavity of a _closed_ (_angiocarpic_) _fruit-body_ as a gleba without a regular arrangement (hymenium wanting). _Pilacre fagi_ on the old stems of the Copper-Beech; _P. petersii_, on dried branches of the Hornbeam, has stalked, capitate fruit-bodies. [Illustration: FIG. 161.--_Tremella lutescens_: I and II fruit-bodies (nat. size); III vertical section through a fruit-body; _b_ basidia; _c_ conidia; IV-VI basidia; VII basidiospore with a second spore; VIII a basidiospore with yeast-like budding (cultivated); IX a conidiophore. (III-IX about 400.)] Series 2. =Autobasidiomycetes.= This second and larger part of the Basidiomycetes is characterised by its more highly differentiated, _undivided_, club-shaped, or cylindrical basidia, which generally bear 4 (seldom 2, 6, 8) apically-placed sterigmata and basidiospores (Fig. 145). The fruit-bodies are partly _gymnocarpic_ (in the first 3 orders and in some Agaricaceæ), partly _hemiangiocarpic_ (in orders 3–6 of the Hymenomycetes and in the Phalloideæ, the fruit-bodies in these orders are in the young conditions more or less angiocarpic, but later on generally open below and bear the hymenium on the under surface of the fruit-body), partly also _angiocarpic_ (in the Gasteromycetes). [Illustration: FIG. 162.--_Dacryomyces deliquescens_: I fruit-body (nat. size); II vertical section through the hymenium; III germinating basidiospore; IV a portion of mycelium with conidia; V a germinating conidium; VI and VII chains of oidia more or less strongly magnified; VIII basidiospore of _D. longisporus_; IX germinating basidiospore of _D. ovisporus_; X and XI _Calocera viscosa_; X fruit-body (nat. size); XI basidia with basidiospores (highly magnified); XII _Dacryomitra glossoides_ (nat. size).] Family 1. =Dacryomycetes.= The _long, club-shaped basidia_ bear _two tapering sterigmata_, which develope remarkably large basidiospores (Fig. 162 II, XI) and form _gymnocarpic_ fruit-bodies with hymenium. 1 order: Order 1. =Dacryomycetaceæ.= This order comprises 4 genera of which the first two develope the hymenium on the whole surface of the fruit-body, but the two last only on its apex. _Dacryomyces_: the folded, gelatinous, _Tremella_-like fruit-bodies break out in winter on dried wood (hedges) in the form of red or yellow drops. _D. deliquescens_ is very common (Fig. 121). The following genera have cartilaginous fruit-bodies.--_Calocera_ (Fig. 162), with club-like, simple, or branched, _Clavaria_-like, fruit-bodies; the orange coloured fruit-bodies of _C. viscosa_ grow aggregated together on the wood of Conifers.--_Guepinia_ resembles a _Peziza_, and has the hymenium only on the hollow upper surface.--_Dacryomitra_ resembles a _Mitrula_ (Fig. 162). Family 2. =Hymenomycetes.= This family is very rich in species (more than 8000 have been described), and to it belong all the “Mushrooms” and “Toadstools.” The _fruit-bodies_ present very various forms; they are generally fleshy, very perishable, seldom leathery or corky, in the last case often perennial. The _basidia_ are more or less _cylindrical_ and bear _generally_ 4 (seldom 2, 6 or 8) _sterigmata and basidiospores_. The hymenium in the fully-formed fruit-bodies lies free on the surface: in orders 1 and 2 and a portion of order 6 it is from the commencement exposed, fruit-bodies _gymnocarpic_; orders 3–6 have _hemiangiocarpic_ fruit-bodies (p. 157). In the first order the basidia (or the hymenium) are developed immediately from the mycelium (Fig. 163); the fruit-bodies of orders 2 and 3 present a higher grade of development, and have between the mycelium and hymenium a special hyphal-tissue, a _stroma_, which is crustaceous, club-like, or coralloid, etc., and in general bears the hymenium on the largest part of the free, smooth surface. In the forms most highly developed (orders 4–6) a new tissue--the _hymenophore_--is introduced between the stroma and hymenium, which appears on the under side of the fruit-body in the form of warts, projections, tubes, folds or lamellæ (Figs. 166, 167, 174 _bc_). _Paraphyses_ are frequently found in the hymenium, among the basidia. In the Hymenomycetes few examples of _conidia_ can be recognised at first. More frequently _chlamydospores_ are found, particularly _oidia_. The _mycelium_ is richly branched, generally colourless, often perennial; it lives in humus or decaying wood, and is seldom parasitic. The hyphæ generally have clamp-connections and unite, sometimes, to form a rhizomorpha (Fig. 177) or sclerotia with coloured, pseudo-parenchymatous covering. [Illustration: FIG. 163.--_Exobasidium vaccinii._ I Hypertrophied stem of _Vaccinium vitis idæa_; II leaf with gall-like swelling; III section of II; IV transverse section: _m_ mycelium between the parenchymatous cells; _p_ hypodermal cells; _e_ epidermis with basidia in various stages of development; V epidermis with germinating spores; VI and VII spores germinating in water (IV-VII × 620).] Order 1. =Tomentellaceæ.= To this order belong the simplest of the Hymenomycetes. The basidia (Fig. 145) arise free and irregularly from the mycelium; a _hymenium_ is _entirely absent_ or _very slightly formed_ (in _Corticium_ it attains its highest development); _fruit-bodies_ are _also wanting_.--In general they form flaky, membranous or leathery coverings on bark and wood. Some are parasites. _Hypochnus_ without conidia.--_Tomentella_ with conidiophores; growing on wood or earth.--_Exobasidium vaccinii_ (Fig. 163), a parasite on _Vaccinium_, _Andromeda_, _Arctostaphylos_, and _Rhododendron_, forms flaky-powdery, white or red coverings and may cause hypertrophy of the parts attacked. _E. warmingii_ is parasitic on _Saxifraga_; _E. lauri_ causes outgrowths on the stem of _Laurus canariensis_ as long as a finger, which formerly were regarded as aerial roots.--_Corticium_ forms membranous to leathery layers or crusts; _C. quercinum_ on wood and bark, particularly Oak, is flesh-coloured; _C. cæruleum_ has a blue hymenium; _C. giganteum_ on the bark of fallen Pine-trees. Order 2. =Clavariaceæ.= The hymenium is situated on a stroma, and either completely _covers the smooth surface_ of the more or less fleshy _gymnocarpic fruit-body_, or is confined to a tolerably well defined _upper portion_ of it (_Typhula_). Paraphyses absent. The vertical, white, yellow, or red fruit-bodies are roundish or club-like, undivided or richly branched (Fig. 125). Generally on the ground in woods, seldom on tree-stems, etc. [Illustration: FIG. 164.--_Clavaria coralloides_ (nat. size).] GENERA: _Clavaria_, generally large Fungi with thick, round branches. _C. botrytis_ has a very thick, tubercular stem with numerous short, flesh-coloured branches: it has an agreeable taste. _C. coralloides_ has a brittle, richly-branched fruit-body (Fig. 164); basidia with two large spores. _C. pistillaris_ consists of a single, undivided club of a yellowish-white colour.--_Sparassis_ has compressed, leaf-like, curled branches; _S. crispa_ has fruit-bodies as large as a white cabbage-head, with an agreeable taste.--_Typhula_ and _Pistillaria_ are small Fungi with filamentous stalks, terminating in a small club. The fruit-bodies of the former often arise from a small, spheroid sclerotium; the latter is distinguished by the basidia bearing only two spores. Order 3. =Thelephoraceæ.= The hymenium is placed on a stroma and _covers the smooth surface_ of the leathery _hemiangiocarpic fruit-body_, generally _on its under side_. The edge of the stroma, which bounds the hymenium, is sometimes especially developed (_Stereum_). Saprophytes. GENERA: _Thelephora_. The fruit-bodies in this genus are brown, very irregularly shaped, and often lobed. The spores too are brown, but in the other genera colourless. The species are found growing on barren soil. _T. laciniata_ (Fig. 165) has imbricate, semicircular, dark-brown pileus, which is jagged at the edge and upper surface. The fruit-bodies are very often raised above the ground, and although this species is not a parasite, yet it destroys young seedlings by growing above and smothering them.--_Stereum_ has a stiffer fruit-body, with a distinct, fibrous, intermediate layer. It grows on bark and wood, projecting like a series of imbricate brackets. _S. hirsutum_ is yellow; its free edge is provided with a number of stiff hairs, the upper surface being divided into a number of zones. _S. purpureum_ has a red-violet hymenium which distinguishes it from the previous species.--_Cyphella_ has a membranous cup- or bell-shaped fruit-body, often borne on a stalk, the concave surface being covered with the hymenium. They are small, white Fungi, growing on Moss and dead stems.--_Solenia_ is closely related to _Cyphella_; its fruit-bodies are smaller and hairy; they are found clustered together forming a crust-like covering on dead wood.--_Craterellus_ has a large, funnel-shaped fruit-body, the hymenium covering the external surface. _C. cornucopioides_ is shaped like a trumpet or a “horn of plenty.” It is dark-grey, several inches in height, and grows gregariously on the ground in forests. It is distinguished by the basidia bearing only two sterigmata. [Illustration: FIG. 165.--_Thelephora laciniata_ (nat. size).] Order 4. =Hydnaceæ.= The fruit-body is most frequently fleshy, and varies considerably in shape, the simplest forms being resupinate,[14] the higher ones umbrella-like. The _hymenophore_ is found on the free or downward-turned surface, and always takes the _form of soft emergences_ hanging vertically downwards. The emergencies may be thorn-, awl-, or wart-like. The species are found growing on the soil and on dead wood. GENERA: _Hydnum_ has subulate, distinct emergences. _H. repandum_ is yellow, the stalk being placed in the centre of the pileus. It is an edible species, and often forms “fairy rings” in woods. _H. auriscalpium_ (Fig. 166) is dark-brown, with stalk placed at the edge of the pileus. It grows on old Fir-cones. _H. erinaceus_ grows on old tree-trunks. The fruit-body is yellow and very large--as big as a human head--with emergences as much as an inch in length.--_Irpex_ has a leathery fruit-body, partly resupinate, partly with free, projecting edge; the under side bears tooth-like emergences which are arranged in rows, and _Irpex_ thus forms a transition to the Agaricaceæ.--_Phlebia_ is entirely resupinate, with radially-arranged folds on the free side, and pectinate border. [Illustration: FIG. 166.--_Hydnum auriscalpium_, upon a Fir-cone, in different stages of development.] Order 5. =Polyporaceæ (Pore-Fungi).= An order very rich in species (about 2000 species are described). The fruit-body is of very different forms--resupinate, projecting like a bracket, hoof-like, or umbrella-shaped. In some it is fleshy and edible, in others leathery or corky, persisting for several years. The hymenophore is situated on the under side of the fruit-body, and consists of wide or narrow _tubes_ or _pores_, whose inner surface is clothed with the hymenium (Fig. 167). In some fruit-bodies large cavities are to be found, which have arisen as interstices between the labyrinthine curved and reticulate folds. Chlamydospores are known in some species. Conidia occur very rarely. Many species work considerable damage: some as parasites on trees, others by destroying timber. [Illustration: FIG. 167.--_Polyporus igniarius._ Section through the under side of the Fungus: _h-h_ is hyphal-tissue between the tubes, formed by irregularly felted hyphæ, many of which are seen cut across; _s_ is the hymenium which covers the walls of the tubes, and from which the basidia with the spores protrude.] GENERA. _Polyporus_ (Pore-Fungus). The tubes are narrow, accurately fitted together, and forming a thick layer on the under side of the fruit-body, appearing as a number of fine holes. The fruit-body most frequently resembles a bracket, or is hoof-shaped, with one side growing from a tree-trunk; it is very often perennial, and a new layer of tubes arises in each succeeding period of vegetation. Strata, corresponding to the periodically interrupted growth, are thus formed in storeys one above the other, and are visible on the upper surface of the fruit-body, as well as in the interior, as a series of concentric belts, sometimes as many as half a score or more in number. _P. fomentarius_ (Touchwood) attacks trees, especially the Beech. The spores germinate on wounds from broken branches, and the hyphæ, following the course of the medullary rays, find their way into the interior of the tree, from whence the mycelium spreads upwards, downwards, and peripherally, so that the wood becomes rotten (“white-rot”) and thick felts of mycelium are formed in radial and tangential directions. A dark line, caused by the youngest parts of the hyphæ containing a brown juice, marks the boundary between the rotten and the unattacked parts of the stem (Fig. 168); at places where the mycelium extends to the bark, the cambium becomes destroyed and further growth is arrested, so that longitudinal furrows arise on the stem. It is at these places, too, that the hoof-shaped, ash-coloured fruit-bodies are developed, which may attain a circumference of upwards of 7 feet. The interior of the fruit-body consists of a dried-up, loosely felted, red-brown mass of hyphæ, which has been used for tinder and as a styptic (“Fungus chirurgorum”). _P. igniarius_ has a harder, dark-brown, more rounded fruit-body; it grows in a similar manner, but especially attacks Oaks, Poplars, and Plum-trees, the wood of which becomes rotten, and is called touchwood. _P. pini_ (_Trametes pini_), (Fig. 170), a parasite on the stems of _Pinus_, causes a kind of “red-rot” in the stem. _P. sulphureus_ has a soft, cheesy, yellow fruit-body; it produces “rot” in Oaks and Apple-trees. _P. officinalis_, Larch-fungus (“Fungus Laricis” in Pharmocopœia), grows on Larch-trees in the south-east of Europe. _P. versicolor_ has thin, semicircular fruit-bodies, with zones of various colours on the upper side; it is one of the most frequent species on tree-stems. _P. frondosus_ grows on soil in woods, and consists of numerous aggregated fruit-bodies, which become very large and fleshy. This species is edible. _P. perennis_ also grows on the soil in woods; it is very leathery, with central stalk, and has concentric zones on the upper surface of the fruit-body. _P. vaporarius_ destroys the wood of living Pines (_Pinus silvestris_) and Firs (_Picea excelsa_), causing it to become red-brown; in timber this Fungus causes “red-strip” followed by a “dry-rot.” _P. squamosus_ destroys many Walnut-trees, and is also very destructive to Limes and Elms. _P. fulvus_ causes a “white-rot” in _Abies alba_. [Illustration: FIG. 168.--Section of stem of a Beech attacked by _P. fomentarius_: _a_ non-attacked parts of the stem; _b_ the furrows where the mycelium has reached the bark, and where the thick mycelium-strands reach the exterior (⅙th of the nat. size).] [Illustration: FIG. 169.--Base of a Fir-tree, with a number of fruit-bodies of _Heterobasidion annosum_ just beneath the surface of the soil, indicated by the dotted line (¼th nat. size).] [Illustration: FIG. 170.--A fully developed fruit-body of _Polyporus pini_ (_Trametes pini_), lateral view (nat. size).] _Heterobasidion annosum_ (_Polyporus annosus_, _Trametes radiciperda_, Fig. 169) is characterized by its _Aspergillus_-like conidiophores. It is a parasite on the Pine, Fir, Birch, Beech, etc., and is the chief cause of a root-disease (red-rot) in Pines and Firs; the fruit-bodies develope a large number of basidiospores; they may be very large and are found just beneath the surface of the soil (on living or dead roots), and exposed to the air (on felled stems and roots, in Scandinavia). _Ptychogaster_ has cushion-like fruit-bodies, which consist chiefly of chlamydospore-chains, formed of ellipsoidal spores, which alternate with short hyphæ having transverse septa and clamp-connections. The hymenial portion is limited to a small group of tubes. _Pt. albus_ (_Oligorus ustilaginoides_) grows on stumps of Conifers and forms irregular cushions, at first white and later on brown, which consist almost entirely of chlamydospores. _Boletus_ (Fig. 171) has a fleshy fruit-body resembling a common Mushroom, with central stalk. The layer of tubes is easily detached from the pileus, and the tubes are easily separable from one another. They grow on the ground in woods. Edible species are: _B. edulis_, with thick, reticulate stalk; _B. scaber_, with thin stalk and rough pileus; _B. luteus_, with a ring on the stalk. _B. luridus_ is poisonous, its tubes have red openings, and the flesh turns quickly blue when broken and exposed to the air. _Fistulina hepatica_ (Beef-steak Fungus), has a red, fleshy, edible fruit-body, with red juice. The tubes are individually distinct; conidia are also developed. Grows on old Oaks. _Merulius lacrymans_ (“Dry-rot”) has a resupinate fruit-body with white, cotton-like border, and the remaining portions covered by reticulate, ramified veins of a rust-brown colour. In favourable vegetative conditions it is fleshy and exudes large drops of water--hence its specific name and also the name “Tear Fungus.” The mycelium is at first colourless, and then yellow-brown; when dry it is tough and leathery. It destroys the timber in damp houses, extends far and wide over boards and beams and even over the masonry, giving rise to a disagreeable smell in the rooms in which it lodges. In woods the Fungus lives on Pine-stems. It is brought from the forest on the logs of timber, and is distributed from log to log by the mycelium and the basidiospores. The living mycelium can be recognised by the clamp-connections shooting out branches. The basidiospores are often ejected a distance of a metre; they are elliptical (10–11µ long and 5–6µ broad), and germinate easily on damp wood, or in fruit-juice which has been neutralized with urine or alkaline carbonates. _Dædalea_ (Labyrinth Fungus), has bracket-like, corky fruit-bodies with irregularly-folded plates or discs on the under side. It forms a transition to the Agaricaceæ. _D. quercina_ is frequent on Oak-stumps. [Illustration: FIG. 171.--_Boletus edulis_ (about ¼th): _b_ longitudinal section of a portion of the pileus.] Order 6. =Agaricaceæ= (=Mushrooms=, =Toadstools=). _The hymenophore consists_ of knife-like plates (_lamellæ_, _gills_), which are situated on the under side of the umbrella-like pileus of the fruit-body, and radiate from the central stalk. Those which are first formed extend from the edge of the pileus to the stalk; those formed later reach only a longer or shorter portion of this distance, according to their age. In structure the lamellæ (Fig. 174) consist of a central mass of hyphæ, the _trama_, continuous with the hyphæ of the pileus; these terminate in a layer of shorter cells, the _subhymenial layer_, immediately beneath the hymenium which is composed of basidia and paraphyses. In a few species, but not in the majority, the lamellæ are branched, and in some they are decurrent. A few have the stalk placed excentrically, or it may be entirely absent. [Illustration: FIG. 172.--Development of _Psalliota campestris_: _a_, _b_, _c_, _d_ show the various stages of the development of the fruit-bodies and the mycelium (_m_) (nat. size); _e_ the fruit-body in a somewhat later stage, slightly magnified; _f_ longitudinal section of _e_; _n_ first formation of the hymenium; _g_ longitudinal section of a more advanced fruit-body (nat. size); _n_ the hymenium; _o_ velum partiale (see Fig. 133.)] In the early stages of its development the fruit-body is more or less enclosed in a hyphal tissue--the “veil” (_velum universale_, or _volva_). The veil at first completely encloses the young fruit-body, but is afterwards ruptured as the latter grows, part remaining at the base of the stalk as the “sheath” (_annulus inferus_), and part on the pileus as scales or warts. In the “Fly Mushroom” (_Amanita muscaria_) the remains of the veil are especially conspicuous as white patches on the bright red ground of the upper surface of the pileus, and as a sheath at the base of the stalk (Fig. 178 _v._). Another veil--the _velum partiale_--a hyphal tissue (Figs. 178 _a_; 173) stretches from the edge of the pileus to the stalk, and encloses the lamellæ. This veil is ruptured as the pileus expands, a portion attached to the stalk remaining as the “upper ring” (_annulus superus_) (Figs. 173, 178 _a_), or a part attached to the pileus hanging down as a fringe round its edge.--Some genera have no veil, the under side of the pileus being exposed from the first (_gymnocarpic_ Agaricaceæ). Those which have a veil (_hemiangiocarpic_ A.) afford a transition to the angiocarpic Gasteromycetes. [Illustration: FIG. 173.--The cultivated Mushroom (_Psalliota campestris_).] The mycelium mostly grows in soils rich in humus or dung, on decaying trees and similar objects. Many species, _e.g. Tricholoma personatum_ and _Marasmius oreades_, form the so-called “fairy rings.” The fruit-bodies in these species are confined to a larger or smaller surface on which they are very regularly arranged in a ring. The reason for this is found in the radial growth of the mycelium, so that the oldest portion, or the starting point, is found at the centre of the ring, and the younger ones, on which the fruit-bodies are formed, at the circumference. The older hyphæ gradually die, and at the same time, the radial growth continuing, the ring of fruit-bodies becomes larger and larger. The “fairy-rings” are marked not only by the fruit-bodies, but also by the more vigorous growth and darker colour of the grass upon these spots. Some species are _parasites_. An example is presented by _Armillaria mellea_, a remarkable and very destructive Fungus in woods and forests (Figs. 176, 177). ~In addition to the filamentous, white mycelium, it has also black, or black-brown, horny, root-like mycelium-strands (rhizomorpha) which were formerly considered to belong to a special genus of Fungi described under the name “_Rhizomorpha_.” The mycelium lives parasitically on the Conifers and other trees, forcing its hyphæ into the bark and between the bark and wood, and thence penetrating into the wood so that the tree is very severely attacked. It may also live saprophytically, and clusters of fruit-bodies are often found on old stumps and stems, on old timber, and in the rich soil of woods. The rhizomorpha, living underground, can extend for considerable distances and infect the roots of neighbouring trees, and spreads in this way the diseases known as “Harzsticken” and “Bark-Canker,” which are very destructive to young trees.~ [Illustration: FIG. 174.--_Psalliota campestris. A_ Tangential section of pileus showing lamellæ (_l_). _B_ Portion of gill more highly magnified; _t_ trama; _hy_ hymenium with basidia and basidiospores; _sh_, subhymenial layer. _C_ A portion of the same more highly magnified; _s′ s′′ s′′′ s′′′′_ various stages in the development of basidiospores; _q_ paraphyses.] The chief characteristics by which the numerous genera are separated are the presence or the absence of the two kinds of veils, the nature of the fruit-body, the form, branching of the lamellæ, and their position and relation with respect to the stem, the shape of the pileus, the colour of the spores, etc., etc. A knowledge of the colour may be obtained by placing the pileus with the lamellæ turned downwards on a piece of white or coloured paper, so that the spores, as they fall off, are collected on the paper, and the arrangement of the lamellæ can then be clearly seen. [Illustration: FIG. 175.--_Cantharellus cibarius_ (reduced).] [Illustration: FIG. 176.--_Armillaria mellea._ (½ nat. size): _a_ root of a Fir; _b_ rhizomorpha-strands; _c-f_ fruit-bodies in four different stages of development.] [Illustration: FIG. 177.--The mycelium of _Armillaria mellea_ (“_Rhizomorpha_”) (nat. size).] About 4,600 species belonging to this order have been described. On account of the large number of species the order is divided into several sections: 1. =Agaricinei=; fruit-body fleshy; lamellæ membranous, knife-like, with sharp edge; basidia crowded together. The FOLLOWING HAVE WHITE SPORES:--_Amanita_ (Fly Mushroom), with volva, and generally also the upper ring on the stalk; many are poisonous, such as _A. muscaria_ (Fig. 178) which has bright red pileus with white spots, _A. pantherina_ and _A. phalloides_; _A. cæsarea_ is edible.--_Lepiota procera_ (Parasol Fungus) is one of the largest Mushrooms; it has a scaly pileus and moveable ring (edible).--_Armillaria mellea_ has been mentioned above (Figs. 176, 177).--_Tricholoma_, lamellæ indented near the stalk; _T. gambosum_ (Pomona Fungus) belongs to the best of edible Fungi; _T. personatum_ often forms fairy rings (see above).--_Clitocybe_, lamella decurrent; _C. nebularis_ is edible.--_Pleurotus_, stalk eccentric; _P. ostreatus_ (Oyster Mushroom) grows in clusters on tree-stems (edible).--_Collybia_ and _Mycena_, species numerous, small.--SPORES ROSE-RED: _Volvaria_ and _Hyporhodius_.--SPORES BROWN: _Cortinarius_, with cobweb-like veil; _Pholiota_, membranous veil and ring; _P. squarrosa_ in clusters on tree-stems; _P. mutabilis_, on tree-stumps (edible).--SPORES VIOLET-PURPLE: _Hypholoma_, _Psalliota_; to this section the common edible Mushroom (Fig. 172–174) belongs, with annulus and chocolate-coloured lamellæ; it is cultivated for the sake of the fine flavour.--SPORES BLACK: _Coprinarius_. [Illustration: FIG. 178.--Fly Mushroom (_Amanita muscaria_).] 2. =Marasmiei.= Fruit-body tough, almost leathery, and persistent; spores white. _Marasmius oreades_ forms large, regular fairy-rings on pastures and commons; it is used as seasoning in food.--_Panus stipticus_ with eccentrically-placed stalk, in clusters on tree-stumps.--_Schizophyllum_ has the edge of the lamellæ divided longitudinally, and the split portions revolute.--_Lentinus_ affords a transition to _Dædalea_ among the Polyporaceæ. 3. =Russulei.= Fruit-body fleshy and fragile, in which two different systems of hyphæ may be distinguished; spores thorny, white, or pale-yellow. Many are poisonous.--_Russula_ has generally fragile and thick lamellæ reaching from stalk to edge of pileus; pileus frequently red.--_Lactarius_ has white or yellow milky juice, which often is very acid. _L. deliciosus_ has red-yellow milky juice, and is of a pleasant flavour. _L. torminosus_ is poisonous. 4. =Hygrophorei.= Lamellæ thick and waxy, widely separated; spores white. Many species of _Hygrophorus_ have brightly-coloured pileus and grow among the grass on moors and commons.--_Nyctalis_ is parasitic on larger Toadstools. It is remarkable for its abundant formation of chlamydospores, whilst the basidiospores are little developed. 5. =Coprinei.= Fruit-bodies very soft, quickly perishable; lamellæ membranous and deliquescent. The basidia are separated from each other by paraphyses. _Coprinus_ has coal-black spores, grows on manure, and sometimes developes sclerotia. 6. =Paxillei.= Fruit-body fleshy; lamellæ easily detached from the pileus and reticulately-joined near the stalk. They form a connecting link between the Agaricaceæ and _Boletus_. 7. =Cantharellei.= Lamellæ reduced to dichotomously-divided folds, decurrent on the stalk. _Cantharellus cibarius_ (Fig. 175) is yolk-yellow, and grows on the ground in woods (edible). It is allied to _Craterellus_. Family 3. =Phalloideæ.= The fruit-bodies before they are ripe are spherical or ovoid, and enclosed by a _fleshy covering_, the peridium, which is _perforated at maturity_ and remains as a sheath (Fig. 179); the fruit-bodies are _hemiangiocarpic_. Order 1. =Phallaceæ= (=Stink-horns=). The peridium has a complicated structure and is composed of three layers, the intermediate one being thick and gelatinous. The gleba (the tissue which bears the hymenium) is situated upon a peculiar receptacle which expands into a porous stalk and by its sudden distension, rupturing the peridium, elevates the gleba and hymenium above the peridium, which remains as a sheath. _The gleba becomes gelatinous and dissolves away as drops._ To this order belong many peculiar and often brightly coloured forms, which are natives of the Southern Hemisphere. _Phallus impudicus_ (Stink-horn) (Fig. 179), has a fruit-body which at first is white, heavy, and soft, and resembles a hen’s egg in shape and size. The peridium is divided into three layers (Fig. 179 _e_, _g_, _f_) of which the external and internal are membranous, and the middle one very thick and gelatinous; each of these has again a laminated structure. The peridium when ruptured remains as a sheath (_k_) at the base of the stalk. The receptacle at first is strongly compressed (_h_) but afterwards expands into a long stalk (_l_) which bears the conical gleba (_m_). Prior to the rupture of the peridium the gleba consists of a greenish mass (_i_) which, when exposed, emits a carrion-like stench serving to attract flies, by whose agency the spores are distributed. It is found commonly in hedgerows and in woods, growing on the ground. The much smaller and less common _P. caninus_ is found on rotten tree-stumps.--In _Clathrus cancellatus_ the receptacle expands into a bright red, reticulate structure. A native of the South of Europe. _Colus_, _Aseroë_, _Mitromyces_. Order 2. =Sphærobolaceæ.= An intermediate layer of the _peridium_ swells when ripe, becomes convex, and _ejects the remaining_ spherical _portion of the fruit-body_ which contains the spores. _Sphærobolus carpobolus_ has small, spherical fruit-bodies which open in the form of a star. [Illustration: FIG. 179.--_Phallus impudicus_ (Stink-horn), somewhat diminished. Fruit-bodies in all stages of development (_b_, _c_, _d_ and _k-m_) are seen arising from a root-like mycelium (_a_); _d_ longitudinal sections through a fruit-body before the covering has ruptured.] Family 4. =Gasteromycetes.= The fruit-body is _angiocarpic_, fleshy at first, and later generally more or less _hard_ and _continues closed after the_ spores _are ripe_. The tissue lying immediately inside the _peridium_ is termed the _gleba_; it is porous, containing a larger or smaller number of chambers lined with the hymenium, which is either a continuous layer of basidia or else it fills up the entire cavity. The basidia as a rule bear four spores, sometimes eight (_Geaster_), or two (_Hymenogaster_). The tissue of the walls (_trama_) consists often (_Lycoperdaceæ_) of two kinds of hyphæ, some thin and rich in protoplasm, divided by transverse septa and bearing the basidia; others thicker and thick-walled which do not dissolve like the former on the ripening of the spores, but continue to grow and form a woolly, elastic mass, the _capillitium_, which may be regarded as highly developed paraphyses. The peridium may be either single or double, and presents many variations in its structure and dehiscence. The mycelium is generally a number of string-like strands, living in soils rich in humus. Order 1. =Tylostomaceæ.= Capillitium present. After the rupture of the peridium the remaining part of the fruit-body is elevated on a long _stalk_. _Tylostoma mammosum_, on heaths. Order 2. =Lycoperdaceæ.= The fruit-body has a double peridium; the external one at length breaks into fragments (_Lycoperdon_, _Bovista_), or it has a compound structure of several layers (_Geaster_) and detaches itself as a continuous envelope from the inner layer, which is membranous and opens at its apex. The interior of the fruit-body consists either solely of the fertile gleba (_Bovista_, _Geaster_), or, in addition, of a sterile tissue at the base (_Lycoperdon_). A capillitium is also present. [Illustration: FIG. 180.--_Lycoperdon gemmatum_ (½ nat. size).] _Lycoperdon_ (Puff-ball) has a sterile part at the base of the fruit-body which often forms a thick stalk. The surface of the peridium is generally covered with warts or projections. When young this Fungus is edible, but when ripe it is dry, and used for stopping the flow of blood. _L. giganteum_, which is often found growing in meadows, attains a considerable size, its diameter reaching as much as eighteen inches. _L. gemmatum_ (Fig. 180) is covered with pyramidal warts; in woods.--_Bovista_ has no sterile basal part; the external peridium is smooth, and falls away in irregular patches. _B. plumbea_, on links near the sea.--_Geaster_ (Earth-star) has an external peridium composed of several layers, which when the fruit-body opens, split into several stellate segments. These segments are very hygroscopic, and in dry weather bend backwards and so raise the inner peridium into the air. The inner peridium contains the spores and capillitia. _G. coliformis_ has several apertures in the inner peridium. The other species have only one regular aperture at the apex. _G. striatus_ has a pedicellate inner peridium, with conical, striped peristome. _G. fornicatus_ has an external peridium split into four segments. This last and several other species produce “mycorhiza” on the roots of Conifers. [Illustration: FIG. 181.--I _Hymenogaster citrinus_ (nat. size); II longitudinal section through _H. tener_ (× 5); III portion of a section of _H. calosporus_; _g_ a chamber; _h_ hymenium; _sp._ spores; _t_ trama (× 178); IV _Rhizopogon luteolus_ (nat. size); V _Scleroderma vulgare_, VI section of V; VII basidia with spores belonging to the same Fungus.] Order 3. =Sclerodermataceæ.= _Capillitium_ wanting. The peridium is simple and thick, gleba with round, closed chambers, which are filled with basidia. _Scleroderma_ has a corky peridium. The fruit-bodies commence their development under ground. _S. vulgare_ (Fig. 181 V-VII), has a hard, slaty-black gleba. Order 4. =Nidulariaceæ= (=Nest-Fungi=). Small Fungi of which the fruit-body at first is spherical or cylindrical but upon maturity it becomes cupular or vase-like, and contains several lenticular “peridiola” lying like eggs in a nest. The peridiola are the chambers which contain the hymenium, covered by a thin layer of the gleba, all the remaining portion of the gleba becoming dissolved. On decaying wood. _Nidularia_ has spherical fruit-bodies containing a large number of lenticular peridiola, embedded in a slimy mass.--_Crucibulum_ has fruit-bodies resembling crucibles with discoid peridiola, each with a spirally-twisted stalk.--_Cyathus_ has a fruit-body, which when open is campanulate, with stratified peridium, and long-stalked, lense-shaped peridiola. Order 5. =Hymenogastraceæ.= Fruit-bodies tubercular, globose and subterranean, resembling very closely the Truffles, from which they can only be distinguished with certainty by microscopic means. The peridium is simple, capillitium wanting, and the gleba encloses a system of labyrinthine passages covered with a continuous hymenium. The fruit-bodies persist for some time, and form a fleshy mass, the spores being only set free by the decay of the fruit-body, or when it is eaten by animals. The majority are South European. _Hymenogaster_, _Melanogaster_, _Rhizopogon_ (Fig. 181 I-IV). APPENDIX TO THE BASIDIOMYCETES: Basidiolichenes (Lichen-forming Basidiomycetes). Several Fungi belonging to the Basidiomycetes have a symbiotic relationship with Algæ exactly similar to that enjoyed by certain Ascomycetes, and these are therefore included under the term Lichens (p. 136). They are chiefly tropical. Order 1. =Hymenolichenes.= To this order belong some gymnocarpic forms: _Cora_, _Dictyonema_, _Laudatea_.[15] Order 2. =Gasterolichenes.= To this belong some angiocarpic forms: _Emericella_, _Trichocoma_. APPENDIX TO THE FUNGI. Fungi imperfecti (Incompletely known Fungi). 1. The =Saccharomyces-forms= are Fungi which are only known in their yeast-conidial form. They are _conidia of higher Fungi_ which can multiply to an unlimited extent by budding in nutritive solutions, and in this way maintain their _definite_ size and shape. The budding takes place _only at the ends_ of the conidia. The wall of the conidium forms at one or at both ends a small wart-like outgrowth, which gradually becomes larger, and is finally separated from its mother-cell as an independent cell, surrounded by a closed cell-wall (Fig. 182 _a_, _b_). [Illustration: FIG. 182.--Beer-yeast (_Saccharomyces cerevisiæ_): _a-b_ (× 400); _c-f_ (× 750); _c_ a cell in the process of forming spores; _d_ a cell with four ripe spores; _e_ the spores liberated by the dissolution of the cell-wall; _f_ three germinating spores; _g_ mycelium-like cell-chains. (× 1000: after Em. Chr. Hansen.)] Under very favourable conditions multiplication occurs so rapidly that the daughter-cells themselves commence to form buds, before they have separated from their mother-cell, with the result that pearl-like chains of cells are produced. When the yeast-cells have only limited nutriment, with an abundant supply of air, at a suitable temperature, an endogenous formation of _spores_ takes place. The protoplasm of the cells divides into 1–4 (rarely a greater number) masses (Fig. 182 _c_, _d_, _e_) which surround themselves with a thick cell-wall, and in this state can withstand adverse conditions and periods of dryness lasting for several months. The _sporangia are not asci_ since they have no definite form, and a definite number, form and size of spores is not found. The spores in the different species and kinds occupy varying periods for their development, although exposed to the same temperature, a fact of importance in determining one from another. On germination the wall of the mother-cell is destroyed, and each spore gives rise to a new cell, multiplication taking place by budding (Fig. 182 _f_). The majority of Yeast-Fungi are able to produce alcoholic fermentation in saccharine fluids. The most important of these Fungi is the Beer-yeast (_Saccharomyces cerevisiæ_) with ovate, ellipsoidal or spherical cells (Fig. 182). It is a plant which has been cultivated from time immemorial, on account of its property of producing alcoholic fermentation in sugar-containing extracts (wort), derived from germinating barley (malt). Carbonic acid is also set free during this process. The “surface-yeast” (Fig. 182 _a_), which produces ordinary beer when the brewing takes place at higher temperatures, has cell-chains; “sedimentary yeast” (Fig. 182 _b_), used in the brewing of Bavarian beer, has spherical cells, solitary, or united in pairs. Both these and the following Yeast-Fungi include, according to Hansen, several species and kinds. [Illustration: FIG. 183.--_Saccharomyces mycoderma._] The “Ferment of Wine” (_Saccharomyces ellipsoideus_) produces wine in the juice of grapes. Uncultivated yeast-cells are always present on grapes; an addition of this species to the “must” is not necessary to secure fermentation. A large number of other “uncultivated” yeast-cells appear in breweries mixed with the cultivated ones, and cause different tastes to the beer (_S. pastorianus_, etc.). _S. ludwigii_, found, for instance, on the slimy discharge from Oaks, produces abundant cell-chains on cultivation. _S. apiculatus_ is very frequently met with on all kinds of sweet fruits, it has orange-like cells. _S. mycoderma_ has cylindrical cells, often united together in chains (Fig. 183): it forms a whitish-gray mass (“fleur de vin”) on wine, beer, fruit-juice, etc., standing in bottles uncorked or not entirely filled. It is thought that this Fungus causes decomposition and oxydises the fluid in which it is found, but it cannot produce alcoholic fermentation in saccharine liquids, and it does not form endospores; hence it is uncertain whether it is true _Saccharomyces_. [Illustration: FIG. 184.--_Oidium lactis_: _a_ branched hypha commonly met with; _b_ a hypha lying in milk and producing aerial hyphæ which give rise to oidia; _c_ a branch giving rise to oidia, the oldest (outermost) oidia are becoming detached from one another; _d_ a chain of divided cells; _e_ germinating oidia in different stages (slightly more magnified than the other figures).] The “Dry-yeast” used in baking white bread is “surface-yeast.” In _leaven_, a kneaded mixture of meal, barm and water, which is used for the manufacture of black bread, _Saccharomyces minor_ is present, and a species allied to this produces alcoholic fermentation in dough with the evolution of carbonic acid, which causes the dough to “rise.” 2. =Oidium-forms.= Of many Fungi only the Oidium-forms are known, which multiply in endless series without employing any higher form of reproduction. _Oidium lactis_ (Fig. 184) is an imperfectly developed form which frequently appears on sour milk and cheese. It can produce a feeble alcoholic fermentation in saccharine liquids. Thrush or aphthæ (_O. albicans_) appears as white spots in the mouths of children. Several similar _Oidium-forms_ are parasites on the skin and hair of human beings, and produce skin diseases, such as scurvy (_O. schoenleinii_) and ringworm (_O. tonsurans_). 3. =Mycorhiza.= These Fungi, which have been found on the roots of many trees and heath-plants, particularly Cupuliferæ and Ericaceæ, consist of septate hyphæ, and belong partly to the Hymenomycetes, partly to the Gasteromycetes. It has been shown that the Mycorhiza enters into a symbiotic relationship with the roots of higher plants. DIVISION II. MUSCINEÆ (MOSSES). In this Division a well-marked alternation of generations is to be found. The development of the first or sexual generation (_gametophyte_),[16] which bears the sexual organs, antheridia and archegonia, commences with the germination of the spore, and consists, in the Liverworts, of a thallus, but in the true Mosses of a filamentous protonema, from which the Moss-plant arises as a lateral bud. The second or asexual generation (_sporophyte_), developed from the fertilised oosphere, consists of a sporangium and stalk. =The sexual generation, the gametophyte.= The protonema in the Liverworts is very insignificant, and not always very sharply demarcated from the more highly developed parts of the nutritive system. In the true Mosses the protonema is well-developed, and consists of a branched, alga-like filament of cells, the dividing cell-walls being always placed obliquely. In the parts exposed to the light it is green, but colourless or brownish in those parts which are underground (Fig. 186). The protonema is considered to be a lower form of the stem, and grows in the same manner by means of an apical cell; at its apex it may directly develope into a leaf-bearing stem, or these arise from it as lateral branches (Fig. 186 _k_). The more highly differentiated part of the vegetative system, the “Moss-plant,” which is thus developed from the protonema, is in the “thalloid” Liverworts generally a dichotomously-branched thallus without any trace of leaf-structures (Fig. 194); in _Marchantia_ (Fig. 197) and others, scale-like leaves (_amphigastria_) are found on the under surface. The higher Liverworts and the Leafy-Mosses are differentiated into a filamentous, ramified stem with distinct leaves arranged in a definite manner, resembling the stem and leaves of the higher plants (Figs. 186, 195, 200). _True roots are wanting_, but are biologically replaced by _rhizoids_. These are developed on the stems or thallus: in the Liverworts they are unicellular, but in the Leafy-Mosses generally multicellular and branched. In the latter group they are considered identical with the protonema, and may become true protonema, and new plants may be developed from them (Fig. 186 _b_). [Illustration: FIG. 186.--_A_ Lower portion of a Moss-plant with rhizoids (_r_), one of which bears a reproductive bud (_b_). The dotted line indicates the surface of the ground; the portions projecting above this become green protonema (_p_); _k_ is a young Moss-plant formed on one of these. _B_ Germinating spore of _Funaria hygrometrica_, with exospore still attached. _C_, _D_ Older stages of the protonema.] The internal structure of the sexual generation is very simple. The leaves in nearly all cases are formed of a single-layered plate of cells; in the Leafy-Mosses, however, a midrib is very often formed, and sometimes, also, marginal veins; and along these lines the leaves are several layers of cells in thickness. The stem is constructed of cells longitudinally elongated, the external ones of which are narrower and sometimes have thicker walls than the more central ones. _Vessels are not found_, but in several Mosses there is in the centre of the stem a conducting strand of narrow, longitudinal cells, which represents the vascular bundle in its first stage of development. This strand contains elements for conveying water as well as sieve-tubes. Stomata are entirely wanting in the sexual generation of the Leafy-Mosses; they are found in a few Liverworts (_Marchantia_), but their structure is not the same as in the higher plants. VEGETATIVE REPRODUCTION takes place by gemmæ or buds which arise on the protenema, the rhizoids, the thallus, or the shoots, and become detached from the mother-plant; or else the protonema and the older parts of the plant simply die off, and their branches thus become independent plants. This well-developed vegetative reproduction explains why so many Mosses grow gregariously. In certain Marchantiaceæ special cupules, in which gemmæ are developed, are found on the surface of the thallus (Fig. 197 _A_, _s-s_). Again, protonema may also arise from the leaves, and thus the leaves may act as reproductive bodies. Certain Mosses nearly always reproduce vegetatively, and in these species the oospheres are seldom fertilised. [Illustration: FIG. 187.--_Marchantia polymorpha_: _a_ mature antheridium.] [Illustration: FIG. 188.--Spermatozoids.] The first generation bears the SEXUAL ORGANS; both kinds are found either on the same plant (monœcious), or on separate plants (diœcious). In the thalloid Liverworts they are often situated on the apex of small stems (_gametophores_), springing from the surface of the thallus. In the Leafy-Liverworts and true Mosses the leaves which enclose the sexual organs often assume a peculiar shape, and are arranged more closely than the other leaves to form the so-called “Moss-flower.” The male sexual organs are called _antheridia_. They are stalked, spheroid, club- or egg-shaped bodies whose walls are formed of one layer of cells (Fig. 187), enclosing a mass of minute cubical cells, each one of which is a mother-cell of a spermatozoid. The spermatozoids are self-motile; they are slightly twisted, with two cilia placed anteriorly (Fig. 188), while posteriorly they are generally a trifle club-shaped, and often bear at that part the remains of the cytoplasm, the spermatozoid itself being _formed from the nucleus_. In the presence of water the ripe antheridium bursts, and its contents are ejected; the spermatozoids, being liberated from their mother-cells, swarm about in the water in order to effect fertilisation. [Illustration: FIG. 189.--_Marchantia polymorpha. A_ A young, and _B_ a ripe archegonium with open neck. _C_ An unripe sporangium enclosed by the archegonium _a_: _st_ the stalk; _f_ the wall of the sporangium. Elaters are seen between the rows of spores.] The female sexual organs are termed _archegonia_. They are flask-shaped bodies (Fig. 189), the lower, swollen portion (_venter_) having a wall, in most cases from 1–2 cells thick, enclosing the oosphere (Fig. 189 _B_, _k_): the long neck is formed of tiers of 4–6 cells, enclosing a central row of cells--_the neck-canal-cells_ (Fig. 189 _A_). When the archegonium is fully developed, the walls of the neck-canal-cells become mucilaginous and force open the neck of the archegonium. The mucilage thus escapes, and, remaining at the mouth of the archegonium, acts in a somewhat similar manner to the stigma and conducting tissue of a carpel, by catching and conducting the spermatozoids to the oosphere (Fig. 189 _B_, _m_), with whose cell-nucleus they coalesce. With regard to the formation of the oosphere, it may further be remarked that the lower part of the archegonium originally encloses the so-called “central cell”; but shortly before the archegonium is ripe, this cuts off a small portion, _the ventral-canal-cell_, which lies immediately beneath the neck, and the larger, lower portion becomes the oosphere. The organs mentioned here, antheridia and archegonia, are present in the Cryptogams (Pteridophyta) and the Gymnosperms. They have always the same fundamental structure, but with slight modifications of detail. These plants are therefore known as the ARCHEGONIATA. The fertilisation of the Mosses cannot be effected without water. Rain and dew therefore play a very important part in this process, and for this end various modifications of structure are found. [Illustration: FIG. 190.--_Andreæa rupestris._ Longitudinal section through a sporangium at the time when the mother-cells of the spores are dividing: _p_ pseudopodium; _f_ foot; _v_ vaginula; _h_ neck; _c_ columella; _w_ wall of the sporangium; _e_ external row of cells; _s_ the spore-sac; _t_ the spore-mother-cells; _r_ the calyptra with the neck of archegonium (_z_).] [Illustration: FIG. 191.--_Andreæa rupestris._ Transverse section through a ripe sporangium. In the middle is seen the four-sided columella, surrounded by the numerous spores, drawn diagrammatically. Surrounding them is seen the wall of the sporangium, whose outer layer of cells is thickened and coloured. The layer of cells is unthickened in four places (_x_), indicating the position of the clefts (see Fig. 193).] Among the sexual organs, paraphyses--filamentous or club-shaped bodies--are to be found. =The asexual generation, the sporophyte= (Moss-fruit or sporogonium). As the result of fertilisation the oosphere surrounds itself with a cell-wall, and then commences to divide in accordance with definite laws.[17] The embryo (Fig. 189 _C_) produced by these divisions remains inside the wall _a-a_ of the archegonium (Figs. 190, 199 _D_, _E_), and developes into the _sporogonium_, which remains attached to the mother-plant, often nourished by it, as if the two were one organism. The lower extremity of the sporogonium, _the foot_ (Figs. 190 _f_; 199 _D_), very often forces its way deep down into the tissue of the mother-plant, but without an actual union taking place. The central portion of the sporogonium becomes a shorter or longer _stalk_ (_seta_), while the sporangium itself is developed at the summit. At a later stage, during the formation of the spores, the sporangium very often assumes the form of a _capsule_, and dehisces in several ways characteristic of the various genera (Figs. 192, 193, 194, 195, 200). The basal portion of the archegonium grows for a longer or shorter period, forming a sheath, the _calyptra_, in which the capsule is developed, but eventually it ceases to enlarge, and is then ruptured in different ways, but quite characteristically, in each group. Anatomically, the asexual generation is often more highly differentiated than the sexual; thus, for instance, stomata are present on the sporangia of the true Mosses, but are absent in the sexual generation. As the capsule developes, an external layer of cells--the _amphithecium_--and an internal mass--the _endothecium_--are differentiated. As a rule the former becomes the wall of the capsule while the latter gives rise to the spores. In this Division, as in the Pteridophyta, the name _archesporium_ (Fig. 190 _t_) is given to the group of cells inside the sporangium which gives rise to the mother-cells of the spores. The archesporium is in general a unicellular layer; in _Sphagnum_ and _Anthoceros_ it is derived from the most internal layer of the amphithecium, but with these exceptions it arises from the endothecium, usually from its most external layer. In the true Mosses and in _Riccia_ only spore-mother-cells are produced from the archesporium, but in the majority of the Liverworts some of these cells are sterile and become elaters (cells with spirally thickened walls, Figs. 196, 189), or serve as “nurse-cells” for the spore-mother-cells, which gradually absorb the nutriment which has been accumulated in them. In _Anthoceros_, and almost all the Leafy-Mosses, a certain mass of cells in the centre of the sporangium (derived from the endothecium) does not take part in the formation of the archesporium, but forms the so called “column” or “columella” (Figs. 190, 191). The _spores_ arise in _tetrads_, _i.e._ four in each mother-cell, and are arranged at the corners of a tetrahedron, each tetrahedron assuming the form of a sphere or a triangular pyramid. The mature spore is a nucleated mass of protoplasm, with starch or oil as reserve material. The wall is divided into two layers: the external coat (exospore) which is cuticularized and in most cases coloured (brown, yellowish), and the internal coat (endospore), which is colourless and not cuticularized. On germination the exospore is thrown off, the endospore protrudes, and cell-division commences and continues with the growth of the protonema (Fig. 186, _B-D_). [Illustration: FIG. 192.--_Andreæa petrophila._ A ripe sporogonium: _a_ an archegonium which has been raised with the pseudopodium; _p_ the foot; _b_ the neck; _d-e_ the dark-coloured portion of the sporangium, whose outer cell-walls are considerably thickened; _c_-_c_ the thin-walled portions where the dehiscence occurs; _o_ the lower extremity of the spore-sac; _f_ calyptra; _g_ the apex of the sporangium. (Mag. 25 times.)] [Illustration: FIG. 193.--_Andreæa petrophila._ An empty capsule; the calyptra has fallen off. (Mag. 25 times.)] The morphological explanation which Celakovsky has given of the sporogonium, and which is not at all improbable, is, that it is homologous with an embryo consisting of a very small stem-portion and a terminal spore-producing leaf. This will be further explained in the introduction to the Flowering-plants (p. 236). In the Liverworts the young sporogonium lives like a parasite, being nourished by the sexual generation (only in _Anthoceros_ has it a slight power of assimilation). In the Leafy-Mosses, on the other hand, with regard to the power of assimilation, all transitions are found from abundant assimilation (_Funaria_, _Physcomitrium_) to almost complete “parasitism” (_Sphagnum_, _Andreæa_). In the majority of the operculate Mosses the sporogonium has a more or less perfect system of assimilation, and is able itself to form a large portion of the material necessary for the development of the spores, so that it chiefly receives from the sexual generation the inorganic substances which must be obtained from the soil. The more highly developed the assimilative system of the sporogonium, the more stomata are present. APOSPORY. In some operculate Mosses it has been possible to obtain a protonema with small Moss-plants from the seta, when severed from its Moss-plant, and grown on damp sand. The Mosses are the lowest plants which are provided with stem and leaf. They are assigned a lower place when compared with the higher Cryptogams, partly because there are still found within the Division so many forms with a mere thallus, partly because typical roots are wanting and the anatomical structure is so extremely simple, and partly also because of the relation between the two generations. The highest Mosses terminate the Division, the Muscineæ and Pteridophyta having had a common origin in the Algæ-like Thallophyta. They are divided into two classes:-- HEPATICÆ, or Liverworts. MUSCI FRONDOSI. True Mosses or Leafy-Mosses. Class 1. =Hepaticæ= (=Liverworts=). The protonema is only slightly developed. The remaining part of the vegetative body is either a prostrate, often dichotomously-branched thallus, pressed to the substratum (thalloid Liverworts), with or without scales on the under side (Figs. 194, 197); or a thin, prostrate, creeping stem, with distinctly-developed leaves, which are borne in two or three rows (Figs. 195, 198), viz., two on the upper and, in most cases, one on the under side. The leaves situated on the ventral side (amphigastria) are differently shaped from the others (Fig. 198 _a_), and are sometimes entirely absent. In contradistinction to the Leafy-Mosses, stress must be laid on the _well-marked dorsiventrality_ of the vegetative organs; _i.e._ the very distinct contrast between the dorsal side exposed to the light and the ventral side turned to the ground. Veins are never found in the leaves. The _ventral part of the archegonium_ (calyptra) continues to grow for some time, and encloses the growing embryo, but when the spores are ripe it is finally ruptured by the sporangium, and remains situated like a sheath (_vaginula_) around its base. The sporangium opens, longitudinally, by _valves_ or _teeth_ (Fig. 194, 195, 197 _b_), very rarely by a lid, or sometimes not at all. _A columella is wanting_ (except in _Anthoceros_, Fig. 194); but on the other hand, a few of the cells lying between the spores are developed into _elaters_ (Fig. 196), _i.e._ spindle-shaped cells with spirally-twisted thickenings, which are hygroscopic, and thus serve to distribute the spores. (They are seen in Fig. 189 _C_, not yet fully developed, as long cells radiating from the base of the sporangium. They are wanting in _Riccia_). [Illustration: FIG. 194.--_Anthoceros lævis_ (nat. size): _K_-_K_ capsules.] [Illustration: FIG. 195.--_Plagiochila asplenioides_: _a_ unripe, and _b_ an open capsule; _p_ involucre. The ventral edge of each leaf is higher than its dorsal edge, and covered by the dorsal edge of the next one.] [Illustration: FIG. 196.--An elater with two spores.] Round the entire archegonium, (or group of archegonia, when several are developed on the same receptacle) a sheath--the _involucre_--is often formed, which persists, and encloses the base of the stalk of the sporangium, together with the sheath of the archegonium (Fig. 195 _p_). In the Marchantiaceæ each archegonium is enclosed in a loose investment, the perigynium, which is developed as an outgrowth from the cells of its stalk. The majority of the Liverworts are found in damp and shady places, pressed to the substratum; a few are found floating in fresh water. Family 1. =Marchantieæ.= This embraces only forms with a thallus, which is more or less distinctly dichotomously branched, in some, one or two rows of thin leaves are situated on its under surface. On the upper surface of the thallus are found large air-chambers. Order 1. =Ricciaceæ.= The sporogonia are, with the exception of a few genera, situated singly on the surface of the thallus, and consist only of a capsule without foot or stalk. They always remain enclosed by the wall of the archegonium (calyptra), and open only by its dissolution. Elaters are not developed. Some genera are found floating like Duckweed.--_Riccia glauca_ grows on damp clay soil. _R. fluitans_ and _R. natans_ float in stagnant waters. [Illustration: FIG. 197.--_Marchantia polymorpha. A_ Female plant (nat. size): _a_ and _b_ are archegoniophores in various stages of development; _s_ cupules with gemmæ (see page 183). _B_ An archegoniophore seen from below, the short-stalked sporangia are seen placed in 8–10 double rows. _C_ Male plant, with a young and an older antheridiophore. _D_ Antheridiophore halved vertically to show the antheridia (_h_); _m_ the aperture of the pits in which they are sunk--the older ones to the left, the younger to the right.] Order 2. =Corsiniaceæ.= (Not native). Intermediate forms between the preceding and the following order. In internal and external structure mainly resembling the Marchantiaceæ. _Corsinia_; _Boschia_. Order 3. =Marchantiaceæ=, are large, fleshy forms. The surface of the thallus is divided into small rhombic areas, in the centre of each of which is found a large, peculiarly constructed stoma (Fig. 197 _A_); beneath each of these a large air-cavity is to be found. From the floor of the air-cavity a number of alga-like cells project into it; these contain chlorophyll and are therefore the assimilating cells. The antheridia and archegonia are each found aggregated on specially formed branches (somewhat resembling Mushrooms) projecting from the surface of the thallus. The antheridia are developed on the upper surface (Fig. 197 _C_, _D_) and the archegonia on the lower (Fig. 197 _A_, _B_), near the centrally-placed stalk. _Marchantia polymorpha_ is diœcious (Fig. 197), and very common on damp places. _Lunularia_ (South Europe), frequently found on flower-pots in conservatories; _Preissia_, _Fegatella_, _Reboulia_, _Targionia_. Family 2. =Anthoceroteæ.= These have an entirely leafless, fleshy, flat, and irregularly-shaped thallus. In its intercellular chambers Nostoc-colonies are often found, which have forced their way through the stomata situated on the under side. The antheridia and archegonia arise from the cells lying inside the thallus. The capsule resembles a long, thin pod; it has two valves and a columella. _Anthoceros_ (_A. lævis_, Fig. 194, and _punctatus_). Family 3. =Jungermannieæ.= Some forms in this family have a thallus in which leaf-like structures are found (_Blasia_), while in others (_e.g. Metzgeria_, _Pellia_, _Aneura_) they are entirely absent. The majority, however, have round, thick stems, bearing dorsally two rows of leaves, and one row ventrally. Some of these have the leaves “underlying” (Fig. 195), while in others (Fig. 198) they are “overlying.” (See Figs. 195, 198, with explanation). The sporangia are spherical, stalked, and situated singly on the apex of the branches, and open by four valves (in _Sphærocarpus_ they are indehiscent). [Illustration: FIG. 198.--_Frullania dilatata._ Portion of a branch seen from the under side: _r_ and _b_ are the anterior and posterior edges of the same dorsal leaf; _a_ ventral leaves (amphigastria). The dorsal leaves are “overlying,” _i.e._ the anterior edge of the leaf overlaps the posterior edge of the preceding one.] All the species in this family were formerly reckoned as belonging to one genus, _Jungermannia_, but now they are divided into several, arranged as follows:-- I. ANACROGYNÆ. The archegonia are situated on the upper side of the thallus or stem, _placed laterally_, and covered by an “involucre,” formed by the calyptra together with the tissue of the stem or thallus. a. ANELATEREÆ. Without any elaters: _Sphærocarpus_, _Riella_. b. ELATEREÆ. α. Thalloid: _Aneura pinguis_, in damp situations; _Metzgeria furcata_, on trees; _Pellia epiphylla_, in damp situations; _Blasia pusilla_, on damp clay soil, in the shade (scales are present on the thallus). β. Foliose and not dorsiventral: _Haplomitrium hookeri_. II. ACROGYNÆ. The apex of the stem or of certain branches is adapted for the formation of female shoots. The archegonia are most frequently aggregated on the apex of the shoots, and are encircled by their leaves (perichætium). Between these and the archegonia, enclosing the latter, a peculiar cup-shaped organ (the involucre) is formed. This group only includes leaf-bearing genera: _Frullania_, _Radula_, _Madotheca_, _Ptilidium_, _Calypogeia_, _Lepidozia_, _Mastigobryum_, _Lophocolea_, _Jungermannia_, _Scapania_, _Plagiochila_. Class 2. =Musci frondosi or veri (True Mosses).= In this class the protonema is well developed, and resembles a branched filamentous Alga, from which it can be easily distinguished by its oblique septa (in _Sphagnum_ it is a cellular expansion). The Moss-plant, which is developed directly from the protonema, generally has an erect, thick, cylindrical stem similarly constructed on all sides. The leaves are arranged spirally, the most frequent divergence being 2/5 or 3/8 (Fig. 200 _A_). A midrib is often present and also marginal veins formed by longitudinally elongated cells; at these veins the leaf is more than one layer in thickness. In _Leucobryum_ the leaves are generally constructed of more than one layer. The stem grows by means of a three-sided, pyramidal, apical cell which gives rise to three rows of segments, each segment forming a leaf. The lateral branches arise from the lower portions of the segments, the upper portion of which does not take any part in the construction of the leaf. From their mode of origin the branches are not axillary, and differ in this respect from the Flowering-plants. The ventral portion of the archegonium is very early ruptured _at its base_ by the growing sporogonium, upon which it remains, and it is thus raised into the air, forming a “hood,” the calyptra (Figs. 192; 200 _B_). In the Sphagnaceæ the hood is not present; in this order, as in the Liverworts, the archegonium remains at the base of the sporogonium. The sporangium opens by circumsessile dehiscence, the upper portion (_operculum_) being separated along a specially constructed ring of cells, and falls off like a “lid” (Fig. 200). Only in a few forms (families 2 and 3) does any variation of this take place. Elaters are never found, but (with the exception of _Archidium_) there is always present in the sporangium a central mass of cells, the _columella_, which take no part in the formation of the spores. The columella, in some, does not reach quite to the operculum and in these cases the spore-sac is bell-shaped and covers the columella (_Andreæa_, Fig. 190; _Sphagnum_, Fig. 199 _D_); but in the majority of Mosses the columella extends to the lid, so that the space containing the spores becomes a hollow cylinder. The _sporangium_ is generally raised on a long stalk; in the great majority this stalk is formed from the lower half of the oospore and belongs to the asexual generation--it is then known as the _seta_. In _Andreæa_ and _Sphagnum_ the seta is very short, and the sporangia are raised upon a long stalk (_pseudopodium_) developed from the summit of the sexual generation (Figs. 190, 192). In the latter figure an archegonium (_a_) is seen attached to the pseudopodium, having been carried up with this during the course of its development. The summit of the pseudopodium is enlarged to embrace the foot of the sporogonium (Figs. 192, 199 _D_). A. The sporangium is supported on a pseudopodium; the columella does not extend to the operculum. [Illustration: FIG. 199.--_Sphagnum acutifolium._--_A_ The upper portion of a plant: _a_ branches with antheridia; _ch_ branches with terminal archegonia and perichætia; _b_ the upper stemleaves. _B_ A male branch whose leaves are partly taken off in order to show the antheridia. _C_ Group of three archegonia: the central one (_a_) is formed from the apical cell. _D_ Sporogonium in longitudinal section: the broad foot (_sg’_) is sunk in the vaginula, _v_; _c_ calyptra; _ar_ neck of the archegonium; _ps_ pseudopodium. _E_ ripe sporangium with operculum, and the remains of the archegonium situated on the pseudopodium which is still surrounded by the perichætium; to the left is a barren branch. _F_ Portion of a foliage-leaf seen from above: _l_ perforations; _b_ chlorophyll-containing cells; _s_ spiral thickenings.] Family 1. =Sphagneæ (Bog-Mosses).= The protonema has been already described. The stem is regularly branched owing to the fact that a branch, or collection of branches, arises at every fourth leaf. These branches are closely covered with leaves, some are erect, while others hang down and surround the stem. No rhizoids are developed. These Mosses are of a whitish-green colour, and when water is present are always saturated with it like a sponge, the reason for this being found in the construction of the stem and leaves. The stems are covered by an external layer of large clear cells, without chlorophyll, but with annular or spiral thickenings on the walls, which are also perforated by large holes. By means of capillary attraction, water is thus raised to the summit of the stem. Similarly constructed cells are also found in the leaves, but they are surrounded by a net of very narrow, chlorophyll-containing cells (Fig. 199 _F_), whose colour is thus to a great extent lost amongst those which are colourless. This anatomical structure is an essential condition for the formation of peat. The Bog-Mosses grow by preference on moors, which they cover with a thick carpet saturated with water. The lower extremities of the plants perish very rapidly, and gradually become converted into peat, and the branches thus separated from each other become independent plants. The sporangia (Fig. 199 _D_, _E_) are spherical, but with a very short stalk. They open by a _lid_, but have no _annulus_. The _archegonium_ (Fig. 199 _C_) persists at the _base of the sporogonium_ as in the Liverworts. Only one genus, _Sphagnum_. Family 2. =Schizocarpeæ.= The Mosses which constitute this family are of a brownish-black colour and are found living on rocks. The sporangium resembles that of the Liverworts inasmuch as it opens by four valves, but these continue attached to each other at the apex as well as at the base (Fig. 193).--There is only one genus: _Andreæa_. =B.= The stalk is formed from the lower portion of the sporogonium. The columella is continued to the summit of the sporangium and united with it (_Archidium_ has no columella.) Family 3. =Cleistocarpeæ.= The fruit does not dehisce in the regular way, but the spores are liberated by decay. They are small Mosses which remain in connection with their protonema until the sporangium is mature. The archegonium remains sessile at the base of the short capsule-stalk, and is not raised into the air (compare Hepaticæ).--_Phascum, Ephemerum, Archidium, Pleuridium._ Family 4. =Stegocarpeæ.= To this belong the majority of the Mosses, about 3,000 species. The capsule opens as in _Sphagnum_ by means of a _lid_ (_operculum_), which is often prolonged into a beak. Round the mouth of the opened capsule, a number of peculiar yellow or red teeth are to be found. These constitute the _peristome_; their number is four, or a multiple of four (8, 16, 32 or 64). The form and thickenings of these teeth are widely different, and on this account are used by Systematists for the purposes of classification. In some Mosses (Fig. 200 _C_, _D_) there is a double row of teeth. Except in _Tetraphis_ they are not formed from entire cells, but from the strongly thickened portions of the wall of certain layers of cells belonging to the lid, and persist when this falls off. They are strongly hygroscopic, and assist greatly in the ejection of the lid, in which operation they are considerably aided by a ring of elastic cells with thickened walls, situated in the wall of the lid near the base of the teeth. This ring is known as the _annulus_. The archegonium is raised into the air like a hood, the calyptra, which either covers the sporangium on all sides (having the shape of a bell), or is split on one side (Fig. 200 _B_, _h_). Among peculiar forms may be mentioned: _Splachnum_, which is especially remarkable for the collar-like expansion at the base of the capsule. _Fissidens_ deviates in having a flat stem and leaves arranged in two rows. The leaves are boat-shaped and half embrace the stem.--_Schistostega_ has two kinds of stems. The barren ones resemble Fern-leaves; they have two rows of leaves, which are attached together vertically, are decurrent and coalesce at their bases. The fertile ones have an ordinary appearance.--_Tetraphis_: the peristome is composed of four teeth, which are formed from entire cells. _T. pellucida_ has peculiar gemmæ. The family is divided into two groups: the Musci acrocarpi, the growth of whose main axis is limited and terminated by the formation of the sexual organs; and the Musci pleurocarpi, whose sporogonia are situated on special lateral shoots, while the growth of the main axis is unlimited. [Illustration: FIG. 200.--_A Hypnum populeum_. _B_ and _C_ Sporangia, with hood (_h_), and operculum (_l’_), and without these (_C_), showing the peristome (_p_). _D_ The mouth of the capsule of _Fontinalis antipyretica_.] A. =Acrocarpi.= Order 1. =Weisiaceæ.= Peristome, with 16 teeth arranged in one series, rarely wanting. Leaf with midrib. _Campylopus_, _Dicranum_ (_D. scoparium_, common in forests), _Dicranella_, _Cynodontium_.--_Weisia_, _Gymnostomum_ (no peristome), _Systegium_. Order 2. =Leucobryaceæ.= Peristome with 16 teeth. Leaves with three or more layers of cells, of which the external ones are air-conducting and perforated (as in the Sphagneæ), the middle one containing chlorophyll. _Leucobryum._ Order 3. =Fissidentaceæ.= Peristome as in the preceding ones. The leaves are arranged in two rows on the plagiotropic shoots; in _Fissidens_ the midrib of the leaf bears wing-shaped outgrowths. _Conomitrium, Fissidens._ Order 4. =Seligeriaceæ.= Peristome with 16 undivided teeth. Very small Rock-mosses. _Seligeria.--Blindia._ Order 5. =Pottiaceæ.= Peristome with 16 teeth, which are divided almost to the base, or with 32 teeth. Calyptra hood-like.--_Barbula (B. muralis, B. ruralis), Trichostomum, Leptotrichum.--Ceratodon purpureus.--Distichium.--Pottia._ Order 6. =Grimmiaceæ.= The leaf-cells are often papillose; in the upper portion of the leaf, small, and of roundish shape. The calyptra is most frequently hood-like or conical. _Eucalypta._--_Orthotrichum_, often with short-stalked capsule, is found on trees.--_Coscinodon._--_Hedwigia._--_Grimmia_, _Racomitrium_.--_Cinclidotus._ Order 7. =Schistostegaceæ.= The stems are of two kinds (see above); _Schistostega osmundacea_, in caves, has a bright emerald protonema. Order 8. =Splachnaceæ.= The capsule has a large, collar-like neck (see above). _Splachnum_ (especially on manure). Order 9. =Funariaceæ.= Capsule pear-shaped. _Funaria_ (_F. hygrometrica_ has a very hygroscopic seta, becoming twisted when dry, and straightening with moisture); _Physcomitrium_; _Discelium_. Order 10. =Bryaceæ.= The capsule is thicker towards the apex; most frequently pendulous. _Philonotis_, _Bartramia_.--_Aulacomnium._--_Paludella Meesea._--_Mnium._--_Bryum_, _Webera_, _Leptobryum_. Order 11. =Polytrichaceæ.= Single peristome, formed by 16, 32, or 64 teeth. Leaves with longitudinal lamellæ on upper surface.--_Polytrichum_ has long, hairy calyptra. _Catharinea_ (_C. undulata_, in forests). Order 12. =Georgiaceæ.= Peristome with 4 teeth (see above). _Tetraphis_ (_T. pellucida_ has gemmæ). Order 13. =Buxbaumiaceæ.= Capsule asymmetrical; double peristome: the interior one conical, with 16 or 32 longitudinal folds.--_Buxbaumia_ (_B. aphylla_); _Diphyscium_. B. =Pleurocarpi.= Order 14. =Fontinalaceæ.= Long, floating Water-Mosses. _Fontinalis_ (_F. antipyretica_ is found in streams). _Dichelyma._ Order 15. =Hookeriaceæ.= _Pterygophyllum._ Order 16. =Leskeaceæ.= Dull-looking Mosses, with papillose or warted leaves.--_Thuidium_, _Thuja_-like with regularly arranged 1–3 doubly pinnate stems; _Anomodon_, _Leskea_. Order 17. =Pterogoniaceæ.= _Pterigynandrum filiforme_, etc. Order 18. =Fabroniaceæ.= _Anacamptodon._ Order 19. =Neckeraceæ.= Stems most frequently with flat, leafy branches. The leaves are smooth, never with longitudinal folds.--_Neckera._ Order 20. =Hypnaceæ.= The leaves are smooth with square, often bladder-like, cells at the edge. _Hylocomium_ (_H. splendens_, _H. triquetrum_); _Hypnum_; _Brachythecium_; _Plagiothecium_.--_Eurhynchium._--_Homalothecium_, _Isothecium_, _Orthothiecium_, _Homalia_.--_Climacium_, _Lescuræa_, _Leucodon_. The Mosses occur all over the globe. Many are found in great numbers, and growing thickly massed together, they form an important feature in landscapes (for example _Sphagnum_ and _Polytrichum_ in the Arctic Tundra). In the Northern and Arctic regions the Mosses are very plentiful, and often form a considerable part of the vegetation, while in the Tropics they are insignificant. Species of _Hypnum_ and _Polytrichum_, like _Sphagnum_, play an important part in the formation of peat. DIVISION III. PTERIDOPHYTA (VASCULAR CRYPTOGAMS). The alternation of generations is as distinct in this Division as in the Mosses, but the sexual generation consists of only a small thallus, the prothallium, which bears directly the sexual organs, _antheridia_ and _archegonia_; and the asexual generation, which arises from the fertilisation of the oosphere, is no longer a single short-lived sporangium, but a highly developed, generally perennial, plant provided with stem, leaves and _true roots_ (Ferns, Horsetails, etc.), the sporangia being borne on the leaves. In this latter generation the tissues are differentiated into epidermis, ground tissue and vascular tissue; in the last named the bundles are closed, and in the majority of cases concentric. The =sexual generation=, =gametophyte=, or =prothallium=, is _always a thallus_, although not always green and leaf-like (Figs. 205, 215, 222, 229, 235, etc.) It is very small, even in cases where it attains the greatest development, and consists only of parenchymatous cells. The prothallium is nourished by hair-like roots (rhizoids) and has only a transitory existence, dying soon after the fertilisation of its oosphere. The ANTHERIDIA exhibit great variations in structure which, however, must be considered as modifications of the fundamental type which is found in the Mosses. These modifications will be mentioned under the various families. The _spermatozoids_ are always spirally-coiled, self-motile, protoplasmic bodies, with most frequently a large number of fine cilia on the anterior end (Figs. 206, 223, 234). They are formed principally from the nucleus of the mother-cell, and portions of the cytoplasm often remain for a time attached to their posterior end. The ARCHEGONIA are more uniform throughout the entire Division, and more closely resemble those of the Mosses. They are, as in the previous Division, principally flask-shaped; but the central portion, which encloses the oosphere, is always embedded in the tissue of the prothallium, so that the neck, which is formed of 4 rows of cells, projects above the surface (Figs. 201 ^3, 222 _h_). The development of the archegonium in a Fern is seen in the accompanying figure (Fig. 201). The archegonium is developed from a surface cell, which divides into three cells by two walls in a direction parallel to the surface of the prothallium (Fig. 201). The most internal cell becomes the ventral portion of the archegonium. The external one (_b_) divides perpendicularly to the surface of the prothallium into four cells, which again divide parallel to the surface and form the neck (_b_, in 2 and 3). The intermediate cell projects upwards into the neck and divides into two, the lower one, after the separation of the ventral canal-cell, becoming the _oosphere_, and the upper one the _neck-canal-cell_ (_c_, in 2 and 3). [Illustration: FIG. 201.--_Pteris serrulata._ Development of archegonia.] As in the Mosses, the divisional walls of the neck-canal-cells become mucilaginous, causing the rupture of the neck of the archegonium. Fertilisation takes place as in the Mosses, and the passage of the spermatozoids, along the neck, to the oosphere, has been observed. Water (rain or dew) is similarly necessary for the movements of the spermatozoids, and hence for fertilisation. The other classes of the Division chiefly deviate from the Ferns in having the archegonium sunk deeper into the prothallium, and the neck reduced in length (compare Fig. 201 with Figs. 216, 222, 235, 236). According to the nature of the spores, the three classes of the Vascular Cryptogams are each divided into isosporous and heterosporous groups. I. The =isosporous= Vascular Cryptogams have _only one kind of spore_. The prothallium developed from this is in some cases monœcious, bearing both antheridia and archegonia; but in others there is a distinct tendency for each prothallium to bear only antheridia or archegonia (diœcious)--true Ferns and _Lycopodium_. In _Equisetum_ there is only one kind of spore, but two kinds of prothallia are developed, one of which bears only antheridia (male), the other only archegonia (female); but the one that bears antheridia may be transformed into the one that bears archegonia and vice versa. II. In the higher group, =heterosporous= Vascular Cryptogams (_Selaginella_ and _Isoëtes_, etc.), there are two distinct kinds of spores, the _small_, microspores, and the _large_, macrospores. The _microspores_ are male, and produce prothallia which bear only antheridia. The _macrospores_ are female, and produce prothallia which bear only archegonia. Corresponding to this difference in the spores, there is also found a difference in the development of the prothallium. In the Isosporeæ the prothallium is large, and either green, leaf-like, and provided with rhizoids (most of the Ferns, Horsetails, etc.), or subterranean, pale-coloured, and globular (_Ophioglossum_, _Lycopodium_). It lives vegetatively for a fairly long time, and generally produces a large and varying number of archegonia and antheridia. The prothallium in the Heterosporeæ is gradually more and more reduced, its independent and vegetative life becomes of less and less importance, it becomes more dependent on the mother-plant, and projects from the spore very slightly, or not at all. The antheridia and archegonia become reduced in number to one, and also degenerate in point of development. It may here be remarked that the gradual development of the asexual generation, the development of the two kinds of spores, and the progressive reduction of the prothallium and sexual organs which is found in this Division, is continued to the Gymnosperms and Angiosperms. The microspores are in these called pollen-grains, and the male prothallium is very rudimentary. The macrospores are termed embryo-sacs, and the female prothallium, the endosperm. The =asexual generation=, =sporophyte=. When the oosphere, which in this case as in all others is a primordial cell, is fertilised, it surrounds itself with a cell-wall and commences to divide into a number of cells, to form the embryo. The first dividing wall (basal wall) is nearly horizontal, and in the direction of the longitudinal axis of the archegonium. The next wall is vertical, and the next perpendicular to the other two. The oosphere, therefore, is now divided into eight octants by these three walls. The basal wall divides the embryo into a hypobasal and an epibasal half. From the first one, by continued divisions, the first root is developed; from the latter, the stem and leaves. After the formation of the octants the development proceeds in somewhat different ways in the various classes. In addition to the stem, leaf, and root, a “foot” is developed from the hypobasal half which remains enclosed in the prothallium, and conveys nourishment from the prothallium to the young plant until it is able to sustain itself (Fig. 202). The formation of these members in the embryo depends on the position of the oosphere in the archegonium and prothallium, and is independent of gravity. [Illustration: FIG. 202.--_Adiantum capillus veneris._ Vertical section through a prothallium (_f f_), with a young plant attached on its under side (mag. about 10 times); _r_ the first root, and _b_ the first leaf of the young Fern-plant; _m_ the foot. In the angle between _m_ and _b_ lies the apex of the stem: _h_ the rhizoids of the prothallium; _æ æ_ unfertilised archegonia.] In the Mosses the asexual generation is the sporogonium, which is limited in its development and in a great measure dependent upon the sexual generation, upon which it is situated; but in the Pteridophyta this generation is an independent and highly developed plant, provided with stem, leaf, and true roots, and has in many instances an unlimited development. The Pteridophyta are the lowest Division with _true roots_. The root which is first formed is very similar in nature to the primary root of the Monocotyledons; it very soon dies and is replaced by others which are more permanent, and developed upon the stem (adventitious roots); roots are wanting in _Salvinia_, _Psilotum_, and some Hymenophyllaceæ. The differentiation is, however, not so complete as in the Flowering-plants, and so many leafy forms are not found. The various members of these plants are anatomically much higher than in the Mosses, having an epidermis, a ground tissue with variously differentiated cells, and a highly developed vascular system. The vascular bundles, like those in the Monocotyledons, are without cambium, and closed; they are therefore incapable of any increase in thickness. In general the bundles are concentric, with the bast round the wood (Fig. 203). The wood is almost entirely made up of scalariform tracheides. In _Isoëtes_ a secondary thickening takes place by a cambium, which is formed inside the cortex, constructing secondary cortex to the exterior, and secondary wood towards the interior.--_Botrychium_ has also a thickening growth. Collateral vascular bundles occur in _Osmundaceæ_, _Equisetaceæ_, and the leaves of many _Polypodiaceæ_, etc. [Illustration: FIG. 203.--Portion of the stem of a Fern. Above is seen the transverse section, with vascular bundles of different form and size. The rhombic figures on the side of the stem are leaf-scars.] It is a point of special interest, that the gigantic forms of Ferns, Equisetums, and Club-Mosses (which flourished in earlier geological periods, when these classes attained their highest development) possessed some means of increasing in thickness. The _sporangia_ are in all cases _capsule-like_, and burst open when ripe to eject the spores. They are nearly always situated on the leaves (in _Lycopodiaceæ_, in the axils of the leaves, or above these, on the stems themselves). In some forms (LEPTOSPORANGIATÆ), the sporangia are developed from a single epidermal cell; in others (EUSPORANGIATÆ), from a group of epidermal cells, or from cells which lie beneath the epidermis. In the first group a primitive mother-cell (archesporium) is formed, which divides commonly into sixteen special mother-cells. In the latter group, on the other hand, a number of primitive spore-mother-cells are developed. In each sporangium three different tissues are generally developed; an innermost _sporogenous_ one (_s_ in Fig. 204 _A_), which arises from the archesporangium; an outermost one, which forms the _wall_ (_a_), and may be one or, more rarely, several layers in thickness; and an intermediate one, the _tapetum_ (Fig. 204 _A_, _B_, _b t_), which is rich in protoplasm, and whose cells are dissolved so that the spores float freely in the fluid thus provided. The spores arise as in the Mosses (in tetrads), by the cross-division of the special mother-cells, and according to the manner in which they are arranged in the mother-cell have either a tetrahedral form, with a large base resembling a segment of a ball, or are oblong (bilateral spores). Their construction is the same as in the Mosses (p. 187). [Illustration: FIG. 204.--_Selaginella inæqualifolia. A_ A young sporangium, which may develope either into a macro-, or a microsporangium. _B_ A microsporangium.] The spore-formation in its earliest commencement takes place in the same way in the Isosporous and the Heterosporous Vascular Cryptogams; but from a certain point, after the tetrahedral division, a difference occurs with regard to the macrosporangia. All the spores formed in the microsporangium may complete their development; but those which are formed in the macrosporangium are generally aborted, with the exception of one or four, and these consequently attain a much larger size (see Fig. 239.--The series to the left are microsporangia; those to the right, macrosporangia). APOGAMY. In some Ferns (_Pteris cretica_; _Aspidium filix mas_, var. _cristatum_; _A. falcatum_; _Todea africana_) the young plant is not developed as a consequence of fertilisation, but as a bud from the prothallium. This is known as apogamy, or loss of the power of sexual reproduction. The antheridia are generally more or less developed; archegonia are entirely wanting in _Asp. filix mas_, var. _cristatum_. This variety has probably only become apogamous through cultivation. Many specimens of _Isoëtes lacustris_, in a lake in the Vosges mountains, produce in the place where the sporangia are usually found, a vegetative shoot which grows into a new plant, so that the sexual generation is wanting in this case. Some specimens have sporangia on some leaves, and shoots on others. Apospory, or the formation of prothallia instead of sporangia and spores on the leaves, is found in _Athyrium filix femina_, var. _clarissimum_. In this case the development of the sporangia proceeds only to a certain point, and from these arrested sporangia the prothallia are produced. Normal sporangia are entirely wanting in this variety, and in _Aspidium angulare_, var. _pulcherrimum_, sporangia are completely wanting. Compare the Mosses (page 188). The Vascular Cryptogams are divided into _three large classes_, in each of which a progressive development can be traced from the isosporous to the heterosporous forms, but some of these are now only known as fossils. Class 1. =Filicinæ= (=Ferns=).--The stem is small in comparison with the leaves, and branches only seldom, and then by lateral shoots. The leaves are scattered, large, often deeply divided, and of various highly developed forms. The undeveloped leaves are rolled up in the bud, having what is termed circinate venation. The sporangia are situated on the edge or on the lower side of the leaves, those on which the sporangia are borne (_sporophylls_) being often the ordinary foliage-leaves; but in a few cases the fertile differ from the barren ones (a higher stage in development). The fertile leaves are not confined to definite parts of the shoot, and do not limit its growth. The archesporium is most frequently unicellular. _A_. =Isosporous=: Sub-Class 1. Filices (True Ferns). _B_. =Heterosporous=: Sub-Class 2. Hydropterideæ (Water Ferns). Class 2. =Equisetinæ= (=Horsetails=), in its widest meaning.--The leaves in this class are small in comparison with the stem. They are arranged in whorls, and unite to form a sheath. The sporangia are situated on specially modified, shield-like leaves, which are closely packed together and form a “cone.” The cone is borne terminally, and limits the growth of the shoot. The sporangia are developed from a large group of epidermal cells, the archesporium being unicellular. The branches are arranged in whorls, and develope acropetally. _A_. =Isosporous=: Sub-Class 1. Equisetaceæ. Existing forms. _B_. =Heterosporous=: Sub-Class 2. Extinct forms. Class 3. =Lycopodinæ= (=Club-Mosses=).--Roots generally branching dichotomously. The leaves are scattered or opposite, and in proportion to the stem very small, undivided, and simple. They are scale-like and triangular, tapering from a broad base to a point. The sporangia are situated singly (except in _Psilotaceæ_), and almost in every case on the upper side of the leaf or in the axil of a leaf; but in some cases they are borne on the stem, just above the leaf-axil. The sporangia arise from groups of epidermal cells. The sporophylls are often modified, and differ from the foliage-leaves; they are then arranged in cones placed terminally on branches, thus limiting their growth. _A_. =Isosporous=: Sub-Class 1. Lycopodieæ. _B._ =Heterosporous=: Sub-Class 2. Selaginelleæ. Class 1. =Filicinæ= (=Ferns=). The characteristics of this class have already been given on page 204. The class is divided into two sub-classes:-- 1. The TRUE FERNS, FILICES, have one kind of spore which generally developes monœcious prothallia, relatively large and green. The sporangia are most frequently situated in groups (_sori_), which are often covered but not enclosed by an _indusium_. 2. WATER FERNS, HYDROPTERIDÆ, have microsporangia with many (4 × 16) microspores, and _macrosporangia, each with one macrospore_. The prothallium is small, and projects but slightly from the germinating spore. The sporangia are situated in groups (_sori_), which are either enclosed by an indusium, or enveloped in a portion of a leaf, to form “fruits” termed _sporocarps_. The old name for the Hydropterideæ, “Rhizocarpeæ,” _i.e._ the “root-fruited,” originated from the erroneous supposition that the sporocarps were borne on the roots. Sub-Class 1. =Filices= (=the True Ferns=). Of the eight orders (with about 4,000 species) comprised in this sub-class, the Polypodiaceæ is the largest (having about 2,800 species) and the most familiar; for this reason it will be taken as typical. =The sexual generation.= When the spore germinates, the external covering (exospore) is ruptured, as in the Mosses. The internal cell-wall (endospore) grows out as a filament, which soon divides and gives rise to the prothallium, a flat, cellular expansion resembling the thallus of a Liverwort. In its fully developed state the prothallium is generally heart-shaped, dark green, and provided with root-hairs, and it attains a diameter of about one centimetre (Fig. 205). It is formed of one layer of cells, except along the central line near the anterior depression, where it becomes several layers of cells in thickness, forming the “cushion,” on the lower side of which the archegonia are developed. The antheridia are first formed; they are thus found on the oldest parts of the prothallium, on its edge, or among the root-hairs. The archegonia are developed later, and are therefore found near the apex. Several tropical Ferns have prothallia[18] deviating from this typical form; _Trichomanes_ (Order _Hymenophyllaceæ_) has filamentous, branched prothallia, which resemble the protonema of a Moss. Others, again, have strap-shaped prothallia, which resemble the thallus of certain Liverworts. [Illustration: FIG. 205.--Prothallium (_p p_) of Maiden hair (_Adiantum capillus veneris_) with a young plant attached: _b_ first leaf; _w′_ primary root; _w″_ adventitious roots; _h h_ root-hairs of the prothallium (× abt. 30).] [Illustration: FIG. 206.--Antheridia of Maiden-hair (× 550). _A_ Unripe; _B_ ripe, but unopened; _C_ open and ejecting the spermatozoids (_s_). Those which have been last ejected are still lying enclosed in their mother-cells, the others are coiled up and drag with them the cytoplasmic remains (_b_); _f_ cells of the prothallium.] The ARCHEGONIA have been already mentioned (p. 199, Fig. 201). The ANTHERIDIA are hemispherical or slightly conical bodies (Fig. 206). They consist, as in the Mosses, of a wall formed by one layer of cells, which encloses a number of spermatozoid-mother-cells (_A_ and _B_). The antheridia when ripe absorb water, and are ruptured, and the spirally-coiled spermatozoids liberated (Fig. 206 _S_). The spermatozoids have been observed to pass down the neck of the archegonium, and to fuse with the oosphere. =The asexual generation.= The first leaf, the “cotyledon,” of the embryo developed from the oospore (Figs. 202, 205) is always small, and has a very simple shape. The leaves which occur later become more perfect, stage by stage, until the permanent form of leaf has been attained.--The STEM is most frequently a subterranean or a semi-aerial rhizome; it is only in the tropical, palm-like Tree-Ferns, that the stem raises itself high in the air and resembles that of a tree, with leaf-scars or with the remains of leaves attached (Figs. 207, 203); in certain species the stem is encased in a thick mat of aerial roots (_Dicksonia antarctica_). When the rhizome is horizontal the internodes are frequently elongated, and the leaves are arranged in two rows, as in _Polypodium vulgare_ and in the Bracken-Fern (_Pteridium aquilinum_), etc.; it is also generally _dorsiventral_, having a dorsal side on which the leaves are situated, and a ventral side, different from the former, on which the roots are borne. When the stem ascends in an oblique direction, or is nearly vertical, its internodes are extremely short, and the leaves are arranged in a spiral line with a complicated phyllotaxis, _e.g._ in _Athyrium filix-fœmina_, _Aspidium filix-mas_, etc. The BRANCHING upon the whole is extremely slight, and is generally confined to the petiole (_e.g. Aspid. filix-mas_), or to the stem near the insertion of the leaves. Several species normally form buds on different parts of the lamina. The buds which are formed on the stem are not confined to the leaf-axil as in the higher plants. The Tree-Ferns, generally, do not branch at all. The VASCULAR BUNDLES are _concentric_, with the wood surrounded by the soft bast. In transverse section they are seen as circles or irregularly-shaped figures (Fig. 203), the name of “King Charles and the Oak” (Bracken-Fern) having originated from the appearance which the bundles present in oblique section. In _Osmunda_ they are collateral and resemble those of the Flowering-plants. Round each individual bundle is often a sheath of thick-walled, hard, brown, sclerenchymatous cells, which act as a mechanical tissue; similar strands are also found in other parts of the stem. [Illustration: FIG. 207.--Various Ferns (1, 2, 3, 4).] The LEAVES in nearly all species are only foliage-leaves, borne in a spiral. They have an apical growth which continues for a long time, and some require several years for their complete development. In the buds they are rolled up (_circinate_); not only the midrib, but also all the lateral veins, and even the terminal portions of a leaf are sometimes rolled up together, the tissues of the leaf being already fully developed and only waiting to expand. The leaves are often excessively divided and compound, with pinnate branches, and have an epidermis with stomata and a well-developed system of venation. Stipules are only found in _Marattiaceæ_ and _Ophioglossaceæ_. Very often peculiar hairs or scales (_paleæ_, _ramenta_), dry, brown, flat and broad, are found on stem and leaf. The SPORANGIA are small, round capsules, which, in a very large number of Ferns, are formed on the back, but more rarely on the edge of the ordinary foliage-leaves. It is very seldom that there is any difference in form between the barren foliage-leaves and the fertile leaves, as is found for example in _Blechnum spicant_ or _Struthiopteris_; or that the fertile part of the leaf is differently constructed from the barren portion of the same leaf, as in the Royal-Fern (_Osmunda_). In such instances the mesophyll of the fertile parts is poorly developed. The sporangia in the _Polypodiaceæ_ are lens-shaped, with long stalk (Fig. 211 _D_): their wall consists of one cell-layer on which a single row of cells, passing vertically over the top (that is along the edge of the sporangium), is developed into the “ring” (annulus). The cells of the annulus are very much thickened on the inner and side walls, and are yellowish-brown. The thickened cells, however, do not entirely encircle the sporangium, and on one side, near the stalk, they pass over into large, flat, thin-walled cells. These form a weak point in the wall, and it is here that the sporangium is opened diagonally by the elongation of the annulus. The sporangium of the Polypodiaceæ opens as it dries. The cells of the annulus are very hygroscopic, and in straightening, the annulus bends back with a jerk, thus ejecting the spores to considerable distances. The cells of the annulus absorb water with great readiness. [The sporangium arises as a single epidermal cell, from which a basal stalk-cell is cut off. Three oblique cell-walls, intersecting near the base, are next formed in the upper cell, and a fourth between these and parallel to the free surface; an inner tetrahedral cell enclosed by four others is thus formed, the outer cells become the wall of the sporangium, while the inner cell, by a series of walls, parallel to its sides, cuts off a layer of cells which eventually form the tapetum, the remaining central cell constituting the archesporium.] The SPORES are either oblong and bilateral, or they are tetrahedric with curved sides, depending upon the way in which the tetrad division has taken place. The sporangia are almost always situated on the nerves and gathered into groups, _sori_, which differ in form in the various genera. The sori, in many genera, may be covered by a scale-like structure, the _indusium_ (Figs. 211 _B_, 212). In the majority of cases, each sorus is situated on a small papilla (_placenta_, or _receptacle_), which is supplied by a small vascular bundle. Between the sporangia, hairs (_paraphyses_) are often situated, which spring either from the placenta or from the stalks of the sporangia. =Systematic Division.= The Ferns may be divided into two groups, characterized by the structure and development of the sporangia. The sporangia in the EUSPORANGIATÆ take their origin from a group of epidermal cells, and their walls are formed by several layers of cells. The archesporium is the (not tetrahedric) hypodermal terminal cell of the axial row of cells which give rise to the sporangium. In the LEPTOSPORANGIATÆ the sporangia are developed from single epidermal cells, and their walls are uni-layered. The archesporium is a central, often tetrahedric cell, from which sixteen spore-mother-cells are developed.[19] It is difficult to say which form is the oldest (according to Prantl, those which have the sori on the nerve-endings); however, the Eusporangiatæ would seem to have made their appearance long before the others, and also well defined Marattiaceæ and Ophioglossaceæ occur in the Kulm and Coal period, before the true Polypodiaceæ. About 4,000 species of Ferns are now existing, and they are found especially in tropical and sub-tropical forests. Family 1. =Eusporangiatæ.= Order 1. =Ophioglossaceæ.= The prothallium differs from that of all other Ferns in being _subterranean_, _free from chlorophyll_, _pale_ and _tuberous_. The stem is extremely short, with short internodes, most frequently unbranched, vertical, and entirely buried in the ground (Fig. 208 _st_). In several species (among which are the native ones) one leaf is produced every year, which has taken three to four years for its development. In _Botrychium_ a closed, sheath-like basal part of each leaf covers the subsequent leaves during their development. In _Ophioglossum_ and others each leaf has at its base an intrapetiolar, cap-like sheath, which protects the succeeding leaf. The leaves are of two kinds: (_a_) foliage, which in _Ophioglossum vulgatum_ are lanceolate and entire, but in _Botrychium_ however, are pinnate (_b_ in Fig. 208 _A_, _B_); and (_b_) fertile, which are found facing the upper side of the foliage-leaves. These latter in _Ophioglossum_ are undivided and spike-like (Fig. 209 _A_), but pinnate in _Botrychium_ (Fig. 208 _B_). Each foliage and fertile leaf are branches from the same petiole. The large sporangia are placed laterally, and open by two valves. No annulus is formed (Fig. 209).--_Ophioglossum_ reproduces vegetatively by adventitious buds on the roots. [Illustration: FIG. 208.--_A Ophioglossum vulgatum_ (Adder’s-tongue); _B Botrychium lunaria_ (Moonwort), both natural size; _r-r_ roots; _bs_ leaf-stalk; _st_ stem; _b_ foliage-leaf; _f_ fertile leaf.] [Illustration: FIG. 209.--Fertile leaf of _Ophioglossum_.] Three genera with about twelve species. Order 2. =Marattiaceæ= are tropical Ferns, whose gigantic leaves resemble those of the Polypodiaceæ, but have stipules in addition. The sporangia are grouped in sori, situated on the lower side of the leaves, the sporangia in each sorus being arranged either in two rows or in a ring. In _Angiopteris_ they are isolated (Fig. 210 _A_), but in the other species (_Kaulfussia_, _Danæa_, _Marattia_), they are united, and form “synangia” divided into a number of chambers corresponding to the sporangia. These open by clefts or pores. _Marattia_ presents the highest development, as its sporangia are completely united in a capsule-like synangium, which is closed until maturity, and then opens by two valves. In each valve there is a row of three to eleven sporangia, each opening by a slit towards the inside (Fig. 210 _B_, _C_). An indusium encloses the sorus, except in _Kaulfussia_; it is formed of flat and lobed hairs, which resemble the hairs of the other portions of the leaves. In _Angiopteris_ and _Marattia_ the indusium is very rudimentary; in _Danæa_ it forms a kind of cupule. The numerous fossil Marattiaceæ (15 genera, with 98 species) present similar differences to those now living, but more various forms are found, for example, with solitary free sporangia. Those now living are the last small remnant (4 genera with only 23 species) of a once dominant family, which existed from very early times, and whose culminating point was reached in the Kulm and Coal periods. The Ophioglossaceæ appear also in the Kulm and Coal periods, and were about as numerous as at the present time (presumably 2 genera, with 19 species). Leptosporangiate Ferns appear however to have occurred first of all in the Trias-formation. [Illustration: FIG. 210.--Sporangia of the Marattiaceæ: _A_ _Angiopteris_; _B_ and _C Marattia_; _C_ is a half sorus with nine sporangia, each of which has opened by a longitudinal cleft.] Family 2. =Leptosporangiatæ.= Order 1. =Polypodiaceæ.= Sporangia on the lower side of the leaves, _stalked_ and provided with a _vertical_, incomplete annulus; dehiscing by a transverse cleft (Fig. 211 _D_).--The genera are distinguished by the form of the indusium and the position of the sori, etc. 1. The sporangia cover the entire lower surface of the leaf (Tropical America and Asia). _Acrostichum_, _Platycerium._ 2. Sori without indusia, circular or oval. _Polypodium_ (Fig. 211 _A_). The leaves are most frequently situated in two rows on the dorsal side of the creeping rhizome, and fall off leaving a smooth scar behind.--_P. vulgare_, common in woods, on stones. (_Phegopteris_ also has no indusium; see page 214). 3. The sporangia are situated in continuous lines just inside the margin of the leaf.--_Pteris_[20]: the sporangia form a continuous line along the entire margin of the leaf (Fig. 211 _C_), which bends over and covers the sporangia, forming a “false-indusium.” _Pteridium_ has linear sori situated on a marginal vascular bundle, covered by two linear basal indusia, of which the outer is bent over like the edge of a leaf.--_P. aquilinum_ (Bracken) has a wide-spreading rhizome with large alternate leaves, placed on opposite sides, at some distance apart. Only one leaf is developed from each branch every year. [Illustration: FIG. 211.--Portions of leaves with sori. _A_ _Polypodium_. _B Aspidium_. _C Pteridium_. _D_ A sporangium of one of the Polypodiaceæ: _r_ the annulus; _s_ spores.] _Adiantum_ (Maiden-hair): sori on the underside of small portions of the edge of the leaf, which are bent over (false indusium). _Cryptogramme_ (_Allosorus_), _Cheilanthes_. 4. The sori are oval or linear, situated on one side of the vascular bundle.--_Asplenium_ (Fig. 212 _A_): sori linear; indusium with one of its edges attached at the external side. _A. ruta muraria_ (Wall-Rue); _A. septentrionale_; _A. trichomanes_.--_Athyrium_: sori linear or curved; _A. filix-fœmina_ (Lady-Fern).--_Scolopendrium_ (Fig. 212 _B_): sori as in _Asplenium_, but situated in pairs across the lanceolate, entire leaves. Each sorus is covered on the external side by an indusium, whose free edges are parallel and approach each other. _S. vulgare_ (Hart’s-tongue).--~_Blechnum_ (_B. spicant_, Hard Fern; the fertile leaves differ from the barren, the pinnæ being narrower, while the underside is almost entirely covered with sori, and hence they are of a much darker brownish hue than the barren ones).--_Ceterach_: indusium rudimentary or absent.~ 5. Sori circular and covered by a shield-like, or reniform indusium.--_Aspidium_ (Fig. 211 _B_); the leaves wither away and leave no scar upon the root-stock. _A. filix-mas_ (Male-Fern); _A. spinulosum_.--_Phegopteris_ has no indusium, the withered bases of the leaf-stalks are persistent; _P. dryopteris_ and _P. polypodioides_. 6. The indusium is situated below the sori, and has the shape of a one-sided scale (_Cystopteris_, _Struthiopteris_), or of a cup or cupule, which in _Woodsia_ is sometimes fimbriate (Fig. 212 _C_, _D_). [Illustration: FIG. 212.--_A Asplenium_. _B Scolopendrium_. _C Woodsia_; _D_ single sorus of the same. _E Cyathea_: the sporangia have fallen off in the upper sori. (All magnified.)] 7. The sori are situated on the margin of the leaf, and at the end of a vascular bundle. Indusium, semi-cupular. _Davallia._ Principally tropical species. 1 in S. Europe. This order is the greatest, comprising about 2,800 species, the majority being perennial plants. A few are large, and known as Tree-Ferns. As plants in conservatories and rooms the following are cultivated: species of _Gymnogramme_ (tropical America), _Lomaria_, _Nephrolepis_, _Pteris_ (_P. serrulata_, _cretica_). Officinal. _Aspidium filix-mas_, rhizome and the withered petioles.--Species of _Alsophila_ and _Cibotium_ give Penghawar Djambi. The rhizome of _Pteridium aquilinum_, var. _esculentum_, contains so much starch that it is used as food. The other orders of true Ferns deviate from the Polypodiaceæ, especially in the formation of the annulus, the bursting of the sporangium and its mode of attachment and development, and in the differences in the formation of the prothallium, etc. The principal are:-- Order 2. =Hymenophyllaceæ.= To this order belong the lowest and most Moss-like Ferns; the leaves, with the exception of the veins, are most frequently formed of _only one layer of cells_, and consequently stomata are wanting; the formation of the prothallium also somewhat resembles the Mosses. Sori marginal, on the _extremities of the vascular bundles_, and surrounded by a _cupular indusium_. The sporangia are sessile, with equatorial annulus. _Hymenophyllum_ (_H. tunbridgense_, European). _Trichomanes_ (_T. speciosum_, European). Species about 200, which live especially on rocks and trees in damp and shady tropical forests. Some have no roots. Order 3. =Cyatheaceæ.= Annulus _complete_ and oblique. To this order belong, principally, the tree-like Ferns with palm-like habit. The number of species is about 200, they are all tropical and form forests in some regions of Australia. _Cibotium_ and _Dicksonia_ have marginal sori, with cupular, basal indusium. (The stem of _D. antarctica_ is covered with aerial roots.) _Alsophila_ (without indusium); _Cyathea_ with cupular, inferior indusium (Fig. 212 _E_). [Illustration: FIG. 213.--_Gleichenia_: _A_ part of a leaf with sori; _B_ a single sorus.] Order 4. =Gleicheniaceæ.= Sporangia with equatorial annulus, and longitudinal dehiscence, most frequently groups of 3–4 in sori without indusium (Fig. 213). _Gleichenia_: the apical growth of the leaves continues for a long time. Order 5. =Schizæaceæ.= Annulus apical. To this order belongs _Aneimia_, which is so commonly cultivated in conservatories. The two lowest pinnæ are metamorphosed, having no leaf parenchyma and being covered with sporangia. _Schizæa. Mohria. Lygodium_, a climber, whose leaves have unlimited growth and attain a length of several metres. About 70 species. Tropical. Order 6. =Osmundaceæ.= The sporangia have at the apex a lateral group of strongly thickened cells, which gradually pass over into the ordinary cells. The sporangia open by a longitudinal cleft. Indusium wanting. _Osmunda_ bears the sporangia upon peculiar, branched pinnæ, without parenchyma (the uppermost in the leaf). _O. regalis_ (Royal-Fern): European. [Illustration: FIG. 214.--_Salvinia natans_: _A_ microsporangium with germinating microspores and protruding prothallia (_s_); _B_ a prothallium with the bicellular antheridium (_s_) growing out of the microsporangium; _C_ the two cells of the antheridium have opened by transverse clefts; beneath is seen the microspores enclosed by the hardened mucilage; _D_ spermatozoids still enclosed in the mother-cells.] [Illustration: FIG. 215.--_Salvinia natans. A_, _B_ Female prothallia, _f-f_, protruding from the macrospore which is still enclosed in the macrosporangium; _œ_ archegonia. _C_ An embryo (× 16) still in connection with the spore (_s_): _a_ the scutiform leaf; _b-e_ the subsequent foliage-leaves, of which _b_ and _c_ stand singly, _d-e-v_ in a whorl; _v_ the submerged-leaf; _f-f_ wing-like lobes of the prothallium: _m_ the foot.] Sub-Class 2. =Hydropterideæ= (formerly Rhizocarpeæ), =Water Ferns=. The following further characteristics must be added to those given on page 205:-- =Sexual generation.= The MICROSPORES produce an extremely rudimentary prothallium, formed of only a single cell, and having also a very much reduced bicellular antheridium with a small number of spermatozoid mother-cells in each cell (in _Salvinia_ 4, in _Marsilia_ and _Pilularia_ 16). In _Salvinia_ the microspores remain embedded in a hard mucilaginous mass (at first frothy) which fills up the cavity of the sporangium. The prothallium must therefore grow out through this slime and also through the wall of the sporangium (Fig. 214), and it thus terminates in a relatively long cell. In _Marsilia_ the microspores are set free from the microsporangium, and the prothallia, with the antheridia, remain in them until the spermatozoids are liberated. The latter are spirally-twisted threads. The MACROSPORES, on germination, give rise to a very reduced prothallium, which in _Salvinia_ bears 3 archegonia; but, if these are not fertilised, the prothallium may continue to grow and become a fairly large, green body with several archegonia (Fig. 215 _A_, _B_). In _Marsilia_ the prothallium is still more reduced, it is enclosed in the macrospore, and only bears one archegonium. The archegonia are similar in structure to those of the Ferns, but are smaller, and sunk more deeply in the tissue of the prothallium. [Illustration: FIG. 216.--_Salvinia natans. A_ An archegonium, unripe, seen in longitudinal section: _h_ the neck-cells; _k_ the neck-canal-cells; _c_ the central cell. _B_ An open archegonium of which the neck-cells have separated off. _C_ An open, old archegonium seen from the top.] =The asexual generation= is developed from the fertilised egg-cell. It is a dorsiventral, horizontal shoot. In _Salvinia_ it bears at first a shield-like leaf, the scutiform leaf (Fig. 215 _C_, _a_), which is succeeded by the ordinary foliage-leaves. The young plants of _Marsilia_, likewise, have less perfect leaves in the very early stage. The formation of the sporangium is the same as in the Leptosporangiate Ferns. (The 16 spore-mother-cells originate from one central, tetrahedric archesporium.) The Hydropterideæ are divided into 2 orders, the chief differences between them being found in the asexual generation. [Illustration: FIG. 217.--_Salvinia natans_ (natural size): _A_ seen from above, floating on the water; _B_ a portion seen from the side in its natural position in the water.] [Illustration: FIG. 218.--Sori of _Salvinia_ in longitudinal section: _h_ microsporangia; _m_ macrosporangia. (× 10.)] Order 1. =Salviniaceæ.= This order more nearly approaches the true Ferns, especially so on account of the form of the indusium. Only one species is found in Europe, _Salvinia natans_ (Fig. 217). This is a small, floating, annual, aquatic plant, entirely _destitute of roots_. The dorsiventral, horizontal stem bears two kinds of leaves, which are arranged in whorls of three. Two of these which turn upwards are oval, entire, “_aerial foliage-leaves_” (Fig. 217 B, _b^2_-_b^3_); the third, the “_water-leaf_” (_b^1_) is submerged and divided into a number of hair-like segments, similar to the submerged leaves in many aquatic plants, for instance, Water-buttercup (see also Fig. 215 _C_). The whorls of leaves alternate with each other; there are thus 4 rows of dorsally-placed aerial leaves, and two rows of ventrally-placed submerged leaves. The sporangia are situated in sori, each sorus being borne on a small column (receptacle or placenta) and enveloped by a _cupular_, but _entirely closed indusium_ (Fig. 218). _The sori are situated on the submerged leaves_ (Fig. 217 _B_, _s-s_) _and are unisexual_, _i.e._ each sorus contains microsporangia only, or macrosporangia. _Azolla_ belongs to this order. It is a very small, floating, tropical water-plant (America and East India), with horizontal, root-bearing stem. The stem branches profusely by lateral buds, and bears the two rows of leaves on its dorsal side, the roots on the ventral side. Each leaf is bifid, and divided into an upper dorsal, and a lower ventral portion. The upper segments float on the surface of the water and are arranged like tiles on a roof, each one overlapping its neighbour. In each floating segment a large cavity is found, in which _Anabæna_ is always present. The lower segments are submerged. Order 2. =Marsiliaceæ.= The characteristic feature of this order, and one not possessed by other Fern-like plants, is that the sori (2–many) are enveloped _in leaf-segments_ which _close round them_ and form a “sporocarp,” just in the same manner as the carpels, in the Angiospermous Flowering-plants, close round the ovules and form ovaries. The sori contain both micro-and macrosporangia. When the spores are ripe, the sporocarp opens in order to disperse the spores (Fig. 220). [Illustration: FIG. 219.--_Marsilia salvatrix_ (natural size): _K_ terminal bud; _b_ leaves; _f_ sporocarps; _x_ point of branching of petiole.] The two genera (with 57 species, Temperate, Tropics) are land-and marsh-plants, whose dorsiventral, creeping stem bears roots on the under surface, and the leaves in two rows on the upper side (Figs. 219, 221). The leaves of _Marsilia_ are compound, and divided into four small leaflets springing from the apex of the petiole (Fig. 219), and resemble the leaves of _Oxalis_. In the bud the leaves are circinate (Fig. 219 _b_), and at night they exhibit the well-known sleep-movements. The sporocarps are borne on the petioles of the fertile leaves, near their bases (Fig. 219 _f_); they are oblong and resemble small beans, the outer cells being hard and sclerenchymatous, while the inner ones are divided into a number of loculi arranged in two rows. On germination, water is absorbed, the two sides separate slightly, as valves (Fig. 220 _A_), and a long vermiform mass of gelatinous, parenchymatous cells (Fig. 220), swollen by the water, emerges, bearing a large number of sori arranged pinnately. Each sorus (_sr_) is covered by a thin indusium. (The thin covering may be considered an indusium physiologically, though not morphologically). [Illustration: FIG. 220.--_Marsilia salvatrix_: _A_ the sporocarp commencing to germinate; _B_ a more advanced stage of germination.] [Illustration: FIG. 221.--_Pilularia globulifera_ (natural size): _s_ sporocarps; _b_ leaves; _k_ the growing point; _r_ roots.] _Marsilia quadrifolia_, in Europe. Many species are found in Australia. The nutritious sporocarps of _M. salvatrix_ were the means of saving the Burke expedition in the interior of Australia, and hence this species has earned its specific name. _Pilularia_ has linear leaves, without lamina. The sporocarps are spheroid (Fig. 221), brown and hard, and situated near the base of the leaves. They are 2–4 chambered and open by a corresponding number of valves. Class 2. =Equisetinæ (Horsetails.)= The characteristics of this class have been described on page 204. It is divided into two sub-classes:-- 1. THE ISOSPOROUS EQUISETINÆ. To this sub-class belong, with certainty, only the EQUISETACEÆ now existent, which are represented by only one genus, _Equisetum_. 2. THE HETEROSPOROUS EQUISETINÆ. Forms which are now extinct. [Illustration: FIG. 222.--_Equisetum arvense._ The prothallium highly magnified. _A_ Male; _s, s_ antheridia. _B_ Portion of a female, cut through vertically; _œ œ_ archegonia, the central one is fertilised; _h h_ root-hairs.] [Illustration: FIG. 223.--_Equisetum maximum._ Spermatozoids: _a_ shows them still enveloped by the mother-cell.] Sub-Class 1. =Isosporous Equisetinæ.= Order. =Equisetaceæ (Horsetails).= =The sexual generation.= The prothallium is green and leaf-like, as in the majority of Ferns, but irregularly branched and curled. It is often unisexual. The male prothallia bear antheridia only, and are smaller and less branched (Fig. 222 _A_) than the female; the latter may attain a diameter of ½ an inch, and bear archegonia only (Fig. 222 _B_). The antheridia and the archegonia resemble those of the Ferns, but the spermatozoids (Fig. 223) are larger and less twisted. On the last curve is situated a more or less elongated appendage of cytoplasm (Fig. 223 _c_). =The asexual generation.= The embryo is similar to that of the Ferns. The fully developed _Equisetum_ is a perennial herb, with widely creeping (in some species tuberous) rhizome, from which extend erect, aerial, most frequently annual shoots. [Illustration: FIG. 224.--_Equisetum arvense_: _a_ fertile branch with cone; _b_ vegetative shoot; _c_ cone; _d_ sporophylls.] The vegetative aerial STEMS are divided into a number of internodes by the whorls of leaves (Fig. 224). The internodes are hollow, the cavities being separated from each other by the transverse partitions of the solid nodes. The lower portion of the internode, which is encased by the leaves, has much thinner and softer cell-walls, so that the stem is easily separated into segments just above the nodes. Each internode has a large number of ridges and furrows, and bears at its apex a whorl of leaves whose number and position correspond to the ridges of the internode. As in the case of other verticillate plants, the whorls are placed alternately, one above the other; the same arrangement is also found in the ridges on two successive internodes. In addition to the large air-cavity in the centre of each internode (the central cavity), a whorl of tubular air-passages is found in the cortex of the stems, opposite the furrows (vallecular canals). There is also a similar air-passage (carinal canals) in each of the vascular bundles, which are placed in a ring, one opposite each ridge, and therefore alternating with the vallecular canals. The vascular bundles are _collateral_ as in the majority of Flowering-plants, but poorly developed. The xylem of each bundle consists of two groups of annular or spiral vessels, close to the outer border of the carinal canal, and two groups of scalariform tracheides, each placed on a radius passing through a group of spiral vessels. The phloëm is placed between these four groups, each of which has only a few vessels. The stiffness of the stems is mainly due to the large amount of silica in the cell-walls of the epidermis, and to the sclerenchymatous cells of the ridges. All LEAVES are situated in _whorls_. The VEGETATIVE are simple, undivided, 1-nerved, and are united into toothed sheaths (Fig. 224 _a_, _b_). The branching of the stems in some species (_E. arvense_) is very abundant. The branches break through the base of the leaf-sheaths (Fig. 224 _b_), and generally _alternate with the teeth_ (leaves). The FERTILE LEAVES (_sporophylls_) are different from the barren ones. They are _free, shield-like_, each one having a short stalk bearing usually an hexagonal plate (Fig. 224 _d_), and closely compressed into an ear or cone (Fig. 224 _a_, _c_). The _Equisetums_ thus present an advance in development distinctly beyond that of the Ferns, which is further emphasized by the circumstance that a transition from the sheath-leaves to the fertile-leaves is found in the involucre or annulus, a “collar” of specially modified leaves situated at the base of the cone (Fig. 224 _a_ and _c_). The cone may be considered as a very rudimentary flower, and the annulus may be regarded as a very early stage in the formation of a flower (perianth). See page 235. The SPORANGIA are situated on the underside of the sporophylls, one at each angle; they are sac-like, and open inwardly by a longitudinal cleft (Fig. 224 _d_). An annulus is wanting; but in the wall of the sporangium, as in the pollen-sacs of the Flowering-plants, a layer of cells, with annular or spiral thickenings, is developed, which assists in the dehiscence of the sporangium. The SPORES are green; the walls composed of four distinct layers, of which the outer is gradually separated, except at one point, and becomes split into four long bands (_elaters_) (Fig. 225). The elaters are extremely hygroscopic, coiling round the spore when moistened, and expanding as soon as dry, presenting a most lively object under the microscope when breathed upon and allowed to dry. The second layer, when germination commences, becomes detached from the inner wall, which is formed of the exospore and endospore. The order has become much reduced, and at the present time includes only one genus, _Equisetum_, with about twenty-five species, which are distributed over the entire globe, particularly in damp situations. In SOME SPECIES the barren shoots are green and very much branched, but the fertile ones are unbranched, pale brown, and possess no chlorophyll (_E. arvense_, Field-Horsetail, Fig. 224, and _E. maximum_). IN OTHERS the fertile and barren shoots are alike green, and either both unbranched (_E. hiemale_), or branched (_E. palustre_, _E. limosum_, etc). The fertile shoots of _E. silvaticum_, up to maturity, resemble those without chylorophyll of _E. arvense_, but after that period they produce green branches, and thus resemble the barren ones. [Illustration: FIG. 225.--Spores of _Equisetum_: _A_ damp, with elaters (_e_) coiled round the spore; _B_ dry, with elaters expanded.] EXTINCT ISOSPOROUS EQUISETINÆ. In addition to several true species of fossilized _Equisetums_, the order of the CALAMITES, which no doubt is closely allied to the Equisetinæ, is also found in the fossil state. These were gigantic forms, attaining about twenty times the size of those of the present day, and stems of nearly 10–12 metres in height are known. They reached the culminating point of their development in the Carboniferous period, and died out towards the close of the Palæozoic. The stems had hollow internodes and alternating grooves, similar to their relatives of the present day. The leaves must either have been absent or very perishable, since they have not been identified with certainty. If the determinations of certain remains of cones which of late have been discovered are correct, they were heterosporous and had two kinds of sporangia as in the following sub-class. A cambium formation and an increase in thickness has been found in the stems. Their USES are very limited. A few species, such as _E. hiemale_ are used for polishing on account of the hard siliceous cell-walls of the epidermis, found in all species of _Equisetum_. Sub-Class 2. =Heterosporous Equisetinæ.= The two orders which come under this head are united by the characteristics, that the verticillate leaves are not united into sheaths (Fig. 226), and that between each whorl of fertile leaves there is also a whorl of barren ones. The fertile whorls in ANNULARIÆ are situated about midway between the barren ones (Fig. 227), but in ASTEROPHYLLITEÆ they occur immediately above a barren whorl (Fig. 228) and contain only half as many members as the latter. The lower whorls bear macrosporangia with one macrospore, the upper, microsporangia with many microspores. [Illustration: FIG. 226.--A. fragment of _Annularia_.] [Illustration: FIG. 227.--Fragment of _Annularia longifolia_, with sporangia; the leaves have partly fallen off: a barren whorls; _s_ fertile whorls.] [Illustration: FIG. 228.--Fragment of cone of _Asterophyllites_ (_Volkmannia elongata_): _a_ and _s_ as in Fig. 227.] The ANNULARIÆ were distichous (Fig. 226), and presumably floating plants. The ASTEROPHYLLITEÆ had verticellate branches. These also died out after the Carboniferous period, at the close of the Palæozoic. Class 3. =Lycopodinæ= (=Club-Mosses=). The characteristics of this class have been given on page 205. It consists of two sub-classes, one embracing isosporous, the other heterosporous forms. Sub-Class 1. =Lycopodieæ= (ISOSPOROUS Lycopodinæ). One kind of spore. Prothallium large, partly green. Leaves without ligule. [Illustration: FIG. 229.--_Lycopodium annotinum_: _A_ embryo (nat. size), with prothallium (_pr_), one embryo is broken off; _B_ the prothallium (slightly magnified); _C_ section through the prothallium and embryo in the direction _a-b_ of _A_, and vertically in the plane of the paper.] [Illustration: FIG. 230.--_Lycopodium clavatum_: portion of a stem, bearing cones (_a_); _s_ a spore; _h_ sporangium in the axil of a leaf, _s_.] Order 1. =Lycopodiaceæ.= The PROTHALLIUM is only known in a few species at present, but in these it is more or less tubercular, and bears both antheridia and archegonia. In _L. annotinum_ the prothallium is a relatively large mass of cells, without chlorophyll, and subterranean, in which the antheridia and archegonia are embedded (Fig. 229). In the widely distributed tropical species, _L. cernuum_, and in _L. inundatum_, it is a small tubercular body which has a subterranean portion, with either little or no chlorophyll; and an aerial green portion. The prothallia of _L. phlegmaria_ and others live saprophytically in the crevices of the bark of trees; they are partly filamentous, branched, and possess no chlorophyll. The =asexual generation=. PERENNIAL PLANTS. The stem branches monopodially (often apparently dichotomously), and is thickly covered by small, simple, triangular or scale-like leaves. The leaves are spirally arranged in some species (Figs. 229, 230), and in others, whose stem is compressed with unequal sides, opposite (Fig. 231). The roots of _Lycopodium_ are dichotomously branched. The SPORANGIA in _Lycopodium_ are situated singly at the base of the leaves, almost in their axils; they are reniform, unilocular and open like a mussel-shell by two valves (Fig. 230 _h_). The sporangia are developed from a group of surface cells. The archesporium is formed from one hypodermal cell (or perhaps a cell-row). [Illustration: FIG. 231.--_Lycopodium complanatum_: _a_ leaves on the edges of the stem; _d_ leaves on the sides.] [Illustration: FIG. 232.--_Lycopodium clavatum._ A tetrahedral spore seen from above, where the three borders join; and a tetrad of bilateral spores, still lying in the mother-cell.] The fertile leaves are collected upon definite regions of the stem. They are either similar to the barren ones, and then the fertile portions of the stem pass gradually, without any break, into the barren portion (_L. selago_); or they differ from the barren leaves, and are then collected into special apical cones (Fig. 230 _a_). The SPORES are tetrahedral or bilateral (Fig. 232). About 100 species, chiefly tropical. Five species of _Lycopodium_ are found in Great Britain. _L. clavatum_ and _L. selago_ are common in mountainous districts. _L. annotinum_ is common in the Highlands of Scotland. The other genus of the order is _Phylloglossum_, with one species, _P. drummondi_ (Australia, Tasmania, and New Zealand), a small plant only a few centimetres high, with two tubers, and about eleven linear leaves at the base of the stem which is terminated by a cone of sporophylls.--FOSSIL Lycopodiaceæ in the Carboniferous period. OFFICINAL: “Lycopodium,” the spores of _L. clavatum_. Family 2. =Psilotaceæ=. The sporangia are placed on the apex of short, two-leaved stems, as 2–3, seldom four, small capsules. Small herbs, with angular stems; leaves small, simple, and one nerved. Only four species.--_Psilotum_ (Madagascar, Moluccas, Sandwich Islands, etc.) is destitute of roots, their place being supplied by special underground stems which bear a few modified leaves, very much reduced, especially when buried deeply in the soil. Three species.--_Tmesipteris_ (Australia), one species. Sub-Class 2. =Selaginelleæ= (HETEROSPOROUS Lycopodinæ). Micro-and macrospores. The prothallia are very much reduced, especially the male; the female does not leave the spore. The leaves are ligulate. [Illustration: FIG. 233.--Germination of the microspores of _Selaginella_: _A_ the spore rendered transparent, seen from above. In the interior is seen the prothallium (_f_), and the first divisions of the antheridium (_a_, _b_, _c_, _d_); in _B_ the spore-wall is removed and all the spermatozoid-mother-cells formed; in _C_, the microspore has opened and the spermatozoids and the mother-cells are escaping together.] =The sexual generation.= In the ~MICROSPORES~ are formed: (1) a very small “vegetative” cell, representing the vegetative part of the prothallium (_f_ in Fig. 233 _A, B_), and (2) a cell many times larger and which divides into a number (4–8) of primordial cells, each of which divides into four spermatozoid-mother-cells, though all of these may not develope spermatozoids. On germination, when the spore-wall is ruptured, the spermatozoids and spermatozoid-mother-cells are ejected into the water. The ~SPERMATOZOIDS~ in _Selaginella_ are elongated and club-shaped, with two cilia (Fig. 234); but in _Isoëtes lacustris_ they are spirally-twisted threads which differ from all other spermatozoids by having a bunch of cilia _at each end_; the other species of _Isoëtes_ have cilia only at the anterior end. The MACROSPORES. Shortly after the macrospores have been set free, or in _Selaginella_, while still enclosed in the sporangium of the mother-plant, they germinate and soon become filled with the cellular tissue of the prothallium, and even in _Selaginella_ the archegonium begins to be formed before the rupture of the spore-cell-wall has commenced (Fig. 235 _A_). [Illustration: FIG. 234.--Spermatozoids of _Selaginella_: _b_ with a remnant of cytoplasm.] [Illustration: FIG. 235.--Macrospore of _Selaginella_: _A_ longitudinal section, before the rupture of the wall, six weeks after being sown. The endosperm (_e_) has not yet filled the entire chamber. Cell-formation is still proceeding in the lower part of the spore. The endosperm and prothallium (_f f_) are separated by a distinct line (diaphragm). _B_ Germinating macrospore seen from outside: _s_ wall of the spore; _æ_ archegonia.] [Illustration: FIG. 236.--Archegonia of _Selaginella_: _A_ unripe, in longitudinal section; _c_ the central cell; _k_ neck-canal-cell, which is wedged in between the two-storied neck-cells; _B_ ripe; _u_ ventral canal-cell; _C_ seen from above, open. It will be noticed that the neck is formed of two tiers of four cells each.] The ARCHEGONIA are constructed on the same plan as those of the other Archegoniatæ, but are quite embedded in the prothallium (Figs. 235 _æ_, 236). =The asexual generation= varies very much in the different orders. [Illustration: FIG. 237.--_Isoëtes lacustris_ (slightly diminished): _st_ the stem; _r_ roots; _b_ leaves.] [Illustration: FIG. 238.--_Isoëtes lacustris_. Longitudinal section through the base of the leaf with a microsporangium. The edge of the groove, in which the microspangium is placed, is continued as a thin covering which envelopes the sporangium. The inferior edge of the ligular groove (_L_) forms a lip (_J_); _t_ sterile cell-rows (trabeculæ) which divide the sporangium into compartments; _l_ vascular bundle.] [Illustration: FIG. 239.--_Selaginella inæqualifolia_. Cone in longitudinal section; microsporangia are seen on the left side, macrosporangia on the right (most frequently each with four macrospores).] Order 1. =Isoëtaceæ (Quill-worts).= The only known genus, _Isoëtes_ (Quill-wort), has an extremely short, tuberous, _unbranched_ stem with very short internodes (Fig. 237). The STEM is remarkable as being the only one among the Vascular Cryptogams which increases in thickness (see page 202). The meristematic cells are situated round the axial cylinder, and form, especially, parenchymatous tissue in two or three directions, giving rise to 2–3 grooves in which the dichotomously-branched ROOTS are produced. The LEAVES are arranged spirally in a close rosette. They are awl-shaped and have at the base a semi-amplexicaul sheath, with a groove (_fovea_), in which a sporangium is situated (Fig. 238). The ligule is a foliar outgrowth from the upper edge of the groove.--The MACROSPORANGIA (each with a number of macrospores), are situated on the outer leaves, the MICROSPORANGIA (Fig. 238), on the inner ones. Between each cycle of fertile leaves there are a number of imperfect or barren ones as in the case of the female plant of _Cycas_. The spores are liberated by the decay of the sporangium. The two kinds of sporangia develope at the commencement in the same way. The archesporium is, at first, a hypodermal layer of cells which grow out in the direction perpendicular to the surface of the leaf, and divide by a number of walls parallel to this direction, forming a sporogenous mass of cells. Some of the cell-rows of this sporogenous mass lose their rich protoplasmic contents, and are arrested in their growth; thus incomplete divisional walls of sterile cells, “_trabeculæ_” arise in the sporangium, dividing it into a number of compartments one above the other (Fig. 238 _t_). (The trabeculæ, according to Goebel, play the same part as the nutritive cells of the sporangium of _Riella_; the tapetal cells, as in the Ferns, are in a great measure dissolved at a later period.) The sporogenous cell-rows, in the microsporangia, give rise to a large number of spore-mother-cells, but in the macrosporangia only one spore-mother-cell, with tapetum, is developed from each fertile archesporial cell. The two native species, and several others, are aquatic plants, the remaining species are land plants, or are amphibious. About 50 species. In temperate and tropical regions.--FOSSIL species in the Tertiary period. Order 2. =Selaginellaceæ.= This order contains only one genus, _Selaginella_. The STEM, in the majority of species, is dorsiventral, long and slender, and apparently branches dichotomously, but in reality _monopodially_, with well developed lateral shoots. The LEAVES are small, round, or ovate, in the majority of species arranged in whorls of two leaves each; these whorls, however, are not decussate, but are considerably inclined towards each other, an arrangement by which four rows of leaves are produced, each whorl having one large and one small leaf. The two leaves in each whorl are of unequal size, the smaller one being placed on the upper surface and the larger on the lower surface of the stem (Fig. 240). Some species have spirally-arranged leaves, more resembling the arrangement in the _Lycopodiums_. The ~FERTILE LEAVES~ most frequently differ from the barren ones, and are collected into spike-like cones (a kind of flower; Fig. 239). Micro-and macrosporangia are found in the same cone (Fig. 239). Each sporangium arises from a group of superficial cells of the stem, directly over the leaf on which it will be situated later on. Each sporangium has a hypodermal, unicellular archesporium, and contains a layer of tapetal cells; these are dissolved later, when the spores are ripe, and not before as in the Ferns. In the very early stages of their development, the micro-and macrosporangia are precisely similar, and the differences between them arise later on. In the microsporangium all the spore-mother-cells divide, and each forms four tetrahedrically-arranged microspores (Fig. 204); but in the macrosporangium only four macrospores are formed, by the division of a _single mother-cell_, while the remaining spore-mother-cells are aborted. It is rarely that the macrosporangia contain 2 or 8 macrospores. [Illustration: FIG. 240.--_Selaginella martensii_: _s_ lower leaves; _r_ upper leaves.] For the ~GERMINATION OF THE SPORES~, see pages 228, 229. The prothallium arises in the macrospore (_f-f_, in Fig. 235 _A_), probably by division of the meniscus-shaped protoplasmic mass, which is marked off at the apex of the spore; primordial cells are thus formed which later on are surrounded by a cell-wall. In six to seven weeks after sowing, the spore-wall is ruptured by the growing prothallium, which already has developed archegonia (Fig. 235 _œ-œ_). The prothallium so formed does not occupy the entire cavity of the spore, but four to five weeks after sowing, the large-celled parenchyma is developed in the lower portion of the spore by free cell-formation; this has been termed by Pfeffer, “endosperm,” since it is similar to the endosperm of Flowering-plants. Goebel, however, has termed it “secondary prothallium,” as the homology with the endosperm of the Angiosperms is very doubtful. The ~FERTILISED OOSPHERE~ divides into an upper (hypobasal) and a lower (epibasal) cell; from the latter alone the embryo is developed with its root, stem, foot, and two _cotyledons_, and the former gives rise to an organ which appears in this instance for the first time, but which occurs in all Flowering-plants, viz. the _suspensor_. This forces the embryo down into the “endosperm,” which is entirely or partially absorbed by the embryo. In the case of the Flowering-plants the embryo is developed with its longitudinal axis in the elongation of the suspensor, but in _Selaginella_ the embryo is situated _transversely_ to it. _Selaginella_ (300–400 species), is essentially tropical, only one species living in the North (_S. spinulosa_), but others grow in Central and South Europe. Order 3. =Lepidodendraceæ= are extinct, tree-like Lycopods, which are found especially in the Lower and Middle Carboniferous. Vegetatively they are most nearly related to _Lycopodium_, but the stem attained much larger proportions (about eleven metres in height and one metre in thickness), and had a cambium by which it increased in thickness. It was regularly dichotomous, and closely studded with spirally-placed leaves, which left behind them peculiar rhombic scars. The large cones resemble Pine-cones, and bore sporangia much larger than any which are now produced (the male ones as much as 2 cm.’s in length). The macrosporangia were situated at the base, and the microsporangia at the apex. Order 4. =Sigillariaceæ.= These are, presumably, another group of extinct tree-like Lycopods (especially in the Middle Carboniferous). The name has been derived from the seal-like scars, which the fallen leaves have left behind in longitudinal rows on the grooved stem. The rhizomes of these plants were formerly termed _Stigmaria_, and placed in a separate genus. Order 5. =Sphenophyllaceæ= form an entirely extinct group. They do not definitely belong to any of the three large classes of Vascular Cryptogams, but it is perhaps best to place them in juxtaposition to these. They were herbaceous plants with verticillate, wedge-shaped leaves, with nerves branching dichotomously into equally strong branches. Micro-and macrosporangia were formed in the same cone; and were situated in the axils of the leaves, as in the Lycopods. The Transition from the Cryptogams to the Phanerogams. All the plants considered in the preceding chapters are included in the term CRYPTOGAMS; all in the following chapters under the head of PHANEROGAMS (see page 3). Hofmeister’s pioneer works (1851, _Vergleichende Untersuchungen der höheren Kryptogamen_, etc.) and the numerous researches published later by other investigators, have closed the gap which was formerly thought to exist between these plants; so that we now, in the series: Bryophyta--Pteridophyta--Gymnospermæ--Angiospermæ see the expression of a single line of development in accordance with a definite plan. The forms through which this gradual development has taken place have in course of time, however, to a great extent died out, and only single links of the chain connecting the lowest to the highest still remain. THE ALTERNATION OF GENERATIONS, which we found indicated in certain Thallophytes, can be proved with the greatest clearness in all the higher Cryptogams, from the Mosses upwards; it is also found in the Phanerogams, but not in such a pronounced degree, because one of the generations is so far reduced that it has almost given up its independence. For the sake of greater clearness, we will begin with the comparison of the sporophyte, asexual (second) generation. =The asexual (2nd) generation of the Cormophytes.= The asexual generation which follows from the further development of the fertilised oosphere, is, in the _Mosses_, only the sporogonium (according to one theory it is perhaps homologous with a spore-bearing leaf, situated upon a short stem, see p. 187); in _Filicinæ_, _Equisetinæ_, and _Lycopodinæ_, on the other hand, it is a highly developed plant differentiated into stem, leaf, and true root, and bearing the sporangia on its leaves. The ~MODIFICATION OF THE SHOOT~ is very slight in _Filicinæ_. The first leaves of the embryo are very simple in form (Fig. 205), but after a certain age all the leaves which arise are essentially alike. The fertile leaves do not differ from the barren ones, and are found associated with them, and their formation does not limit the growth in length of the stem. It is only in a few of the true Ferns, and in the Hydropterideæ, that the fertile leaves differ considerably from the barren ones. A division of labour in which certain leaves are set apart for nutrition, and others for reproduction, is found more pronouncedly in the _Equisetinæ_ and _Lycopodinæ_, for in these groups, with a few exceptions, the fertile and barren leaves are very dissimilar; the former are collected in special ear-like _cones_, which _terminate the further growth_ of the short stems on which they are borne. In connection with the cone, leaves are sometimes developed which form a transition from the barren to the fertile ones (the “annulus” in Equisetaceæ), and in these cases the first indication of a flower with perianth or floral-leaves is to be traced. Among the Cryptogams the highest division of labour is found in _Selaginella_ and _Isoëtes_, which have the two kinds of sporangia borne on _different_ leaves. The division of labour (modification) is, however, still more pronounced in the _Phanerogams_: the leaves which bear the microsporangia (“pollen-sacs”) have quite different forms from those which bear macrosporangia (the “nucellus” in the ovule), the former are termed _stamens_, the latter _carpels_; in certain instances, too, there is even a contrast between the “male plants” and the “female plants.” Moreover, a division of labour, in a much greater degree, takes place in the leaves which do not directly take part in reproduction, and it is thus possible in many plants to draw a sharp line not only between stamens and carpels, but also between four or five distinct kinds of leaves, which differ in _form_, _structure_, and corresponding _functions_, and which appear in regular sequence on the shoot: namely, between “scale-leaves” and “foliage-leaves,”[21] both of which occur in the Cryptogams, and the “floral-leaves,” including the bracts and leaves of the “perianth,” which latter often differ from each other in form and colour, and are then separated into _sepals_ and _petals_. The _leaves_--stamens and carpels--_which bear the sporangia_ are termed sporophylls, and the shoot, or extremity of a shoot, whose leaves are modified into sporophylls, is _terminated in its further growth by their production, and is known as a flower_. The flower which is most completely furnished has calyx, corolla, stamens, and carpels arranged in this order. If the only sporophylls present are stamens, then it is said to be a _male_ (_staminate_) flower, and if only carpels, then a _female_ (_pistillate_) flower, and in both these cases the flowers are _unisexual_, or diclinous. If stamens and carpels are both present in the same flower, it is termed _hermaphrodite_. Diclinous plants in which the female flowers are situated on one plant, and the male flowers on another, are termed _diœcious_; and those in which the same plant bears the two kinds of flowers are termed _monœcious_. When the male, female, and hermaphrodite flowers are found in the same species, the plant is said to be _polygamous_. =The sporangia-bearing leaves--Sporophylls.= In the Mosses the asexual generation is only represented by the sporogonium, and if the theory is correct which considers the sporogonium to be an embryo consisting of a rudimentary stem and terminal leaf, then the spores are produced on the leaves in these plants. The sporangia in the Filicinæ are situated in groups (sori) on the back or on the edge of the leaves. The number of sporangia in the sorus diminishes very greatly in the Marattiaceæ and Gleicheniaceæ (three to four in the latter, Fig. 213). In the Equisetinæ the sporangia are situated in a small number on the underside of shield-like leaves, and in Lycopodinæ, singly, in the axils of the fertile leaves, which are alike and bear either micro- or macrosporangia. In the Phanerogams there is a great difference between the stamens and carpels. [Illustration: FIG. 241.--_Cycas_: _a_ stamen (nat. size) seen from the under side; _b_ four pollen-sacs, not yet open, forming a “sorus”; _c_ three open pollen-sacs; _d_ a pollen-grain.] [Illustration: FIG. 242.--Stamens of _Araucaria_ (pollen-sacs long and pendulous).] [Illustration: FIG. 243.--Male flower of _Taxus_.] [Illustration: FIG. 244.--_A_ Cross section through a quadrilocular anther in different stages of development: _s_ the seam where it bursts open; _vf_ vascular bundle; _k_ connective. _B_ A stamen. _C_ Another stamen seen from the front (_f_) and from the back (_b_).] =Stamens.= In the lowest Phanerogams (_Cycadeæ_) there are many indications of relationship to the Ferns. The stamens are flat and broad, and have _on the back many pollen-sacs_ (_microsporangia_) arranged in small groups (true _sori_), which even have a small “placenta,” similar to the one possessed by the Ferns, and open towards the inside by a longitudinal cleft (Fig. 241, compare Fig. 213). A section of the _Coniferæ_ agree more closely with the Equisetaceæ, in having a few (three to eight) pollen-sacs arranged on the underside of more or less shield-like leaves (Figs. 242, 243, compare with Fig. 224 _a_, _c_, _d_). In the Abietaceæ the number of sporangia is diminished to two, which are placed also on the lower side (Fig. 267) of a stamen. The number of _pollen-sacs_ (microsporangia) in the _Angiosperms_ is nearly always four to each stamen; they are longitudinal projections which are placed in pairs on each side of the central line of the stamen, two on the edge, and the other two generally on the side which is turned inwards; the pollen-sacs generally dehisce longitudinally (quadrilocular anthers, Fig. 244). A few, for instance Orchidaceæ and Asclepiadaceæ, have only two pollen-sacs (bilocular anthers); and in others, such as _Solanum_ and the Ericaceæ, they open by pores; in Lauraceæ and Berberidaceæ, by valves. The part of the stamen which bears the pollen-sacs is termed the _anther_. Most frequently this is supported by a stalk known as the _filament_. [Illustration: FIG. 245.--A carpel of _Cycas revoluta_ with 5 ovules (_s_), at half to one-third nat. size.] [Illustration: FIG. 246.--Carpel with 2 ovules of _Ceratozamia robusta_ (1/1).] =Carpels.= The simplest forms of carpels are found in _Cycas_. In this genus both the foliage and fertile leaves are pinnate, and hence present great similarity; the ovules (macrosporangia) are situated on the margin of the central portion, just as the sporangia are placed on the edge of the fertile leaf of _Ophioglossum_ (Fig. 245, compare with Fig. 209). The carpels of the other Cycadeæ present greater divergence from the foliage-leaves, being peltate, for instance, in _Zamia_ and _Ceratozamia_ (Fig. 246). The ovules in the Coniferæ are situated on the upper side and near the base of the ovuliferous scales, almost in the same position as the sporangia in the Lycopodinæ (Figs. 269, 272, 273 _H_, compare Figs. 230, 239). In _Taxus_ the uninclosed ovule is placed on the apex of a shoot (Fig. 264). In all these plants the ovules are _not enclosed_ by the carpels, that is, they are not enclosed in chambers formed by the turning in of the walls of the carpel, and hence the name _Gymnospermæ_ is given to them. In the higher Flowering-plants, the _Angiospermæ_, the ovules are distinctly situated on the edge, the upper surface, or base of the carpel; but the carpel closes round the ovules which are therefore enclosed in a chamber--the _ovary_. In a few cases, for example in the Polygonaceæ, an ovule is situated apparently on the apex of the stem itself, as in the Yew; in other cases, as in the Primulaceæ, many ovules are apparently developed on the apex of the stem, which seems to have been specially adapted as a placenta, but it is also possible and correct in these cases to suppose that the ovules are in reality developed on the carpels.[22] A single fully-developed carpel or a collection of carpels joined together is termed the _pistil_. The extremity of the carpel, which is specially developed to catch the pollen-grains and form a suitable nidus on which they may germinate, is called the _stigma_. The united edges of a carpel which bear the ovules are termed the _ventral suture_. The back of the carpel forms the _dorsal suture_. The Marsiliaceæ take a position among the Hydropterideæ analogous to that occupied by the Angiosperms; the sporangia are in a corresponding manner enveloped in a closed leaf. The collection of stamens in a flower is termed the _andrœcium_, and all the carpels, whether individually free or united into one pistil, the _gynœceum_. The =Sporangia=. The asexual generation of the _Mosses_ is the sporogonium, in which the spores arise in tetrads from the mother-cells. The sporangia in the _Filicinæ_ take their origin either from a single cell (Leptosporangiatæ) or, what probably may be regarded as an older stand-point, from a group of cells (Eusporangiatæ). In both cases there may be distinguished in a mature sporangium three tissues, which have different significance (Fig. 204): (1) an external layer, the _sporangium-wall_, most frequently composed of one layer of cells made up of cells of dissimilar structure, so that on desiccation the wall is ruptured and the sporangium opens in a definite manner; (2) an internal group of cells, consisting of the _spore-mother-cells_, developed from an archesporium, and which by division into four gives rise to the _spores_; (3) a layer of cells lying between the two already mentioned, which is dissolved before maturity. The intermediate cellular layer, which directly surrounds the spore-forming cells, is in form and contents more worthy of note than the others, and is termed the _tapetum_. The construction of the sporangium in the _Equisetinæ_ and _Lycopodinæ_ is in the main the same. [Illustration: FIG. 247.--Development of an anther. _A_ Transverse section of a young anther of _Doronicum macrophyllum_. The formation of the 4 pollen-sacs commences by divisions of the hypodermal cells (at _m_, for instance). These cells divide by periclinal walls into external cells which only take part in forming the anther-wall; and internal cells, which correspond to the Archesporium, and from which the spores are derived. These spore-forming cells are drawn with thicker walls in _B-E_. The commencement of the vascular bundle is seen in the centre. _B_ An older stage; the pollen-sacs already project considerably. It is the cells in the hypodermal layer which are active and in which tangential divisions particularly occur; _fv_ vascular bundle. _C_ A corresponding longitudinal section. _D_ Transverse section through an older anther, the thickness of the wall outside the mother-cells of the pollen-grains is already increased, and it becomes still thicker by the division of the hypodermal cells: its most external layer of cells but one, becomes transformed into the “fibrous cells.” _E_ Transverse section of a still older pollen-sac of _Menyanthes_; _sm_ are the mother-cells of the pollen-grains surrounded by the tapetum (_t_), external to the tapetum is the anther-wall, which is still far from being fully developed. The sub-epidermal layer becomes “fibrous,” and the cells lying inside it become dissolved, together with the tapetum.] In the PHANEROGAMS the =Microsporangia= are termed =Pollen-sacs=. They take their origin from a large group of cells, which, in the Angiosperms, lie immediately beneath the epidermal cells of the anther. In the developed, but not yet mature, sporangium (pollen-sac) there are to be found: (as in the Vascular Cryptogams) (1) an internal group of mother-cells which give rise to the _pollen-grains_ (_microspores_), in this case also formed in tetrads; (2) a group of cells surrounding these, of which the internal ones form a _tapetal layer_, similar to that in the Vascular Cryptogams; the tapetum and some of the cells surrounding it in this group, become dissolved before maturity; the more external ones, on the other hand, are provided with peculiar thickenings, and form the “fibrous” layer by the aid of which the dehiscence of the anther takes place; (3) an external layer, the epidermis, enclosing all the other layers (Fig. 247). In some Coniferæ (_Cupressus_, _Thuja_, and several species of _Juniperus_) the microsporangia (pollen-sacs), which are situated on the under side of the stamen, are covered by a thin structure which seems to be a continuation of the lamina and which is supposed to be homologous with the indusium of the Ferns. [Illustration: FIG. 248.--Development of the ovule in the Red Currant, _Ribes rubrum_, arranged alphabetically in the order of development. _A_ Is the youngest stage, _E_ the oldest. _ii_ Inner integument; _ie_ outer integument; _nc_ nucellus; _m_ archespore (mother-cell of the embryo-sac).] =The Ovule= in the Phanerogams arises most frequently on a projecting portion of the carpel, termed the _placenta_. The ovules (compare the sporangium of the Eusporangiatæ and especially the pollen-sac) take their origin from a _group of cells which lies beneath the epidermis_ (Fig. 248 _A_, _B_). First of all a small papilla is formed, which is later on provided with a _vascular bundle_ and becomes the _funicle_; this probably has the same value as the projections (“placenta”) on which the sori in the Ferns are attached. Only _one_ =macrosporangium= (_nucellus_; Fig. 248 _nc_) is developed at the apex of the funicle. This arises by a process of cell-division exactly corresponding to that by which the pollen-sacs are formed (Fig. 248 _C-E_), with this difference only, that while a great _many_ cells may be distinguished in each pollen-sac, which forms pollen-grains by tetrad-division, only a few are found in the ovule, and all these moreover are _suppressed, with one single exception_ which developes into the =macrospore= (=embryo-sac=) without undergoing a division into tetrads. The wall of the embryo-sac, in the Gymnosperms, may be thick and divided into two layers and partly cuticularized, as in the spores of the Cryptogams which are to be set free. In the Angiosperms, on the other hand, the wall is extremely thin. The pollen-sac thus stands in the same relation to the nucellus as the microsporangium does to the macrosporangium: in the pollen-sacs and microsporangia a _number_ of spores arise by the tetrad-division of several mother-cells; in the nucellus and macrosporangium, a reduction of the cells already formed takes place to such an extent that the number of macrospores becomes one (_Salvinia_, _Marsilia_, Phanerogams) or four (_Selaginella_), or rarely a large number as in _Isoëtes_. In the Ferns, as stated on page 210, etc., _indusia_ covering the sori very often occur. Horsetails and Club-Mosses have no indusium; but in all Phanerogams cupular or sac-like structures (_integuments_) are found which envelop the nucellus. These develope from the upper end of the funicle (_ii_ and _ie_, in Fig. 248; _y_ and _i_, in Fig. 249) and enclose the nucellus on all sides as a sac, leaving only a small channel at the apex of the nucellus--the _micropyle_--(Fig. 249) through which the pollen-tube proceeds to the embryo-sac. The ovules of the Gymnosperms have only one integument (Figs. 251, 264, 269, 274) and the same is the case with the majority of the Sympetalæ and a few Choripetalæ; but the Monocotyledons and most of the Choripetalæ have two integuments (Fig. 249). [Illustration: FIG. 249.--Various forms of ovules: _A_ an erect ovule (_orthotropous_); _B_ reversed (_anatropous_); _C_ curved (_campylotropous_): _k_ the nucellus (shaded in all the figures); _s_ the embryo-sac; _ch_ the base of the ovule (chalaza); _y_ and _i_ the external and internal integuments, the dotted line denotes the place where the scar (_hilum_) will form when the seed is detached from the funicle.] In shape the integuments resemble very closely the cupular indusium of the Hymenophyllaceæ, certain Cyatheaceæ (Fig. 212 _E_), and _Salvinia_ (Fig. 218); that they are really homologous with these is probable, but is not proven. Some authorities regard them as structures found only in the Phanerogams. The ovule is thus a “_monangic_” (_i.e._ reduced to 1 sporangium, the _nucellus_) _sorus_, situated on a funicle, and enclosed by one or two cupular _indusia_, the integuments. Some of the ovules are _erect_ (_orthotropous_), others _curved_ (_campylotropous_), the majority _reversed_ (_anatropous_) (Fig. 249). [Goebel (1884 and earlier) with Strasburger considered the entire ovule of the Phanerogams as homologous with the macrosporangium, the integuments however as new structures in contradistinction to the Ferns: the funicle then corresponds to the stalk of the sporangium. The integuments of the ovule (according to Goebel, 1882) differ from the indusium of the Fern-like plants in being developed from the basal portion of the nucellus and are not, as in the Ferns and _Isoëtes_, a portion (outgrowth) of the leaf which bears the sporangia (_K_).] The nucellus is the only macrosporangium which never opens; _the macrospore remains enclosed in it_, and _the macrosporangium remains attached to the mother-plant_. It is therefore essential that the _method of fertilisation_ which is employed should be very different from that of the Cryptogams. _The pollen-grains must be transferred to the ovule_, and retained either by a drop of mucilage at the micropyle (Gymnosperms) or by the stigma on the carpels (Angiosperms). Fertilisation by spermatozoids, which are freely motile in water, is abandoned in the Phanerogams. Many other modifications, unknown in plants of more simple structure, take place, for instance, in the shoots which bear the fertile leaves; especially in the form of the stem or _thalamus_ (hypogynous, perigynous, epigynous); in the development of the perianth which stands in intimate connection with the special means employed to effect fertilisation; with respect to the different grades of union found in the leaves; in the union of the flowers into aggregations of a higher order (inflorescences), and at the same time the production of “floral-leaves” (page 235). =The sexual generation. The Fertilisation.= The sexual generation in the _Mosses_ is relatively well developed, because not only the protonema, but all the other vegetative parts of the Moss-plant, in addition to the archegonia and antheridia, belong to it. In the groups which follow, a gradual but increasing reduction of the sexual generation takes place, and at the same time an indication of sex is found in the prothallia, which finds expression in the forms of the spores themselves. In the majority of cases among the _isosporous_ Vascular Cryptogams, the sexual generation--prothallium--is a green, leafy expansion which can sustain itself by the assimilation of carbonic acid, and by the absorption of nutriment from the soil by means of root-hairs. In some plants (_Ophioglossaceæ_, _Lycopodium annotinum_) the prothallium is a subterranean, pale, tubercular body, but in these instances it is relatively large. In the _heterosporous_ Vascular Cryptogams and in the _Phanerogams_, the prothallium is much more reduced, both as regards its size, and also with respect to the number and structure of the antheridia and archegonia. 1. =The Microspores.= The PROTHALLIUM in all Vascular Cryptogams which have unequal spores, consists of a single, vegetative (barren) cell, which plays a very unimportant part in the life of the prothallium (Fig. 233 _A_). In _Salvinia_ it is somewhat elongated and tubular, because it must break through the sporangium (Fig. 214); but in other cases it is very small and lenticular. In all these plants only one antheridium is formed. In _Salvinia_ it consists of 2 cells whose walls are ruptured in order that the spermatozoids may be liberated (Fig. 214 _B_, _C_). In _Marsilia_, _Isoëtes_, and _Selaginella_ the prothallium does not leave the spore, and consists for the most part of primordial spermatozoid-mother-cells _without cell-wall_, which on germination are ejected so that the spermatozoids are set free. In the Phanerogams, the microspores have from olden times been termed _pollen-grains_. In the GYMNOSPERMS the prothallium is reduced to 1, 2 or 3 small cells, placed on one side of the mature pollen-grain (at the top in Fig. 250 _I_, _II_, and in Fig. 267 _N_) and which do not play any part in the germination of the pollen-grain. The antheridium is represented by the remaining portions of the interior of the pollen-grain, that is, it consists of a large cell with a nucleus which does not even go so far as the antheridium of _Selaginella_ and become divided into spermatozoid-mother-cells without cell-wall, for even these cells are not formed. The unicellular antheridium grows, on the germination of the pollen-grain, into a tubular body known as the _pollen-tube_, formed from the inner wall of the pollen-grain (Fig. 250), which works its way down the micropyle to the oosphere. The fertilisation takes place by diosmosis through the cell-wall, and consists here also of the coalescence of the nucleus of the pollen-tube (the sperm-nucleus, male pronucleus) with that of the oosphere. In the ANGIOSPERMS the reductions proceed still further. The barren cell, which represents the prothallium, was in the last group separated from the antheridium by a true cell-wall, but in the Angiosperms a membrane at most, but no firm cell-wall, is formed. The pollen-grain contains two cells, a vegetative and a free generative cell. Both these pass into the pollen-tube, but the vegetative cell disappears about the time the pollen-tube reaches the ovule; while the generative cell divides into two: one, the sperm-nucleus coalescing with the nucleus of the oosphere, the other being absorbed (_Lilium_, after Guinard). The Gymnosperms prove in yet another point that they are more closely related to the Cryptogams than are the Angiosperms. When the pollen-grain begins to germinate the external wall ruptures as in the Cryptogams (Fig. 250), but in the Angiosperms special germ-pores are formed in the cell-wall for the emergence of the pollen-tube. [Illustration: FIG. 250.--_I_ Pollen-grains of _Cupressus_; at the top is seen one prothallium-cell. _II_ Germinating; _c_ pollen-tube; _a_ the extine; _b_ the intine.] 2. =The Macrospores.= The prothallium in _Salvinia_ and _Marsilia_ is still rather large, green, and capable of the independent assimilation of carbon. It projects more or less from the macrospore and bears (in _Marsilia_ only one, in _Salvinia_ several) archegonia, which however are embedded to a greater degree in the prothallium, and are more reduced than the archegonia of the true Ferns and Horsetails (Figs. 215, 216). The prothallium is still more reduced in _Isoëtes_ and _Selaginella_; _partly_ because it is smaller and is in a higher degree enclosed in the spore, it also contains less chlorophyll, or is entirely without chlorophyll, and in consequence incapable of independent existence, whilst the number of archegonia is less; and _partly_ because the archegonia are themselves reduced, the cells of the neck are fewer and embedded to the level of the surface of the prothallium without any, or with only a very slight projection (Figs. 235, 236).--Finally, the prothallium with its archegonia begins to develope in _Selaginella_ while the macrospore is still within its sporangium, and before it is set free from the mother-plant. After the spores are set free and germination has commenced, the spore-wall ruptures and the prothallium is exposed. [Illustration: FIG. 251.--Longitudinal section of ovule of _Abies canadensis_. Inside the integument (_i_) is seen the nucellus, _n_; _m_ the micropyle. In the interior of the nucellus is seen an oval mass of cells, the endosperm, and at its top two archegonia, _c_. The ovule is turned in such a way that the micropyle points upwards, but usually it turns downward in the _Abietineæ_.] [Illustration: FIG. 252.--The apex of the nucellus (_n_) of an ovule of _Abies_: _l_ long-shaped cells which guide the pollen-tube; _s_ the wall of the macrospore (embryo-sac); _h_ the neck-cells of the archegonium; _k_ the ventral canal-cell; and _c_ the central cell (oosphere). The archegonia of the Cryptogams should be compared with this (see pages 181, 208, 216).] The GYMNOSPERMS go still further. The macrospore (embryo-sac) germinates and forms internally a cellular tissue, designated in former times by the name of _albumen_ (endosperm), which is _homologous with the prothallium_. It always _remains enclosed in the embryo-sac_, and is a parenchymatous mass containing a large supply of nourishment. In the upper part of the endosperm a number of archegonia are developed which are in the main constructed in the same manner as those in the Cryptogams, but are still more reduced, the neck consisting only of 4, 2, or 1 cell (Figs. 251, 252). The ventral canal-cell is also formed, in the majority, as a small portion cut off from the large central cell just beneath the neck; the larger remaining portion becomes the oosphere. When the pollen-tube has passed down to the oosphere (Fig. 253) and fertilisation has been effected, the oospore commences a cell-formation, the final result of which is the formation of _an embryo_ (_the asexual generation_) which is provided with a thinner, lower end, termed the suspensor. The embryo is forced more or less into the endosperm in which it may rest for a longer or shorter time, and generally is developed to such an extent that it has a distinct primary-root (radicle) and stem (plumule) with one or more embryo-leaves (cotyledons). When the oosphere has been fertilised its nucleus sinks down to its lower end, and by repeated division into two, forms four cells lying in one plane (Fig. 253, see base of the left archegonium). Three tiers of cells are now formed by transverse division of these four. It is the intermediate one of these which elongates and forms the suspensor, or four suspensors, if they separate from each other, which push the lowermost four cells deep down into the endosperm. It is from these four lower cells that the embryo (or four embryos when the suspensors separate) is developed, but never more than one embryo attains full development. As several archegonia are contained in one and the same ovule, all of which are capable of forming embryos, there is the possibility that several embryos may be developed in a seed (polyembryony), but usually only one embryo attains perfect development. [Illustration: FIG. 253.--The apex of the nucellus (_n_) of _Abies_ in longitudinal section: _c_, _c_ the oospheres of the two archegonia; the embryo-formation has commenced at the bottom of the left archegonium; _s_ wall of the macrospore; _p_ pollen-grains; _r_ pollen-tubes.] [Illustration: FIG. 254.--Embryo-sac of _Carex præcox_: _syn_ synergidæ; _kb_ the oosphere; _c_ the central nucleus; _ant_ the antipodal cells.] At the same time that the embryo is being developed, other changes are taking place in the ovule, especially in the integument which becomes the shell of the seed (_testa_). The endosperm grows, and the embryo-sac supplants the cells of the nucellus. The _seed_ is now formed, and it consists in its most complete development, as in this instance, of three parts: (1) The _testa of the seed_, formed by the enveloping integuments, with the remainder of the tissue of the nucellus lying outside the embryo-sac (the macrosporangium). (2) The _endosperm_ or prothallium. (3) The _embryo_. [Illustration: FIG. 255.--Diagrammatic longitudinal section through an anatropous ovule shortly after fertilisation; _a_ and _i_ are the two integuments; _f_ the funicle; _k_ the nucellus; _S_ the embryo-sac, with the incipient formation of nutritive-tissue; _E_ the embryo; _P_ the pollen-tube passing through the micropyle (_n_) to the oosphere.] The reduction in the ANGIOSPERMS is carried to the extreme limit. In the embryo-sac (the macrospore) the nucleus by continued division produces a prothallium consisting of primordial cells (Fig. 254). In the upper end of the embryo-sac (which is nearest the micropyle) are three cells, two of which are termed the “co-operating cells” (_synergidæ_) and the third is the _oosphere_. Three others are placed at the opposite end of the embryo-sac and are therefore termed the “antipodal cells.” Finally, a large cell is also formed, which occupies the space between the two groups and whose cell-nucleus, the central definitive nucleus, lies in the centre of the embryo-sac. These primordial cells are the slight remnant of the prothallium. The entire structure of the archegonium, with its neck and canal-cells, has disappeared, and nothing is left but the indispensable _oosphere_. When the oosphere has been fertilised, and has commenced the cellular divisions which lead to the formation of the embryo (Fig. 255), the synergidæ and antipodal cells are absorbed, and a cell-formation begins by a new process which emanates from the definitive nucleus and by which a parenchymatous cell-tissue, the nutritive-tissue, arises which may perhaps be considered as homologous with the endosperm of the Gymnosperms. The difference is that the nutritive-tissue of the Angiosperms is formed in two parts with an intervening interruption; the primary nutritive-tissue is first formed, and after fertilisation is absorbed, with the exception of one cell, which continues the development and gives rise to the nutritive-tissue proper, which is formed in the first instance of primordial cells, and later on of a cellular tissue; this nutritive-tissue formed in the embryo-sac is termed “endosperm”; in a few instances[23] a tissue which is derived from the nucellus functions as nutritive-tissue, and is termed “perisperm.” In many plants the seeds, when ripe, contain a very rich nutritive-tissue, in addition to the embryo, for the purpose of its nourishment during germination. These are termed albuminous (endospermous) seeds, in distinction to the ex-albuminous, or those in which the nutritive-tissue is stored in the embryo itself, before it is completely developed, and used for its sustenance. In addition to the changes which fertilisation produces in the ovule itself, it also gives the impetus to a series of changes in the entire shoot which bears the ovule. The perianth, stamens, and style, generally wither, because the part they play is at an end; the wall of the ovary grows and becomes the wall of the fruit (pericarp). The entire gynœcium of a flower, transformed as a consequence of fertilisation, is termed a _fruit_. It consists of two parts, the _pericarp_ and the _seeds_, and according to the nature of the pericarp, the fruit is termed a capsule, nut, berry, or drupe. The chief characteristic of the Phanerogams does not lie in the formation of the flower (although they may quite properly be termed “Flowering-plants”), because Equisetums and Lycopods have reproductive shoots as highly differentiated as those of certain Gymnosperms and other Phanerogams. As regards the SEXUAL GENERATION the characteristics are found:--(1) in its great reduction; (2) in the transmission of the microspore (pollen-grain) to the macrosporangium, and its germination, with the formation of a _pollen-tube_ (antheridium), the protoplasm of which is not differentiated into spermatozoids; (3) in the fact that the macrospore (embryo-sac) never leaves its sporangium (nucellus); and further in the Angiosperms, (4) in the peculiar development of the nutritive-tissue in two parts; and (5) in the great reduction of the archegonium. As regards the ASEXUAL GENERATION the characteristic feature is that this generation is formed whilst the sporangium is still attached to the mother-plant, and for a long time is nourished by it; and that after the sporangium has become detached from the mother-plant, it spends a longer or shorter resting period as the embryo in the seed (enveloped by the testa), and does not make its appearance until the “germination” of the seed. In addition the shoot which bears sporangia undergoes greater modification than in the case of the Flowerless-plants. The Phanerogams are separated into two Divisions as follows:-- Division 4. =Gymnospermæ.= The ovules, as well as the seeds, are borne _naked_ on the surface of _open carpels_, or on the apex of a stem (ovary wanting). The pollen-grains are conveyed by the wind to the ovules, and caught by drops of mucilage, secreted by the micropyle. A “stigma” is _wanting_. The entire _female prothallium_ (_the endosperm_), which serves for the nourishment of the embryo, is _formed before fertilisation_. The archegonia are _embedded in the upper part of the prothallium. The pollen-grains are “multicellular,” i.e._ there is always in their interior a distinct prothallium, formed by 1–3 cells, and a larger cell which gives rise to the pollen-tube. Division 5. =Angiospermæ.= The carpels surround the ovules and form an entirely closed chamber (_ovary_), in which the ovules mature and ripen into seeds. The surface of a portion of the apex of the carpel is transformed into the “stigma,” which, by a sticky fluid and also by hair-structures, is capable of retaining the pollen-grains conveyed to it by the wind, or more frequently by insects. The pollen-tube grows from the stigma, through the “conducting cellular tissue” (_style_), to the ovules. The pollen-grains contain two cells, a vegetative and a free generative cell. The latter passes into the pollen-tube and there divides into two, one of which is the sperm-nucleus. The female prothallium, which is intended to serve as nutritive-tissue, is formed _after fertilisation_. Archegonia are wanting. DIVISION IV. GYMNOSPERMÆ. The following characters should be added to those already given on page 2:-- The Gymnosperms comprise only trees or shrubs. The flowers are always _unisexual_ and destitute of perianth (except _Gnetaceæ_); the female plant of _Cycas_ is the only one which has no flower. The MALE FLOWERS are constructed on the same type as the cones of the Horsetails and Club-Mosses, and are _most frequently long shoots_ (Figs. 243, 258, 260 _A_, 267 _J_) bearing a number of spiral or verticillate stamens. The FEMALE FLOWERS are of a more varied structure (see the orders). The OVULE _is orthotropous_ (except _Podocarpus_ which is anatropous) and projects from the carpel uprightly, inverted, or horizontally; it has usually _only one integument_ (compare however Taxaceæ) which proceeds from the upper part of the nucellus, so that the embryo-sac in part is placed below the integuments (Figs. 251, 264). The drop of mucilage which catches the pollen-grains dries up and draws the pollen-grain through the micropyle to a space just above the nucellus--_the pollen-chamber_--in which the germination of the pollen-grain commences. In each seed, only one of the many embryos which are formed proceeds to its full development. The seed is always _endospermous_, and the embryo has one, two, or a whorl of several cotyledons. A vigorous primary root is developed on germination. THE VASCULAR BUNDLES in the stem are arranged in a ring, and _increase in thickness_ takes place by a closed cambium-ring which forms bast (_phlœem_) externally, and wood (_xylem_) internally with distinct annual rings, _as in the Dicotyledons_. Only certain of the Cycadeæ deviate from this arrangement. The _secondary wood_ is very uniform, as it is almost exclusively _formed of tracheides_ with bordered pits, but _true vessels are wanting_; this also indicates a relationship with the Pteridophyta (see page 202). The Gymnosperms are biologically lower than the Angiosperms; they are wind-fertilised, and without extra floral-nectaries. This Division embraces three classes: CYCADEÆ, CONIFERÆ, And GNETEÆ. It is no doubt monophyletic, and has taken its origin from heterosporous Ferns, now extinct, most nearly related to the Ophioglossaceæ and Marattiaceæ. The Cycadeæ appear to be the oldest class. The Coniferæ are related to these through Ginkgo. The Gnetaceæ are more isolated. The Division is not continued into the higher Flowering-plants; it has evidently attained its highest development, and is now in a retrograde condition. The similarity which has often been pointed out between certain Coniferæ and Lycopodinæ is only in analogous resemblances, and does not entitle one to suppose that there is a nearer relationship, or that the former take their origin from the latter. Class 1. =Cycadeæ.= The stem is very _rarely ramified_. The leaves are _large_, _pinnate_, and arranged spirally. The flowers are _diœcious, without perianth_. [Illustration: FIG. 256.--_Cycas circinalis_ (female plant). The carpels are seen hanging from the top of the stem. Three leaves with the leaflets still rolled up project almost vertically into the air, from the centre of the crown.] There is only one order, the =Cycadaceæ=.--In habit they resemble the Ferns, especially the Tree-Ferns (compare Figs. 207 and 256). The stem is tubercular (Fig. 258), or cylindrical (Fig. 256), but not very tall (as much as about 12 metres), and very rarely ramified. [In Ceylon, unbranched specimens of _Cycas_ are rarely met with in the wild state. The stems of _C. circinalis_ occasionally branch in greenhouses.] The LEAVES are arranged spirally, and so closely together that no free stem-surface is left between them, and have only a slight sheath (which is not amplexicaul, as in the Palms). They are compound (most frequently pinnate; in _Bowenia_, bipinnate); in some genera the leaves are rolled up in various ways, resembling the vernation in Ferns (Fig. 257); they are leathery and perennial. In some, stipules are present, as in the Marattiaceæ. Groups of scale-leaves alternate in the majority with groups of foliage-leaves. [Illustration: FIG. 257.--_Cycas circinalis._ Part of a young leaf with circinate leaflets.] [Illustration: FIG. 258.--A male plant of _Stangeria paradoxa_ (about 1/15 nat. size).] [Illustration: FIG. 259.--Female cone of _Zamia integrifolia_ (½-⅓ nat. size). The male cone is very similar externally.] The FLOWERS are without perianth. The MALE FLOWER is sometimes an enormous collection of stamens (Fig. 258), which are flat in some (_Cycas_, Fig. 241), shield-like in others (_Zamia_, _Ceratozamia_) like the sporophylls in Horsetail (Fig. 259); but in all, the pollen-sacs are situated in large and varying numbers on the back of the stamens, and arranged in groups of 2–5, like the sporangia in the sori of the Ferns (Fig. 241 _b_, _c_). FEMALE FLOWERS _are wanting_ in _Cycas_, because the carpels do not terminate the apical growth of the stem. After a group of foliage-and of scale-leaves, a group of carpels is developed, which are pinnate and resemble the foliage-leaves, bearing on their edges a number of ovules (most frequently 5–6) (Figs. 245, 256); the same stem produces successively scale-leaves, foliage-leaves, and carpels. The differentiation is not much more advanced than in certain Ferns (_Struthiopteris_, _Blechnum_), where barren and fertile leaves of different form regularly alternate. _The other genera have female flowers_; the carpels are shield-like in _Zamia_ and _Ceratozamia_ (Fig. 246), and collected into cone-like flowers, which terminate the growth of the stem (Fig. 259). The number of ovules in these instances is two to each carpel. The SEEDS are large (most frequently 2–6 centimetres long) and plum-like; the external layer of the testa is fleshy, while the internal one is hard and horny. There are two systems of vascular bundles in the testa, one outside, the other inside the stone. The embryo is straight, attached to the end of the suspensor, which is often long, filamentous, and rolled up; it has one or two cotyledons. The embryo in _Ceratozamia_ and others is very slightly developed, at the time when the ripe seed is detached from the carpel; and it is not until after sowing that its further development and germination proceed. This calls to mind the Cryptogams, especially _Selaginella_, whose macrospores are thrown off filled with endosperm; but the oosphere is not fertilised till after the separation of the macrospore from the parent-plant, while in the Cycadeæ fertilisation is effected before the separation. In _Cycas_ the testa may rupture, and the endosperm grow and become green in the light, even though no embryo has been formed. This also is an indication of its prothalloid nature. Gum-passages are present in all organs. Collateral vascular bundles, with spiral and scalariform tracheides, are found; and normal thickening takes place by means of a cambium. An exceptional mode of growth is found in _Cycas_ and _Encephalartos_, the cambium ceases to divide after a time and is replaced by a new cambium which arises in the cortical parenchyma just outside the bast, and which forms a new ring of xylem and phlœem. This may be repeated so that a number of concentric rings are produced. In _Ceratozamia_, structures resembling corals extend from the roots in a vertical direction and appear on the surface of the soil; these are peculiar roots, in which a symbiotic Alga (_Anabæna_) is found. The Cycadeæ were formerly (from the Coal period to the Later Cretaceous) far more numerous than at the present day. They appear to have been most numerous in the Trias and Jurassic. The remnant (75 species) which have persisted to the present time are found in all tropical countries. _Cycas_ (Trop. and Sub-trop., Eastern Hemisphere); _Dioon_ (Mexico); _Macrozamia_ (Australia); _Encephalartos_ (Trop. and S. Africa); _Stangeria_ (Fig. 258, Sub-trop. South and East Africa); _Bowenia_ (Trop. Australia); _Ceratozamia_ (Mexico, New Granada, Western Brazil); _Microcycas_ (Cuba); _Zamia_ (Trop. and Sub-trop. N. America.) USES. Sago is made from the starch-containing pith of _Cycas revoluta_ and _circinalis_. The leaves are often used at funerals and church festivals, under the name of “palm-branches.” Class 2. =Coniferæ= (=Pine-trees=). The stem _branches freely_. The leaves are _entire_, relatively small, linear or reduced to scales. The flowers are without perianth. The ovules naked. It is seldom that the female flower is reduced to only one carpel. Whilst the Cycadeæ principally resemble the Ferns, the Conifers partly resemble the Lycopods, and partly the Equisetums--the former especially in the _needle- or scale-like_, leathery, simple, and often perennial leaves (“evergreen plants”), which _never possess stipules_ (Figs. 263, 270, 272). _Ginkgo_ deviates from this, being no doubt the oldest, and the Conifer which stands nearest to the Cycadeæ (Fig. 260). The resemblance to the Equisetums is especially owing to the fact that the stem ramifies abundantly, and often very regularly, forming a pyramid with verticillate branches. In addition to the foliage-leaves, scale-leaves (bud-scales) are present in the majority of species. The FLOWERS are monœcious or more rarely diœcious. _Perianth is wanting._ The stamens of the _catkin-like male flowers_ (Fig. 267, _J_) are of different forms, but as a rule more or less shield-like. As in the Cycadeæ, the pollen-sacs are in all cases situated _on the underside_. There are, as a rule, two pollen-sacs (the Abietaceæ, Fig. 267), or 3–5, (the Cupressaceæ and Taxaceæ, Fig. 243); a few have more, _e.g. Araucaria_ (Fig. 242); they dehisce by clefts. If, in commencing our consideration of the _female flower_, we begin with that of _Ginkgo_, we shall observe in the corner of a scale- or foliage-leaf a small flower, which consists of two carpels, each bearing one ovule, and reduced almost to the ovule itself (Fig. 260 _C_, _D_). The flower in _Podocarpus_ is still further reduced, viz. to a single carpel with one ovule, which is anatropous and has two integuments. This ovule is situated in the axil of a cover-scale (_c_, in Fig. 262 _D_), and several female flowers of this description are collected in a small cone, the stalk and bracts of which become fleshy (Fig. 262 _C_). The external integument also becomes fleshy (an aril). _Dacrydium_, which is clearly related to _Podocarpus_, has an external integument which developes more independently as a fleshy aril (Fig. 262 _B_, _B’_). _Microcachrys_ also is clearly allied to these: the bracts are more fleshy, and the ovule (_i.e._ the female flower) is protruded beyond the bract (Fig. 262 _A_, _A’_). _Taxus_ stands in a more isolated position: a flower which has been reduced to an ovule is situated, in this instance, on the apex of a secondary branch which is studded with floral-leaves (Figs. 263, 264); an external integument is developed on all sides and surrounds the seed as a scarlet aril. According to this conception _the aril corresponds to an external integument_, and the Taxoideæ thus possess a partly dichlamydeous ovule. Only _Ginkgo_ and _Cephalotaxus_ appear to deviate from this, as in these there is only one integument (unless the small outgrowth indicated by _ar_, in Fig. 260 _D_, really is a rudimentary, external integument); in CYCADEÆ, to which _Ginkgo_ is most closely related, there is likewise only one integument. But in these genera the testa is differentiated into two layers, and the seed resembles a drupe; like the Cycadeæ there is an external fleshy covering and an internal hard one, and these two layers may probably be considered homologous with the two integuments. This theory is also borne out by the arrangement of the vascular bundles in _Cephalotaxus_ and _Podocarpus_, which present the xylem in the fleshy external layer to the _outside_ of the testa, which is therefore the upper side of the integument (Celakovsky). The coalescence of the integuments into one is only slight in _Torreya_, more pronounced in _Podocarpus_ and strongest in _Cephalotaxus_ and _Ginkgo_. Celakovsky terms these ovules “holochlamydeous.” If we pass from these to the order PINOIDEÆ, we find the female flowers collected into catkin-like cones, which have been considered from various points of view to be sometimes single flowers, at other times compound inflorescences. The structure in ABIETACEÆ is as follows: a number of spirally arranged, scale-like leaves, _cover-scales_ (Figs. 267, 268), are situated on a long axis. In the axil of each cover-scale a larger leaf-like projection, _the ovuliferous scale_, is borne, which turns the upper side towards its cover-scale (which is shown by the fact that the wood of its vascular bundles is turned downwards and towards the wood in the bundles of the cover-scale: Fig. 269). Two ovules, with micropyles turned towards the central axis, and with apparently only one integument (Fig. 268), are situated on the dorsal side of each ovuliferous scale, _i.e._ the side turned away from the cover-scale. The ovuliferous scales grow after fertilisation, into the woody or leathery “cone-scales,” which are usually much larger than the cover-scales. This ovuliferous scale with its axis may, according to Celakovsky, be considered as a dwarf-branch which is situated in the axil of the cover-scale, and bears two ovules (in the same way as in _Ginkgo_, one long-stalked flower, reduced to two ovules, is situated in the axil of a leaf), and _in this case the external integument of the ovules_ is expanded into leaf-like bodies, which have united to form one “_symphyllodium_” (_ovuliferous scale_) which is inverted so that its dorsal side is turned upwards and bears the nucellus and the other integument (“hemichlamydeous” ovules). The carpel itself is therefore in this instance extremely reduced. The keel, or (in _Pinus_) “mucro” (Fig. 268 _B_), which is found in several genera, represents then a third carpel, which is sterile. In the other orders of the Pinoideæ the cover-scales and ovuliferous scales grow more and more together and finally form one structure, which also is termed a “cone-scale,” although from its development it cannot be homologous with the cone-scales of the Abietaceæ. This connation is least in the TAXODIACEÆ and ARAUCARIACEÆ and may be traced on the upper surface of the “cone-scale” by the presence of a stronger or slighter ridge or pad, the free portion of the ovuliferous scale (Figs. 256, 266, 269). It is most strongly pronounced in the CUPRESSACEÆ, in which the two scales form one single structure, the cone-scale (Fig. 274). The vascular bundles in the under portion corresponding to the cover-scale, have the xylem towards the upper side as usual in leaves, whilst the bundles present in the upper side of the cone-scale, which thus represents the ovuliferous scale, turn their xylem downwards. The hemichlamydeous ovules are then situated on the upper side of this cone-scale. According to this theory the CUPRESSACEÆ appear to be the youngest type, a view which corresponds with their vegetative structure. If there is only one ovule in these orders as in _Agathis_ (Fig. 265) and _Araucaria_, then the flower is reduced to a single carpel and one ovule, as in the case of _Dacrydium_ and _Microcachrys_. If two or more ovules are present, then the same number of carpels may be supposed to exist, the external integuments of their ovules being developed into leaf-like structures which collaterally coalesce to form a “symphyllodium,” or are suppressed. According to this theory, which is based on the researches of Celakovsky, the female flowers of the Coniferæ may be classed thus:-- 1. In all cases situated in the axil of a bract and collected into cones, with numerous flowers or with few or one flower. In _Ginkgo_ only, are they situated in the axil of foliage- or scale-leaves. 2. It is only in _Taxus_ that bracteoles are present. 3. They are formed only from rudimentary carpels, in which the stem takes no part. 4. The number of carpels in each flower varies from one to many, most frequently three, of which the central one remains sterile. 5. Each carpel bears only one ovule. The flower which is formed of only one carpel appears to consist of only one ovule. 6. The ovule has in Taxaceæ either a double integument (Podocarpeæ, Taxeæ), of which the external is the “aril,” or, as in the Cycadeæ, a single one, which is homologous with the two united together. 7. The external integument in the Pinoideæ is expanded to form a leaf-like structure--the ovuliferous scale--and bears on its dorsal side the ovules, which are thus only provided with one, and that the inner, integument. This later interpretation of the female cones in the Coniferæ is more probably correct than the older ones; that, however, which appeared in the former issues of this book, may also be stated. It was to the effect that each catkin-like female cone is in reality a single flower; the cone-scales in the Cupressaceæ were single leaves, namely carpels, which bore the ovules on the side which is turned upwards; the division into two parts which makes its appearance in the other orders, and becomes most prominent in the Abietaceæ, was compared with the division of a leaf into a barren and a fertile portion, which is found especially in Ophioglossaceæ and Marsiliaceæ, or with the ligule in _Isoëtes_. POLLINATION is accomplished by means of the wind. At the period of pollination the leaves are always so widely separated from one another, that the ovules can catch the pollen-grains carried to them by the wind; this is often effected by the mucilaginous drops which appear at the micropyle, and by the evaporation of which the pollen-grains are brought in contact with the nucellus. The entire cone grows considerably as soon as fertilisation has taken place, and the cone-scales in Pinoideæ close together so that the seeds while maturing are enclosed, and it is not until the seeds are ready for distribution that the cone-scales again become separated. In the Pinoideæ, the fully developed ovuliferous scales are hard and woody; and in this condition the collection of female flowers is termed a _cone_. In the Taxoideæ, true cones are the exception. 2–15 cotyledons are present, arranged in a whorl. The characteristic feature of this class is the abundance of _resin_, which is to be found in isolated cells (especially in the cortex), partly in intercellular glands or passages (both in the cortex and wood). _Taxus_ is the only genus which has no resin. There are about 350 species, mostly from the Northern Temperate zone (especially North America and Siberia), where they grow gregariously and form the most northern forests. The Juniper, Scotch Fir, and Yew are natives of Great Britain. This class may be divided into two families:-- 1. =Taxoideæ.= The ovules have either one integument, the external part of which is fleshy, and the internal hard and stone-like; or two integuments, of which the external is the fleshy and coloured “aril.” “Ovuliferous scales” are wanting. The cones are never woody, but are generally succulent, the bracts become fleshy, or cones usually are not developed. The seeds project more or less freely beyond the bracts. 2. =Pinoideæ.= The ovules have two integuments, the external one of which is leaf-like and becomes developed as the “ovuliferous scale”; if there are several of these in each flower they unite and form a “symphyllodium.” This may remain free or unite with the bract. The cones are most frequently woody, rarely succulent. The seeds are hidden among the cone-scales. Family 1. =Taxoideæ.= This family, considered to be most nearly related to the Cycadeæ, also made its appearance at a very early period. There is only one order. Order. =Taxaceæ.= The characters have been given above. _A._ CEPHALOTAXEÆ is the oldest group, presumably the connecting link between the Cycadeæ and the other Coniferæ. The flower consists normally of two ovules. Aril wanting. One integument. Seeds drupaceous.--The flowers in _Ginkgo biloba_ (_Salisburia_) are situated in the axil of foliage- or scale-leaves. The stamens bear only two pollen-sacs (Fig. 260 _A_). The female flower has two ovules, placed together at the end of a long, bare axis (Fig. 260 _C_). Round the base of the ovule a small collar (_ar_, in Fig. 260 _D_) is found, which may probably be considered homologous with the collar-like outgrowth which surrounds the base of the _Cycas_-ovule. The seed resembles a Plum, and has a fleshy external coat, surrounding a hard internal layer. The embryo is developed after the seed has fallen off. The Ginkgo-tree has long-stalked, fan-shaped leaves, more or less indented, with dichotomous veins resembling certain Ferns--the Adiantums. It is a native of East Asia, and the only surviving species of a genus which in earlier times was very rich in species, and distributed over the entire Northern Hemisphere. _Cephalotaxus_ (Eastern Asia) is related to it. [Illustration: FIG. 260.--_Ginkgo_ (nat. size): _A_ a branch with a small flowering dwarf-branch (male flower); _B_ a leaf; _C_ a flower with two ovules; _D_ a ripe seed; _ar_ collar.] [Illustration: FIG. 261.--_Phyllocladus glaucus_: a branch with female flowers (nat. size).] _B._ PODOCARPEÆ. The female flower is reduced to one ovule, placed in the axil of a bract, or a little forward upon it. The ovule has an aril (2 integuments).--_Phyllocladus_ (Fig. 261), from New Zealand and Tasmania, has obtained its name from its flat, _leaf-like branches_, the leaves proper being scale-like (_f_). The ovules stand _erect_ in the axil of the scale-like leaves (_c_), and several are collected at the end of short branches.--_Microcachrys tetragona_ (Tasmania) has a small female catkin with several spirally-placed, fleshy bracts, at the end of which the inward and downward turned ovule is attached (Fig. 262 _A_, _A’_). The ripe cones are red, succulent, and resemble Strawberries.--In _Dacrydium_ (Tasmania, New Zealand, Malaysia) the female cone has most frequently only 1–2 (–6) bracts, which resemble the vegetative leaves; they have also a fleshy aril (Fig. 262 _B_, _B’_).--_Podocarpus_ (40 species, East Asia, S. Temp.); the bracts of the female flowers become fleshy, and unite together; only 1 or 2 are of use in supporting the flowers. The ovules project high above the apex of the bract, and are _anatropous_, the micropyle being turned downwards (Fig. 262 _C_, _D_). An aril commences to develope in the flowering period as an external coating, and later on it becomes fleshy and coloured. [Illustration: FIG. 262.--_A Microcachrys_: female cone (2/1). _A’_ A single carpel with its ovule. _B Dacrydium_: branch with female flower (3/1). _B’_ The flower; _cp_ the bract; _ar_ the aril; _ov_ ovule. _C Podocarpus_: female flower with 2 ovules. _D_ Another female flower with 1 ovule, in longitudinal section.] [Illustration: FIG. 263.--_Taxus baccata_: branch with two ripe seeds (nat. size).] _C._ TAXEÆ. The female flower is reduced to one ovule, which is situated _terminally_ on an axis which bears 2–3 pairs of opposite, scale-like bracteoles; on this account the Taxeæ form a very isolated group among the Coniferæ.--_Taxus_ (_T. baccata_, the Yew-tree). _Diœcious_. _The female flower consists of only one ovule_, placed _at the end_ of a short secondary branch (Fig. 264), which is studded with scale-like leaves. The aril when ripe is thick, fleshy, and scarlet (sometimes yellow), and only loosely envelopes the seed (Fig. 263). The leaves are scattered, flat, linear, and pointed (Fig. 263, 264). The short male flowers have 5–8 pollen-sacs, pendent from the stamens, and are surrounded at their bases by scale-like bracteoles (Fig. 243). _Torreya_ (4 species, N. America and Japan) is closely allied to _Taxus_. The aril ultimately fuses with the woody inner integument, and hence the ovule becomes drupaceous, as in Cephalotaxaceæ. [Illustration: FIG. 264.--_Taxus baccata_: _A_ shoot of _Taxus_ with female flowers at the time when the ovules are ready for pollination. _B_ Leaf with flower in its axil (nat. size). _C_ Longitudinal median section through a female shoot; _v_ growing point of primary shoot; _a_ commencement of aril; _i_ integument; _n_ nucellus; _m_ micropyle.] USES. _Taxus baccata_ is usually planted in gardens, especially in hedges. Its wood is very hard and is used for wood-carving. The shoots are poisonous, but not the aril, which is often eaten by children and by birds. Family 2. =Pinoideæ.= The four orders differ from one another partly in the arrangement of the leaves (_Cupressaceæ_ have opposite or verticillately placed leaves, flowers, and inflorescences; in the others they are placed spirally), but chiefly in the greater or less degree of union which takes place between the female flower (the leaf-like “symphyllodium”) and its supporting cover-scale, and in the position of the ovules (the micropyle being turned upwards or downwards). The “cone-scales” in _Abietaceæ_ are formed by “symphyllodia” alone, in the others by their union with the cover-scale. Order 1. =Araucariaceæ.= This order most frequently has _solitary_ ovules, _turned downwards_ and attached _to the centre_ of the cone-scales. In _Agathis_ (_Dammara_) the arrangement is the most simple, a winged seed (Fig. 265), which hangs _freely_ downwards, being borne in the centre of the undivided cone-scale. In _Araucaria_, the stamens with the _free, pendulous_ pollen-sacs have been represented in Fig. 242; the ovuliferous scale is united for nearly its whole length with the bract, and projects from its apex in the shape of a sheath-like, dentate scale, resembling the ligule in _Isoëtes_, and may therefore be termed a “ligule.” _Araucaria_ (S. America, Australia) has often rather broad leaves (_A. brasiliensis_). The ovuliferous scale in _Cunninghamia_ is more distinct, and stretches transversely over the entire cover-scale; it bears three inverted ovules (Fig. 266) (Eastern Asia). [Illustration: FIG. 265.--_Agathis (Dammara) australis._ Cone-scale with the seed. _A_ Longitudinal section; _A’_ from within; _fv_, _fv’_ vascular bundles; _v_ wing.] [Illustration: FIG. 266.--_Cunninghamia sinensis._ Cone-scale with three ovules, interior view: _d_ cover-scale; _f_ ovuliferous scale.] [Illustration: FIG. 267.--_A-G Pseudotsuga douglasii_: _A_ cone, _B_ cone-scale, with the inner side turned forward; the points of the cover-scale are seen behind it; _C-G_ transitions from the acicular leaf to the cover scale, from the base of a ♀ cone. _H Pinus montana._ Young ovuliferous scale, with the inner side turned forward; the ovules are now in the stage for pollination. _J-M Abies alba_: _J_ male cone; _b_ bud-scale; _a_ anthers; _K L M_ individual anthers.--_Pinus montana_: _N_ pollen-grain; the two lateral expansions are the air-bladders; in the upper part of the interior of the grain a vegetative cell may be seen, and in the centre the large cell-nucleus.] Dammara-resin, which is used for varnish, is obtained from _Agathis_ (_Dammara_) species (New Zealand, Philippine Islands). Order 2. =Abietaceæ (Pine and Fir Trees).= The leaves are spirally arranged and needle-like. The flowers are _monœcious_. The male flowers are long, and catkin-like, with numerous stamens, each bearing two _oblong pollen-sacs_. The pollen-grains are most frequently tri-lobed, having two bladder-like appendages, formed as outgrowths of the exospore, to assist in their distribution by the wind (Fig. 267 _N_). The bracts are arranged spirally. The union between the bract and the ovuliferous scale, which is found in the preceding order, is not in this instance so complete; these scales make their appearance as two free parts, and are attached only at their bases (Fig. 268); the lower portion, that is the cover-scale, in most instances remains quite small (Fir, Red Pine, and others), it is only in the “Noble Pine” (_Abies_) and _Pseudotsuga douglasii_, that it attains a greater length than the ovuliferous scale (Fig. 267, _B-G_). On the other hand the upper part, _the ovuliferous scale_ (the vascular bundles of which have the bast turned upwards), grows strongly and elongates, especially after fertilisation, becoming woody or leathery; it is commonly termed the “_cone-scale_,” but is in reality only homologous with a part of the “cone-scale” in the other order of Pinoideæ. On the side of the ovuliferous scale, turned towards the axis, are situated _two ovules_ with micropyles _directed inwards_. The seeds are most frequently provided with _a false wing_ (a tissue-like part of the surface of the ovuliferous scale). Cotyledons, _more than_ 2, _verticillate_. _Fertilisation does not take place until some time after pollination._ In _Pinus_, for instance, the pollen-tube only penetrates the nucellus for a short distance during the year of pollination, and then ceases its further growth, fertilisation not taking place until after the middle of the next year; whilst the seeds ripen about a year and a half after pollination. In the Larch and others, the seeds are mature in the autumn succeeding pollination. [Illustration: FIG. 268.--_A Abies_: _c_ the cover-scale; _s_ ovuliferous scale, or “cone-scale”; _sk_ ovules in a young condition. _B Pinus_: ovuliferous scale with two ovules (_s_); _m_ the two-lobed micropyle; _c_ “mucro”; _b_ the cover-scale behind. _C Abies_: ripe “cone-scale” with two seeds (_sa_); _f_ wing of seed.] _Abies_ (Fir). The leaves are often (_e.g. Ab. pectinata_) displaced into 2 rows, flat and indented at the apex, with 2 white (wax-covered) lines on the under surface, in which the stomata are situated. The leaf-scars are nearly circular and do not project. The cones are erect. _The cover-scales and the ovuliferous scales separate from the axis_, to which they remain attached in other genera.--~_Tsuga_ has leaves like _Abies_, but by the slightly projecting leaf-scars, and cones with persistent scales, it forms the transition to _Picea_.--_Pseudotsuga_ has leaves similar to those of _Abies_ and persistent carpels as in _Picea_, but the cover-scales grow as in _Abies_ and project beyond the ovuliferous scales (_P. douglasii_, Fig. 267). These two genera are considered as sub-genera of _Abies_.~--_Picea_. The leaves project on all sides, square and pointed; the leaf-scars are rhombic, on projecting leaf-cushions. The cones are pendulous. The cover-scales are much shorter than the leathery, persisting ovuliferous scales.--The genus _Larix_ (Larch) differs from all the others in having deciduous leaves (the three preceding have leaves which persist for eleven to twelve years). It has _long-branches_ with linear foliage-leaves and short, thick, _perennial dwarf-branches_, which each year form a new rosette of foliage-leaves, similar to those on the long-branches. The male flowers and the erect cones resemble those of _Picea_, and are borne on dwarf-branches.--_Cedrus_ (Cedar) resembles _Larix_ to some extent, but has persistent leaves (_C. libani_, _C. deodara_).--_Pinus_ (Pine) has long-branches and dwarf-branches. The leaves of the long-branches are scale-like and not green; the dwarf-branches have very limited growth, and persist for three years; they arise in the axils of the scales borne on the long-branches of the self-same year, and each bears 2–5 foliage-leaves, they are also surrounded at the base by a number of membranous bud-scales. The cone-scales have a _thick, rhomboid extremity_ (the “shield”). The buds which develope into long-branches arise at the apex of other long-branches, and being very close together, form false whorls. The female cones occupy the position of long-branches, and take about two years for their development. The male flowers arise close together, and form a spike-like inflorescence at the base of a long-branch of the same year. The male flowers occupy the position of dwarf-branches, so that a female cone may be considered to be a modified long-branch, and a male cone a modified dwarf-branch. The main axis of the seedling has needle-like leaves, similar to those found on the older parts, and on dwarf-branches; it is not until some time later that the dwarf-branches are developed and the permanent arrangement attained. USES. Several species are commonly cultivated in this country, partly on heaths and moors, and partly in plantations and as ornamental trees, such as Mountain Pine (_Pinus montana_, Cen. Eur.); Austrian Pine (_P. laricio_, Eur.); Scotch Fir (_P. silvestris_, Eur.); Weymouth Pine (_P. strobus_, N. Am.); common Red Pine (_Picea excelsa_, Cen. and N. Eur.); White Pine (_P. alba_, N. Am.); _Abies pectinata_ (Common Fir, S. and Cen. Eur); _A. nordmanniana_ (Crimea, Caucasus); _A. balsamea_ (N. Am.); _Tsuga canadensis_ (N. Am.); _Pseudotsuga douglasii_ (N.W. Am.); Larch (_Larix europæa_, Alps, Carpathians); _L. sibirica_ (N.E. Russia, Siberia).--The wood of many species, especially Pine, on account of its lightness and because it is so easily worked, is very well adapted for many useful purposes. The wood of the Yew-tree is very hard and is used for ornamental turning. Resin and Turpentine (_i.e._ Resin with essential oils, the name being derived from the Terebinth-tree, from which formerly a similar material was obtained) are extracted from _Pinus laricio_ and _P. pinaster_. Oil of Turpentine is obtained by distillation of turpentine with water; Tar by dry distillation of Pine-wood. Canada-balsam is from North American _Abies_-species (_A. balsamea_ and _Fraseri_). The officinal Turpentine is mainly obtained from _Pinus pinaster_ (South of France), _P. tæda_, _australis_, _strobus_ (Weymouth Pine) and other North American species; more recently also from _P. silvestris_ (Scotch Fir), _maritima_, _laricio_, _Picea excelsa_, and others; Venetian Turpentine, from Larch (S. Eur.) Amber is resin from a Tertiary plant (_Pityoxylon succiniferum_), closely related to the Pine, which grew especially in the countries round the South-East coast of the Baltic. _Pinus pinea_ (the Pine, S. Eur.) has edible seeds and also _P. cembra_ (in Cen. Eur. and Siberia). Order 3. =Taxodiaceæ.= The vegetative leaves and cone-scales are arranged spirally. The ovules (2–9) are situated either at the base of the ovuliferous scales, in which case they are erect; or at their centre, when they are generally more or less inverted. The ovuliferous scale is more or less united with the cover-scale, and projects beyond the surface of the cone-scale, like a comb (Fig. 269). The vascular bundles, which extend into the cover-scale, have the usual leaf-arrangement, viz. the wood placed above the bast; while those bundles which enter the ovuliferous scale have this arrangement of the bundles reversed. [Illustration: FIG. 269.--_Cryptomeria japonica._ Portion of longitudinal section through female flower. _d_ cover-scale; _f_ ovuliferous scale; _ov_ ovules; _fv_ and _fv’_ vascular bundles; the xylem is indicated by a wavy line, and the phlœm by a straight line.] _Taxodium distichum_ (the North American “Swamp Cypress”) has annual dwarf-branches, with distichous leaves, and cone-like “pneumathodia.” In the Tertiary period it was very common in the Polar regions. _Sequoia (Wellingtonia) gigantea_ is the famous Californian Giant-Fir, or Mammoth-Tree, which attains a height of 300 feet, a diameter of 36 feet, and is said to live for 1,500 years. _Cryptomeria japonica_ (Japan, China) has the least adnate ovuliferous scales; _Glyptostrobus_ (China); _Arthrotaxis_ (Tasmania); _Sciadopitys verticillata_ (the only species in Japan) has, like _Pinus_, scale-like leaves on the long-branches, of which those which are situated at the apex of the annual shoots support “double needles,” _i.e._ _dwarf-branches_ similar to the two-leaved dwarf-branches in _Pinus_, but without bud-scales, and with the two leaves fused together at the edges into one needle, which turns its upper surface away from the long-branch. Order 4. =Cupressaceæ= (=Cypresses=). _The leaves are opposite or verticillate_, sometimes acicular, but most frequently scale-like (Fig. 270). In the species with scale-like leaves, the seedlings often commence with acicular leaves (Fig. 272), and branches are sometimes found on the older plants which revert to this form, seeming to indicate that the acicular leaf was the original form (atavism). The so-called “_Retinospora_” species are seedling-forms of _Biota_, _Thuja_, _Chamæcyparis_, which have been propagated by cuttings, and retain the seedling-form. The flowers are monœcious or diœcious. The male flowers are short, and have shield-like stamens, bearing most frequently several pollen-sacs. The cover-scales and ovuliferous scales are entirely fused together and form _undivided_ cone-scales, _opposite or whorled_; _the ovuliferous scales_ have slight projections near _the base_ on which 1–2–several _erect ovules_ are developed (Fig. 274). Most frequently 2 cotyledons.--_Evergreen_ trees and shrubs. [Illustration: FIG. 270.--_Cupressus goveniana._] [Illustration: FIG. 271.--Portion of a branch of _Thuja orientalis_ (magnified). The leaf at the base on the right has a branch in its axil.] [Illustration: FIG. 272.--Seedling of _Thuja occidentalis_. The branch (_g_) is borne in the axil of the leaf _s_.] _Juniperus_ (Juniper). _Diœcious._ The cone-scales become fleshy and fuse together to form most frequently a 1–3 seeded “berry-cone.” ~_J. communis_ (Common Juniper) has acicular leaves, borne in whorls of three, and the “berry-cone” is formed by a trimerous whorl of cone-scales (Fig. 273). _J. sabina_ and _J. virginiana_ have “berry-cones” formed from several dimerous whorls of cone-scales; the leaves are connate and opposite, needle-and scale-like leaves are found on the same plant.~ _Cupressus_ (Cypress). _Monœcious._ The cones are spherical; the cone-scales shield-like, generally five-cornered and woody (Fig. 270), each having many seeds. The leaves are scale-like.--_Thuja. Monœcious._ Cones oblong. The cone-scales are dry, as in the Cypress, but leathery and imbricate, and not shield-like; each cone-scale bears 2–3 seeds. The leaves are most frequently dimorphic; those leaves which are situated on the edges of the flat branches are compressed, and only these bear buds, which are developed with great regularity, generally alternately, on both sides of the branch; those which are situated on the flattened surfaces are pressed flat and broad, and never bear branches (Fig. 271). Along the central line of each leaf there is a resin-canal (Fig. 271).--~_Chamæcyparis_, _Callitris_, _Libocedrus_, _Thujopsis_ (1 species: _T. dolabrata_; in Japan).~ [Illustration: FIG. 273.--Branch of Juniper with “berry-cones.”] [Illustration: FIG. 274.--_Cupressus lawsoniana._ Longitudinal section through female cone. Two ovules (_ov_) are bisected; _f_ ovuliferous scales.] OFFICINAL. _Juniperus sabina_ from Central and South of Europe (the young branches yield an essential oil). The wood of _J. communis_ is used in the production of an essential oil, and _J. oxycedrus_ in the production of empyreumatic oil. The “berry-cone” of _J. communis_ is officinal, and is also used for gin.--The wood of _J. virginiana_ (N. Am.) is known as red cedar, and is used for lead-pencils. Sandarack resin is obtained from _Callitris quadrivalvis_ (N.W. Africa). THE FOLLOWING ARE CULTIVATED IN GARDENS:--_Thuja occidentalis_ (Arbor vitæ) (N. Am.), and _orientalis_ (China, Japan); _Juniperus sabina_ and _virginiana_; _Thujopsis dolabrata_ (Japan); _Cupressus lawsoniana_ (California), _C. sempervirens_ (S. Eur., W. Asia), and other species, are grown especially in conservatories, and in Southern Europe particularly in cemeteries.--The _Retinospora_ species which are so often planted, do not belong to an independent genus, but are obtained from cuttings, taken from seedling-plants with acicular leaves (see page 267). Class III. =Gneteæ.= This class, independent of extinct forms, comprises the most highly developed of the Gymnosperms, partly from the circumstance that a perianth of 2–4 members encloses the _terminally placed ovule_, which is provided with one, or (in _Gnetum_) two, integuments, and partly owing to the fact that the wood has true vessels. There is only one order. [Illustration: FIG. 275.--_Welwitschia mirabilis_ (considerably reduced). The horizontal lines indicate the surface of the soil.] Order. =Gnetaceæ.= The three known genera differ very much in appearance. _Welwitschia mirabilis_ (from the deserts of South Western Africa) is the oldest (?) genus now living. It resembles a giant radish, in that the hypocotyl is the only part of the main axis of the stem which becomes developed. It attains a circumference of upwards of four metres with a length of 1/2½-⅔ of a metre. It bears _only_ two oblong, leathery leaves (Fig. 275) which are torn into segments at the apex and lie on the surface of the soil; these are the two first foliage-leaves which succeed the cotyledons, and they are remarkable for their enormous length (upwards of two metres) as well as for their long duration, living as long as the plant itself. In their axils are situated the 4-rowed, spike-like male and scarlet-coloured female cones, upon dichotomous branches. The perianth consists in the ♂ of 2 alternating pairs of leaves, the inner ones of which are slightly united. The andrœcium likewise consists of 2 whorls: the external (transverse) with 2, the internal with 4 stamens; the lower halves of the 6 filaments uniting to form a cup. Each of the terminal anthers corresponds to a sorus of 3 sporangia, the sporangia being fused together, and opening at the top by _one_ three-rayed cleft. In the centre of the ♂-flower there is a sterile ovule. In the ♀-flower a perianth of two connate leaves is present.--_Ephedra_ (desert plants, especially in the Mediterranean and W. Asia) at first sight resembles an _Equisetum_; the stems are thin, long-jointed, and the leaves opposite, small, and united into a bidentate sheath; ♂-perianth of two connate leaves (median leaves); 2–8 stamens united into a column. Each anther is formed of 2 sporangia (is bilocular). ♀ mainly, as in _Welwitschia_. The seeds are surrounded by the perianth which finally becomes red and fleshy. There are 30 species.--_Gnetum_ has opposite, lanceolate, pinnately-veined, leathery leaves. They are mostly climbers (Lianas) from Tropical Asia and America. The ♂-flowers have a tubular perianth, (formed from two median leaves) which surrounds a centrally-placed filament, bearing 2 anthers. In the ♀-flower there is a similar perianth, surrounding an ovule provided with 2 integuments. The perianth becomes fleshy and envelops the hard seed. 20 species. From the circumstance of _Welwitschia_ having ♂ flowers which, besides stamens, possess also a rudiment of an ovule, Celakovsky draws the inference that the earliest Gymnosperms had hermaphrodite flowers which from this structure became differentiated entirely into ♂-and ♀-flowers, with the exception of _Welwitschia_ only, in which this differentiation was only carried out in the ♀-flower. This theory has so far been scarcely proved. =Fossil Gymnosperms.= The earliest continental plants which are known belong to the CORDAITACEÆ, a group of plants which existed as early as the Silurian period; they were Gymnosperms, but it has not yet been determined whether they were Cycads or Conifers. The CYCADS, even in the Coal period, were scarce; they attained their fullest development in Jurassic and Cretaceous periods, during which they were rich in species and genera, and extended as far as the Polar regions. In addition to these, Taxaceæ, Abietaceæ, and Taxodiaceæ appeared in the Carboniferous period. The TAXACEÆ appear to have attained their culmination in the Jurassic and Cretaceous periods; _Ginkgo_ appears in the Rhætic; _Torreya_, in the Cretaceous; _Taxus_ and _Podocarpus_ in the Tertiary periods. The ABIETACEÆ also appear in the Carboniferous; _Pinus_ was first known with certainty in the English Weald and in the Cretaceous; almost all other contemporary genera are represented in this latter period. The ARAUCARIACEÆ first appear, with certainty, in the Jurassic. The TAXODIACEÆ may be traced back as far as the Carboniferous (?); _Sequoia_ is first found in the lowest Cretaceous, at that period it spread throughout the entire Arctic zone, and being represented by a large number of species, formed an essential part of the forest vegetation. _Sequoia_ played a similar part in the Tertiary period. The CUPRESSACEÆ are first known with certainty in the Jurassic, but they appeared more frequently and numerously in the Tertiary period, in which most of the present living genera were to be found. The GNETACEÆ, according to a theory advanced by Renault were represented in the Coal period by the genus _Stephanospermum_, which had four ovules enclosed by an envelope. DIVISION V. ANGIOSPERMÆ. See pages 3 and 224. To this Division belong the majority of the Flowering-plants. They are divided into two parallel classes, the Monocotyledons and the Dicotyledons, which differ from each other not only in the number of cotyledons, which, with a few exceptions, is one in the former, two in the latter, but also in the internal structure of the stem, the venation of the leaves, the number of the parts of the flower, etc. ~Assuming that these two classes have sprang from a common origin, it is amongst the Helobieæ in the first, and amongst the Polycarpicæ in the second class that we might expect to find closely allied forms, which might reasonably be supposed to have varied less from this original type. As for the rest, they seem to stand quite parallel, without exhibiting any close relationship. It is scarcely proved that the Monocotyledons are the older class.~ [Our knowledge of the forms included under the Angiosperms has recently been considerably increased by Treub (_Ann. d. Jar. Bot. d. Buitenzorg_, 1891), who has shown that the Casuarinas differ in many important points from the typical Angiosperms. Among other characters the pollen-tube is found to enter the ovule near the chalaza and therefore at the opposite end to the micropyle, and Treub therefore suggests that these plants should be placed in a subdivision termed Chalazogams. According to this view the principal divisions of the Angiosperms would be represented thus:-- =Angiospermæ.= Sub-division. Sub-division. CHALAZOGAMES. POROGAMES. Class. Classes. Chalazogames. Monocotyledones, Dicotyledones. More recently Nawaschin (_Bull. Acad. Imp. Sci. St. Petersb._, ser. iii., xxxv.) has shown that _Betula_, and Miss Benson (_Trans. Linn. Soc._, 1894) that _Alnus_, _Corylus_, and _Carpinus_ also belong to the Chalazogams. Our knowledge, however, is still so incomplete that one would hesitate to accord the full systematic value which Dr. Treub attaches to his discovery until the limits of the Chalazogamic group are better defined; and it would hardly be justifiable to include the Casuarinas and the above-noted genera in one family.] Class 1. =Monocotyledones.= _The embryo has only one cotyledon; the leaves are as a rule scattered, with parallel venation; the vascular bundles of the stem are closed, there is no increase of thickness. The flower is typically constructed of five 3-merous whorls, placed alternately._ THE EMBRYO is generally small in proportion to the abundant endosperm (exceptions, see _Helobieæ_), and its single cotyledon is often sheath-like, and very large. On the germination of the seed either the entire cotyledon, or its apex only, most generally remains in the seed and absorbs the nutritive-tissue, while the lower portion elongates and pushes out the plumule and radicle, which then proceed with their further growth. The primary root in most cases soon ceases to grow, but at the same time, however, numerous lateral roots break out from the stem, and become as vigorous as the primary root, or even more so. Increase in thickness does not take place in these roots; they branch very little or not at all, and generally die after a longer or shorter time. THE STEM is frequently a corm, bulb, or other variety of underground stem, as the majority of the Monocotyledons are perennial, herbaceous plants; it has scattered, closed vascular bundles (Fig. 276), and no cambium by which a continuous thickening may take place. The stem of the Palms, however, attains a very considerable thickness, which is due to the meristem of its growing-point continually increasing in diameter for a lengthened period (often for many years), until it has reached a certain size. In this condition the growing-point has the form of an inverted cone, and it is only when this cone has attained its requisite size that the formation of a vertical cylindrical stem commences. Certain tree-like Liliaceæ, as _Dracæna_, _Aloe_, etc., have a continuous increase in thickness; this is due to a meristematic layer, which arises in the cortex, outside the original vascular bundles, which were formed at the growing-point of the stem. This meristem continues to form thick-walled parenchyma and new, scattered vascular bundles. The primary vascular bundles, in the Palms and others, run in a curved line from their entrance into the stem at the base of the leaf, towards the centre of the stem, and then bend outwards and proceed downwards in a direction more parallel to the sides of the stem (Fig. 277). The bundles formed later, in those stems which increase in thickness, are not continued into the leaves. THE BRANCHING as a rule is very slight, the axillary buds of the majority of the leaves never attaining development, _e.g._ in the Palms, bulbous plants and others. As the cotyledon arises singly, the succeeding leaves also must be scattered, but they are frequently arranged in two rows (Grasses, Iris, etc). _The first leaf borne on a branch_ (the “Fore-leaf,”[24]--the bracteole, if on a floral shoot) has generally, in the Monocotyledons, a characteristic form and position, being situated on the posterior side of its own shoot, and hence turned towards the main axis; it is sometimes provided with two laterally-placed keels (Figs. 279 _f_, 290 _øi_), but the midrib is often absent. It arises in some cases from two primordia, which at the beginning are quite distinct, and thus has been regarded as formed by two leaves. It is, however, only one leaf, a fact which is evident from several circumstances, one being that it never supports more than one shoot, and this stands in the median plane (Fig. 279). [Illustration: FIG. 276.--Transverse section of the stem of a Palm: _v v_ is the wood portion, _b b_ the bast portion of the vascular bundled.] [Illustration: FIG. 277.--Diagrammatic representation of the course of the vascular bundles, from the stem into the leaves in a Monocotyledon.] THE LEAVES are _amplexicaul_, and have a large sheath but no stipules; the blade is most frequently long, ligulate, or linear, entire, with parallel venation, the veins being straight or curved (Figs. 300, 309). Connecting the large number of veins which run longitudinally, there are as a rule only weak transverse ones. It is very rarely that other forms of leaves are found, such as cordate (Figs. 302, 312), or that the blade is branched, or the venation is, for example, pinnate or palmate (Figs. 225, 298); these deviations are especially found in the Araceæ, the Palms, the Scitamineæ (Fig. 308), the Dioscoreaceæ, and in several aquatic plants. The incisions in the Palm-leaf are derived by the splitting of an originally entire leaf. THE STRUCTURE OF THE FLOWER is generally as follows: Pr3 + 3, A3 + 3, G3, rarely S3 + P3 with the other members unchanged.[25] Instead of 3, the numbers 2 and 4 may occur; rarely others. In all these instances there are 5 whorls, which regularly alternate with one another, most frequently in the 3-merous flower, as in the diagram (Fig. 278). This diagram is found in the following orders: Liliaceæ, Convallariaceæ, Juncaceæ, Bromeliaceæ, Amaryllidaceæ, Dioscoreaceæ, Palmæ, some Araceæ, and in some small orders, and may be considered as the typical structure and also the starting point for the exceptional orders. The ovary in many Monocotyledons has many ovules, and the fruit becomes a many-seeded berry or capsule; this form is no doubt the oldest. In others the number of seeds becomes reduced to 1, and the fruit then becomes a cypsela, or a drupe (_e.g. Gramineæ_, _Cyperaceæ_, _Palmæ_, etc). [Illustration: FIG. 278.--Diagram of the ordinary, regular flower in the Monocotyledons: _s_ is the bract.] [Illustration: FIG. 279.--Diagram of _Iris_: _f_ the bracteole; in its axil is a shoot with its bracteole.] [Illustration: FIG. 280.--Diagram of _Orchis_: _l_ the lip; σ σ the two staminodes.] Deviations from this typical floral structure in some instances may be traced to _suppression_, very rarely to a _splitting_ of certain members, the typical relative positions not being changed. Thus, the Iridaceæ, the Cyperaceæ, most of the Gramineæ and some Juncaceæ deviate in having only 3 stamens (Fig. 279), the inner whorl (indicated by *) not becoming developed. The Musaceæ differ in the posterior stamen not being developed; _Zingiberaceæ_ (Fig. 314), _Marantaceæ_, and _Cannaceæ_, in the fact that only 1 of all the stamens bears an anther, and the others are either suppressed or developed into petaloid staminodes, with some perhaps cleft in addition. The Orchideæ deviate in having, generally, only the anterior stamen of all the 6 developed (Fig. 280). In this, as in other instances, the suppression of certain parts of the flower is often connected with _zygomorphy_ (_i.e._ symmetry in _one_ plane), chiefly in the inner perianth-whorl, but also in the other whorls. In the Orchids, the perianth-leaf (the labellum, Fig. 280 _l_) which is directly opposite the fertile stamen, is larger and altogether different from the others. The perianth-leaves may also be suppressed; see, for example, the two diagrams of the Cyperaceæ (Fig. 284). In some orders the suppression of these leaves, which form the basis of the diagram, is so complete that it is hard to reduce the actual structure of the flower to the theoretical type, _e.g._ the Grasses (Fig. 290) and _Lemna_ (Fig. 303). In the first family, which especially comprises water-plants, a somewhat different structure is found; thus Fig. 282 differs somewhat from the ordinary type, and other flowers much more so; but the floral diagrams which occur in this family may perhaps be considered as the most probable representatives of an older type, from which the ordinary pentacyclic forms have taken their origin. In favour of this theory we have the larger number of whorls, the spiral arrangement of some of these in the flower, with a large and indefinite number of stamens and carpels, the perfectly apocarpous gynœceum which sometimes occurs, etc., etc. The Monocotyledons are divided into 7 Families:-- 1. HELOBIEÆ. This family forms a group complete in itself. It commences with hypogynous, perfect flowers, whose gynœcium is apocarpous and terminates in epigynous and more or less reduced forms. 2. GLUMIFLORÆ. These have as a starting point the same diagram as the following families, but otherwise develope independently. 3. SPADICIFLORÆ. Also an independent branch, or perhaps two different ones which terminate in much reduced forms. 4. ENANTIOBLASTÆ. These ought perhaps to be amalgamated with the following family. 5. LILIIFLORÆ. These advance from forms with the typical diagram and hypogynous flower, to epigynous and reduced forms. 6. SCITAMINEÆ and 7. GYNANDRÆ. Two isolated families, which probably have taken their origin from Liliifloræ, and have epigynous, mostly zygomorphic, and much reduced forms. Family 1. =Helobieæ.= To this family belong _only water- or marsh-plants_; _the endosperm is wanting_, and they possess an embryo with a very _large hypocotyl_ prolonged downwards and often club-like. The perianth is often differentiated into calyx and corolla; the flower is regular, and in the first orders to be considered, may be reduced to the ordinary Monocotyledonous type; there are, however, _usually found two_ 3-_merous whorls of carpels_ (Fig. 282), and thus in all 6 whorls, or again, the _number of carpels may be indefinite_; the number of stamens also may be increased, either by the division of the members of a whorl, or by the development of additional whorls. _Syncarps_,[26] with nut or follicular fruitlets, are _very common_, for example, in the first orders; in the last (Hydrocharitaceæ) the carpels are not only united, but the ovary is even inferior. The primitive type appears to be a hypogynous flower, similar to that of the Juncaginaceæ or Alismaceæ, with several 3-merous whorls, and free carpels, each with many ovules; the green perianth in this instance being no doubt older than the coloured ones. If we take a flower with this structure as the starting point, then the family developes partly into epigynous forms, partly into others which are so strongly reduced and exceptional that it is scarcely possible to refer them to the ordinary type. The family, through the peculiar _Zostereæ_, appears to approach the Araceæ, in which _Potamogetonaceæ_ and _Najadaceæ_ are included by some authorities. However, the inclusion of _Potamogeton_, and with it _Ruppia_ and _Zannichellia_, in the Juncaginaceæ appears quite correct. It would scarcely be right to separate _Zostereæ_ from these. Great stress has often been laid upon the similarity with the Ranunculaceæ which is found in the Alismaceæ, but it is scarcely more than an analogous resemblance. Order 1. =Juncaginaceæ.= The ☿, regular, _hypogynous_ flowers have the _perianth_ 3 + 3, _sepaloid_, stamens 3 + 3 (with extrorse anthers), and carpels 3 + 3 (free or united), of which last, however, one whorl may be suppressed (in _Triglochin maritima_ all 6 carpels are developed, in _T. palustris_ the inner whorl is unfertile). Inflorescence long spikes. Embryo _straight_.--Marsh-plants with radical, rush-like leaves, arranged in two rows, and often sheathing and ligulate (“squamulæ intravaginales”); the inflorescence is a spike or raceme.--_Scheuchzeria._ Carpels almost free; in each at least two ovules. Follicles.--_Triglochin_ has long, fine racemes without bracts or bracteoles; one ovule in each carpel. The carpels in the two native species are united, but separate when ripe as a schizocarp, loosening from below; they open along the ventral suture or remain closed; a linear central column remains. ~The most reduced is Lilæa (1–2 sp. Am.)--Protogynous. About 10 species. Temp. Fossils in Tertiary.~ Order 2. =Potamogetonaceæ.= The aquatic plants belonging to this order are perennial, living entirely submerged, or with floating leaves, and preferring still water. The leaves are alternate, in some linear and grass-like, in others there is an elliptical floating blade, supported by a linear submerged petiole. Axillary scales. The fruit is generally a syncarp with _nuts_ or _drupes_; the _embryo is curved_, of very various forms. _Potamogeton_ (Pond-weed). The rhizome is creeping, sympodial (with two internodes in each shoot-generation); the inflorescence is a terminal, many-flowered spike, without floral-leaves; below it are found 2 foliage-leaves placed nearly at the same height, from whose axils the branching is continued cymosely. The flowers are ☿, 4-_merous_, naked, and consist only of 4 _stamens_, with the _connectives, broadly developed_ at the back of the anthers, _resembling a perianth_, and of 4 _free, sessile carpels_. They are common plants in fresh water. ~The spike, during the flowering, is raised above the water. Wind-pollinated and protogynous.--Closely allied is _Ruppia_ (Tassel Pond-weed), in salt or brackish water. The spike has only two naked flowers, each consisting of 2 stamens and 4 carpels. The stalks of the individual carpels are considerably prolonged.--_Zannichellia_ (Horned Pond-weed) is monœcious; the ♀-flower consists of 4 (2–9) carpels, with membranous, bell-shaped perianth; long styles; the ♂-flower has 1 (-2) stamens. _Althenia._~ _Zostera_ (Grass-wrack) is an entirely submerged, marine plant with creeping rhizome (with displacement of buds) and strap-shaped leaves. The flowering shoots are sympodia with displacement of the axes (Fig. 281). The inflorescence is a peculiar, flatly-compressed spike, on _one_ side of which the flowers are borne (Fig. 281). ~This inflorescence may be considered, no doubt correctly, to be derived from the symmetrical spike of _Potamogeton_ by strongly dorsiventral development, and by a strong suppression of the floral parts taking place simultaneously. Two rows of flowers are developed, but of these one is so pressed into the other that apparently only one is present.~ Each flower consists of only 1 stamen and 1 carpel situated at the same height (Fig. 281); the unilocular ovary encloses 1 pendulous ovule and bears a bifid style. As regards the perianth (?) one leaf may be present (_Z. nana_, Fig. 281 _D_). The pollen-grains are filamentous. Pollination takes place under water. ~_Posidonia_ and _Cymodocea_ are allied to these. About 70 species.~ [Illustration: FIG. 281.--_Zostera._ A Diagram of the branching of the floral shoots: _I_, _II_ ... are the successive shoot-generations, every other one being shaded; _g_{1}_ _g_{2}_ ... fore-leaves; _sp_{1} sp_{2}_ ... spathes for the successive spikes. Each shoot is united for some distance with the parent axis (indicated by the half-shaded internodes). Each shoot commences with a fore-leaf turning towards the parent axis, _g_; succeeding this is the spathe, _sp_; and then the inflorescence. The fore-leaf supports a new lateral shoot. _B_ Diagram of a shoot, _II_, which is borne laterally in the axil of the fore-leaf _g_{1}_, on the shoot _I_, _g_{2}_ its fore-leaf; _sp_{2}_ its spathe; _sti_ squamulæ intravaginales. _II_ Is the spadix with stamens and carpels; _b_ a perianth-leaf (or connective expansion, similar to those which occur in _Potamogeton_). _C_ The upper portion of a young spadix with development of flowers. _D_ Part of a spadix with 2 flowers; the parts which theoretically belong to one another are connected by a dotted line.] Order 3. =Aponogetonaceæ.= Aquatic plants with tuberous stem. They have a single, petaloid perianth (3–2–1–leaved), most frequently 6 stamens and 3(-6) carpels. Straight embryo.--About 15 species (Africa, Madagascar, Tropical Asia and Australia).--_Aponogeton distachyos_ and _A._ (_Ouvirandra_) _fenestralis_ are grown in conservatories; the latter has lattice-like, perforated leaves. Order 4. =Najadaceæ.= Only one genus _Najas_ (about 10 species); annual fresh water plants with leaves in pairs and solitary, unisexual flowers. The ♂ flower is remarkable in having a terminal stamen, which has either 4 longitudinal loculi or 1 central one; on this account the stamen of _Najas_ is considered by some authorities to be a stem and not a leaf-structure. The unilocular gynœceum and the single, erect, anatropous ovule are also terminal. Pollination takes place under the water. Order 5. =Alismaceæ.= The regular, _hypogynous_ flowers are in some species unisexual by the suppression of either andrœcium or gynœceum; they have a 6-merous perianth, _generally_ differentiated into 3 sepals and 3 petals; generally 6 _stamens in the outer whorl_ (by the division of the 3; Fig. 282) and often several 3-merous whorls inside these, and 6–∞ _free_ carpels arranged cyclically or spirally. Fruit a syncarp.--Marsh- or water-plants with radical leaves and long-stalked inflorescences. =A.= _Butomeæ. Follicles with many seeds, which are borne on nearly the whole of the inner surface of the cyclic carpels_ (as in Nymphæaceæ). Embryo _straight_.--_Butomus_ (Flowering Rush, Fig. 282), has an umbel (generally composed of 3 helicoid cymes). _S_ 3, _P_ 3, stamens 9 (6 + 3, _i.e._ the outer whorl doubled), _G_ 3 + 3. ~_B. umbellatus_; creeping rhizome with triangular Iris-like leaves.--_Hydrocleis. Limnocharis._~ [Illustration: FIG. 282.--Diagram of _Butomus_: _f_ bracteole.] =B.= _Alismeæ._ Fruit achenes. Latex common (in the intercellular spaces). The flowers are arranged most frequently in single or compound whorls. Embryo _curved_, horse-shoe shaped.--_Alisma_ has _S_ 3, _P_ 3, _A_ 6 (in 1 whorl, grouped in pairs, _i.e._ doubled in front of the sepals), and 1 _whorl_ of 1-seeded achenes on a flat receptacle. The leaves are most frequently radicle, long-stalked; the lamina have curved longitudinal veins, and a richly branched venation. _A. plantago._--_Elisma_ (_E. natans_) has epitropous (turned inwards) ovules, whilst the ovules of _Alisma_, _Sagittaria_ and others are apotropous (turned outwards).--_Echinodorus_ (_E. ranunculoides_) has a convex receptacle, carpels many, united and capitate. _Damasonium_.--_Sagittaria_ (Arrow-head) has _monœcious_ flowers, several whorls of stamens and _spirally-arranged achenes_ on a very convex receptacle. ~_S. sagittifolia_ reproduces by tuberous buds formed at the end of long, submerged branches. The leaves, in deep and rapidly running water, are long and strap-shaped, but in the air arrow-shaped.~ Honey is secreted in the flower and pollination effected by insects. _Alisma plantago_ has 12 nectaries. The submerged flowers of _Elisma natans_ remain closed and are self-pollinated. _Butomus_ has protandrous flowers. There are about 50 species, which mostly grow outside the Tropics.--Uses insignificant. The rhizome of some is farinaceous. Order 6. =Hydrocharitaceæ.= This order differs chiefly from the preceding in its _epigynous_ flowers. These are in general unisexual (_diœcious_), and surrounded by a 2-leaved or bipartite _spathe_; they are 3-merous in all whorls, but the number of whorls is generally greater than 5, sometimes even indefinite. The perianth is divided into _calyx_ and _corolla_. The ovary is _unilocular_ with parietal placentation, or more or less incompletely plurilocular. The fruit is berry-like, but usually ruptures irregularly when ripe. Embryo straight.--Most often submerged water-plants, leaves seldom floating on the surface. Axillary scales (_squamulæ intravaginales_). _Hydrocharis._ Floating water-plants with round cordate leaves; S3, P3 (folded in the bud); ♂-flowers: 3 (-more) flowers inside each spathe; stamens 9–15, the most internal sterile. ♀-flowers solitary; three staminodes; ovary 6-locular, with many ovules attached to the septa; styles 6, short, bifid. [The petals of the ♀-flowers bear nectaries at the base. In this and the following genus the pollination is without doubt effected by insects.] ~_H. morsus ranæ_ (Frog-bit) has runners; it hibernates by means of special winter-buds.~--_Stratiotes_; floating plants with a rosette of linear, thick, stiff leaves with spiny margin, springing from a short stem, from which numerous roots descend into the mud. Inflorescence, perianth, and ovary nearly the same as in _Hydrocharis_, but the ♂-flower has 12 stamens in 3 whorls, of which the outer 6 are in 1 whorl (dédoublement), and inside the perianth in both flowers there are numerous (15–30) nectaries (staminodes?). _S. aloides_ (Water-soldier); in N. Eur. only ♀-plants.--~_Vallisneria spiralis_ is a tropical or sub-tropical plant, growing gregariously on the mud in fresh water. The leaves are grass-like, and the plants diœcious; the ♂-flowers are detached from the plant, and rise to the surface of the water, where they pollinate the ♀-flowers. These are borne on long, spirally-twisted peduncles which contract after pollination, so that the ♀-flower is again drawn under the water, and the fruits ripen deeply submerged.--_Elodea canadensis_ is also an entirely submerged plant. The leaves are arranged in whorls on a well-developed stem. Only ♀-plants in Europe (introduced about 1836 from N. Am). This plant spreads with great rapidity throughout the country, the reproduction being entirely vegetative. _Hydrilla_, _Halophila_, _Thalassia_, _Enhalus_.--In many of these genera the number of whorls in the flower is remarkably reduced; for example, in _Vallisneria_, in the ♂-flowers to 2: Pr 3, A (1-) 3, in the ♀ to 3: Pr 3, Staminodes 3, G 3.--About 40 species; Temp. and Trop.~ Family 2. =Glumifloræ.= The _hypogynous_ flowers in the Juncaceæ are completely developed on the _pentacyclic, trimerous_ type, with _dry, scarious perianth_. Even in these the interior whorl of stamens becomes suppressed, and the ovary, which in _Juncus_ is trilocular with many ovules, becomes in _Luzula_ almost unilocular, but still with 3 ovules. The perianth in the Cyperaceæ and Gramineæ is reduced from hairs, in the first of these, to nothing, the flowers at the same time collecting more closely on the inflorescence (spike) supported by _dry_ bracts (_chaff_); the number of stamens is almost constantly 3; stigmas linear; the ovary has only 1 loculus with 1 ovule, and the fruit, which is a capsule in the Juncaceæ, becomes a nut or caryopsis.--The endosperm is large and floury, the embryo being placed at its lower extremity (Figs. 286 _B_, 291).--The plants belonging to this order, with the exception of a few tropical species, are annual or perennial herbs. The stems above ground are thin, and for the most part have long internodes, with linear, parallel-veined leaves which have long _sheaths_, and often a _ligule_, _i.e._ a membranous projection, arising transversely from the leaf at the junction of the sheath and blade. The underground stems are short or creeping rhizomes. The flowers are small and insignificant. Wind- or self-pollination. Order 1. =Juncaceæ= (=Rushes=). The regular, hermaphrodite, hypogynous flowers have 3 + 3 brown, dry, free perianth-leaves projecting like a star during the opening of the flower; stamens 3 + 3 (seldom 3 + 0) and 3 carpels united into one gynœceum (Fig. 283); the ovary is 3- or 1-locular; there is as a rule 1 style, which becomes divided at the summit into 3 stigmas, often bearing branches twisted to the right (Fig. 283). _Fruit a capsule_ with loculicidal dehiscence. The embryo is an extremely small, ellipsoidal, cellular mass, without differentiation into the external organs. [Illustration: FIG. 283.--Flower of _Luzula_.] _Juncus_ (Rush) has glabrous foliage-leaves, generally cylindrical, rarely flat; the edges of the leaf-sheath are free (“_open_” leaf-sheaths) and cover one another. The capsule, 1- or 3-locular, with _many_ seeds--_Luzula_ (Wood-Rush) has flat, grass-like leaves with ciliated edges; the edges of the leaf-sheath are united (“_closed_” leaf-sheath). The capsule unilocular and _3-seeded_.--_Prionium_: S. Africa; resembling a _Tacona_. The _interior_ whorl of stamens, in some species, disappears partially or entirely (_J. supinus_, _capitatus_, _conglomerates_, etc.) Some of the numerous _Juncus_-species (_e.g. J. effusus_, _glaucus_, _conglomeratus_, etc.), have false, lateral inflorescences, the axis of the inflorescence being pushed to one side by its subtending leaf, which apparently forms a direct continuation of the stem, and resembles it both in external and internal structure. The foliage-leaves of this genus were formerly described as “unfertile stems,” because they are cylindrical, erect, and resemble stems, and consequently the stem was said to be “leafless”: _J. effusus_, _glaucus_, _conglomeratus_. Stellate parenchynatous cells are found in the pith of these stems and in the leaves. Other species have distinct terminal inflorescences and grooved leaves; _J. bufonius_ (Toad-rush), _compressus_, and others. The _inflorescences_ most often present the peculiarity of having the lateral axes protruding above the main axis. Their composition is as follows:--The flowers have either no bracteoles, and the inflorescences are then capitulate; or they have 1–several bracteoles. Each branch has then, first, a 2-keeled fore-leaf placed posteriorly (“basal-leaf”), and succeeding this are generally several leaves borne alternately and in the same plane as the basal-leaf, the two uppermost (the “spathe-leaves”) being always barren; those which lie between the basal-leaves and the spathe-leaves are termed “intermediate-leaves.” If only branches occur in the axils of the basal-leaves, then the succeeding branches are always borne on the posterior side of the axis, and form a fan[27]; if the basal-leaf is barren, and if there is only one fertile intermediate-leaf, then the lateral axes are always on the upper side, and a sickle[27]-like inflorescence occurs; if there are 2 fertile intermediate-leaves, then a dichasium is formed, and in the case of there being several, then a raceme, or spike. _Juncaceæ_ are, by several authors, classed among the Liliifloræ, but there are so many morphological and partly anatomical features agreeing with the two following orders, that they may, no doubt, most properly be regarded as the starting point of these, especially of the _Cyperaceæ_, which they resemble in the type of flowers, the inflorescence, the type of mechanical system, and the stomata. POLLINATION by means of the wind. Cross-pollination is often established by protogyny. _J. bufonius_ has partly triandrous and cleistogamic, partly hexandrous, open flowers.--DISTRIBUTION. The 200 species are spread over the entire globe, but especially in cold and temperate countries; they are seldom found in the Tropics.--USES. Very slight; plaiting, for instance. Order 2. =Cyperaceæ.= The majority are _perennial_ (seldom annual) _herbs_ living in damp situations, with a sympodial rhizome and grass-like appearance. The stems are seldom hollow, or have swollen nodes, but generally _triangular_, with the upper internode just below the inflorescence generally very long. The leaves are often arranged in 3 _rows_, the leaf-sheath is _closed_ (very seldom split), and the ligule is absent or insignificant. The flowers are arranged in _spikes_ (_spikelets_) which may be united into other forms of inflorescences (chiefly spikes or racemes). The flowers are supported by a bract, but have _no bracteoles_. In some genera the perianth is distinctly represented by six bristles corresponding to six leaves (Figs. 284 _A_, 286 _A_); in others it is represented by an indefinite number of hairs (Fig. 284 _B_), and very frequently it is altogether wanting. _The inner whorl of stamens is absent_, and the flower has therefore 3 stamens (rarely more or less than 3), the anthers _are attached by their bases to the filament_ (innate) and are not bifid (Figs. 286). Gynœceum simple, formed of 3 or 2 carpels; 1 style, which is divided at the extremity, as in the Juncaceæ, into 3 or 2 arms; the single loculus of the ovary contains one basal, erect, anatropous ovule; the stigmas are not feather-like. _Fruit a nut_, whose seed is generally not united with the pericarp. The embryo is small, and lies at the _base of the seed in the central line_, surrounded on the inner side by the endosperm (Fig. 286 _B_). On germination the cotyledon _does not remain_ in the seed. [Illustration: FIG. 284.--Diagram of structure of: _A Scirpus silvaticus_; _B Eriophorum angustifolium_.] A regular perianth, with 6 scale-like perianth-leaves in 2 whorls, is found in _Oreobolus_. In _Scirpus littoralis_ the perianth-leaves are spreading at the apex, and divided pinnately. The branching of the inflorescence is often the same as in the Juncaceæ, and supports the theory that these two orders are related. In _Rhynchospora_ and others, the “spikelets” are really only “spike-like” and to some extent compound. =A.= SCIRPEÆ. HERMAPHRODITE FLOWERS. 1. Spikelets cylindrical, the bracts arranged spirally (in many rows). The lower ones are often barren, each of the others supports a flower.--_Scirpus_ (Club-rush). The spikelets are many-flowered; the perianth is bristle-like or absent, and does not continue to grow during the ripening of the fruit (Fig. 286 _A_). Closely allied to this is _Heleocharis_, with terminal spikes.--_Eriophorum_ (Cotton-grass) differs chiefly in having the perianth-hairs prolonged, and forming a bunch of white, woolly hairs (Fig. 284 _B_). _Cladium_ and _Rhynchospora_ (Beak-rush) differs especially in the _few_-flowered, compound spikelets which are collected into small bunches; the latter has received its name from the fact that the lowermost portion of the style remains attached to the fruit as a beak. 2. Spikelets compressed, the bracts arranged only in _two rows_; the other characters as in the first-mentioned. _Cyperus_ (spikelets many-flowered); _Schœnus_ (Bog-rush); spikelets few-flowered; _S. nigricans_ has an open sheath. [Illustration: FIG. 285.--_Carex_: _A_ diagram of a male flower; _B_ of a female flower with 3 stigmas; _C_ of a female flower with 2 stigmas; _D_ diagrammatic figure of a female flower; _E_ similar one of the androgynous (false) spikelet of _Elyna_. The ♂ is here represented placed laterally; it is terminal, according to Pax.] [Illustration: FIG. 286.--_A_ Flower of _Scirpus lacustris_. _B_ Seed of _Carex_ in longitudinal section.] =B.= CARICEÆ. UNISEXUAL FLOWERS. In the ♂-flowers there is no trace of a carpel, and in the ♀ no trace of a stamen. Floral-leaves in many rows. In some (_Scleria_, certain _Carex_-species), ♂-and ♀-flowers are borne in the same spikelet, the latter at the base or the reverse; in the majority each spikelet is unisexual. _Carex_ (Fig. 285) has _naked_, most frequently monœcious flowers. The ♂-_spikes_, which are generally placed at the summit of the whole compound inflorescence, are _not compound_; in the axil of each floral-leaf (bract) _a flower is borne, consisting only_ of a short axis with three stamens (Fig. 285 _A_). The ♀-_spikes are compound_; in the axil of each floral-leaf is borne a very small branch (Fig. 285 _D_, _a_) which _bears only one leaf_, namely, a _2-keeled fore-leaf_ (_utriculus_, _utr._ in the figures) which is turned posteriorly (as the fore-leaves of the other Monocotyledons), and being obliquely sheath-like, envelopes the branch (in the same manner as the sheath of the vegetative leaves), and forms a pitcher-like body. In the axil of _this_ leaf the ♀-flower is situated as a branch of the 3rd order, bearing only the 2–3 carpels, which are united into one gynœceum. The style protrudes through the mouth of the utriculus. ~The axis of the 2nd order (_a_ in Fig. 285 _D_) may sometimes elongate as a bristle-like projection (normally in _Uncinia_, in which it ends as a hook, hence the name); this projection is in most cases barren, but it sometimes bears 1–several bracts which support male-flowers; this is normal in _Elyna_ (or _Kobresia_) and _Schœnoxiphium_; the axis (_a_ in 285 _E_) bears at its base a female-flower supported by the utriculus, and above it a male-flower supported by its bract.~ POLLINATION by means of the wind. Protogynous. Sometimes self-pollinated. The order embraces nearly 3,000 species, found all over the world. _Carex_ and _Scirpus_ are most numerous in cold and temperate climates, and become less numerous towards the equator. The reverse is the case with _Cyperus_ and other tropical genera. They generally confine themselves to sour, swampy districts; some, on the other hand, are characteristic of sand-dunes, such as Sand-star (_Carex arenaria_). There are about 70 native species of _Carex_. USES. In spite of their large number, the Cyperaceæ are of no importance as fodder-grasses, as they are dry and contain a large amount of silica; hence the edges of many of the triangular stems or leaves are exceedingly sharp and cutting. _Cyperus esculentus_ has tuberous rhizomes, which contain a large amount of fatty oil and are edible (earth-almonds); it has its home in the countries of the Mediterranean, where it is cultivated. _Cyperus papyrus_ (W. Asia, Egypt, Sicily) attains a height of several metres, and has stems of the thickness of an arm which were used by the ancient Egyptians for making paper (papyrus). Some serve for plaiting, mats, etc. (_Scirpus lacustris_, etc.). _Isolepis_ is an ornamental plant. [Illustration: FIG. 287.--_Triticum_: _A_ axis (rachis) of ear showing the notches where the spikelets were inserted; _B_ an entire spikelet; _C_ a flower with the pales; _D_ a flower without the pales, showing the lodicules at the base; _E_ glume; _F_ outer pale; _G_ inner pale; _H_ fruit; _I_ longitudinal section of fruit.] Order 3. =Gramineæ= (=Grasses=). The stems are cylindrical, generally _hollow_ with _swollen nodes_, that is, a swelling is found at the base of each leaf which apparently belongs to the stem, but in reality it is the swollen base of the leaf. The leaves are _exactly alternate_; the sheath is _split_ (excep. _Bromus_-species, _Poa pratensis_, _P. trivialis_, _Melica_, _Dactylis_, etc., in which the sheath is not split), and the edges overlap alternately, the right over the left, and _vice versâ_; the _ligule_ is nearly always well developed. In general, the flowers are hermaphrodite; they are borne in _spikelets_ with _alternate floral-leaves_, and the spikelets themselves are borne in either _spikes_ or _panicles_. The two (seldom more) _lowest floral-leaves_ in each spikelet (Fig. 289 _øY_, _nY_) are _barren_ (as the covering-leaves in many umbels and capitula); these are termed the _glumes_. The succeeding floral-leaves, each of which supports one flower as its bract, are called the _outer pales_ (_nI_); these sometimes each bear an “awn” (a bristle-like body which projects in the median line either from the apex or the back); sometimes the upper ones are barren. Each flower has a _bracteole_, which is placed on the inside opposite the main axis; it is thin, _binerved_ or _two-keeled_, and never has an awn; it is known as the _inner pale_ (_øI_). Immediately succeeding the bracteole are: (_a_) some _small, delicate scales_ (_lodicules_, Figs. 287 _D_, 288 _C_, 290 _L_); (_b_) _three stamens_ with anthers _versatile_, so as to be easily moved, and usually notched at each end (Fig. 287 _C_); and (_c_) a simple gynœceum formed of _one carpel_ with _two styles_ having generally _spirally-branched stigmas_ (Figs. 287 _D_, 288 _C_). The ovary is _unilocular_, and contains one ascending or pendulous, anatropous ovule. _Fruit a nut_, whose seed is always _firmly united with the thin pericarp_ (“caryopsis”). The embryo is larger than in the Cyperaceæ and is placed at the base of the seed, but on the _outer convex surface_ of the pericarp (Figs. 287 _I_, 288 288 _D_, 291), _outside the endosperm_; plumule large with several leaf-primordia. On germination the cotyledon remains in the seed. The majority of Grasses are annual or perennial herbs; tree-like forms being only found in the Tropics, for example, the Bamboos; they branch (in tufts), especially from the axils of the basal-leaves, while those which are borne higher on the stem are separated by longer internodes and have no vegetative branches in their axils, though a few forms, like _Bambusa_ and _Calamagrostis lanceolata_, produce branches in these axils. [Illustration: FIG. 288.--_Bromus mollis_: _A_ inflorescence; _B_ the uppermost flower of a spikelet, with its axis turned forward; in front is seen the two-keeled inner pale (bracteole) and the stamens protrude between this and the outer pale (bract); _C_ an ovary with the 2 stigmas on its anterior side, the 2 lodicules, and the 3 stamens; _D_ the fruit seen from the dorsal side; _E_ the same from the ventral side.] [Illustration: FIG. 289.--Diagrammatic outline of a spikelet: _n Y_ lower glume; _ø Y_ upper glume; _n I_ upper pale; _ø I_ the inner pale; _l_-_l_ lodicules; _st_ stamens; _I_-_I_ main axes; _II_ lateral axes.] [Illustration: FIG. 290.--Diagram of the Grass-flower: _ni_ outer pale; _øi_ inner pale; _l_-_l_ lodicules.] [Illustration: FIG. 291.--Longitudinal section of an Oat-grain: _a_ the skin (pericarp and testa); _b_ the endosperm; _c_ the cotyledon; _d_ the plumule.] Only a few Grasses have a _solid stem_, such as Maize, Sugar-cane, and _Andropogon_. The _blade_ is flat in the meadow-grasses, but the Grasses which live on dry places (“prairie-grass”) exposed to the sun, often have the blade tightly rolled up and almost filiform or bristle-like, with anomalous anatomical structure. A _closed_ tubular _sheath_ is found in _Melica uniflora_, _Bromus_-species, _Poa pratensis_ and _trivialis_, _Briza_ and some _Glyceria_-species. The sheath is developed for the purpose of supporting the young internodes while their growth is proceeding at the base. The “nodes” (the swollen joints which are seen on stems of Grasses) are not really part of the stem but are formed by the base of the leaf-sheath. They play a part in assisting the haulms to regain a vertical position when laid prostrate by wind or rain. The _awn_ on the pale is homologous with the blade of the Grass-leaf, and the pale itself is the sheath. The arrangement of the leaves in the _spikelet_ is similar to that in _Cyperus_ and other Cyperaceæ, their floral-leaves being borne in several rows in _Streptochæta_. More than two barren “glumes” are found in _Streptochæta_, several Phalarideæ and others. The spikelets, too, are again arranged in two rows in the axils of suppressed floral-leaves. The inflorescence becomes a “compound spike” (ear) when the spikelets are sessile. In the majority of instances the spikelets are borne on long stalks; when these branch, then the secondary branches, and similarly all branches of higher order, are placed so far down upon the mother-axis that they all appear to be of equal value and to arise in a semicircle from the mother-axis itself, though in reality they arise from each other (_Panicle_, Fig. 288 _A_). Sometimes the main axis and branches of different orders unite together as in _Alopecurus_, _Phleum_, and some other Grasses, and hence the single (short-stalked) spikelets appear to arise singly and spirally, or without any definite order, directly from the main axis, with the production of a _cylindrical_ inflorescence bearing “spikes” _on all sides_, that is, a “_spike-like panicle_.”--Many inflorescences are somewhat dorsiventral. The _flower_ is rarely unisexual (_Zea mais_) or barren. Considerable difficulty is experienced in reducing the Grass-flower to the ordinary 3-merous Monocotyledonous type. Some authorities consider the _lodicules_, which are present in all Grasses but absent in the Cyperaceæ, to be homologous with a perianth. According to a more recent theory they are bracteoles, and hence the Gramineæ, like many of the Juncaceæ, have 2–3 bracteoles placed in two rows in the median plane. If this theory be correct, the _flower is naked_. The lodicules expand quickly and cause the opening of the flower (_i.e._ the two pales become separated from each other). Generally only 3 _stamens_ belonging to the outer whorl are present (Fig. 290), as in _Iris_ (Fig. 279), certain Juncaceæ and Cyperaceæ (Fig. 284), but in some, such as the Rice and certain species of Bamboos, all 6 are found. _Pariana_ has more than 6. Only 1 of the _carpels_ is present, namely, the anterior (of those in Fig. 284), so that the ventral suture and the place of attachment of the ovule are situated at the back of the ovary. The number of styles does not correspond with the number of carpels, and the styles may therefore be supposed to arise from the edges of the leaf to the right and left--a position which is not without analogy. In addition, a stylar projection is sometimes found on the anterior side and in the median line (_e.g._ in _Phragmites_), and the solitary style in _Nardus_ has exactly this position; a similar arrangement is found in some species of _Bambusa_ which have only one style; other species of _Bambusa_ have three styles. A tripartite style is found in _Pharus_. [The Grass-flower may be reduced to the ordinary Monocotyledonous type thus:--The outer pale is the bract of the flower since it bears in its axil the floral shoot; the inner pale occupies the customary position of the bracteole. The fact that it is binerved can be explained by its having been pressed against the main-axis during development. Similar binerved bracteoles are found in _Iris_ (Fig. 279). These bracteoles in both Grass and Iris arise from single primordia, and are not produced by the coalescence of two leaves. The lodicules are the only parts of the perianth remaining, the outer whorl having been suppressed, and also the posterior leaf of the inner whorl; a posterior lodicule, however, is found in the Rice and some species of Bamboo. The outer whorl of stamens is usually absent, though this again is present in the Rice and Bamboo. The three carpels are reduced to one with two or sometimes three stigmas.] THE FLOWERING. In the panicles the flowers open in basipetal order; the flowers in the spikes situated somewhat above the middle, commence to open first, and the flowering proceeds upwards and downwards. A few Grass-flowers never open (cleistogamic); _Leersia oryzoides_, _Stipa_-species, and _e.g._ Wheat and Rye in cold damp weather; some open their pales so wide that the anthers and stigmas may protrude at the top; most frequently the lodicules expand and force the pales suddenly and widely apart. The filaments elongate considerably, so that the anthers are pendulous and the stigmas unfold. In some Grasses _e.g._ Wheat, the blooming of each flower only lasts a short time. POLLINATION is generally effected by the wind. The _Rye_ separates the pales very widely in the morning, and allows the anthers and stigmas to appear; it is almost entirely sterile when self-pollinated. The _Wheat_ flowers at any time of the day, each flower lasting only a quarter of an hour. The pales open suddenly, but only half way, and the anthers scatter one-third of the pollen in their own flower and two-thirds outside. Self-pollination is effectual, but crossing gives better results. In _Hordeum vulgare_ (all flowers ☿) the flowers of the 4 outer rows behave as in the Wheat, but those in the two central rows always remain closed. The ☿-flowers in the two central rows of _H. distichum_ remain closed and fertilise themselves; they open exceptionally, and may be pollinated by the ♂-flowers in the 4 lateral rows. _H. hexastichum_ is cleistogamic. _Oats_ pollinate themselves. [Illustration: FIG. 292.--Barley grain: _A_ section through the skin (_a-d_) and the most external part of the endosperm; _Gl_ the “aleurone layer”; _st_ starch-containing cells; _B_ starch grains.] [Illustration: FIG. 293.--Wheat-grain germinating: _g_ the plumule; _b_ the first leaf succeeding the cotyledon; _r^1_ the primary root; _r^2_ lateral root.] [Illustration: FIG. 294.--Older seedling of the Wheat: _s_ the second sheathing-leaf; _l_ first foliage-leaf.] _The ripe Grass-fruit_, in some species of Bamboo, is a berry; in some other Grasses a nut with _loosely_ lying seed, in some even a capsule, but otherwise a “caryopsis.” In some instances it is loosely enveloped by the pales (Oat), in others firmly attached to these (Barley), and finally, in others, “naked,” _i.e._ it is entirely free from the pales (Wheat and Rye). On the ventral side there is a groove (Fig. 288 _E_); on the anterior side (dorsal suture), which is turned towards the inner pale, it is convex, and at the base on this side, inside the testa, lies the embryo (Fig. 288 _D_). The apex of the fruit is often hairy (Fig. 293). The _skin_ (Fig. 291, _a_) is formed by the pericarp and testa, and in some cases (Barley) the pales also form the outer portion. The endosperm (_b_) is large, and formed of parenchymatous, starch-containing cells: aleurone (proteid) grains may also be found among them. When the starch-grains and the aleurone-grains adhere together the endosperm becomes “horny,” but is “floury” when the starch-grains lie loosely with air between them. In the most external region, just beneath the skin, 1–several layers of nearly cubical cells (filled principally with aleurone-grains and fat) are found, the _aleurone_-layer (Fig. 292). The embryo (Fig. 291 _c-d_) contains large quantities of fatty oil; the large shield-like structure, attached to the embryo and turned inwards towards the endosperm (_c_), is the cotyledon (scutellum); it remains enclosed in the seed during germination, and dissolves the endosperm by means of the peculiar epithelial cells developed on the dorsal surface. The radicle, on germination, is obliged to perforate a mass of cells derived from the suspensor and which form the “root-sheath” (coleorhiza, Fig. 293) round its base. In addition to the tap-root, lateral roots are frequently developed before germination; these quickly break through, and later on are followed by others which appear at the base of the leaf (Figs. 293, 294). The DISTRIBUTION OF THE FRUIT is most frequently effected by the wind. The spirally-twisted and hygroscopic awn which persists on the fruits of some species (_Avena_, _Stipa_, etc.) assists in their dissemination, and even helps to bury them in the ground. The two preceding orders are more closely related to each other than they are to the Gramineæ. The generic differences are chiefly founded on the form of the inflorescence, the number and sex of the flowers in the spikelets, the shape and relative length of the pales, awns, etc. In addition to these the structure of the fruit and seed presents a great many differences; some have compound starch-grains, while in others they are single; some have 1 layer of aleurone-cells, others have several (Fig. 292), etc. =1.= BAMBUSEÆ. Tall Grasses with woody, very siliceous stems which bear many branches in the axils of the leaves. 6 stamens. _Bambusa_ (Bamboo). =2.= ORYZEÆ. _Oryza sativa_ (Rice) is a herbaceous marsh-plant, with panicle and small, 1-flowered spikelets, with two small glumes and two large, boat-shaped, strongly siliceous pales. 6 stamens.--_Leersia._ _Lygeum. Pharus. Zizania aquatica._ =3.= MAYDEÆ. _Zea mais_ (Indian-corn, Maize); the spikelets are unisexual; the ♂-spikelets in a terminal panicle; the ♀-spikelets closely crowded and arranged in many rows in a thick, axillary spike, enclosed by large sheathing-leaves. The ♀-spikelets are 1-(2-) flowered; the ovary bears one, long, filamentous style, with bifid stigma.--_Euchlæna_; _Coix_. =4.= ANDROPOGONEÆ. _Saccharum_ (Sugar-cane); the spikelets are exceptionally small, 1-flowered, and borne in pairs in many-flowered, long-haired panicles. Tall grasses with solid, sappy stem.--_Andropogon._ =5.= FESTUCEÆ. Grasses with panicle (or spike-like panicle) and 2–several-flowered spikelets. Glumes small, in each case shorter than the spikelet.--_Festuca_ (Fescue) and _Bromus_ (Brome, Fig. 288) have the awn placed at the _apex_ of the pale, or slightly below it. _Festuca_ has perennial species, with only a sparsely-branched panicle with branches solitary or in pairs, and round spikelets; the leaf-sheath is widely open. _Bromus_ has the branches borne in half whorls, and the leaf-sheath scarcely half open. _Brachypodium_ has very short-stalked spikelets in a raceme.--_Poa_ (Meadow-grass), _Briza_ (Quaking-grass) and _Glyceria_ have awnless spikelets; these in _Poa_ are ovoid, compressed, and with sharply-keeled glumes; in _Briza_ they are broad, cordate and drooping, with boat-shaped glumes; in _Glyceria_ round, long, many-flowered, linear or lanceolate; some species of _Glyceria_ have closed leaf-sheaths.--_Dactylis_ (Cock’s-foot) differs from all others in the somewhat crowded and unilateral (subsecund) spikelets, which are compressed and oblique (_i.e._ one side more convex than the other).--_Phragmites_ (_P. communis_, Reed); the lowermost flowers of the spikelet are ♂; its axis is covered with long, silky hairs; pales without awns, but acuminate. Perennial marsh-plants.--_Melica_; panicle small, sparsely-branched with round, awnless, few-flowered, usually drooping spikelets. The upper pales, with arrested flowers, are generally united into a club-like mass.--_Molinia_, _Eragrostis_, _Koeleria_, _Catabrosa_.--_Cynosurus_ (Dog’s-tail) has a small, spicate panicle with unilateral spikelets, some of which are fertile, some barren, each supported by a pectinate scale. _Arundo. Sesleria. Gynerium. Triodia._ =6.= AVENEÆ. Panicles with 2–many-flowered spikelets; at least one of the glumes is quite as long as the entire spikelet.--_Avena_ (Oat). The pale is boat-shaped, often bifid, and at about the middle of the back has a twisted, bent awn.--_Aira_ (Hair-grass) has a long-branched panicle with small, 2-flowered spikelets; the pale has a dentate apex and bears an awn on the posterior side close to the base.--_Weingærtneria._--_Holcus_ (Yorkshire-fog); a soft, hairy Grass with an open panicle, keeled glumes; 2 flowers in the spikelet, of which the lower one is ☿, the upper ♂; the pale which supports the ☿-flower has no awn, but that which supports the ♂-flower, on the contrary, is awned. =7.= AGROSTIDEÆ. Panicles or spike-like panicles with 1-flowered spikelets. Generally 2 glumes and only 1 pale.--The following have PANICLES: _Milium_ with square panicle-branches and round spikelets; _Agrostis_ (Fiorin), with compressed, glabrous spikelets, whose glumes are longer than the pales. _Calamagrostis_ differs in having a chaplet of long hairs at the base of the pale.--_Stipa_ (Feather-grass) has a long, twisted awn.--The following have SPIKELIKE PANICLES: _Phleum_ (Cat’s-tail, Timothy-grass) has sharply pointed, entirely free glumes, which are much longer than the awnless pales. _Alopecurus_ (Fox-tail); glumes united below; pale with awn. _Ammophila_ (_Psamma_). _A. arundinacea_; pales hairy at base; perennial, stiff-leaved, glaucous sand-grass with creeping rhizome. _Aristida. Sporobolus._ =8.= PHALARIDEÆ. Panicles and spike-like panicles. The spikelet has in the upper part a single fertile flower; below it are placed 4 pales, of which the upper 1–2 sometimes support ♂-flowers. On the whole, 6 floral-leaves of the first order are present.--_Phalaris_ (_P. canariensis_, Canary-grass) has an ovate, spike-like panicle, the spikelets are compressed, convex on the outer side, concave on the inner. The large glumes are winged on the back.--_Digraphis_ (_D. arundinacea_) is closely allied to _Phalaris_, but the keel of the glumes is not winged.--_Anthoxanthum_ (_A. odoratum_, Sweet-vernal) has a small, lanceolate, open, spike-like panicle; the spikelets have below 2 barren flowers, and above these an ☿-flower with 2 stamens. The upper glume is longer than the flower.--_Hierochloa._ =9.= CHLORIDEÆ. The spikelets are arranged in the form of a spike in two rows on one side of an often flatly-compressed axis; they are mostly 1-flowered.--_Chloris_; _Ctenium_; _Cynodon_; _Eleusine_; _Microchloa_. =10.= PANICEÆ. The spikelets are borne in panicles or spikes, which may be arranged like fingers or in a raceme. There is a centrally-placed ☿-flower; below it is sometimes a ♂-flower.--_Panicum_; _Paspalum_; _Oplismenus_; _Setaria_ has an almost cylindrical spike-like panicle with several barren branchlets, which project as stiff, rough bristles.--_Cenchrus_; _Pennisetum_. =11.= HORDEÆ. Spikes compound; spikelets sessile in the notches of a toothed axis. =A.= Spikelets solitary.--_Triticum_ (Wheat, Fig. 287) has in each tooth of the main axis, a several-flowered spikelet which turns its _flat side_ towards the central axis. The cultivated species (true Wheat) are 1-2-annual, the wild ones (_T. repens_, Couch, also as an independent genus, _Agropyrum_) are perennial, with creeping rhizome and lanceolate glumes.--_Lolium_ (Rye-grass) has in each tooth of the main axis a many-flowered, compressed spikelet, which is placed _edgewise_ towards it and (with the exception of _L. perenne_) has only one outwardly-turned glume (_L. temulentum_ has a rudiment of the inwardly-turned lower glume); the terminal spikelet has two glumes.--_Secale_ (Rye). A two-flowered spikelet in each tooth; small, lanceolate, acuminate glumes. _Nardus_ and _Lepturus_ have very narrow spikes, the former with unilateral spikelets. =B.= In each notch of the axis 2 or more spikelets are placed close together.--_Hordeum_ (Barley). In each tooth three 1-flowered spikelets. _H. hexastichum_ (6-rowed Barley), has 6 rows of fruits, since all the spikelets are fertile, and _H. distichum_ (2-rowed Barley) 2 rows, since the lateral spikelets are (♂, and barren (p. 292).--_Elymus_ has 2–6 many-flowered spikelets in each joint of the main axis. _Ægilops_ has awns upon the glumes. DISTRIBUTION. 315 genera with 3,500 species. The order is distributed over the whole world, and as regards number of individuals is perhaps the richest. In the Tropics, large, broad-leaved, tree-like forms are found (_Bambuseæ_, _Olyreæ_, _Andropogoneæ_, etc.; in S. Europe, _Arundo donax_); in England, next to the Compositæ, it is the order most rich in species (about 134).--The origin of some of the cultivated Grasses is lost in obscurity. The Maize, no doubt, was indigenous to America, where its nearest relatives are found, and where it has also been discovered in ancient Indian graves; Durra or Guinea-corn, Millet and Sugar-cane are South Asiatic plants, and our own cereals no doubt have sprung primarily from Western Asia and South-Eastern Europe (Barley from Armenia and Persia, where a very closely related wild species is found; Wheat from the same districts; Rye from the perennial species _S. montanum_). _Panicum altissimum_ and Rice have come from Africa. USES. The Grasses play a very important part as cereals and fodder plants. The following are the most important of the cultivated ones: _Triticum vulgare_ (common Wheat), _turgidum_, _amyleum_, _polonicum_, _spelta_, _durum_, etc.; _Secale cereale_ (Rye); Barley (_Hordeum_-species, see under the genus); Maize; Oats (_Avena sativa_, _orientalis_, _nuda_); Millet (_Panicum miliaceum_); Durra (Turkish Millet, or Guinea-corn, _Sorghum vulgare_, _cernuum_ and _saccharatum_); Manna-grass (_Glyceria fluitans_). As fodder-plants especially: Rye-grass (_Lolium perenne_); Oat-grass (_Avena elatior_); Timothy (_Phleum pratense_); Fox-tail (_Alopecurus pratensis_); Cock’s foot (_Dactylis glomerata_); Dog’s tail (_Cynosurus cristatus_); Sweet-vernal (_Anthoxanthum odoratum_); Soft grass, or Yorkshire-fog (_Holcus lanatus_ and _mollis_); Quaking-grass (_Briza media_); species of Meadow-grass (_Poa_); Fescue (_Festuca_) and Brome (_Bromus_).--Several cultivated species of Grass are also used in the preparation of _fermented liquors_, the starch in the seeds being transformed to _sugar_ (beer from “Malt,” _i.e._ the germinated Barley; arrack from Rice); or the stem becomes specially saccharine before flowering: the Sugar-cane, _Sorghum saccharatum_. OFFICINAL. The rhizome of _Triticum repens_, Oat-grain, flour of Barley, and the starch of Wheat, also sugar. The seeds of _Lolium temulentum_ are considered _poisonous_.--The stems of many species (including our common grains) are used in the manufacture of paper, especially “Esparto grass” (_Stipa tenacissima_) from Spain and N. Africa, and the sheathing-leaves of the ♀-spike of _Maize_. Sand Lyme-grass (_Elymus arenarius_), and especially _Psamma arenaria_, are important.--But few Grass-species are _sweet-scented_: _Anthoxanthum odoratum_ and _Hierochloa odorata_ contain coumarin; _Andropogon_-species have essential oils (“Citronella oil”).--ORNAMENTAL PLANTS are: the “Ribbon-grass” (a variety of _Digraphis arundinacea_), _Stipa pennata_ (whose awn is exceedingly long and feathery), _Gynerium argenteum_ (Pampas-grass), _Lagurus ovatus_, _Hordeum jubatum_, _Bromus briziformis_. Family 3. =Spadicifloræ.= The primitive form resembles that of the preceding family. In it we find the typical, perfectly developed, Monocotyledonous flower, sometimes even with free carpels and with a dry or somewhat fleshy, but never petaloid perianth; and this passes over into very different forms by the suppression of the floral-leaves, perianth and sporophylls (unisexual flowers are common), and by the close aggregation of the flowers in the inflorescence. The flower is _hypogynous_ in every case. The inflorescence is a _spike_ which may be either single or branched, and has often a thick and fleshy axis (a _spadix_). In Palms and Araceæ it is enveloped, at any rate prior to the opening of the flowers, by a very large floral-leaf, _the spathe_, which may be petaloid (Figs. 297, 301). The fruit is most frequently fleshy (_berry_, _drupe_) or a _nut_, never a capsule. The embryo is small, with large, fleshy endosperm (Fig. 299 _C_); very rarely the endosperm is wanting. [Illustration: FIG. 295.--Piassava (_Attalea funifera_).] [Illustration: FIG. 296.--A portion of the stem of _Attalea funifera_ with persistent leaf-bases.] The numerous plants belonging to this family are large, herbaceous or tree-like, and the leaves seldom have the usual Monocotyledonous form, _i.e._ linear with parallel venation, but most frequently have pinnate or palmate venation. Order 1. =Palmæ (Palms).= The majority are trees with an _unbranched_, cylindrical _stem_, having short internodes and covered with leaf-scars or the bases of the leaf-stalks (Fig. 296), and at the summit a rosette of large leaves closely packed together (Fig. 295). An exception to this is found in _Calamus_ (Cane, “Rotang”), whose thin, creeping or climbing stems have long internodes; sparsely[28] branched is, _e.g._ the African Doum-palm (_Hyphæne_). Notwithstanding their often enormous stems the Palms have fibrous roots, like the bulbous Monocotyledons. The leaves are pinnate (Feather-palms, Fig. 298) or palmate (Fan-palms, Fig. 295) and often very large; they have a well-developed petiole with an _amplexicaul sheath_, which is often more or less separated into a large number of fibres. _In the bud the blade is entire but folded_, as the leaf expands the lines of folding are torn, either those which are turned upwards (thus ∨ ∨ ∨ ∨, _e.g. Pritchardia_, _Livistona_, _Phœnix_, _Chamærops_) or those turned downwards (thus ∧ ∧ ∧ ∧, _e.g. Cocos_, _Chamædorea_, _Calamus_). The inflorescence is usually lateral; when, as in Sago-palm (_Metroxylon rumphii_) or Talipot (_Corypha umbraculifera_) it is terminal, the plant is monocarpic, and dies after flowering; it is often a very _large_ and _branched spadix_ with numerous flowers either borne externally or embedded in it, and enclosed either in one woody, boat-shaped _spathe_ (Fig. 297) or several spathes, in the latter case one for each branch. The flowers are sessile or even embedded, regular, generally _unisexual_ (monœcious or diœcious) with the usual diagram (Fig. 278); the perianth is inconspicuous, green or yellow, persistent, and more or less leathery or fleshy. 6, rarely 3 or many stamens. The 3 carpels remain either _distinct_ or form one, generally 3-locular, ovary. The style is short. There is _one ovule in each carpel_. Often during ripening 2 carpels with their ovules are aborted. The fruit is a _berry_, _drupe_ or _nut_, generally one-seeded, with a large horny or bony endosperm with hard thick-walled cells (_e.g._ Date-palm). In some (_e.g._ Cocoanut) it is thin-walled, soft, and oily; in several “ruminate.” When _germination_ commences in the Cocoanut, Date, etc., the apex of the cotyledon remains in the seed and developes into a spongy mass to withdraw the endosperm; in the Cocoanut it attains a considerable size (Fig. 299 _C_) and assumes the form of the fruit. The endosperm in the Cocoanut is hollow and the interior is filled with “milk.” In the Date-palm and the Vegetable-ivory (_Phytelephas_) the cell-walls of the hard endosperm serve as reserve material. =1.= PHŒNICEÆ. _Phœnix_ (Date-palm) has pinnate leaves with channeled leaflets and diœcious flowers with 8 free carpels, of which usually only one developes into a berry with membranous endocarp; the large seed has a deep furrow on the inner side, and horny endosperm. [Illustration: FIG. 297.--Inflorescence of a Palm with spathe. At the top ♂-, at the base ♀-flowers.] [Illustration: FIG. 298.--_Livistona australis._] =2.= SABALEÆ. These have fan-like leaves with channeled segments; flowers ☿ or polygamous, rarely diœcious, with 3 separate or only slightly united carpels, all of which are sometimes developed into fruits (berry or drupe, with thin stone).--_Chamærops_, the Dwarf-palm. The pericarp is externally fleshy, internally more fibrous, and provided with a membranous inner layer. The endosperm is ruminate (that is, the testa is several times deeply folded into the endosperm).--_Sabal_, _Copernicia_, _Livistona_ (Fig. 298), _Thrinax_, _Corypha_, _Brahea_, and others. [Illustration: FIG. 299.--_A_ Longitudinal section of a Cocoanut (diminished), the inner layer only (the stone) not being divided _B_ End view of the stone, showing the sutures for the 3 carpels (_a_), and the 3 germ-pores; the embryo emerges from the lowest one when germination begins. _C_ Germinating; inside the stone is seen the hollow endosperm and the enlarging cotyledon.] =3.= COCOINEÆ. With pinnate leaves. Monœcious inflorescence. The carpels are united into a 3-locular ovary. The fruit is most frequently 1-locular, only 1 of the loculi becoming developed, rarely 3-locular; it is a drupe with a large, fibrous, external layer (_mesocarp_) and most frequently a very hard inner layer (_endocarp_, stone) which has 3 germ-pores, the 2 of these, however, which correspond to the suppressed loculi are closed; internal to the third lies the small embryo (Fig. 299). Endosperm containing abundance of oil. _Cocos_ (the Cocoanut-palm), _Attalea_, _Elæis_, _Acrocomia_, _Bactris_. =4.= LEPIDOCARYINÆ. The floral-leaves and flowers are borne in 2 rows on the spadix. The carpels are united into one 3-locular ovary; the fruit is coated by a layer of hard, shining, imbricate scales. The majority of the species are thorny, and climb by means of the thorny leaves. Some have fan-like (_Mauritia_), others pinnate leaves (_Raphia_, _Calamus_, _Eugeissonia_, _Metroxylon_; the stems of the latter die after the first flowering). =5.= BORASSINÆ. Large Fan-palms without thorns, with 3-locular ovary. Drupe with separate stones. _Latania_ and _Lodoicea_ have many stamens; _Hyphæne_; _Borassus_ (Palmyra-palm). =6.= ARECINEÆ. The most numerous group. Feather-palms. Berry. _Areca_, _Euterpe_, _Oreodoxa_, _Ceroxylon_, _Chamædorea_, _Geonoma_, _Caryota_ with bipinnate leaves. =7.= PHYTELEPHANTINÆ. Flowers with rudimentary perianth united in close capitula. _Phytelephas_ (Vegetable-ivory). _Nipa._ DISTRIBUTION. About 1,100 species are known. In Europe only the Dwarf-palm (_Chamærops humilis_) is wild (Western Mediterranean). The Date palm (_Phœnix dactylifera_) belongs to North Africa and West Asia. Other African genera are _Hyphæne_ (Doum-palm) and _Elæis_ (_E. guineensis_, Oil-palm). A large majority of the genera are found in South America and in the East Indies. The following are AMERICAN:--_Mauritia_, _Acrocomia_, _Bactris_, _Chamædorea_, _Oreodoxa_, _Euterpe_, _Attalea_, etc. ASIATIC:--_Metroxylon_, _Calamus_, _Areca_, _Borassus_, _Lodoicea_ (“Double-cocoanuts,” Seychelles) and others. The Cocoanut-palm has perhaps an American origin; all the other species of the same genus being endemic in America; it is the only Palm found on the coral islands of the Pacific Ocean, and is also the only one which is common to both hemispheres. USES. Palms belong to the most useful plants; they contain no poison, and are of little medicinal interest, but are largely employed in the arts and manufactures, the hard timber being adapted for many purposes on account of the hard tissue in which the vascular bundles are embedded. “Cane” is the stem of _Calamus_-species (from India). SAGO is obtained from the pith of _Metroxylon rumphii_ (Sago-palm, Sunda-Is., Moluccas), _Mauritia flexuosa_, etc. Sugar-containing sap (“palm wine”) is obtained from the American _Mauritia vinifera_ and _flexuosa_, _Borassus flabelliformis_ (Asiatic Palmyra-palm), _Arenga saccharifera_, etc., by cutting off the young inflorescences, or by perforating the stem before the flowering (_arrack_ is distilled from this). _Vascular strands_ for the manufacture of mats and brushes, etc., are obtained from the outer covering (mesocarp) of the Cocoanut, and from the detached leaf-sheaths of _Attalea funifera_ (Brazil) (Fig. 296). WAX is yielded by the leaves of _Copernicia cerifera_ (carnaueba-wax, Amazon region), and by the stem of _Ceroxylon andicola_ (palm-wax, Andes); East Indian _Dragon’s blood_ is from the fruit of _Calamus draco_; the young buds of many species, especially _Euterpe_, _Cocos_, _Attalea_, etc., are used as “cabbage.” Palm-oil is obtained from the oily mesocarp of the plum-like fruits of _Elæis guineensis_ (W. Africa), and from the seeds, when it is largely used in the manufacture of soap. EDIBLE FRUITS from the Date-palm (_Phœnix dactylifera_, Arabia, Egypt, W. Africa), and the endosperm of the Cocoanut (_Cocos nucifera_). The seeds and the unripe fruits of the Areca-palm (_Areca catechu_) are chewed with the leaves of the Betelpeper, principally in Asia. VEGETABLE IVORY from the hard endosperm of _Phytelephas macrocarpa_ (S. America.)--Many species are cultivated in the tropics as ornamental plants, but in this country only _Chamærops humilis_, _Livistona australis_ and _chinensis_ are generally grown. In addition to the few just mentioned, many others are of importance, but these are much the most useful. Order 2. =Cyclanthaceæ.= This is a small order related to the Palms (44 species from Tropical America), with fan-like, folded leaves. The flowers are unisexual and arranged in whorls or close spirals on an unbranched spadix. Ovary unilocular, ovules numerous. To this belongs _Carludovica palmata_, whose leaves are used for Panama hats. Order 3. =Pandanaceæ= (Screw-pines) is another small order, forming a transition to the Araceæ. The woody, (apparently) dichotomous stem is supported by a large number of aerial roots, which sometimes entirely support it when the lower portion of the stem has decayed. The leaves are closely crowded together, and arranged on the branches in three rows, which are often obliquely displaced, with the formation of three spiral lines; they are, as in the Bromeliaceæ, amplexicaul, long, linear, the edge and lower midrib often provided with thorns. The ♂-flowers are borne in branched, the ♀ in unbranched spadices or capitula, which resemble those of _Sparganium_, but have no floral-leaves. Perianth absent. The drupes or berries unite into multiple fruits.--About 80 species in the islands of the Indian Ocean.--_Pandanus_, _Freycinetia_.--Fossils perhaps in the chalk of the Harz. Order 4. =Typhaceæ.= The flowers are unisexual, monœcious, and borne on a cylindrical spike or globose capitulum; ♂ inflorescences above, the ♀ below. The perianth consists of a definite number of scales (_Sparganium_), or in its place numerous irregularly-arranged hairs are found (_Typha_); in the ♂-flower there are generally three stamens; the gynœceum is formed of 1–2 carpels with 1 prolonged style; 1 pendulous ovule. The seeds are furnished with a seed-cover, which is cast off on germination.--The few species (about 20) which belong to this order are marsh plants with creeping rhizome (and hence grow in clusters); the leaves on the aerial shoots are borne in two rows, entire, very long and linear. _Sparganium_ (Bur-reed). The flowers are borne in globose capitula; the perianth distinct, generally consisting of 3 small scales; pistil bicarpellate. Drupe, dry and woody. ~The stalk of the lower ♀ capitula is sometimes united with the main axis, and consequently the capitula are situated high above their subtending-leaf.~ _Typha_ (Bulrush, Reed-mace) has a long, cylindrical, brown spike, the lower portion bearing ♀-flowers, and the upper ♂-flowers, which is divided into joints by alternate leaves. The ♀-flowers have 1 carpel. The perianth is wanting, represented by a number of fine, irregularly-placed hairs; pistil unicarpellate. Fruit a nut. The two genera, according to some, are related to the 2nd order. In both genera native species are found. The pollination is effected by the wind, and consequently the anthers project considerably, and the stigma is large and hairy. _Typha_ is protandrous, _Sparganium_ protogynous. The small, fine hairs surrounding the nut of _Typha_ assist in its distribution by the wind.--Fossil _Typhas_ in the Tertiary. Order 5. =Araceæ= (=Arums=). The flowers are small, and always borne _without bracts or bracteoles_ on _an unbranched_, often very fleshy spike, which is enclosed by a spathe, often petaloid and coloured (Fig. 301). The fruit is a _berry_. Outer integument of the seed fleshy.--The leaves have generally sheath, stalk, and blade with distinctly _reticulate_ venation; they are chiefly cordate or sagittate (Fig. 302), seldom long with parallel venation as in the other Monocotyledons (_Acorus_, Fig. 300). The Araceæ are quite _glabrous_, generally _perennial herbs_ with tubers or rhizomes. Many have latex.--For the rest the structure of these plants varies; for example, while some have a perianth, in others it is wanting; in some the perianth-leaves are free, in others united; some have hermaphrodite flowers, but the majority unisexual (monœcious); some have free, others united stamens; the ovules are orthotropous, anatropous, or campylotropous, erect or pendulous; the ovary is 1–many-locular; some have seeds with endosperm, others without. ~_In habit_ there are great differences. While some, _e.g. Colocasia_ (Fig. 302), have a thick, more or less upright stem, with leaf-scars, but not woody, others are climbers, epiphytic, and maintain themselves firmly by means of adventitious roots, on the stems and branches of trees, or even on steep rocks, _e.g. Philodendron_; the cordate, penninerved leaf is the most common (Fig. 302), but various branched forms appear; the pedate leaves of _Helicophyllum_, _Dracunculus_, etc., are cymosely branched; the leaves of _Monstera deliciosa_, perforated by tearing, should be noticed (the vascular bundles while in the bud grow faster than the tissue between them, causing the latter to be torn, and the leaf perforated). With regard to the anatomical structure, the presence or absence of latex, raphides, resin-passages, groups of mucilage-cells should be noted. Engler makes use of these anatomical peculiarities for a scientific arrangement of the order.~ =A.= ORONTIEÆ, CALAMUS-GROUP. ☿, hypogynous flowers of a completely formed monocotyledonous type (number in the whorls 2, 3, or 4).--_Acorus_ (_A. calamus_, Sweet-flag) has a regular, 3-merous, pentacyclic flower (Fig. 300 _C_, _D_). They are marsh-plants, with creeping rhizome, triangular stem, and long, sword-like leaves (Fig. 300 _A_); the inflorescence is terminal, apparently lateral, being pushed to one side by the upright, sword-like spathe (Fig. 300 _B_).--~_Anthurium_ (Pr2+2, A2+2, G2); _Pothos_; _Orontium_ (unilocular ovary with one ovule), etc.~ [Illustration: FIG. 300.--_Acorus calamus_: _A_ habit (much reduced); _B_ inflorescence; _C_ a flower; _D_ diagram; _E_ longitudinal section of an ovary; _F_ an ovule.] [Illustration: FIG. 301.--_Arum maculatum._ The spathe (_h_) in _B_ is longitudinally divided.] [Illustration: FIG. 302.--_Colocasia Boryi._] =B.= CALLEÆ. Flowers hypogynous, naked, ☿.--_Calla_ (_C. palustris_). All flowers in the spike are fertile, or the upper ones are ♂; 6–9 stamens; ovary unilocular with many basal ovules. Marsh-plants with creeping rhizome and cordate leaves.--_Monstera_, _Rhaphidophora_, etc. =C.= ARINEÆ. Flowers monœcious, naked, ♂-flowers on the upper, ♀ on the lower part of the spadix.--_Arum_ (Fig. 301). The spadix terminates in a naked, club-like portion (_k_); below this is a number of sessile bodies (rudimentary flowers), with broad bases and prolonged, pointed tips (_b_); underneath these are the ♂-flowers (_m_), each consisting only of 3–4 short stamens, which eject vermiform pollen-masses through the terminal pores; then follow, last of all, ♀-flowers (_f_), each of which consists of one unilocular ovary, with several ovules. Perennial herbs, tuberous, with cordate leaves.--~_Dracunculus_; _Biarum_; _Arisarum_; _Pinellia (Atherurus) ternata_ with leaves bearing 1–2 buds. _Zantedeschia æthiopica_ (_Richardia_, Nile-lily); ♂, 2–3 stamens; ♀ with 3 staminodes, 1–5-locular ovary (S. Africa.)--In some genera sterile flowers are present between the ♂ and ♀ portions of the spadix (_e.g._ in _Philodendron_); in _Ambrosinia_ a lateral, wing-like broadening of the axis of the spadix divides the cavity of the spathe into two chambers, the anterior containing one ♀, and the posterior 8–10 ♂-flowers in two series; in some the stamens in the single ♂-flowers unite and form a columnar “synandrium” (_e.g._ in _Dieffenbachia_, _Colocasia_, _Alocasia_, _Caladium_, _Taccarum_, _Syngonium_). A remarkable spadix is found in _Spathicarpa_; it is united for its entire length, on one side, with the spathe, and the flowers are arranged upon it in rows, the ♀ to the outside, and the ♂ in the middle (_Zostera_ has a similar one).--_Pistia_ similarly deviates considerably, it is a floating water-plant, with hairy, round rosettes of leaves; in it also the spathe and spadix are united; at the base a ♀-flower is borne, which consists of one unilocular ovary, and above several ♂-flowers, each composed of two united stamens.~ BIOLOGY. The inflorescences are adapted for _insect-pollination_; they are protogynous, since the viscous, almost sessile stigmas come to maturity and wither before the pollen, which is generally dehisced by apical pores, is shed; some pollinate themselves freely by the pollen from the higher ♂-flowers falling upon the ♀-flowers below them, and in some it is conjectured that the pollination is effected by snails. The coloured spathe, and the naked end of the spadix (often coloured) of certain genera function as the coloured perianth in other orders; during flowering a very powerful smell is often emitted. _Arum maculatum_ is worthy of notice; small flies and midges creep down into the spathe, between the sterile flowers (Fig. 301 _b_), which are situated where the spathe is constricted, and pointing obliquely downwards prevent the escape of the insects; in the meantime, the stigmas are in a condition to receive any pollen they may have brought with them; after pollination the stigmas wither, and exude small drops of honey as a compensation to the flies for their imprisonment; after this the anthers (_m_) open and shed their pollen, the sterile flowers wither, and the insects are then able to escape, and enter and pollinate other inflorescences.--In many, a _rise of temperature_ and evolution of carbonic acid takes place during flowering; a spadix may be raised as much as 30°C. above the temperature of the surrounding air.--Again, under certain conditions, many species absorb such large quantities of water by their roots that water is forced out in drops from the tip of the leaf; this may often be observed in _Zantedeschia_. About 900 species in 100 genera. Home, the Tropics, especially S. America, India, and the Indian Islands, preferably in shady, damp forests growing as epiphytes upon trees, and on the banks of streams. Outside the Tropics few are found. _Acorus calamus_ was introduced into Europe from Asia about 300 years ago; it, however, never sets any fruit, as the pollen is unfertile. In England _Arum maculatum_ is a very common plant; this and _A. italicum_ are the only native species. _Colocasia antiquorum_ comes from Polynesia and the Indian Islands, and also _Alocasia macrorrhiza_. Fossils in Cretaceous and Tertiary. USES. Many species have pungent, and even _poisonous properties_ (_e.g. Dieffenbachia_, _Lagenandra_, _Arum_), which are easily removed by boiling or roasting; the _rhizomes_ of many species of _Caladium_, _Colocasia_ (_C. antiquorum_, _esculenta_, etc.), are very rich in starch, and in the Tropics form an important source of food. An uncommon occurrence in the order is the highly aromatic rhizome of _Acorus calamus_; this contains calamus-oil and acorin which are used in perfumery. Many are ornamental plants, _e.g. Zantedeschia æthiopica_ (South Africa), generally known as “Calla,” and _Monstera deliciosa_; many other species are grown in greenhouses. Order 6. =Lemnaceæ (Duck-weeds).= These are the most reduced form of the Spadicifloræ. They are very small, free-swimming water-plants. The vegetative system resembles a small, leaf-like body (Fig. 303 _f-f_), from which roots hang downwards; this branches by producing a new, similar leaf-like body, which springs from a pocket-like hollow (indicated by a dotted line in the figure) on each side of the older one, at its base (or only on one side). ~The branching is thus dichasial or helicoid (Fig. 303 _A_, where _f, f′, f″, f″′_ indicate shoots of 1st, 2nd, 3rd, 4th generations respectively). The leaf-like bodies are, according to Hegelmaier, leaf-like stems, and thus _Lemna_ has no other leaves than the spathe and the sporophylls; according to the investigations of Engler they are stems whose upper portion (above the “pocket”) is a leaf, which is not sharply separated from the underlying stem-portion. The inflorescence is a very much reduced Araceous-spadix, consisting in _Lemna_ of 1 or 2 stamens of unequal length (1-stamened ♂-flowers), 1 unilocular carpel (♀-flower), and 1 thin spathe (_B_). [The same is found in _Spirodela polyrrhiza_, etc., whose daughter-shoots begin in addition with 1 basal-leaf. _Wolffia arrhiza_, etc., have no roots, no spathe, and only 1 ♂-flower in the inflorescence (Engler).]--On the germination of the seed a portion of the testa is thrown off as a lid, so that an exit is opened for the radicle.--19 species. In stagnant fresh water, both Temp. and Tropical.--In Europe the species are _Lemna minor, trisulca, gibba; Spirodela polyrrhiza_, and _Wolffia arrhiza_, the smallest Flowering-plant.~ [Illustration: FIG. 303.--_Lemna_: _A_ vegetative system; _B_ portion of a plant with flowers; one stamen and tip of the carpel project; the remaining portions being indicated by the dotted line.] Family 4. =Enantioblastæ.= The flowers in this family are _hypogynous_ and have in part the general monocotyledonous type with 5 trimerous whorls completely developed in a regular hermaphrodite flower, and in part the flowers so much reduced that the type is very difficult to trace. On the one hand the family is well developed and has capitate inflorescences (_Eriocaulaceæ_) and on the other hand it is distinctly reduced (_Centrolepidaceceæ_). This family has taken its name from the fact that the ovule is not, as in the Liliifloræ and nearly all other Monocotyledons, anatropous, but _orthotropous_, so that the embryo (βλάστη) becomes placed _at the end of the seed opposite_ (ἐναντίος) _to the hilum_. Large, mealy endosperm.--The orders belonging to this family are by certain authors grouped with the _Bromeliaceæ_ and _Pontederiaceæ_, etc., into one family, FARINOSEÆ, so named on account of the mealy endosperm, the distinguishing character of the Liliifloræ then being that the endosperm is fleshy and horny. Order 1. =Commelinaceæ.= The complete Liliaceous structure without great reductions in the number of whorls, but with generally few ovules in each loculus of the ovary, is found in the Commelinaceæ, an almost exclusively tropical order with about 317 species; herbs, some of which are introduced into our gardens and greenhouses. The stems are nodose; the leaves often _clasping_; the flowers are arranged in unipared scorpioid cymes, often so that they form a zig-zag series falling in the median line of the bracts, and after flowering they bend regularly to the right or left, outwards or inwards. They are more or less _zygomorphic_, particularly in the stamens, which in the same flower are of different forms or partially suppressed. The outer series of the _perianth_ is sepaloid, the inner petaloid, generally violet or blue; the filaments are sometimes clothed with hairs formed of rows of bead-like cells (well known for showing protoplasmic movements). Fruit a trilocular _capsule_ with loculicidal dehiscence (generally few-seeded); in some a nut. The radicle is covered by an external, warty, projecting covering which is cast off on germination.--The abundant raphides lie in elongated cells whose transverse walls they perforate.--_Commelina, Tradescantia, Tinantia, Cyanotis, Dichorisandra_. Order 2. =Mayacaceæ.= This order is closely allied to the Commelinaceæ. 7 species. American marsh- or water-plants. In many of the following orders of this family the flowers are united into compound inflorescences, with which is accompanied a reduction in the flower. Order 3. =Xyridaceæ= (50 species). Marsh-plants with radical, often equitant leaves arranged in 2 rows, and short spikes on long (twisted) stalks. The flowers, as in the Commelinaceæ, have sepals (which however are more chaffy) and petals, but the outer series of stamens is wanting. Capsule (generally many-seeded). Order 4. =Rapateaceæ.= Marsh-plants with radical leaves, usually in two rows, and several spikelets on the summit of the main axis, clustered into a capitulum or unilateral spike. Each spikelet has numerous imbricate floral-leaves and one flower. 24 species. South America. Order 5. =Eriocaulaceæ.= The “Compositæ among Monocotyledons,” a tropical order. The flowers are borne in a _capitulum_ surrounded by an _involucre_, very similar to that of the Compositæ. The flowers are very small, unisexual, ♂ and ♀ often mixed indiscriminately in the same capitulum; they have the usual pentacyclic structure; the leaves of the inner perianth are often connate and more membranous than the outer; in some the outer series of stamens are suppressed; in each of the 3 loculi is one pendulous ovule. Capsule. The leaves are generally radical and grass-like.--335 species; _Eriocaulon_, _Paepalanthus_, etc., _E. septangulare_ on the west coast of Scotland, and Ireland, and in North America. Order 6. =Restiaceæ.= A small, especially S. African and S. Australian, xerophilous order (about 235 species), which is quite similar in habit to the Juncaceæ and Cyperaceæ. The leaves are often reduced to sheaths. The flowers are diœcious, the perianth as in _Juncus_, but the outer series of stamens suppressed. The ovary and fruit as in Eriocaulaceæ; the ovary, however, may be unilocular, and the fruit a nut. _Restio_, etc. Order 7. =Centrolepidaceæ.= These are the most reduced plants in the family; small grass- or rush-like herbs. The flowers are very small, naked. Stamens 1–2, carpels 1–∞. 32 species. Australia.--_Centrolepis_ (flowers generally ☿ with 1 stamen and 2–∞ carpels). Family 5. =Liliifloræ.= The flower is constructed on the general monocotyledonous type, with 5 alternating, 3-merous whorls (Fig. 278), but exceptions are found as in the Iridaceæ (Fig. 279) by the suppression of the _inner_ whorl of stamens; in a few the position in relation to the bract differs from that represented in Fig. 278, and in some instead of the trimerous, di- or tetramerous flowers are found (_e.g. Majanthemum_, _Paris_). Flowers generally _regular, hermaphrodite_, with simple, _petaloid_, coloured perianth (except, for example, Bromeliaceæ); ovary trilocular, generally with 2 ovules or 2 rows of ovules in the inner angle of each loculus (Fig. 304 _C_, _D_). _Endosperm_ always present.--A very natural family, of which some divisions in part overlap each other. The habit varies; the leaves are however long, entire, with parallel venation, except in Dioscoreaceæ (Fig. 313). In the first orders of this family the flowers are hypogynous, and in the first of all the styles are free, and the capsule dehisces septicidally; in the following the flowers are epigynous and in some reduced in number or unisexual; capsule with loculicidal dehiscence, or a berry. HYPOGYNOUS flowers: Colchicaceæ, Liliaceæ, Convallariaceæ, Bromeliaceæ (in part). EPIGYNOUS flowers: Amaryllidaceæ, Iridaceæ, Bromeliaceæ (in part), Dioscoreaceæ. Order 1. =Colchicaceæ.= The flower (Fig. 304 _A_) is ☿, regular, _hypogynous_, trimerous in all five whorls (6 _stamens_); anthers usually _extrorse_. Gynœceum with 3 _free styles_ (_A, D_); fruit a _capsule with septicidal dehiscence_ (_E_); embryo very small (_F_). The underground stem is generally a corm or rhizome, seldom a bulb. =A.= VERATREÆ.--_Veratrum_; perennial herbs, stem tall with long internodes and broad, folded leaves; the flowers andromonœcious, with free, widely opening perianth-leaves (Fig. 304 _A_), and globular anthers; inflorescence a panicle.--_Zygadenus, Melanthium, Schœnocaulon, Uvularia, Tricyrtis_. =B.= TOFIELDIEÆ.--_Narthecium_ and _Tofieldia_ have leaves alternate (arranged in two rows), sword-like and borne in rosettes; racemes or spikes. _Narthecium_ forms an exception to the order by having a simple style and fruit with loculicidal dehiscence; _Tofieldia_ by the introrse anthers. In this they are related to the Liliaceæ. _Narthecium_ has poisonous properties, like many other Colchicaceæ. [Illustration: FIG. 304.--_Veratrum_: _A_ flower; _B_ stamen; _C_ transverse section of ovary; _D_ gynœceum, with one carpel bisected longitudinally, and the third removed; _E_ fruit after dehiscence; _F_ longitudinal section of a seed.] =C.= COLCHICEÆ.--_Colchicum_ (Autumn Crocus); perennial herbs, with a long, _funnel-shaped, gamophyllous perianth_, and introrse anthers. The flowers of _C. autumnale_ spring up immediately from the underground stem, which is in reality a _corm_ formed of one internode. ~_Colchicum autumnale_ flowers in autumn without leaves; in spring the radical foliage-leaves appear simultaneously with the fruit. The flower is protogynous, and is pollinated by insects (humble-bees, etc.) which seek the honey secreted by the free part of the stamen a little way down the tube. The length of the tube protects the fruit, and not, as in other cases, the nectary.--_Bulbocodium_ and _Merendera_ have unguiculate perianth-leaves, free, but closing together like a tube.~ 175 species; chiefly in North America and South Africa. _Tofieldia_ is an Arctic plant. The order is rich in pungent, poisonous alkaloids (veratrin, colchicin, etc.). OFFICINAL; the seeds of _Colchicum autumnale_ (Europe) and _Schœnocaulon officinale_ (Mexico), and the rhizome of _Veratrum album_ (mountains of Central Europe). [Illustration: FIG. 305.--_Colchicum autumnale. A_ Corm seen from the front: _k_ corm; _s′ s″_ scale-leaves embracing the flower-stalk; _wh_ base of flower-stalk with roots (_w_). _B_ Longitudinal section of corm and flower-stalk: _hh_ brown membrane surrounding the underground portion of the plant; _st_ flower-and leaf-stalk of previous year, the swollen basal portion forming the reservoir of reserve material. The new plant is a lateral shoot from the base of the corm (_k_) and has the following parts: the base bearing the roots (_w_), the central part (_k’_) which becomes the corm in the next year, the axis bearing the scale-leaves (_s’, s″_), the foliage-leaves (_l, l′″_), and the flowers (_b, b’_) which are borne in the axils of the uppermost foliage-leaves.] Order 2. =Liliaceæ (Lilies).= Flowers as in the Colchicaceæ but with _introrse_ anthers; _ovary free, 3-locular, with single style; capsule_ 3-locular with _loculicidal_ dehiscence.--The majority are herbs with _bulbs_; the inflorescence is _terminal_. In many species reproduction takes place by means of bulbils (small bulbs) formed in the axils of the foliage-leaves (_e.g. Lilium bulbiferum_, _lancifolium_, etc., _Gagea lancifolia_, etc.), or in the bracts of the inflorescence (many species of _Allium_); in many species several buds are developed as bulbs in the axils of the bulb-scales themselves (accessory buds arising close together), and in some the formation of buds is common on the leaves. =A.= TULIPEÆ, TULIP GROUP. Bulbs. The aerial, elongated stem bears the foliage-leaves. Flowers few but generally large, with free perianth-leaves. _Tulipa_; style absent, no honey; flowers generally solitary, erect.--_Fritillaria_ perianth campanulate with a round or oblong nectary at the base of each perianth-leaf.--_Lilium_; perianth widely open, generally turned back with a covered nectary-groove in the centre of each segment. Anthers versatile.--_Lloydia; Erythronium._ =B.= HYACINTHEÆ, HYACINTH GROUP. Bulbs. Leaves radical; aerial stem leafless with raceme or spike. In some the perianth-segments are free, in others united. Honey is produced often in glands or in the septa of the ovary (septal glands).--_Ornithogalum_ has a leafy stem; _Scilla_; _Eucomis_ has a tuft of floral-leaves above the raceme; _Agraphis_; _Hyacinthus_; _Puschkinia_; _Chionodoxa_; _Muscari_; _Veltheimia_; _Urginea_. =C.= ALLIEÆ, ONION GROUP. Generally bulbs. Leaves radical. Stem leafless with a compound umbellate or capitate inflorescence of unipared helicoid cymes, which before flowering are surrounded by two broad involucral leaves.--~_Allium._ Filaments often petaloid and bidentate; in many species bulbils are found in the inflorescence.--Some species have flat leaves: _A. sativum_, Garlic; _A. porrum_, Leek; _A. ursinum_; others have round, hollow leaves: _A. cepa_, Onion; _A. fistulosum_, Winter Onion; _A. ascalonicum_, Eschalot; _A. schænoprasum_, Chive.~--_Gagea_; honey is secreted at the base of the perianth, no special nectary; inflorescence few-flowered.--_Agapanthus; Triteleia._ =D.= ANTHERICEÆ. Rhizome; raceme; the leaves not fleshy and thick.--_Anthericum_; _Asphodelus_; _Bulbine_; _Chlorophytum_; _Bowiea_ has an almost leafless stem with curved, climbing branches. =E.= ALOINEÆ, ALOES. Stem generally aerial and tree-like, bearing on its summit thick, fleshy leaves, often with a thorny edge (Fig. 306). Raceme branched or unbranched.--_Aloë_; _Gasteria_; _Yucca_ (has secondary thickening, p. 274). =F.= HEMEROCALLIDEÆ. _Phormium_, (_Ph. tenax._ New Zealand Flax); _Funckia_ (_Hosta_); _Hemerocallis_. At this point the following are best placed: _Aphyllanthes_ (_A. monspeliensis_); _Xanthorrhæa_ (Black-boy); _Xerotes_; _Lomandra_; _Kingia_; the very membranous, dry perianth of the last resembles that of the Juncaceæ, and also there are only 1–few ovules in the loculi. POLLINATION by insects. Honey in some is produced on the perianth (see Tulipeæ), in others by glands on the carpels (in the septa and parietal placentæ, septal glands): _Hyacinthus_, _Allium_, _Anthericum_, _Asphodelus_, _Yucca_, _Funckia_, _Hemerocallis_, etc. Some _Allium_-species are protandrous. _Fritillaria_ is visited by bees, _Lilium martagon_ by moths, _L. bulbiferum_ by butterflies, _Phormium_ (New Zealand) by honey-birds. [Illustration: FIG. 306.--Aloë.] About 1,580 species; rare in cold climates; their home is in sunny plains with firm, hard soil, and warm or mild climate, particularly in the Old World (S. Africa; As. Steppes; Mediterranean); at the commencement of spring the flowers appear in great profusion, and after the course of a few weeks disappear; during the hot season their life lies dormant in the bulb, hidden underground. The woody species are tropical.--The majority of the _introduced_ Liliaceæ (_Fritillaria imperialis_, Crown-imperial; _Lilium candidum_; _Tulipa gesneriana_; Hyacinth; _Muscari_-species; _Scilla_-species; _Ornithogalum nutans_; _Hemerocallis fulva_ and _flava_; _Asphodelus luteus_ and _albus_) come from the Mediterranean and W. Asia; _Funckia_ from China and Japan; several Lilies from Japan and the Himalayas; _Agapanthus_ from the Cape; _Allium sativum_ is a native of the Kerghis-Steppes; _A. cepa_ from Persia (?); _A. ascalonicum_ is not known wild (according to others a native of Asia Minor), perhaps a form of _A. cepa_; _A. schænoprasum_ from the N. temp. region. Many bulbs have pungent properties; many Onions are used as culinary plants. The bast fibres of _Phormium tenax_ (New Zealand Flax) are used technically. Dyes are obtained from the _Aloe_; gum for varnish from the stem of _Xanthorrhæa hostile_ and _australe_. OFFICINAL; “Aloes,” the dried sap of S. African species of _Aloe_ (_A. Africana_, _A. ferox_, etc.); the bulb known as “Squills” from _Urginea_ (_Scilla_) _maritima_ (Mediterranean). Order 3. =Convallariaceæ.= This order differs from the Liliaceæ in having the _fruit a berry_ (Fig. 308) and _in never being bulbous_; the seeds are less numerous. =A.= CONVALLARIEÆ, LILY OF THE VALLEY GROUP. Rhizome (Fig. 307) and normal foliage-leaves.--_Polygonatum_: rhizome creeping; aerial shoot leafy, bearing the flowers in racemes in the axils of the foliage-leaves; perianth tubular. _P. multiflorum_ (Solomon’s seal), _P. officinale_, etc.--_Majanthemum_: flower 2-merous; perianth almost polyphyllous, spreading. _Smilacina. Streptopus_ (_S. amplexifolius_; the flowers or inflorescence unite with the entire succeeding internode).--_Convallaria_ (1 species _C. majalis_, Lily of the valley); flowers in terminal racemes; 2 basal foliage-leaves; perianth globose, bell-shaped. _Reineckea carnea_ (Japan, China) in gardens.--_Paris_ (_P. quadrifolia_, Herb-Paris); flowers solitary, terminal, 4-merous, polyphyllous; styles 4, free (approaching the Colchicaceæ; it is also poisonous); a whorl of 4 (-more) 3-nerved, reticulate leaves on each shoot.--Ornamental plants: species of _Trillium_, _Aspidistra elatior_ (Japan). [Illustration: FIG. 307.--Rhizome of _Polygonatum multiflorum_: _a_ bud; _b_ shoot; _c d_ scars left by shoots of previous years.] [Illustration: FIG. 308.--_Smilax pseudosyphilitica_: _A_ shoot of male plant; _C_ ♂-flower; _D_ berry, almost ripe; _E_ the same in longitudinal section. _B Smilax syphilitica_: portion of branch with base of leaf and tendrils.] =B.= ASPARAGEÆ, ASPARAGUS GROUP. Scale-like leaves and green assimilating branches.--_Asparagus_: horizontal rhizome. The aerial shoots are very richly branched; the numerous needle-like bodies upon the plant are _leafless shoots_, which are crowded together in double scorpioid cymes in the axils of the scale-leaves; the two first lateral axes, placed outside to the left and right, generally bear flowers. Polygamous.--~_Ruscus_ (Butcher’s broom) is a S. European _shrub_ with _leaf-like_, ovoid or elliptical shoots (phylloclades) which are borne in the axils of scale-like leaves, and bear flowers on the central line. Diœcious. Stamens 3, united, anthers extrorse. _Semele androgyna_ bears its flowers on the edge of the flat shoot.~ =C.= SMILACEÆ. _Smilax_ (Sarsaparilla) (Fig. 308); _climbing_ shrubs with the leaf-sheath produced into tendrils. The leaves have 3–5 strong nerves proceeding from the base, and are reticulate. Orthotropous or semi-anatropous ovules. Diœcious (Fig. 308 _C_, _E_). =D.= DRACÆNEÆ. Fruit in some a berry, in others a capsule. The stem of DRACÆNA, when old, has the appearance of being dichotomously branched; it has the power of increase in thickness, and may become enormously thick. The Dragon-tree of Teneriffe, measured by Humboldt, attained a circumference of 14 m. and a height of 22 m.; the leaves are large, linear or linear-lanceolate.--_Cordyline_ (East Asia), various species in gardens and greenhouses (_Yucca_ is closely allied). _Astelia._ POLLINATION. _Paris quadrifolia_ and _Convallaria majalis_ have no honey, and are chiefly visited by pollen-collecting bees (in the absence of insect visits self-pollination takes place); _Polygonatum multiflorum_ has honey secreted by septal glands and protected by the base of the tubular perianth; it is pollinated by humble-bees, etc. _Asparagus officinalis_ has small, polygamous, greenish, honey-bearing flowers; the ♂-flower is almost twice as large as the ♀; both have rudiments of the opposite sex. About 555 species; especially from N. America, Europe, and Central Asia. OFFICINAL: “Dragons’-blood,” a red resinous juice from the stem of _Dracæna_ and the roots of some Central American species of _Smilax_. The tuberous stems of the Eastern Asiatic _Smilax glabra_ are officinal. The flowers of _Convallaria majalis_ have been lately used as a substitute for _Digitalis_. Pungent, poisonous properties are possessed by _Paris_. None of the species are used as food, except the young annual shoots of _Asparagus officinalis_, a shore-plant which is used as a vegetable. Order 4. =Pontederiaceæ.= Flowers generally zygomorphic, hypogynous, ☿, with handsome, white or violet, petaloid perianth which forms a tube at its base. The stamens are inserted at different heights in the perianth-tube, and are reduced to three (in _Heteranthera_ seldom to one). In some the ovary is trilocular with ∞ ovules (_Eichhornia_), in others reduced to one loculus with one ovule (_Pontederia_). Fruit a capsule or nut. Embryo as long as the abundant, mealy endosperm.--Tropical water-plants (22 species) with peculiar sympodial branching, nearly the same as in _Zostera_. Spikes without floral-leaves. Many intercellular spaces in the stem and leaf.--In greenhouses: _Eichhornia azurea_, _E. crassipes_ (both from tropical and sub-tropical S. America); the latter has swollen petioles which serve as floats and enable it to float freely on the water, sending down its roots into the mud. _Heteranthera reniformis, H. zosterifolia. Pontederia cordata._ Order 5. =Amaryllidaceæ (Narcissi).= The flower is _epigynous_, otherwise exactly the same as in the Liliaceæ (6 stamens). The majority, like these, are also _perennial_ herbs with bulbs and scapes. The fruit and the other characters as in the Liliaceæ. The external appearance is, however, very different. =A.= AMARYLLEÆ have bulbs and the leaves generally arranged in two rows; the flowers are borne singly or in umbel-like inflorescences on lateral scapes, while the main axis of the bulb is unlimited. Beneath the inflorescence is an _involucre_ (Fig. 309).--_Galanthus_, Snowdrop, has a polyphyllous perianth without corona; the three inner perianth-leaves are emarginate and shorter than the outer; the anthers dehisce apically. ~_Leucojum_ differs in having the perianth-leaves equal in length.--_Amaryllis_ has a funnel-shaped perianth, entirely or nearly polyphyllous, but somewhat zygomorphic. _Crinum; Hæmanthus; Clivia._~--_Narcissus_ has a tubular _corona_, a ligular structure arising from the perianth-tube exterior to the outer stamens. ~In _Pancratium_ (Fig. 309) the corona is united with the filaments which appear to spring from its edge. _Eucharis amazonica._~ [Illustration: FIG. 309.--_Pancratium caribæum._] =B.= HYPOXIDEÆ. The leaves, which are grass-like, dry, folded, and in some hairy, spring from a rhizome, generally with a divergence of 1/3. Flowers small, perianth polyphyllous, persistent, on which account perhaps the Hypoxideæ may be considered as the least altered type. The chief characteristic is that the embryo is separated from the hilum. _Hypoxis_; _Curculigo_ (_C. recurvata_, a favourite ornamental plant; S.E. Asia). =C.= ALSTRŒMERIEÆ. (_Alstrœmeria_, _Bomarea_); stems long, leafy, often climbing. =D.= VELLOSIEÆ (_Vellosia_, _Barbacenia_); stem woody, usually dichotomously branched, with terminal, single flowers; it bears numerous aerial roots which pierce the leaves and surround the stem. Stamens often (by splitting) 6–18. High table-lands of S. America and S. Africa. =E.= AGAVEÆ. Very similar to the Bromeliaceæ both in their distribution (nearly all American) and in external appearance. They appear as gigantic bulbous plants with perennial, aerial, generally short stem, and perennial, large, lanceolate or linear, stiff, thick, and often thorny leaves, which form a large rosette; after the course of several (8–20) years the terminal inflorescence is developed, which is 10–12 m. high, paniculate, and freely branched. Before the inflorescence expands, a large quantity of sugar-containing sap is collected from _A. americana_ by removing the terminal bud; this on distillation yields “pulque,” the national drink of Mexico. After flowering the entire shoot dies, but the subterranean lateral shoots survive and reproduce the plant.--_Agave americana_, etc.; _Fourcroya_; _Polianthes tuberosa_ (Tuberose; Central America). DISTRIBUTION. The 650 species are chiefly natives of S. Africa and S. America. _Clivia_, _Hæmanthus_, _Amaryllis_ are from the Cape; _Narcissus_ from S. Europe, whence many species have been introduced; _Galanthus_ and _Leucojum_ are especially from S. and Central Europe, and from the Caucasus. USES, few, except as ornamental plants: _Galanthus nivalis_; _Leucojum_; _Narcissus pseudonarcissus_, _N. poeticus_, _N. jonquilla_, _N. tazetta_, etc.; _Amaryllis_, _Alstrœmeria_, _Eucharis_, _Crinum_, _Vallota_, etc. The vascular bundles of the various species of _Agave_ (_Agave rigida_, var. _sisalana_, sisal hemp,) are used for cordage, etc. Order 6. =Bromeliaceæ.= The flowers are hypogynous, epigynous or semi-epigynous; the perianth is divided into _calyx_ and _corolla_; stamens 6. The fruit is a capsule or berry with many seeds. Endosperm _mealy_, embryo small, at the edge of the endosperm, but not enclosed by it. [Illustration: FIG. 310.--_Aechmea miniata._] [Illustration: FIG. 311.--Multiple-fruit of _Ananassa sativa_.] Perennial herbs with a very _characteristic appearance_ (Fig. 310); the stem is most often short, thick, and crowned by a _rosette_ of many leaves, which are long, often very narrow, _leathery_, stiff, and with a _spiny_ edge; they are usually channeled, completely closing round each other, with their edges forming a tightly closed hollow, in which generally water is collected (this among other things insulates the inflorescence and thus prevents the access of creeping insects, such as ants). The presence of numerous stellate, water-containing hairs often gives the leaves a grey appearance, and the layers of cells beneath the upper epidermis of the lamina form an “aqueous tissue,” which serves as a protection against the rays of the sun and regulates the evaporation. The stomata are often situated in furrows on the underside of the leaf, and hence cause a striped appearance. They _are all American_ (525 species), especially from S. America, where they live partly as epiphytes _on trees_, partly in the _clefts of rocks_, often on the steepest slopes, to which they firmly attach themselves by aerial roots; some are terrestrial. The stem is seldom tree-like or many metres in height (_Puya_, in Chili; _Hechtia_, in Mexico). _The inflorescence_ is a terminal spike, raceme, or panicle, often with large and brightly-coloured floral-leaves. The flowers are without scent. The seeds, in the species whose fruit is a capsule, are often provided with wings (hairs, expansions, etc).--_Ananassa sativa_, Pine-apple (W. Indies, Central America) is cultivated for the sake of its juicy, aromatic fruits, which coalesce with their fleshy bracts and form a large spike-like fruit-cluster (multiple-fruits,[29] Fig. 311) bearing on its apex a leafy shoot, which may be used as a cutting. Seeds very rarely developed.--_Tillandsia_ (_T. usneoides_ is a filamentous, richly branched, rootless epiphyte hanging in masses from trees; Trop. Am.), _Aechmea_, _Billbergia_, _Pitcairnia_, etc. USES. The leaves of the Pine-apple, in its native country, are used for the manufacture of cloth. Order 7. =Hæmodoraceæ.= 120 species; in all parts of the world except Europe; perennial, often tomentose and resembling the Bromeliaceæ, Iridaceæ and Amaryllidaceæ. _Hæmodorum_ (Australia).--To this order belong _Ophiopogon_, _Peliosanthes_, _Sanseviera_, and others. Order 8. The =Iridaceæ= have _epigynous_, hermaphrodite flowers with petaloid perianth as in the Amaryllidaceæ, but the _interior whorl of stamens is entirely suppressed_, and the 3 developed _outer_ stamens have _extrorse_ anthers (Fig. 279); there is 1 style with 3 large, generally _more or less leaf-like branches bearing the stigmas_. Ovary and capsule as in the Amaryllidaceæ and Liliaceæ.--Perennial herbs; _bulbs are rarely found_, but horizontal rhizomes, corms, etc., take their place. The leaves are (except _Crocus_) as in the _Iris_, _two-rowed_, _equitant_ and _sword-like_. Flowers or inflorescences terminal. The _Iris_ (Flag) has a horizontal rhizome. The flowers are borne in the leaf-axils in fan-like inflorescences (rhipidium). The branches of the style are large and _petaloid_; on their under surface may be seen a small projecting shelf (Fig. 312 _a_) having on its upper surface the stigmatic hairs. Beneath the branches of the style are 3 well protected stamens, and immediately outside these the external perianth-leaves. ~The honey is secreted in the perianth-tube, and the insects, endeavouring to obtain it through the narrow passages at the base of the stamens, settle upon the outer perianth-leaves, which are bent backwards and often very hairy along their central line. The insects then rub their backs on the anthers just above them, beneath the branches of the style; they readily deposit the pollen on the stigma of another flower as they enter it, but cannot do so in withdrawing, since the stigma is pushed back, and self-fertilisation is thus avoided. The stylar branches lie close to the outer perianth-leaves, which are just beneath them, or separated by a distance of only 6–10 mm.; the first form of flower is adapted for _Rhingia rostrata_, the latter for bees~.--_Crocus_ has vertical, _tuberous_, underground stems surrounded by the leaf-sheaths (corms), and terminal flowers; the linear leaves _are not equitant_, but have two longitudinal furrows on the under side. The perianth is gamophyllous and funnel-shaped. The stylar branches (stigmas) are fleshy, _rolled together in the shape of a horn_, and split along the edge.--_Gladiolus_ has corms like the _Crocus_; spikes with slightly zygomorphic, almost bilabiate flowers, most frequently turning to one side. Position of the leaves as in the Iris.--~_Diplarrhena_ has 2 fertile and 1 barren stamen; _Hermodactylus_ has a unilocular ovary with 3 parietal placentæ. _Cypella_ and _Tigridia_ have bulbs.~ [Illustration: FIG. 312.--_Iris pseudacorus._ One external and two internal perianth-leaves, and one of the stylar-branches have been removed, _y_ The outer, _i_ the inner perianth-leaves; _g_ stylar-branch; _a_ stigma; _s_ anther. The ovary is seen in longitudinal section.] 770 species; chiefly in the countries round the Mediterranean, and in Africa, especially the Cape (_Gladiolus_, _Ferraria_, _Moræa_, _Galaxia_, _Sparaxis_, _Antholyza_, _Tritonia_, _Ixia_, etc.), Australia and Tropical America (_Sisyrinchium_, _Tigridia_, _Cipura_, _Cypella_, etc). A great number are ornamental plants: the cultivated _Crocus_-species are from the South of Europe and Asia; _Gladiolus communis_ from S. Europe; the other species principally from S. Africa. The native species of _Iris_ are _I. pseudacorus_ (yellow) and _I. fœtidissima_. OFFICINAL: the stigmas of _Crocus sativus_ (Oriental, cultivated in France, Spain, Italy, and Austria), used as a colouring matter, saffron; the rhizomes of the S. European _Iris florentina_, _pallida_, and _germanica_ (“Orris-root”). [Illustration: FIG. 313.--_Dioscorea batatas_: _A_ ♂-plant; _B_ ♂-flower; _C_ ♀-plant (nat. size); _D_, _E_ ♀-flowers (mag.); _F_ seed; _G_ embryo.] Order 9. =Dioscoreaceæ.= Perennial herbs with fleshy, often very large _tuberous rhizomes_ (or roots); _twining_ stems; leaves stalked, often arrow- or heart-shaped, lobed, _palminerved_ and _finely reticulate_ as in the Dicotyledons (Fig. 313). The flower is _diclinous_ (most frequently _diœcious_), regular, _epigynous_, _small_, and of a _greenish colour_, but otherwise typical (Pr3 + 3, and A3 + 3, or G3); in most instances 2 ovules are placed one above the other in each loculus. The inflorescence is a _spike_ or _raceme_, sometimes richly branched and paniculate.--The order approaches most nearly to the Amaryllidaceæ. _Tamus_ (Bryony) has a berry, _Dioscorea_ (Yam) a thin-walled, 3-edged or 3-winged capsule (Fig. 313). Both have subterranean or aerial tubers; the Yam very often also developes tubers in the axils of the foliage-leaves; tuberous roots are said to occur in _D. batatas_. The tubers of many species of Yams (_D. batatas_ from China and Japan, _D. alata_, South Sea Islands and India, _D. bulbifera_) are a very important source of food in the Tropics, especially the first-named.--_Testudinaria_; _Rajania_.--~The tuberous stem of _Tamus communis_ and _Testudinaria elephantipes_, and some species of _Dioscorea_ is formed from one single internode (epicotyl), and the aerial shoots are developed from adventitious buds; in _T. elephantipes_ the stem is aerial, and covered with thick scales of cork, regularly arranged, and separated by grooves.~ Tropical order (167 species); 2 species (_Tamus communis_ and _Borderea pyrenaica_) in Europe. Family 6. =Scitamineæ.= The flowers belong to the ordinary monocotyledonous type. They are hermaphrodite, _epigynous_, and have either a petaloid perianth, or calyx and corolla; they are, however, _zygomorphic_ or _unsymmetrical_, and of the stamens most frequently only one is _completely developed_, the others being generally represented by petaloid staminodes. The ovary has 3 loculi, more rarely it is unilocular with the suppression of 2 loculi. Endosperm is absent (except _Zingiberaceæ_); but, on the other hand, there is a _large perisperm_. To this family belong large, glabrous, especially _perennial herbs_ with rhizomes; leaves large, distinctly divided into sheath, stalk, and blade, the latter being more or less elliptical or lanceolate, entire, with pinnate venation, and always with a very _well-pronounced midrib_, gradually tapering towards the apex, and giving off numerous branches, which run outwards, towards the margin, at a larger or smaller angle; these _lateral veins_ are closely packed, and parallel, but with only weak, connecting branches between them; the leaves, therefore, are easily torn pinnately (Figs. 314, 317). The leaf-sheaths close tightly round each other and form a false stem. This very natural family comprises orders closely connected with each other, but is not itself nearly allied to any other family. First in the series stands:-- Order 1. =Musaceæ.= The _petaloid_ perianth is strongly zygomorphic, the anterior leaf being very large (a kind of “labellum”), the posterior one small; only the posterior stamen is wanting, or is rudimentary, the other five are developed, and have quadrilocular anthers; ovary, 3-locular. Seed with straight embryo in mealy perisperm. [Illustration: FIG. 314.--Two _Musa_-species.] The best-known genus is _Musa_, the Banana (Fig. 314). From the short rhizome arise enormously large, spirally-placed leaves, whose sheaths envelope one another, and form an apparently aerial stem, several metres in height. The inflorescence is a terminal _spike_ with floral-leaves placed spirally, and sometimes magnificently coloured; in the axils of each of these several flowers are situated in two transverse rows (accessory buds); the lowest flowers in the inflorescence are ♀, the central ones ☿, the upper ones ♂, so that fruits are only found in the lower region of the inflorescence, the remaining portion persisting as a naked axis after the floral-leaves and flowers have fallen off; the inflorescence terminates in an ovoid bud formed by the flowers which have not yet opened (Fig. 314, the left-hand figure). The perianth-leaves are united (except the posterior one). The fruit (known as a “Banana”) is a _berry_, having the form of a smooth, short, three-cornered Cucumber (as much as 30 cm. in length); inside the tough skin is found a farinaceous, aromatic pulp. No seed is developed in the cultivated species.--~Several _Musa_-species are cultivated in the Tropics for the sake of the fruit (_M. paradisiaca_, _M. sapientum_); for the fibrovascular bundles, _M. textilis_ (Manilla Hemp).--Their home is, no doubt, the Tropics of the Old World; they were introduced into America before the arrival of Europeans. _Musa ensete_ has dry, leathery fruits; an ornamental plant.~ In _Musa_ the barren, posterior stamen belongs to the inner whorl; and also in _Strelitzia_ and _Ravenala_; the latter may have all 6 stamens developed. In _Heliconia_, on the contrary, it belongs to the outer whorl; in _Heliconia_ the perianth-leaves are differently arranged, and there is only one ovule in each loculus. The three latter genera have dry fruits and leaves arranged in two rows. In the “Travellers’ Palm” (_Ravenala madagascariensis_) the foliage-leaves form an enormous fan.--Tropical; about 50 species. The order may be divided as follows:--1. Museæ: _Musa_, _Ravenala_, _Strelitzia_ in the Old World. 2. Heliconiæ: _Heliconia_ in the New World. [Illustration: FIG. 315.--Diagram of a _Zingiberaceous_ flower (_Kæmpferia ovalifolia_): _b_ bract; _v_ bracteole; _k_ calyx; _p^1_, _p^2_, _p^3_ the petals; _sst_, lateral staminodes (“wings”); _lab_ labellum (formed of two staminodes); _st_ the fertile stamen; * position of suppressed stamen. The ovary is in the centre of the diagram.] Order 2. =Zingiberaceæ.= Perianth most frequently divided into _calyx_ and _corolla_. Calyx gamosepalous. Only 1 _fertile stamen_ (the posterior, Fig. 315, belonging to the inner whorl) with quadrilocular anther, which encloses the style in a furrow; the 2 stamens in the outer whorl are staminodes, the median one (the anterior) is wanting. The 2 lateral staminodes of the inner whorl form the “labellum” (Fig. 315 _lab_), which usually is the largest segment of the flower, and is often bilobed. Ovules many. The fruit in some is a leathery, 3-valved capsule, with loculicidal dehiscence; in others it is more or less berry-like and indehiscent, or irregularly dehiscent. Straight embryo.--The aerial stem is seldom developed to any extent, and the inflorescences, which are (compound) spikes or racemes, often with coloured floral-leaves, spring in some (_e.g. Zingiber officinale_) directly from the rhizome. The leaves are arranged in two rows.--The ovary in a few instances (_Globba_ and others) is unilocular, with 3 parietal placentæ. They are perennial herbs with fleshy and tuberous rhizomes, which are used as condiments and in medicine on account of their pungent and aromatic properties and also for starch, dyes, etc. OFFICINAL: _rhizomes_ of _Zingiber officinale_ (Ginger, unknown wild, but cultivated generally in the Tropics), of _Curcuma longa_ (Turmeric, a dye, E. India) and _C. zedoaria_, of _C. angustifolia_ and others (as E. India Arrowroot), of _Alpinia officinarum_, China (galangal). “Preserved Ginger” from _Alpinia galanga_. Similar aromatic materials (volatile oils) are present also, for example, in _the fruits_; Cardamom fruits and seeds (from _Elettaria cardamomum_, China, seldom from _E. major_). 315 species; Tropics, preponderating in the Eastern Hemisphere, India, and especially S. Asia, whence all the aromatic species originate; they are now commonly cultivated in the Tropics. Some are ornamental plants in greenhouses, _e.g._ _Hedychium_, _Costus_, etc. _Globba_ (with axillary buds in the inflorescence, as in _Ficaria_), _Renealmia_, _Kæmpferia_. [Illustration: FIG. 316.--Flower of _Canna_: _f_ ovary; _pa_ calyx; _pi_ corolla; _l_ labellum; _st_ stamens; _an_ anther; _g_ stigma; α and β staminodes.] Order 3. =Cannaceæ.= American herbs without aromatic properties. Flowers asymmetric (Fig. 316). Calyx polysepalous. The stamens are _petaloid_ (Fig. 316 _st_) and barren with the exception of one (the posterior), which bears on one of its _edges_ a bilocular anther; another, which is especially large and coloured, is termed the _labellum_. The style is compressed and leaf-like, with a small stigma at the apex. Ovules numerous in the 3 loculi. The capsule is furnished with warts or soft prickles. _Embryo straight._ _Canna_ (30 species; Trop. Am.). The inflorescence is a terminal spike with 2-flowered unipared scorpioid cymes in the axils of the floral-leaves. Ornamental plants: _Canna indica_, etc. The diagram of the andrœcium of the Cannaceæ and Marantaceæ may be represented in the following manner (calyx, corolla and gynœceum being omitted):-- CANNACEÆ. MARANTACEÆ. _w_ _w_ _w_ _w_ _st_ _st_ _w_ _lab_ _wi_ _c_ * * _w_ The lateral staminodes, “wings;” _st_ fertile stamen; * the suppressed stamen; _lab_ labellum; _c_ hood; _wi_ inner-wing. The labellum of the Cannaceæ corresponds with the hood of the Marantaceæ and not with the labellum of the Zingiberaceæ. [Illustration: FIG. 317.--_Calathea zebrina._] Order 4. =Marantaceæ.= The flower is asymmetrical. Only 1 or 2 of the 3 stamens in the outer whorl are present as staminodes; in the inner whorl 2 are petaloid and of the sixth stamen one-half is developed as a staminode and the other half bears a bilocular anther. One ovule only in each loculus. The style is strongly curved and at first enclosed in one of the staminodes (hood) of the inner whorl; later on it springs elastically forward towards the other staminode (inner-wing) of the same whorl. The stigma is very oblique or 2-lipped. Two of the three loculi of the ovary, in some (_Maranta_, _Thalia_) become small and empty. Embryo _curved_. Leaves in two rows, with sheath, stalk, and blade (Fig. 317); at the base of the last is a _characteristic swelling_ (_articulus_).--~_Phrynium_, _Calathea_, _Stromanthe_, _Ctenanthe_, _Saranthe_, etc. About 150 species; tropical, especially America. The starch of the rhizome of _Maranta arundinacea_ is OFFICINAL, “West Indian Arrowroot.”~ Family 7. =Gynandræ.= The flowers are hermaphrodite and constructed on the ordinary 3-merous, pentacyclic type with petaloid, _epigynous, strongly zygomorphic_ perianth, and generally _one-stamened_ by the suppression of the other 5 stamens. The family has derived its name from the fact that the stamen is united with the style into a “_stylar column_” (except _Burmanniaceæ_). All are herbs; many grow as epiphytes on other plants. This family and the Scitamineæ occupy correspondingly high positions among the Monocotyledons; these two families may therefore be placed close together, although one cannot be derived from the other. The first of the two orders is very small, but the second is very rich in species. The Apostasieæ are best classed with the Orchidaceæ and have no independent place. Order 1. =Burmanniaceæ.= This order forms a transitional link between the Gynandræ and the epigynous Liliifloræ (_Amaryllidaceæ_), in having a 6-leaved perianth, and 6–8 stamens; but some have a labiate perianth (the median perianth-leaf of the _outer_ whorl being very large). The ovary is most frequently unilocular with three parietal placentæ; but in some it is 3-locular with axile placentation. Capsule. Seeds ∞, small, with _endosperm_. The relationship to the Orchidaceæ is shown especially in the very imperfectly developed embryo and in the ovary. Small, tropical herbs (59 species); some are saprophytes. [Illustration: FIG. 318.--_A_ Diagram of an Orchid-flower. _B_, _Cephalanthera_. Stylar-column: _a_ anther; _s_ stigma; at the foot are seen scars indicating the position of the parts which have been removed.] Order 2. =Orchidaceæ.= The epigynous, petaloid perianth is strongly zygomorphic in having the _posterior_ leaf of the interior whorl, the _lip_ (labellum), differing from all the other leaves in form, size, and colour (except _Apostasieæ_); the position of the labellum is very frequently reversed, being turned _forwards and downwards_ by the twisting of the ovary (Fig. 318 _A_). _Only_ 1 of the stamens--the anterior of the external whorl--is developed and bears an anther (by the twisting of the ovary it is turned posteriorly and upwards); the others are entirely wanting (indicated by * in Fig. 318 _A_) or present as staminodes (Fig. 318 _A_, δ δ) (except _Apostasieæ_, _Cypripedileæ_); the filaments are united with the style to form a column (Fig. 318 _B_), the _stylar-column_[30] (_gynostemium_), and the anther (_a_) is thus placed on its apex and exactly behind or over the stigma (_s_). The anther is 4-locular; the pollen-grains do not separate (except _Apostasieæ_, _Cypripedileæ_) but remain united either in tetrads or in masses, which correspond to a pollen-mother-cell (Fig. 320 _C_, _D_, _E_); or the pollen-grains, formed in each of the two anther-halves, remain united and form one or a few wax-like masses (pollen-masses, pollinia). The 3 carpels form a _unilocular ovary_ with 3 parietal, deeply bifid placentæ (except _Apostasieæ_, _Selenipedilum_). Only the two lateral carpels are prolonged and developed into the stigma (Fig. 318 _B_, _s_), while the one lying in the median line, which is situated just within the anther (Fig. 318 _A_), becomes either rudimentary or developed into the “_rostellum_” (“a small beak”), on which the sticky bodies (_glandulæ_) arise; by aid of these the heavy, connected pollen-masses may be glued to the insects which visit the flower, and pollination is thus secured (in _Apostasieæ_ and _Cypripedileæ_ the 3 carpels each contribute to the formation of the stigma). The fruit is a _capsule_ which most often dehisces _by 6 valves_, 3 of which are broader and bear the placentæ, and 3 alternating with them are narrower and barren (except _Vanilla_). The very numerous and exceedingly small seeds have _no endosperm_, and have a somewhat _spherical embryo without any trace of external organs_. The testa is membranous and loose. The Orchids are _all perennial herbs_ with diverse habits and varying morphological structure (see the genera); the leaves are scattered, of the usual Liliaceous form, and the inflorescences in all cases are _racemes or spikes_ (sometimes branched), with subtending bracts, but without bracteoles. The forms which are the least modified are described first. =1.= APOSTASIEÆ. The perianth-leaves are almost alike and free. The column is straight, with 3 equally-developed stigmas. _Neuwiedia_ has 3 perfect stamens (1 median of the outer whorl, and 2 lateral of the inner whorl); _Apostasia_ has only 2 perfect (inner lateral) and one barren (the median of the outer whorl), which however may be entirely wanting. The 3 _posterior_ stamens are entirely suppressed. The pollen is powdery. The ovary is 3-locular with axile placenta. 7 species (Tropical East India, Australia). [Illustration: FIG. 319.--_Cypripedilum calceolus_: 1 front view of the flower; 2 lateral view, after the removal of all the perianth-leaves with the exception of the labellum, which has been divided longitudinally; 3 the stylar-column; _ov_ ovary; _s_-_s_ exterior, _p_ interior perianth; _p’_ the labellum; _a_ the two fertile stamens; _a’_ the staminode; _st_ the stigma; _i_ entrance for the insects; _ex_ exit.] =2.= CYPRIPEDILEÆ.[31] The flower is strongly zygomorphic with a large boat-shaped labellum. There are two perfect stamens belonging to the _inner_ whorl, and the median anterior (later on the posterior) stamen of the outer whorl is transformed into a large, barren, shield-shaped body (Fig. 319). _Selenipedilum_ has a 3-locular ovary, but _Cypripedilum_ (Ladies’-slipper) has a unilocular ovary with 3 parietal placentæ--the typical structure for the Orchids. The pollen-grains are _separate_ (not in tetrads) and all the 3 lobes of the stigma are constructed to receive them. This group is therefore, next to the Apostasieæ, the least modified among the Orchids; in all the following groups, one of the lobes of the stigma is differently developed from the others, and there is only one stamen.--Terrestial Orchids.--~The pollination of _C. calceolus_ is effected by the forcible entrance of insects into the boat-shaped labellum (Fig. 319 _p’_) at _i_, and their escape at _ex_ (in 2) where the anthers are situated; in this way the stigmas will first be touched and then the anthers. The pollen-grains are surrounded by a sticky mass in order that they may adhere to the insects.~ =3.= NEOTTIEÆ. The majority are terrestrial Orchids with creeping, sympodial rhizomes; the blades of the leaves are not detached from the stem at joints, and have convolute vernation. The anthers do not drop off, but persist in the withered condition; their _apex_ is brought in contact with the rostellum (acrotonous Orchids). The pollen-grains are united in _tetrads_, which, however, often hang loosely together in pollinia, attached to a sticky part of the rostellum (“adhesive disc”), so that they adhere to the insects, and are by them transferred to the stigmas. _Spiranthes. Listera_; _Neottia_. ~_N. nidus-avis_ (Bird’s-nest) is brown (it has little chlorophyll) in colour, has no foliage-leaves, and lives mainly as a saprophyte; the rhizome is studded with unbranched, fleshy roots which may form buds at their extremities.~--_Vanilla_ climbs by aerial roots. The fruit is fleshy and hardly opens, or does so irregularly.--_Epipactis_, _Cephalanthera_.--_Epipogon_ and _Limodorum_ are saprophytes without chlorophyll. [Illustration: FIG. 320.--A Flower of _Orchis maculata_ (front view): a stamen; _b_ the cup; _n_ the stigmas; _x_ staminodes; _sp_ the spur; _spe_ the entrance to it; _sm_-_sl_-_sl_ exterior perianth-leaves; _pm_ the labellum, and _pl_-_pl_ the other 2 interior perianth-leaves. _B-E Orchis mascula_: _B_ lateral view of the column; _C_ a pollinium with massulæ (_p_), caudicle (_c_) and adhesive disc (_d_); _D_ caudicles with the cup (_r_), front view; the latter is depressed so that the adhesive disc is seen lying inside it; _E_ a pollinium, more highly magnified; some massulæ are removed. _F Ophrys aranifera_: rostellum and the base of the anther-loculus; an adhesive disc is seen on the right.] =4.= OPHRYDEÆ. Anthers 2-locular, not falling off, on a very short column. The anther is united at _its base_ with the rostellum (_basitonous_ Orchids, Fig. 320 _A_, _B_), while in all other Orchids it is connected at the apex (acrotonous Orchids). The pollen-grains in each loculus are united into small “masses” (massulæ), each of which corresponds to a pollen-mother-cell in the anther, and which hang together by elastic threads (Fig. 320 _C_, _E_). Each pollinium is attached at the base by a stalk (caudicle) to an adhesive disc, formed by the modified stigma (rostellum), and is easily liberated from it (Fig. 320 _C_, _D_, _F_). The pollinium, which is formed in an anther-loculus, together with its caudicle and adhesive disc, is termed “pollinarium” (Fig. 320 _C_).--All Ophrydeæ are terrestrial with _tuberous roots_, two of which are present in the flowering period, an older one (from the preceding year) containing the nourishment for the flowering-shoot of the year, and a young one which is intended to contain the reserve material for the following year. Inflorescence terminal. _Orchis._ The lip has a spur; each of the club-like pollinia is attached to its own adhesive disc, the discs being enclosed in a common pouch formed by the rostellum (Fig. 320 _C_, _D_). ~Tubers ovate, undivided: _O. morio_, _mascula_; tubers palmate: _O. incarnata_, _maculata_, _majalis_.~--_Ophrys_; no spur, the two adhesive discs are each enclosed in a separate pouch (Fig. 320 _F_).--_Anacamptis_ and _Serapias_ have one adhesive disc.--_Habenaria_, _Gymnadenia_, _Platanthera_, _Herminium_, _Nigritella_, _Cœloglossum_, etc., have naked adhesive discs (no rostellum). =5.= EPIDENDREÆ. Acrotonous Orchids with deciduous anthers (except _Malaxis_); 2-8 wax-like pollinia, with or without caudicles; generally no adhesive discs. _Malaxis_ (the flower is twisted through a complete circle, causing the labellum to be turned upwards), _Sturmia_ and _Corallorhiza_[32] (Coral-root); the latter has a creeping, coral-like rhizome _without roots, and is destitute of chlorophyll_ except in the ovary. The other two somewhat resemble the tropical Orchids in having the lower internodes of the axis of the inflorescence tuberous. _Liparis_; _Calypso_. Most of the genera are tropical epiphytes and many have aerial, green tubers formed from one or more stem-internodes; _Dendrobium_, _Eria_, _Phaius_, _Bletia_, _Epidendrum_, _Cattleya_, _Lælia_, _Pleurothallis_, _Restrepia_, _Masdevallia_, _Bulbophyllum_, etc. =6.= VANDEÆ. These resemble the preceding but have only 2 wax-like pollinia in each anther, which are attached by a caudicle to the adhesive disc of the rostellum. Nearly all are tropical epiphytes. _Stanhopea_, _Catasetum_, _Maxillaria_, _Oncidium_, _Vanda_, _Polystachya_, etc. 6,000 (10,000?) species. The majority live in the Tropics and occur, especially, as epiphytes on trees or in the crevices of rocks, to which they are attached by aerial roots. These _aerial roots_, like those of Araceæ, are covered by several layers of spirally-thickened cells (tracheides) which contain air and form the velamen--an apparatus to absorb moisture from the air. The roots have a white appearance when the cells are filled with air, which changes to a greenish hue when they are filled with water, the chlorophyll then shining through. They generally have horizontal rhizomes; the ascending shoots, which bear the foliage-leaves, may vary, but they very often swell and assume the form of a tuber, which persists for several years fresh and green after the leaves have fallen off (Fig. 321). _Vanilla_ is an exception (see above). Our Orchids are all terrestrial (or marsh-plants); the largest number of species is found in calcareous soils. POLLINATION takes place principally by means of insects, but self-pollination occurs in some. The lip serves as a landing-stage for the insect visitors, which, on sucking the honey, cause the adhesive discs, with the pollinia attached to them, to adhere to their bodies (generally to the probosces) and so carry them away to other flowers. In some species parts of the flower are sensitive or irritable, which has some connection with the pollination. Without doubt there are a great many biological differences which are closely connected with the infinite multiplicity of forms; Darwin (1862) has already shown an enormous variety, never even dreamt of before, in the European species. The genus _Catasetum_ has ♂-♀-and ☿-plants with flowers of such different appearances that they have been classed in various genera (_Myanthus_, _Monacanthus_). _Platanthera_ is pollinated by hawk-moths; _Ophrys_, by flies; _Epipactis latifolia_, by wasps; _Orchis_, by bees, especially humble-bees, etc. [Illustration: FIG. 321.--_Chysis bractescens._] The DISTRIBUTION OF SEEDS is effected by the wind, the seeds being so exceedingly small and light. Many species moreover have peculiar, elater-like, fine, hygroscopic hairs in the ovary, which eject the seeds in a manner similar to the elaters of the Liverworts. The USES are few, mostly as ornamental plants in conservatories. The tubers of several _Orchis_-species are OFFICINAL; they contain starch and mucilage and are used us “salep.” The fruits of _Vanilla planifolia_ are used as condiments and differ from other _Orchid_-fruits in being rather fleshy and in dehiscing irregularly; the seeds are very small, shining and black. Class II. =Dicotyledones.= In this class THE EMBRYO has 2 seed-leaves, a rule from which there are few exceptions (_e.g. Ficaria_, _Cyclamen_, _Pinguicula_, certain species of _Corydalis_, with only 1; and a few, mostly parasitic forms, _e.g. Monotropa_, _Orobanche_, _Pyrola_, entirely without cotyledons). On germination the cotyledons nearly always raise themselves above the ground as green, assimilating leaves and are then termed aerial or epigean, in contradistinction to the underground or hypogean which are always buried. The structure of the seed varies (endospermous or exendospermous); the embryo may be straight or curved. In many instances the primary root grows as a vigorous tap-root, with weaker branches arising acropetally (in annuals, biennials, many perennials, especially woody plants); but in a large number of herbaceous perennials, which have rhizomes, the root behaves very much as in the Monocotyledons. The roots generally increase in thickness by means of a cambium. THE STEM, when seen in transverse section, has its vascular bundles arranged in a ring; in reality, however, they form a kind of cylindrical network in the stem; the bundles are open, and thickening takes place by means of a cambium; annual rings are formed in the perennial stems. There is a rich and very varied form of _branching_. The two first leaves of a shoot (fore-leaves) are placed nearly always to the right and to the left; the same arrangement is found in the two first leaves developed on the flower-stalk, and these are, as a rule, the only two; they are found below the calyx and are usually termed the “_bracteoles_.” It has become customary to indicate the bracteoles by the letters α and β, according to their sequence of growth, and in that sense these letters will be employed in the following diagrams. THE ARRANGEMENT OF THE LEAVES varies very much; there is also a great variety of shapes in the leaves and their venation, but the linear leaves, with parallel venation, so frequent in the Monocotyledons, are seldom met with, as also the large sheaths (though the sheath is well developed in the Umbelliferous plants); stipules occur much more frequently. THE FLOWER is most commonly cyclic, but acyclic or hemicyclic forms also occur. The type which may be taken as a basis consists in the majority of instances, as in the Monocotyledons, of 5 whorls, of which the 4 outer ones (calyx, corolla, and the 2 whorls of stamens) are most frequently 4 or 5 in number and placed in regular alternation, whilst the innermost one (the carpels) has generally fewer members, probably on account of space (Figs. 360, 361, 421, 429, 487, etc.). Trimerous (Figs. 384, 387, etc.) flowers, or those in which the members of the flower are in threes or a multiple of three, also occur, as well as dimerous flowers; other numbers are rare. It is of the greatest importance in connection with the relative position of the members of the flower to the axis and bract (orientation), whether the bracteoles are typically present (even though they may not be developed), or are typically absent. If there are 2 bracteoles present, then their position in a pentamerous flower is often as follows: the first sepal turns obliquely forward, the second is posterior and median, the third obliquely forward, the fourth and fifth obliquely backward; quincuncial æstivation is often found in these buds (Figs. 360, 429, 471, 475, 584). The first and third leaves, in the following chapters, are most frequently alluded to as the “anterior,” the fourth and fifth as the “lateral” leaves. The _reversed_ arrangement, with the median sepal in the front, occurs for instance in _Papilionaceæ_ (Fig. 511), _Lobeliaceæ_ (Fig. 594), _Rhodoracecæ_. If any bracteoles are present below a tetramerous flower, the relation is generally that 2 sepals (the first ones) stand in the median plane, the two next ones transversely (Fig. 393), and the corolla then adopts a diagonal position (Fig. 397); but a diagonal position of the calyx generally shows that the flower is not, strictly speaking, tetramerous, as in _Plantago_ (Fig. 567), _Veronica_ (Fig. 559 _C_) and others. If the bracteoles are _not_ typically present, then the position of the sepals is changed accordingly, and the two outer sepals endeavour to assume the position which the bracteoles would otherwise have occupied, _e.g._ in _Primula_ (Fig. 547). Other positions are also found when the number of bracteoles is more or less than two. The leaves which follow the sepals occupy definite positions with regard to them, which we may consider later. An arrangement must, however, be mentioned here; when the flower is “_diplostemonous_” that is, has two whorls of stamens (thus, Sn, Pn, An + n), these may be arranged in two ways. _Either_ the first-formed whorl of stamens, which are termed the “calyx-stamens,” stands directly in front of the sepals (that is “episepalous”), and is the _outermost_ whorl, and in this case a regular alternation takes place between sepals, petals and the two whorls of stamens, which is also continued into the carpels if their number is the same as that of the other whorls: the carpels are then placed opposite the sepals (Fig. 278) and the flower is _isomerous_ and Gn should be added to the formula above. _Or_, the calyx-stamens form the _innermost_ whorl, and the corolla-stamens, which are subsequently formed (“epipetalous” stamens), stand _outside_ these (Figs. 360, 429); if the number of carpels is the same as that of the preceding whorls, they are often placed _right in front_ of the petals and the corolla-stamens. The first-mentioned arrangement is termed _Diplostemonous_, and the second _Obdiplostemonous_. ~Both arrangements may be found in one and the same order, _e.g._ Caryophyllaceæ. The size and relation of the members of the flowers, and also the contact with other members in the early stages of their development, play an important part in determining the arrangement.~ The great number of structural arrangements found in this enormously large class, may, as is the case in the Monocotyledons, be further varied by _suppression and division_ of certain leaves (especially the stamens). Instances of this will occur in the following (Figs. 559, 568.--426, 441, 445, etc.). The Dicotyledons were formerly divided into 3 sub-classes: Apetalæ (those without corolla), Sympetalæ or Gamopetalæ (those with the petals united), and Choripetalæ or Polypetalæ (the petals not united). This division has now been abandoned because it has been proved that the Apetalæ were merely reduced or incomplete forms of the Choripetalæ, and they have therefore been distributed among the various families of the latter sub-class. With regard to the Sympetalæ (or Gamopetalæ) it may be stated that they form to a very great extent a closely connected and natural group, having in common not only the character that the corolla is gamopetalous and the stamens united with it (this being also found in the Choripetalæ), but also a great many others (such as persistent calyx, cyclic flowers with the formula S5, P5, A5 and as a rule G2, the two carpels being united to form the ovary; seeds with a thick integument and a very small nucellus). They are therefore considered as an independent sub-class, and must be placed at the close of the system of classification as the forms which presumably have arisen the latest. In the future systems of classification this arrangement will very probably be changed, and the first families of the Sympetalæ, the Bicornes and others will for instance be to a certain extent united with the families or orders of the Choripetalæ. The Sympetalæ may certainly be considered as the youngest types, the strongly pronounced metamorphosis supporting this theory, as also the formation of the integument of the ovule, the one thick integument being undoubtedly derived from the coalescence of two--a holochlamydeous ovule, etc. The Apetalæ and Choripetalæ are united into one sub-class. The leaves of the perianth in this case are, as a rule, free from each other, the structure of the flowers presents many differences, and the ovules have as a rule 2 integuments and a large nucellus. Considerable uncertainty still prevails regarding the arrangement and the relationship of the individual families of the Choripetalæ, and some of the following families are hardly quite natural; but the best arrangement arrived at so far has been adopted here. At the beginning of the book a review of the orders of the Dicotyledons will be found. Sub-Class 1. =Choripetalæ. Petals free.= Family 1. =Salicifloræ.= Trees and shrubs, which, in the structure of the vegetative shoot and the catkin-like inflorescences, resemble the Quercifloræ, but the structure of the flower differs so much from them, that the only order brought under this heading--_Salicaceæ_--well deserves to be separated and to form a family of its own, the nearest relatives of which are still doubtful. ~As Juglandaceæ and Myricaceæ also deserve to be placed in a special family, the name _Amentaceæ_ (_Catkin-bearers_), hitherto applied to all of these plants, cannot be retained as the name of a family.~ [Illustration: FIG. 322.--Male and female catkins of _Salix caprea_.] There is only one order. Order. =Salicaceæ= (=Willows=). Trees with simple, scattered, _stipulate leaves_. _Diœcious_. The flowers are arranged in _simple inflorescences_ (spikes or racemes) which are termed catkins, and which fall off as a whole after flowering (♂) or after the ripening of the fruit (♀) (Fig. 322). The perianth is very imperfect[33] or wanting, particularly in _Salix_ (Fig. 323 _o_); the ♂-flower with 2–several stamens and without any trace of a carpel (_a_, _b_, _c_): the ♀-flower has a free bicarpellate ovary, _unilocular_, and formed from 2 lateral carpels with 2 _parietal_ (_median_) _placentæ_ and generally ∞ ovules; the style divides into two stigmas (_d_, _e_, _f_). The fruit is a two-valved _capsule_ and the very small seeds bear a _tuft of hairs_ at the base. _Endosperm absent._--~The catkins are situated on dwarf-branches, which in some species often develop before the leaves and bear at their base only scale-leaves; in others foliage-leaves are borne beneath the catkins. The vegetative bud commences with 2 bud-scales which are united on the anterior side into a scale. The capsule opens by the dorsal suture. The seed-hairs spring from the funicle.~ [Illustration: FIG. 323.--_Salix_: male flowers of _S. pentandra_ (_a_), _S. aurita_ (_b_), _S. rubra_ (_c_), female flowers of _S. aurita_ (_d_), _S. nigricans_ (_e_), _S. mollissima_ (_f_).] _Salix_ (Willow) has short-stalked, most frequently lanceolate leaves and erect catkins with undivided bracts (Fig. 322). The flowers are naked; 1 (_o_ in _a-f_) or 2 yellowish glands situated in the median line. In the ♂-flower generally two stamens, situated laterally like the carpels in the ♀-flower. ~Various forms are seen in Fig. 323.--The terminal bud of the branches often aborts regularly, the uppermost lateral bud taking its place.~ _Populus_ (Aspen, Poplar) has long-stalked, more or less round or cordate leaves with drawn-out apex; catkin pendulous; lobed bracts; perianth cup-like with oblique edge; stamens usually numerous; stigmas often divided.--~_P. tremula_ (Aspen) has received its name from the tremor of the leaves: _cf._ “to shake like an aspen leaf.”~ POLLINATION. The Poplars are wind-pollinated. The Willows have sticky pollen and are pollinated by insects. The catkins of the Willows, especially the ♂, are more conspicuous, from the numerous, closely-packed, yellow flowers, rich in honey and pollen. The catkins often appear before the foliage and so are much more easily seen, whilst at this time of the year the number of competing honey-flowers is smaller, and the insect visits consequently more numerous. On many catkins of the Willow the flowers open earliest on the side which is turned towards the sun and in descending order, _i.e._ the upper flowers develop before the lower ones. Hybrids frequently appear. There are about 180 species existing in the northern, cold and temperate latitudes. Some in the Polar regions are scarcely more than an inch in height, and have a creeping rhizome (_Salix herbacea_, _polaris_, _reticulata_). Fossil forms are found in the Tertiary and perhaps also in the Upper Cretaceous. USES. Principally for ornamental trees, as they grow very quickly and are easily propagated by cuttings, _S. babylonica_, Weeping Willow; _S. purpurea_; _Populus alba_, Silver Poplar; _P. pyramidalis_, Pyramid Poplar--a form of _P. nigra_; _P. monilifera_, Canadian Poplar. The wood is very poor and little used; the branches of many Willows are cultivated for basket-making, etc. The wood of the Aspen is used for matches. The bark contains tannin and, in many Willows, a very bitter extract, _Salicin_ (_S. pentandra_, _fragilis_). Salicylic acid (officinal) is obtained from _Salix_. Balsam is extracted from the buds of many Poplars, especially when the leaves are shooting. Family 2. =Casuarinifloræ.= Trees with verticillate, scale-like leaves forming sheaths at the nodes. Monœcious. Flowers unisexual. ♂-flowers in catkins; ♀ in short spikes. _Pollen-tube entering the ovule at the chalaza_, and not through the micropyle. Ovary 1-seeded, unilocular. Carpels uniting into a multiple fruit. Only one order. Order. =Casuarinaceæ.= Trees (30 species), from Australia and certain parts of S.E. Asia, with peculiar, equisetum-like appearance. The leaves are verticillate, scale-like and united into sheaths. The internodes are furrowed. Branching verticillate. The unisexual flowers are situated in catkins or short spikes. The ♂-flower has a central stamen, surrounded by 2 median, scale-like perianth-leaves and 2 lateral bracteoles. The ♀-flower has a 1-chambered ovary (2 ascending, orthotropous ovules), no perianth, but 2 large, lateral bracteoles which finally become woody and form two valves, between which the nut-like fruit is situated. The multiple-fruits therefore resemble small cones.--_Casuarina equisetifolia_, cultivated, gives “iron-wood.” [The Casuarinas differ from the ordinary Dicotyledons in many important respects which may be briefly summarised thus:--The bicarpellate ♀-flower has a well-pronounced stylar-cylinder terminated by two stigmas, but the cavity of the ovary closes very soon after its formation, and in it are developed two parietal ovules; these are united by a bridge of cellulose to the stylar-cylinder or summit of the ovary, and hence the ovules are connected with the walls of the ovary by the bridge (above), as well as by the funicle (below). The archespore is developed from the hypodermal cells at the summit of the nucellus, two primordial mother-cells are first formed and from these by tangential divisions a central cylindrical mass of cells (sporogenous-tissue) is produced which is surrounded by tapetal cells. The cells of the sporogenous tissue correspond to the mother-cells of the embryo-sac of other Angiosperms; they divide transversely and from 16–20 macrospores are formed together with inactive cells which are not crushed together as in the case of other Phanerogams. The sexual apparatus is developed from a single cell, but the number of cells composing this apparatus is subject to variation, the oosphere being accompanied by one or two neighbouring cells which resemble canal-cells rather than synergidæ. The sexual apparatus is found in the majority of the macrospores, but in most of these it remains as a number of naked cells; while in the fertile macrospores the cells are invested by walls of cellulose (usually only one fertile macrospore is found in each ovule). Antipodal cells are never developed. The macrospores elongate considerably towards the chalaza, into which some penetrate. The pollen-tube traverses the stylar-cylinder and enters the ovules at the chalaza, its passage through the tissue of the nucellus being assisted by the prolongation of the macrospores. About the centre of the nucellus the pollen-tube is ruptured; the apical portion which alone takes part in the fertilisation being firmly attached to the macrospore. Although the actual impregnation has not been observed, Treub considers that the endosperm begins to be formed before fertilisation.] Family 3. =Quercifloræ.= _Trees_ and _shrubs_ with small, unisexual, _monœcious_ flowers, having no perianth or a simple inconspicuous one. The ♂ and ♀ flowers are very different and generally placed in separate inflorescences. The ♂-flowers are most often adnate to the bracts. The stamens are placed _opposite the perianth-leaves_, when they are present in equal numbers. The ♀-flower is _naked_, or has a _superior_ perianth. The ovary at the base is 2- or 3-(-6) locular with 1 or 2 pendulous ovules in each loculus, only one of which is developed; the fruit is a one-seeded _nut_; _endosperm absent_; embryo straight. The inflorescences, which are either compound and mixed (small dichasia in spikes) or simple, are here also termed _catkins_; but, strictly speaking, this term is applied to the ♂-inflorescences only. In all Quercifloræ the leaves are _scattered_ (usually in 2 rows) _simple_, and _penninerved_, and with _deciduous stipules_. It is worthy of remark that in _Betulaceæ_, _Corylaceæ_ and _Quercus_ the ovules, and to some extent the loculi of the ovary are not developed till after pollination, so that the development of the pollen-tube proceeds very slowly. The smallness of the flowers, the absence of honey, the dryness and lightness of the pollen, the size of the stigma and the abundance of hairs found on many stigmas are all adaptations for wind-pollination. It is also an advantage that the flowers are generally pollinated before the foliage-leaves are developed, thus preventing the pollen being entangled by the leaves. The two orders _Betulaceæ_ and _Corylaceæ_ mentioned here are by other authors united into one order. [It is doubtful whether these two should be retained in the family Quercifloræ, as recent researches (p. 273) have shown that they differ from the Cupuliferæ in many important points, and agree with the Casuarinas in the fact that the pollen-tube enters the ovule through the chalaza.] Order 1. =Betulaceæ= (=Birches=). Monœcious, with thick, cylindrical, _compound_ ♂ and ♀ inflorescences (2- or 3-flowered dichasia in a spike with spirally-placed floral-leaves) (Figs. 324, 326, 328). When the perianth in the ♂-flower is completely developed, it is composed of 4 somewhat united leaves, which are placed opposite the 4 stamens (Figs. 325, 326 _A_). The female flowers are _naked_; the ovary is bilocular, with two styles and one _pendulous_ ovule in each loculus. The subtending floral-leaves unite with the bracteoles and form a 3–5-lobed cover-scale, which is not attached to the fruit (Figs. 325 _D_, 326 _B_). Fruit a _nut without cupule_ (see _Corylaceæ_ and _Cupuliferæ_). ~In the bud the leaves are flat. The stipules are deciduous. On germination the cotyledons are raised above the ground. Terminal buds are only found on old Alder trees; the Birch has sympodial branches.~ [Illustration: FIG. 324.--_Alnus glutinosus._ Branch of Alder with ♂-(_n_) and ♀-(_m_) catkins: _k_ bud; _b_ fruit-bearing catkin (“cone.”)] _Alnus_ (Alder) (Figs. 324–326). In the majority of species the ♂-and ♀-catkins are both developed in the year previous to their flowering, and pass the winter naked and bloom before the leaves expand. ♂-flower: 4 stamens. ♀-flower: the 5-lobed cover-scales of the ♀-catkin are woody and remain attached to the axis, so that the entire catkin when ripe resembles a small cone (Fig. 324 _b_). Each cover-scale supports two winged or wingless nuts. ~In the native species of Alder the buds are stalked (Fig. 324 _k_). The bud-scales are formed by the stipules of the lowest leaves.~ _Betula_ (Birch). The ♂-catkins, in the native species, appear in autumn, the ♀-catkins in the flowering year on leaf-bearing, short-lived shoots. ♂-flowers: 2 stamens, divided (Fig. 328 _A_). The 3-lobed cover-scales (Fig. 327 _a_) of the ♀-catkin are detached from the axis; each cover-scale supports 3 broadly winged nuts (_b_). ~The stem has cork with annual rings. The young twigs and leaves have aromatic resin glands.~ [Illustration: FIG. 325.--_Alnus glutinosa_: _A_ dichasium of ♂-flowers seen from the front; _B_ the same from inside; _C_ the same from the back; _D_ dichasium of ♀-flowers with subtending-leaf and four bracteoles. The letters _b_, α, β, β′, β are the same as in Fig. 326 _A_.] [Illustration: FIG. 326.--_Alnus glutinosa_: diagram of dichasia of ♂ (_A_) and ♀ (_C_) catkins; _B_ a cone-scale. All the bracteoles in _A_ and _C_ are slightly pressed from their normal position.] THE INFLORESCENCES OF THE ALDER.--In the axil of each cover-scale [_b_ in the Figs] is situated, in the ♂-catkins (Figs. 326 _A_, 325 _A-C_) a 3-flowered dichasium, the flowers of which have a 4-partite perianth, the posterior perianth-segments being sometimes almost suppressed, and 4 stamens with undivided filaments. In the ♀-catkin (Figs. 325 _D_, 326 _C_) a 2-flowered dichasium is found, the middle flower being suppressed (indicated by a star in _C_). In both instances the inflorescences have two bracteoles (α-β) and the flowers borne in their axils have each one bracteole (β′), the other one (α′) being suppressed and therefore in 326 _A_ and _C_ only represented by a dotted line; these four bracteoles unite with the cover-scale (_b_) which supports the entire dichasium, to form the 5-lobed “cone-scale” (Fig. 326 _B_) which in the ♀-catkin eventually becomes woody. THE INFLORESCENCES OF THE BIRCH.--A 3-flowered dichasium is situated in the axil of the cover-scale in both ♂-and ♀-catkins (Fig. 328 _A_, _B_); only the central flower has bracteoles (α-β) (the lateral flowers having no bracteoles), and these bracteoles unite, as in the Alder, with the supporting cover-scale (_b_), and form a three-lobed cone-scale (Fig. 327 _a_). While the ♀-flower exactly resembles that of the Alder, the reduction of the ♂-flower, already described in the Alder, is carried further, so that often only the 2 median perianth-leaves are developed (Fig. 328 _A_); there are also _only_ 2 stamens, these being deeply cleft, while the other 2 are suppressed. About 50 species; N. Temp.--Fossil-forms certainly occur in the Oligocene. During the Glacial period the Dwarf-birch (_B. nana_) extended over Europe; at the present time it is confined to the moors and mountains of N. Europe and N. America and Asia. Wind-pollinated. USES.--Important forest trees. The bark contains tannic acid. The tar of the Birch is used in the preparation of Russia leather; whilst its spring sap is very saccharine, and is used in some places for making a fermented drink. Its external bark is used for roofing, for baskets, etc. [Illustration: FIG. 327.--_Betula verrucosa_: _a_ cone-scale; _b_ fruit.] [Illustration: FIG. 328.--Diagrams of dichasia in the ♂-(_A_) and ♀-(_B_) catkins of Birch.] Order 2. =Corylaceæ= (=Hazel-nuts=). Monœcious. The ♂-catkins are long and cylindrical; the ♂-flowers are placed singly in the axil of the subtending-leaf (cover-scale); they are _naked_ and formed of a number of _divided_ stamens, which are partly united with the cover-scale, 4 in the Hazel, apparently 8 (Figs. 330 _A_, 329 _B_, _C_), more on the Hornbeam. The ♀-flowers have a very small, _superior_ perianth; in the axil of each cover-scale a 2-flowered dichasium (Fig. 329 _D_) is present, of which the central flower (* in Fig. 330 _B_) is suppressed. The gynœceum is bicarpellary as in the Birches; the ovary is bilocular, with two long styles (Fig. 329 _D-F_); the loculi have 1 (-2) ovules (Fig. 330 _B_). Each single ♀-flower and fruit is surrounded by a _leaf-like covering_, the _cupule_ (husk), which is _formed of three floral-leaves_ (namely, the bract of a lateral flower, and its own bracteoles; thus in Fig. 330 _B_, α, α′, β’ form the cupule for the left-hand flower, and β, α_[1}, β_[1}, the cupule for the right-hand). _Corylus_ (Hazel-nut, Fig. 329). The long, cylindrical ♂-catkins pass the winter naked, 2–3 together, on short branches. The very small ♀-catkins are enclosed in buds, in which they pass the winter; these buds are situated in the axils of the fallen foliage-leaves, and it is only by their larger size that they may be distinguished from the ordinary foliage-buds. In spring the ♀-catkins are easily recognised by their red, projecting stigmas (Fig. 329 _A_). The cupule--the “husk”--is tubular, fringed, and envelopes the nut. ~The leaves are alternate and unsymmetrical, the external side being larger than the internal; this is connected with the vernation, the blade being conduplicate in the bud; the stipules are deciduous. The bud-scales are formed of stipules, the most internal having a leaf-blade attached to them which is suppressed in the external ones. The cotyledons remain underground on germination.~ [Illustration: FIG. 329.--_Corylus avellana_: _A_ branch at the time of flowering with ♂-and ♀-catkins; _B_ ♂-flower with subtending-leaf (bract) and two bracteoles; _C_ the same without the anthers; _D_ view of interior of ♀-dichasium shortly after fertilisation; _E_ young fruit with cupule; _F_ similar one with the cupule opened; _G_ mature ♀-fruits; _H_ nut.] _Carpinus_ (_C. betulus_, Hornbeam). The ♂-and ♀-catkins do not appear till the leaves are shooting. The ♀-catkin in this instance is also long and cylindrical. The cupule in _C. betulus_ is 3-lobed, and to a slight extent only embraces the base of the ribbed nut (Fig. 331); each lobe corresponds to a floral-leaf. ~Whilst the carpels are placed medianly in _Corylus_, in _Carpinus_, on the other hand, they are situated transversely, as in the case of the _Betulaceæ_. The lamina of the leaf is not conduplicate in the bud, but flat, and folded only along the lateral veins, which are also indicated in the form of the fully-developed leaf; otherwise the vegetative characters are essentially the same as in the Hazel. The cotyledons are aerial.--_Ostrya_ resembles the Hornbeam, but the cupule completely envelopes the nut, as a sac open at the apex (Eur., N. Am., Japan).~ N. Am., Asia, and Europe; 25 species.--Fossil forms in the Oligocene. Wind-pollinated. USES. As timber (_Carpinus betulus_) and firewood. The fruits of _C. avellana_ (ordinary Hazel-nut), _C. tubulosa_ (Lambert’s nut) and _C. colurna_ (Turkish Filbert) are edible. [Illustration: FIG. 330.--Diagrams of the ♂-flower (_A_) of _Corylus_ and the dichasium of the ♀-flowers (_B_).] [Illustration: FIG. 331.--Nut of the Hornbeam with cupule.] Order 3. =Cupuliferæ.= Monœcious. The inflorescences make their appearance with the leaves, arising in the axils of the leaves of the same year. _A woody cupule_ furnished externally with scales or spines is _common_, and surrounds 1-several flowers (the cupule in the Corylaceæ never encloses more than a _single_ flower or fruit). The ♂-flower has a united perianth, which is, however, 4–6 partite, and encloses an indefinite number of undivided stamens. The ♀-flower has a _superior, 6-merous_ perianth (3 + 3, compare Figs. 332 _D_, 334); the gynœceum is formed of 3 (or in _Castanea_ 4–6) carpels with a corresponding number of stigmas (Figs. 332 _D_, _H_; 334, 335); and the ovary has at the base 3 (-6) loculi (Fig. 333), each of which has 2 pendulous anatropous ovules; the fruit is a one-seeded nut (Figs. 332 _H_, 336). The cupule of the Cupuliferæ, according to the opinion of Eichler, is formed by united bracteoles, (compare Fig. 333, where the four valves in the cupule of Castanea are considered as bracteoles of the lateral flowers of the dichasium); according to another view (see Prantl, in Engler’s _Bot. Jahrb._, viii., 1889), it is a ring-like axial outgrowth independent of the bracteoles of the flower, whose scales and spines are floral-leaves. The cupule in the Oak only encloses the base of the fruit, but in the Eating-chestnut and Beech the fruit is completely enclosed, and consequently the cupule must divide into a number of valves (generally 4) to allow the fruit to escape. In the 3-flowered dichasia of _Pasania_, Sect. Eupasania (Trop. Ind.), each individual flower has its own cupule of the same structure and development as in _Quercus_; and, moreover, each group of flowers has externally the typical six bracteoles. [Illustration: FIG. 332.--_Castanea vesca_: _A_ branch with inflorescences; _B_ ♂-flower; _C_ young cupule with three ♀-flowers; _D_ ♀-flower; _E_ the same in longitudinal section; _F_ cupule with 3 nuts (diminished); _G_, _H_ nuts (_G_ in longitudinal section to show embryo).] _Castanea_ (Eating-chestnut, Fig. 332). The catkins are erect (_A_), cylindrical, with the ♀ at the base and the ♂ at the top, or some are entirely ♂ and _composed of small dichasia_. The _cupule_ (_C_, _F_) is 4-_valved_, provided with spines, and entirely envelops the 3 _nuts_; it is already developed at the time of flowering.--~♂-flowers are most frequently borne in 7-flowered dichasia, and have a well developed perianth, most frequently consisting of 6 leaves in two whorls (Fig. 332 _B_), and a large number of stamens. ♀-flowers are most frequently borne in 3-flowered dichasia (Figs. 332 _C_, 333); the letters in Fig. 333 indicate the older theory, according to which the 4 bracteoles (α′-β′) of the two lateral flowers are thick and united into a single 4-valved, _woody cupule_, which surrounds the 3 nuts, and is furnished externally with spines; the spines are well developed hair-structures.--6 carpels in two whorls.--The leaves in the vertical shoots have a divergence of 2/5, 3/8, 5/13; on the horizontal shoots they are alternate. The cotyledons remain underground on germination.~ [Illustration: FIG. 333.--Diagram of the cupule of _Castanea_.] [Illustration: FIG. 334.--Female flower of _Fagus_ (mag.)] _Fagus_ (Beech). The ♂-catkins are pendulous, capitate; the ♂-flowers have an obliquely bell-shaped, fringed perianth, with 6–20 stamens. ♀-catkins erect, 2-flowered, borne singly in the axil of foliage-leaves of the same year; the ♀-flower has a gynœceum formed of 3 carpels, bearing an epigynous, 6-leaved perianth (Fig. 334). In this genus _the dichasium has only 2 flowers_, the central one being suppressed. _The cupule contains_, therefore, only 2 triangular nuts (“mast”). ~All the shoots have the leaves arranged in two rows; the rows are on the underside, being only about 90° distant from each other; the buds on the other hand approach each other towards the upper side. The bud-scales are stipules without laminæ; in vernation the laminæ are folded along the lateral ribs, the upper lateral portion being the largest (as in Hornbeam and Chestnut). The cotyledons are folded, and at germination are aerial, large, and reniform. 4 species (Europe, Japan, N. Am.)--_Nothofagus_ (S. Am., New Zealand, S. Austr.)~ _Quercus_ (Oak, Fig. 335). Catkins simple. ♂-catkins long, thin, _pendulous_, few-flowered. ♀-catkins erect; the cupule is _cup-like_, _entire_, and encloses only the base of the solitary nut (“acorn”).--~The ♂-flower has a similar construction to that of the Chestnut. The ♀-catkin has not more than 5 flowers (single-flowered dichasia, in which _only the central flower is developed_). The scales on the cupules are no doubt leaf-structures in this case also. According to another theory, the scales are hair-structures; they arise on the internal face of the young cupule apparently in descending, but really in ascending order. The rim of the cupule gradually expands. In the ♀-flower (Fig. 335) the loculi of the gynœceum, together with the ovules, are not developed until _after_ pollination.--The leaves in all cases have a divergence of 2/5; the lowermost leaves on the shoots are reduced to stipules which serve as the bud-scales (5 rows). The laminæ are conduplicate, as in _Corylus_, and the external side is the broadest. The cotyledons are fleshy and remain underground. 200 species.--_Pasania_ (100 species).~ [Illustration: FIG. 335.--_Quercus_: _A_ ♀-flower in its cupule (mag.); _B_ longitudinal section through _A_, showing cupule, perianth, and inferior ovary.] [Illustration: FIG. 336.--Fruit of _Quercus_.] 368 species, in temperate climates, especially in Europe and N. America. Authenticated forests have been found in the Oligocene. The Beech has one species, _Fagus sylvatica_, in Europe; it is a most important forest tree (in Denmark the most important) and reaches its most northern limit near Alvesund in Norway (60° N.L.), its northern boundary line passing from Alvesund in a zig-zag line through Ludwigsort, south of Königsberg, in Prussia, towards the Crimea. According to Steenstrup and Vaupell, the Beech did not make its appearance in Denmark until a comparatively recent time, the Oak then being partially supplanted. Other species of Beech are found in N. America and Japan. Several species of _Nothofagus_ occur in the South West of S. America, and in the colder regions of the southern hemisphere. The Oaks grow especially in temperate regions, _e.g._ in Western Asia, N. America, and the mountains of Mexico. Evergreen species are found in Tropical Asia, Himalaya, Japan and the Mediterranean region. In this country there is one species of Oak (_Q. robur_), of which there are three varieties (_Q. pedunculata, intermedia, sessiliflora_). The Eating-chestnut is found in the South of Europe, but is cultivated in the midland and southern counties of England.--USES. The wood of these trees is very useful as timber. The wood of _Q. tinctoria_ has a yellow colouring matter (Quercitron-wood). The bark of the Oak contains a large quantity of tannic acid, and is used for tanning; for this purpose also the cupules of _Q. vallonea_, _ægilops_, _græca_, and others from the Eastern Mediterranean, are used under the name of “Valloons.” The Cork-oak (_Q. suber_; S.W. Europe) is the most important tree from which cork is obtained, its bark being very largely developed and stripped for cork. Gall-nuts are found on many species; those of _Q. lusitanica_, var. _infectoria_ (Eastern Mediterranean) are officinal, and likewise the fruits (acorns) and the bark of _Quercus pedunculata_ and _sessiliflora_. Oil is obtained from the Beech “mast.” The nuts of the Chestnut tree are edible. Family 4. =Juglandifloræ.= This family resembles the Quercifloræ in the catkin-like inflorescences, the imperfect, _unisexual_ flowers, the epigynous perianth and the woody shoots with scattered leaves, etc., though it is in other respects very dissimilar; one point of difference is the presence of _aromatic_ compounds, but a more important divergence is found in the structure of the gynœceum, which is formed of two carpels with _one loculus_ and has one _basal_, _orthotropous and erect_ ovule, which, as in the Quercifloræ, does not become developed until after pollination; the fruit too is very different, being generally a _drupe_. _Endosperm absent._ [Illustration: FIG. 337.--_Juglans regia_: _A_ ♂-flower seen from below with bract (cover-scale) (_b_), bracteoles (α and β), perianth-leaves (_p_); _B_ the same from the front; _C_ lateral view of the same; _D_ diagram of _A_; _E_ ♀-flower with bract, the bracteoles are united with the ovary, their edge being visible as an indented line below the perianth; _F_ 2 ♀-flowers at the end of a foliage-shoot; _G_ fruit (without the fleshy covering) in longitudinal section; _H_ transverse section of the same.] Order 1. =Juglandaceæ (Walnuts).= Leaves _scattered_, _imparipinnate_, rich in _aromatic_ compounds. _Stipules absent._ Flowers unisexual. _Monœcious._ The ♂-catkins are lateral, generally on naked branches of the previous year, cylindrical, pendulous, many-flowered; the two bracteoles and the 2–4-leaved perianth of the ♂-flower unite with the subtending bract; the ♂-flower has indefinite stamens (6–20 in _Juglans_, Fig. 337 _A-D_). The ♀-catkins are terminal, generally on branches of the same year, few-flowered (Fig. 337 _F_); the ♀-flowers have a _superior_, 4-leaved perianth, a bicarpellate gynœceum, two styles with stigmas on the internal surface. The ovary, bracteoles and bract all unite together (Fig. 337 _E_). The fruit is generally a green or black _drupe_,[34] whose flesh (outer soft portion) in _Carya_ and _Juglans_ ruptures more or less irregularly, and frees the stone (“Walnut”).--~The stone in _Juglans_ is divided internally by one true (Fig. 337 _H_) and by several false, low partition walls into several _incomplete_ compartments, so that the two large _cotyledons_ become lobed and incised to fit like a cast into the irregularities of the inner surface of the stone; the embryo is exendospermous and covered with a thin testa.--THE LEAF SCARS are large and cordate with 3 groups of vascular bundles. The PITH in _Juglans_ and _Pterocarya_ is divided into chambers. The stone ruptures, on germination, along the dorsal suture into 2 valves; the cotyledons remain underground. In _Juglans regia_ a long row of accessory buds is found on the lowest internode (epicotyl) above the axils of the cotyledons. _Pollination by the wind._ Both protogynous and protandrous examples of _Juglans regia_ occur.--33 species, mostly in temperate North America.--USES. Walnuts are obtained from _J. nigra_ and _regia_; Hickory from North American species of _Carya_. The oil-containing seeds of several species are edible. _Pterocarya_ and others are cultivated as ornamental plants.~ [Illustration: FIG. 338.--_Myrica gale_: _a_ young fruit; × the bracteoles with numerous glands; _b_ longitudinal section of fruit.] Order 2. =Myricaceæ=. To this order belong shrubs or trees which have penninerved, simple, at most lobed or pinnatifid leaves, with or without stipules, and with yellow, aromatic, resin glands (Fig. 338 _a_). The flowers, situated in catkin-like spikes, are unisexual and _naked_, and supported by scale-like floral-leaves. ♂-flower: 4–6 (–16) stamens with short filaments; ♀: generally situated singly. The gynœceum has a short style with 2 long stigmas, and unites with the bracteoles, which form wing-like outgrowths on the ripe drupe as in _Pterocarya_ in the Juglandaceæ (Fig. 338). Cotyledons fleshy (Fig. 338 _b_).--_Myrica_; _Comptonia_. 40 species; Temperate.--_Myrica gale_ (Sweet-gale, Bog-myrtle) has been used in the preparation of beer (Sweet-willow beer) on account of its resinous essential oil. _M. cerifera_ (N. America) and species from the Cape, _M. quercifolia_ and others, form wax on the fruit which is used in the preparation of candles. Family 5. =Urticifloræ.= The flowers are regular, _hypogynous_, nearly always unisexual, _small_ and insignificant, with _single_, green perianth of 4–5 leaves. Stamens 4–5, _placed opposite_ the leaves of the perianth. Ovary formed of 1 or 2 carpels, most frequently _unilocular_, with one ovule (Fig. 340). The fruit is a _nut_, more rarely a drupe, with one seed, _generally endospermous_. ~The Nettles are the sole order in the family which has only one carpel (1 stigma); this turns the posterior side to the front (Fig. 340). The others have two carpels (2 stigmas) but the anterior only is fertile (Fig. 346) except in a few Ulmaceæ and Moraceæ.~ The majority are trees or shrubs with petiolated leaves, _stipulate_; _rough hairs_ are very frequently developed upon the leaves. The flowers are very often crowded together in the inflorescence, which is rarely catkin-like. Peculiar aggregations of fruits are found in some orders. _Latex_ and tough _bast_, which is used technically, are also frequently found. Cystoliths are found in the epidermis of many species of _Ficus_, _Urtica_, and others. ~_Wind-_ or _self-pollination_ is most common, as in the Quercifloræ and Juglandifloræ.~ In ~the Urticaceæ, _Morus_ and some others, the stamens lie incurved in the bud, and when ripe straighten themselves suddenly and elastically, and thus small clouds of pollen-grains are ejected with considerable violence on to the stigmas, which are often provided with brush-like hairs (Fig. 341). The formation of honey does not take place.~ Order 1. =Ulmaceæ= (=Elms=).--Trees or shrubs without latex. Leaves simple, arranged in two rows (divergence 1/2), oblique (the inner side, nearer the axis, being the larger), strongly penninerved, dentate, hispid; stipules deciduous. In opposition to the other Nettle-like plants the flowers are often ☿ with a united cup- or saucer-like, generally 4–(5)–6-divided perianth, and a corresponding or larger number of opposite _erect_ stamens. The gynœceum has two carpels (2 stigmas), generally one loculus with one pendulous, anatropous or amphitropous ovule,[35] seldom two loculi and 2 ovules. Fruit one-seeded (nut or drupe). Embryo without endosperm. =A.= ULMEÆ. The fruit is a _winged nut_ (Fig. 339), the embryo straight, without endosperm. Anthers extrorse.--_Ulmus_ (Elm). The flowers are situated in inflorescences which develop from the lower buds of the shoot of the preceding year. ~The lowermost bud-scales are empty, the uppermost support either solitary flowers, or small, dichasial or unipared scorpioid inflorescences. The terminal bud on the vegetative shoot quickly falls off, and the upper lateral bud continues the growth sympodially. Flowering takes place before the leaf-buds open. The flowers are wind-pollinated and have no honey. Fossil species have been found in the Oligocene.~ 20 species; North Temp. (2 species in this country). Important as timber. The Cork-elm (_U. suberosa_) has a rather thick cork, which, however, is of no technical use. The bast is used as Lime-bast. =B.= CELTIDEÆ. The fruit is a drupe, the embryo curved, with folded or rolled up cotyledons, with or without endosperm. The anthers are introrse. The flowers are borne on a shoot of the same year. _Planera_ (N. America); _Zelkova_.--About 114 species; especially N. Temp., Trop. [Illustration: FIG. 339.--_A Ulmus campestris_, flower with exceptionally aborted gynœceum; _B_, _U. effusa_, flower with 8 stamens; _C_, _U. campestris_, fruit opened in front to show the seed pendulous from the apex of the loculus; one loculus is aborted.] Order 2. =Urticaceæ= (=Nettles=).--The majority of species are herbs with simple, stipulate leaves; they have _no latex_; _stinging hairs_ abundant. The flowers (Fig. 340) are _unisexual_, generally 2-merous and arranged _in clusters_, which are united into catkin-like inflorescences. The perianth is composed very often of 4 (2 + 2) free, or in the ♀-flowers generally united, green leaves; the 4 (2 + 2) stamens are opposite the perianth-leaves, the filaments are _bent inwards_ in the bud and throw themselves elastically towards the outside. The gynœceum has _one style_ and _one stigma_ (capitate or brush-like, Fig. 341); the ovary is unilocular, with _one orthotropous_, _erect_ ovule (all other orders of this family have inverted or curved ovules). Fruit, a nut or drupe. _Endosperm present_ (in _Urtica_ very little), oily. Embryo straight. ~The STINGING HAIRS are club-shaped, very turgid, and provided with a siliceous, brittle apex, which breaks off in an oblique direction and allows the poisonous cell-sap to be forced out. In many tropical Nettles this is so strong that it may produce partial paralysis. There is no rudiment of an ovary in the ♂-flowers (Fig. 340 A). The PERIANTH in the ♀-flower differs from that of the ♂ in having the two internal leaves generally much larger and enveloping the fruit (Fig. 340 _B_); it often happens that all the perianth-leaves are united to form a gamophyllous envelope. ☿-flowers may occur among the others.--THE INFLORESCENCES among our native species are dichasia, which become transformed into unilateral scorpioid cymes by the development of the bud of the 2nd bracteole. In _Parietaria_ they are more pressed together, and the floral-leaves at the same time are also raised on their axillary shoots to just beneath the flower. As a rule, not only in this order but also in those related to it, a small vegetative branch is situated in the axil of the foliage-leaf, and this bears an inflorescence on each side at its base.~ _Urtica_ (Nettle) has opposite leaves with distinct stipules and stinging hairs. The perianth-leaves of the ♀-flower are free (Fig. 340).--_Parietaria_ (Pellitory) has scattered leaves without large stipules, and stinging hairs are absent. The ♀-perianth is 4-toothed, flask- or bell-shaped.--~_Pilea_ is a tropical genus with trimerous, zygomorphic ♀-flowers, the posterior perianth-leaf being much larger than the two others, and more or less hood shaped.--The flower of _Forskohlea_ is the most reduced; the ♂-flower has only one stamen, and the ♀-as well as the ♂-flowers have a one-sided, tongue like perianth (?). _Pouzolzia._~ [Illustration: FIG. 340.--Diagram of ♂-and ♀-flowers of _Urtica dioica_.] [Illustration: FIG. 341.--_Parietaria diffusa_; hermaphrodite flower: _a_ in the female, _b_ at the commencement of the male stage; the stigma has fallen off, but the anthers have not yet dehisced.] WIND-POLLINATED. The pollen is shot out of the anthers, when they spring forward, and is caught by long stigmatic hairs. _Parietaria diffusa_ is protogynous (Fig. 341). 500 species; chiefly in the Tropics, although the few species which occur in Europe are represented by a much larger number of individuals.--USES. The bast of the native species _Urtica dioica_ and _urens_, of _U. cannabina_ (Siberia), etc.; of _Boehmeria nivea_ “Ramié” and “China-grass” (from Sunda Is., China), and others, is used in the manufacture of muslin. Order 3. =Moraceæ= (=Mulberries=). Nearly all trees or shrubs, seldom herbs, generally with latex. The leaves are scattered, and not infrequently lobed. The flowers are _unisexual_ (monœcious or diœcious) and arranged in catkin- or capitulum-like, compound inflorescences. Perianth-leaves 2–6, generally 4, with an equal number of stamens opposite to them, as in the Nettles. The ovary is 1–seldom 2-locular, and has 2 stigmas (it is thus formed from 2 carpels) seldom only one style with one stigma. One ovule in each loculus, more or less curved, and _pendulous_; micropyle directed upwards. Fruit usually a drupe. The embryo is generally curved inside the _fleshy endosperm_, or it is exendospermous. [Illustration: FIG. 342.--_Morus alba_ ♂ flower (6/1).] [Illustration: FIG. 343.-_Morus alba_ ♀ inflorescence.] [Illustration: FIG. 344.--_Morus nigra_ fruits.] =A.= MOREÆ. The filaments are incurved in the bud. Leaves folded in the bud--_Morus_ (Mulberry) (Figs. 342–344). Monœcious. The inflorescences are catkin-like in appearance, but in reality composed of many small dichasia. The flowers are similar to those of the Nettle, but with 2 carpels: in the ♂ with perianth 2 + 2, and stamens 2 + 2 (Fig. 342), in the ♀, perianth 2 + 2, and 2 carpels in regular alternation. The small drupes are enveloped by _the perianth, which eventually becomes fleshy_, and as all the flowers on the axis very accurately fit together, the collection of fruits is formed, which we call a Mulberry (Fig. 344). The leaves are folded in the buds, and have small stipules. ~The following are allied to _Morus_:--_Maclura_, _Broussonetia_ (the Paper-mulberry tree) which has spheroid ♀ inflorescences (made up of dichasia), etc.~ _Dorstenia_ presents an interesting transitional form to the Fig in its flat, open, and, in some instances, lobed inflorescence on which the ♂ and ♀ flowers are sunk in grooves. Indications of a somewhat similar structure are found in certain Nettles, the sympodial axes of the dichasia becoming flatly expanded. The fruits are 1-seeded, but, nevertheless, spring open and eject their seeds. =B.= ARTOCARPEÆ. Filaments straight in the bud; foliage-leaves with convolute vernation. An interpetiolar leaf-sheath (ocrea) formed in the axil of each leaf by the connate stipules, covers the younger leaves as a hood. It falls off as the leaf expands, and leaves a ring-like scar on the stem.--_Ficus_ (the Fig). The inflorescence (the so-called syconus) has a pear-shaped, fleshy, but hollow axis, on the interior surface of which the flowers are situated (Fig. 345). It is a kind of capitulum, with a hollow receptacle, whose “involucral” leaves close over the entrance to the interior; it is not, however, a simple capitulum, but a coalescence of cymose inflorescences. The edible parts are the fleshy stem-portion and perianth-leaves. The ♂-flower has a 2–6 divided perianth, 1–2 (–6) stamens; the ♀-flower has an oblique ovary. The fruits are drupes, with thin flesh.--~Many species have aerial roots, and some live as epiphytes on trees. POLLINATION, in the edible Fig, is effected by a small Gall-wasp (_Cynips psenes_ L.), which lays its eggs in the Fig, and hence carries the pollen away. Even in very ancient times it was customary to hang infected wild Figs on the branches of cultivated ones, so that the young Gall-wasps, as they emerged, could immediately effect the pollination (caprification). _Ficus carica_, and other species, have two kinds of ♀-flowers, besides the ♂-flowers. One kind has a short style and no stigmatic hairs, and it is only in the ovaries of these that the wasps lay their eggs (gall-flowers); the other kind has a long style and well-developed stigmatic-hairs, but the wasps cannot reach their ovaries--these are “seed-flowers.” There are, moreover, two kinds of plants of _Ficus carica_; ♀-plants, which have only seed-flowers, and bear the edible Figs, and ♂-plants (called “Caprificus”), which bear inedible fruits, and have ♂-flowers at the upper part of the Fig, but gall-flowers at the base. [The Caprificus, at Naples, bears three crops of inedible Figs each year, viz. _Mamme_ (April), _Profichi_ (June), _Mamnoni_ (August). The ♂-flowers are produced especially in June, the first Figs being almost entirely ♀, and the last having but few ♂-flowers. Each crop produces a new generation of Fig-wasps. The female wasp enters the Figs on the Caprificus, and lays one egg in each flower, with the result that the flower developes into a kind of gall. The mother-wasp dies within the Fig. The male wasp is wingless; it bites a small passage into the ovaries containing the female wasps, and impregnates them; the female wasps then escape from the Fig, those in the _Profichi_ carrying pollen away with them as they pass out. They then enter another Fig, lay their eggs, and die. The edible Fig-tree similarly has three crops in the year, _Fiori di fico_, _Pedagnuoli_, _Cimaruoli_. The wasps, entering these Figs, are unable to lay their eggs in the ovary, but, nevertheless, they effect cross-pollination on entering the _Pedagnuoli_, which bear fertile seeds.]~ [Illustration: FIG. 345.--A Fig in longitudinal section.] The flowers of _Brosimum_ are the most reduced. The perianth is wanting, and the ♂-flower has only 1 stamen. _Cecropia_ (Trumpet-tree), in S. Am., has its pith divided into chambers; these are inhabited by ants, which feed upon small food-bodies formed on the swollen base of the petioles. The leaves are petiolated, often shield-like, fringed or lobed, and sometimes with white felted hairs. They serve as food for _Bradypus_ (the Sloth). _Sorocea_; _Castilloa_. About 300 species exclusively in the warmer climates. The white Mulberry (_M. alba_, from China, India, Mongolia) is cultivated for the sake of its leaves, which are the indispensable food for silkworms. The black Mulberry (_M. nigra_, W. Asia) is cultivated for its fruits, which are used for the officinal Mulberry juice. The ordinary Fig-tree (_Ficus carica_) is from the Mediterranean. The fruit of the well-known Oriental Sycamore (_F. sycomorus_) is edible. The Bread-fruit tree (_Artocarpus incisa_) and the Jack (_A. integrifolia_) have their home in the South Sea Islands, and are cultivated in tropical countries. The Bread-fruit is morphologically the same as the Mulberry. It has a very large, spheroid inflorescence, whose floral-leaves and perianth become fleshy and united into one nutritious mass, together with the axis, which is also fleshy. The milky juice of the India-rubber tree (_Ficus elastica_, East Indies, a common house-plant), and of _Castilloa elastica_ (Am.) is the raw material of India-rubber. The milky juice of _Galactodendron utile_ (Cow-tree, S. Am.) is saccharine and nutritious, but in _Antiaris toxicaria_ (the Upas-tree, of Java) it is a strong poison. The bast of the Paper-Mulberry tree (_Br. papyrifera_, Eastern Asia); is used in Japan for paper. Shellac is obtained from a small, hemipterous insect (_Coccus lacca_), which lives upon _Ficus laccifera_ and _F. religiosa_ (the Bo-tree, sacred to Buddha), E. India. The wood of _Maclura aurantica_ (Am.) has a yellow colour, and is known as yellow Brazilian wood. Order 4. =Cannabaceæ.= The plants which belong to this order are _aromatic herbs_, either annuals or perennials, _without latex_. Leaves _palminerved_, and more or less divided, hispid, and with free, persistent stipules. Flowers always _diœcious_; ♂-flowers in panicles, formed of dichasia, passing over into uniparous scorpioid cymes. They differ from the Nettles, particularly in the 5-leaved perianth of the ♂-flower, the 5 stamens (Fig. 346–351) with filaments _erect_ in the bud, and in the ♀-flower by the small, entire, cup-like perianth, which surrounds the base of the ovary (Fig. 346, p. 352). The ovary has two styles, or one divided into two, with two stigmas and a pendulous, curved ovule (Fig. 346 _B_, 352 _B_); the fruit is a nut; the _embryo_ is _curved_ (Hemp, Fig. 353), or rolled (Hop, Fig. 349), _without endosperm_. [Illustration: FIG. 346.--Diagram of male and female flowers of the Hop and Hemp: _b_ the bract, _p_ the perianth. The position of the embryo is indicated.] Only 2 genera with 3 species (Asiatic), of which two are cultivated.--_Humulus lupulus_ (Hop, Figs. 347–349) is a twining, perennial plant, twisting to the right, with opposite, palmilobed, rough leaves, and large, interpetiolar stipules. The ♀-flowers are situated in closely-flowered, cone-like, compound inflorescences, with ultimately large, thin, imbricate floral-leaves (Fig. 348) which bear the yellow, glandular hairs, containing lupulin. ~This inflorescence is made up as follows:--The most external floral-leaves are situated in pairs, and are the persistent stipules of a leaf, the blade of which has become suppressed, or in any case is rudimentary. Such a pair of stipules supports 4 (2–6) flowers in a double uniparous cyme, whose central axis does not develope into a flower. The bracts of these flowers (bracteoles of the partial inflorescence) become, at maturity, very large, spathe-like, and, together with the stipules, produce a cone-like appearance.~ [Illustration: FIG. 347–348.--_Humulus lupulus_: 347, twining stem; 348, branch with strobiles.] _Cannabis sativa_ (Hemp, Figs. 350–353) is an East Indian herb, with palmilobed leaves, and differs from the Hop in being annual, erect, and in having its leaves opposite at the base and scattered above. The ♀-inflorescence is not cone-like as in the Hop, but the flowers are similar in construction. ~The main difference is to be found in the axillary shoot, which was suppressed in the Hop, and is in the Hemp developed into a leaf-bearing shoot which on each side bears only one ♀-flower, and in the fact that the bracts are not so strongly developed.~ The “Hops” (the female inflorescences) are used in brewing, and medicinally on account of the yellow glands which contain lupulin. The Indian variety of _Cannabis sativa_ contains an abundance of glandular hairs and resin. The withered inflorescences are used in medicine and are officinal. The bast of the stems of the Hemp is also used and the fat oil of the seeds. In Oriental countries the entire plant is used in the preparation of an intoxicating drink (haschisch), the narcotic material being found in the glandular hairs. [Illustration: FIG. 349.--_Humulus lupulus_: fruit in longitudinal section.] [Illustration: FIGS. 350–353.--_Cannabis sativa_: Fig. 350, ♂-plant; Fig. 351, ♂-flower; Fig. 352, ♀-flower, entire and in longitudinal section; Fig. 353, fruit in longitudinal section.] Family 6. =Polygonifloræ.= This family is on one side closely allied to the _Urticaceæ_ by its solitary, _basal_, _vertical_, and _straight_ ovule, and by the conical ocrea which envelopes the younger leaves in the bud, similar characters being present in the Urticaceæ. On the other side it is related to the Curvembryæ. The flowers are small, often _trimerous_, regular and slightly perigynous (~in _Chloranthaceæ_, if they properly belong to this family, and _Houttuynia_, more or less epigynous~). Syncarps are present in some Piperaceæ, but the fruit is generally a single fruit, one-seeded berry, nut or drupe. The leaves are generally scattered. Order 1. =Polygonaceæ.= The majority are herbaceous plants with round, often jointed stems, scattered leaves and _ocrea_, that is a membranous, tubular, ligular or stipular structure _inside_ the base of the leaf, which clasps the stem and axillary bud; the edges of the lamina are rolled backwards in the bud. The flowers are regular, small, generally ☿, slightly perigynous, with inconspicuous, simple, green or white perianth of 5–6 free segments; stamens 5–9 (Fig. 354) sometimes arranged in two series; gynœceum 2–3 carpels, ovary _unilocular_ with _one basal_, _straight_ (orthotropous) _ovule_, 2–3 _free styles_. The fruit is a 2–3-angular nut; the embryo, with mealy endosperm, is straight or curved (Fig. 355 _H_), often unsymmetrical.--~The inflorescences are compound, and generally branch from the axils of the bracteoles, so that the last partial-inflorescences become coiled, uniparous scorpioid cymes; in _Polygonum_ the two bracteoles unite into a membranous tube; in _Rheum_ and _Rumex_ there is only one bracteole.~ [Illustration: FIG. 354.--_A_ Diagram of _Rheum_; _B_ of _Rumex_; _C_ of _Polygonum fagopyrum_; _D_ of _P. lapathifolium_. The ovules are indicated inside the ovaries; bracts and bracteoles are not shown.] _Rheum_ (Rhubarb, Fig. 354 _A_) has a 6-leaved, _petaloid_ perianth (Pn 3 + 3) and 9 stamens (A 3^2 + 3). The _3-winged_ nut is _not_ enclosed by the perianth. _Rumex_ (Dock, Fig. 354 _B_) has 6 stamens (A 3^2 + 0); the perianth is 6-leaved (Pr 3 + 3), green or red, and the triangular nut is enveloped by the 3 interior perianth-leaves, which point upwards and continue to grow after flowering. These perianth-leaves often have warts on their outer surface. ~The following are monœcious: _R. acetosa_ and _R. acetosella_.~ _Polygonum_ (Knot-grass, Figs. 354 _C_, _D_; 355). The _petaloid_ perianth is most frequently 5-merous (2/5 spiral); 5–8 stamens. The nut is triangular (Fig. 354 _C_, 355), or lenticular (Fig. 354 _D_). ~There are two whorls of stamens, the external with introrse, and the internal with extrorse anthers. The gynœceum is often bicarpellate (Fig. 354 _D_).~ The flowers may be considered as constructed upon the monocotyledonous type. _Pterostegia_ has a perfectly monocotyledonous flower with 5 trimerous whorls. _Rheum_ likewise, but here the external staminal whorl is doubled (Fig. 254 _A_). _Oxyria_ has a dimerous _Rheum_-flower (4-leaved perianth, 6 stamens, 2 stigmas). _Rumex_ has a _Rheum_-flower with the suppression of the internal whorl of stamens (Fig. 354 _B_); _Emex_ is a dimerous _Rumex_. _Polygonum_, to which _Coccoloba_, _Muehlenbeckia_ and others are related, differs from _Rheum_ chiefly in having one of the leaves, which in the latter takes part in the formation of the perianth, developed in this case into a bracteole (so that the perianth is reduced to five members), and several or all the stamens in the inner whorl become suppressed.--The perianth in _Coccoloba_ and _Muehlenbeckia_ is more or less perigynous and becomes fleshy, enclosing the fruit. _Muehlenbeckia platyclada_ has flat branches with rudimentary leaves; sometimes branches with normal, arrow-shaped leaves are found. _Atraphaxis._ [Illustration: FIG. 355.--_Polygonum fagopyrum_: _A_ branch with flower and fruits (nat. size); _B_ flower; _C_ the same in longitudinal section; _D_ anterior and posterior view of stamen; _E_ gynœceum; _F_ fruit (mag.); _G_ fruit in longitudinal section; _H_ transverse section, showing the curved cotyledons embedded in the endosperm; _I_ the embryo.] POLLINATION. _Rumex_ is wind-pollinated, the stigmas are therefore large and brush-like (indicated in Fig. 354 _B_). _Rheum_ and _Polygonum_ are insect-pollinated and have therefore capitate stigmas, etc.; honey-glands are situated at the base of the stamens (_d_, in Fig. 354 _C_, and _n_ in Fig. 356); a few small-flowered _Polygonum_ species are self-pollinated; Buckwheat (_P. fagopyrum_) is dimorphic and has long-styled and short-styled flowers (Fig. 356). _Pol. bistorta_ is protandrous and homostyled. About 750 species, most of which are found in the temperate regions of the Northern Hemisphere, some reaching as far as the snow line or into the Arctic regions (_Oxyria_, _Kœnigia_). Trees and shrubs are found in the Tropics: _Coccoloba_, _Triplaris_. _Rheum_ is Central Asiatic.--The thick rhizomes of _R. officinale_ (_Rhubarb_) are _officinal_. The rhizomes of the ordinarily cultivated species, _R. undulatum_ and _rhaponticum_, are used in veterinary medicine. The following are cultivated as culinary plants for the sake of their leaves:--_Rumex acetosa_ (Sorrel), _R. patientia_, _R. scutatus_, and _Rheum undulatum_ (petioles). Several species of _Polygonum_ (_P. hydropiper_ and others) have a sharp, pungent taste. “Buckwheat” is the mealy fruit of _Polygonum fagopyrum_ (Central Asia) and is of value as a farinaceous food. _P. cuspidatum_ (_P. sieboldi_, Japan) is an ornamental plant.--_Calligonum_ in sandy and stony deserts. [Illustration: FIG. 356.--Flower of _Polygonum fagopyrum_ in longitudinal section: 1, long-styled; 2, short-styled; _a_ the anthers; _st_ the stigmas; _n_ nectary.] Order 2. =Piperaceæ (Peppers).= Shrubs or herbs, often with nodose, jointed stem; leaves simple, entire, often with curved veins; stipules wanting (_Peperomia_) or intrapetiolar and cap-like, often enclosing the terminal buds (_Piper_). The flowers in the group _Pipereæ_ (_Piper_, Fig. 357, and _Peperomia_) are borne in spikes with fleshy axes (_club-like_), seldom in racemes, the outer ones are crowded and are ☿ or unisexual, always small, _naked_ and without bracteoles; ~generally stamens 3 + 3, and gynœceum 3, but the number of the stamens may be reduced by suppression to 2, and the carpels to 1~. The flowers are situated in the axils of the small, generally shield-like floral-leaves. The ovary is always _unilocular_ and has _one upright, orthotropous_ ovule. Fruit a berry or drupe. Both endosperm and _perisperm_ are present, the latter being especially well developed (Fig. 359). _Piper_; generally shrubs with scattered leaves, and terminal inflorescences which are crowded to one side by the development of the highest lateral bud, so that they are situated opposite the leaves (Fig. 357). Many species have stems with an abnormal anatomical structure.--_Peperomia_; chiefly succulent herbs, often epiphytes, with opposite or verticillate leaves having aqueous tissue on the upper side. [Illustration: FIG. 357.--_Piper nigrum_: branch with fruit (½)] The group _Saurureæ_ (considered by some as an order, and perhaps representing a more original type) has 3–4 carpels with many ovules. _Lactoris_ stands the highest with regular 3-merous perianth, 3 + 3 stamens and 3 carpels, which are united at the base. Fruit a capsule with several seeds. (It has one species from the island of Juan Fernandez, and is also placed in an order of its own, Lactoridaceæ, allied to the Magnoliaceæ, through _Drimys_).--_Saururus_ has naked flowers; most frequently 6 stamens, and 4 carpels, free or united at the base, each with 2-4 orthotropous ovules. Fruit, small berries.--_Houttuynia_; stamens situated a little upward on the ovaries; placentation parietal; capsule many-seeded. About 1,000 species; entirely tropical, especially from South America and East India. They are found chiefly among the underwood in damp, shady places; some, which are fleshy (_Peperomia_), live as epiphytes on trees; a few climb by roots.--USES. Several Piperaceæ are used medicinally and for spices on account of their pungent properties and the essential oils found in nearly all parts of the plant. The following are _officinal_: “Black-pepper” (the unripe, dried fruits) and “White-pepper” (the seeds of the ripe fruits) of _Piper nigrum_ (climbing shrub, East Indian); “Cubeb” berries of _P. cubeba_ (climbing shrub, Java). “Long-pepper” is the unripe inflorescence of _P. longum_, East India. The leaves of _P. angustifolia_ (Matico) are officinal. The leaves of the Betelpepper (East India) are used together with the nuts of the Areca-palm to form the well-known East Indian intoxicating compound “Betel.” A good many others are also used. [Illustration: FIG. 358.--_Piper nigrum_ (Diagram). In addition to the bract there are two structures resembling bracteoles.] [Illustration: FIG. 359.--_Piper nigrum_: Fruit in longitudinal section, showing the endosperm, perisperm, and pericarp.] Order 3. =Chloranthaceæ.= (_Chloranthus_, _Hedyosmum_) have opposite leaves, with stipules more or less united at the base, and inferior “drupes.” Ovules pendulous. Only endosperm. About 33 species, Tropical. Family 7. =Curvembryæ.= The plants in this family have a _curved ovule_, and most frequently a _kidney-shaped seed_ (generally provided with fine, cuticular, projecting warts, Fig. 362 _B_), with a _curved, peripheral embryo enclosing the endosperm which is most frequently floury_ (Figs. 362 _C_, 365 _H_; for exceptions, see Fig. 366); the seeds in all cases are borne on a _centrally-placed_, and in most cases _free_, placenta (they are “basal” when there is only 1 ovule in the ovary, Fig. 364). The flower is regular, hypogynous or perigynous (Fig. 364) (only rarely epigynous) and usually 5-_merous_. The flower which is most complete has 5 whorls (S5, P5, A5+5, G2-3–5), as in some genera of the Caryophyllaceæ (Figs. 360, 361); but from this type it becomes reduced, the petals and stamens being suppressed, so that finally 5 perianth-leaves, 5 stamens (opposite the perianth-leaves), and 2 carpels (Fig. 361 _F_) only are present; for example, in certain genera of the _Caryophyllaceæ_, in the _Chenopodiaceæ_, _Amarantaceæ_, and others. When the number of stamens is increased to more than 5 in the whorl, it is always possible to show that some of the stamens have been divided. The number of the carpels and ovules also becomes reduced; in the highest there is a central placenta, not free in its early stages, with a large number of ovules; in those which are most reduced there is only a single ovule, which is placed centrally at the base of the ovary [Fig. 364]. Somewhat corresponding changes are found in the fruit, which is a many-seeded _capsule_ in those which have many ovules, but a one-seeded _nut_ where there is one ovule. In the most reduced forms the flowers are generally unisexual.--Similar features are also present in the vegetative parts. Almost all the species are herbaceous, the leaves are simple and most frequently without stipules. ~The structure of the stem, especially in Chenopodiaceæ, Amarantaceæ, Nyctaginiaceæ and others, often differs from that of the ordinary Dicotyledon. In the woody portion of the stem and root several rings are sometimes formed which resemble annual rings but which are formed by new cambium-rings arising outside the old ones which then cease to divide.~ Order 1. =Caryophyllaceæ.= Herbaceous plants, with round, nodose stem; leaves _opposite_, slightly amplexicaul, simple, with sessile, undivided, entire lamina; stipules nearly always absent; the inflorescences are _dichasia_ passing over into unipared scorpioid cymes. The flowers are regular, ☿ or unisexual, hypogynous or perigynous, 5-(or 4-) merous with 2–3–4–5 carpels; calyx persistent; corolla polypetalous. The ovary is unilocular (or originally, and sometimes also in the later stages, plurilocular below, _e.g._ _Viscaria_), with _free styles_ and 1–several curved ovules on a _central_, free placenta. The fruit is a nut or a capsule opening apically with long or short valves (teeth, Fig. 362), equal to or double the carpels. For the seeds refer to the family. ~In _Dianthus_ the embryo is straight.~ The flowers which are most complete have _Sn_, _Pn_, _An_ + _n_ (obdiplostemonous), _Gn_ where _n_ = 5 (Figs. 360, 361 _A_) or 4 (Fig. 361 _B_); the carpels may be placed opposite to the sepals (Fig. 360) or opposite to the petals (Fig. 361 _A_, _B_). Without any change taking place in the position of the other whorls, the carpels are next found reduced to 2–3–4 (see the genera); their number may easily be recognised by that of the styles. This is the construction in the majority of the genera in the two first groups. _Stellaria media_ differs considerably. It may have (_a_) the flower as described above, with _G3_; (_b_), the corolla only absent, or (_c_) only the petal-stamens (A5 + 0, Fig. 361 _C_), or (_d_) all these as well as some of the sepal-stamens. The same applies to _Sagina_, _Alsine_, _Cerastium_, and others, and, finally, a series of genera are formed, with certain conditions of reduction which have become constant, and by a gradual series of steps lead to the most reduced form, which has only 5 sepals and 5 (or even as far as only 1) sepal-stamens (Fig. 361 _D_, _E_, _F_).--The PETALS in the _Alsineæ_ are often deeply bifid. The sepal-stamens are most frequently the longest, and bear nectaries at the base (Fig. 363 _st_). In the most complete forms the ovary has partition-walls in the lower portion (Fig. 360); these do not, however, reach to the top, and generally soon disappear. The ovules, when numerous, are situated on the placenta in as many double rows as there are carpels. In the number of ovules a reduction from many to 1 takes place (Fig. 361). A comparison proves that the “free, centrally placed” placenta is formed by the ventral portion of the carpels. The single basal ovule in _Herniaria_ (Fig. 364), _Scleranthus_, and others, is also borne on the carpels. The vegetative _branching_ is characteristic. One of the leaves in a pair is formed before the other, and has a more vigorous axillary bud; these stronger leaves stand in a ¼-spiral, the fifth above the first one, and the branches are consequently arranged in the same manner. In the inflorescence, however, it is the upper or second bracteole (β) whose axillary bud (_w_ in Fig. 361) is most advanced. The bud of the first bracteole (α) becomes sometimes entirely suppressed, or in some this bracteole itself is suppressed. [Illustration: FIG. 360.--Diagram of _Lychnis_: α, β bracteoles.] [Illustration: FIG. 361.--_A-F_ Diagrams of flowers of the Caryophyllaceæ: _A Agrostemma_; _B Sagina_; _C Stellaria_; _D Corrigiola_; _E Paronychia_; _F Herniaria_.] The most original type appears to be represented by the Alsineæ. From this form on one side the Sileneæ, adapted in a higher degree for insect-pollination, are developed, and on the other side the Paronychieæ, with various reductions. =1.= ALSINEÆ, STITCHWORT GROUP. Sepals free, and connected with them stellately expanded, slightly unguiculate (white or inodorous) petals; these, however, often become suppressed (Fig. 363). The fruit is a capsule. [Illustration: FIG. 362.--_Cerastium arvense_: _A_ fruit; _B_ seed; _C_ section of seed.] =a.= As many carpels as sepals (4 or 5). _Cerastium_ (Chickweed). The petals are bifid. Capsule cylindrical, frequently _curved_ at the top, and opening by 10 teeth (Fig. 362).--~_Malachium_ differs only in the 5-toothed capsule with bifid teeth.~--_Spergula_ (Spurry). The petals are not bifid, capsule 5-valved; seeds winged. The leaves are linear, and appear as if placed in large numbers in a whorl, a branch being situated in the axil of each with leaves placed very close together at its base; _stipules membranous_.--~Sagina has Sn, Pn, An + n, or An, Gn, where n = 4 or 5. The corolla is often wanting.~ =b.= 3 (rarely 2) carpels (Fig. 361 _C_). _Stellaria_ (Stitchwort) has deeply cleft petals. The number of stamens varies (see above).--_Arenaria_ has entire petals. ~(To this group belong _Alsine_, _Moehringia_, _Halianthus_, or _Honckenya_ (Fig. 363), which differ from each other, especially in the form of the seed and number of the capsular valves.) _Spergularia_ has membranous stipules, as in _Spergula_.--_Holosteum._~ [Illustration: FIG. 363.--_Arenaria_ (_Halianthus_) _peploides_: ♀-(_A_) and ♂-flower (_B_, _C_).] =2.= PARONYCHIEÆ (Figs. 361 _D_, _E_, _F_; 364). Small, greenish plants. The leaves, in the majority, are opposite, with _membranous stipules_. The flowers are most frequently arranged in small _dichasia_; they are small and insignificant, perigynous (Fig. 364) or hypogynous. The corolla is in most cases wanting, and when present is very small; in general the calyx-stamens are developed, but the corolla-stamens may be represented by small scales (Fig. 364). Ovary most frequently with 1 ovule. Fruit, a _nut_, rarely a capsule; it is enclosed by the strongly perigynous floral axis (torus). _Scleranthus_ (Knapwell) is perigynous with bell-shaped torus; no corolla; corolla-stamens are wanting or rudimentary; some calyx-stamens may also be absent.--_Corrigiola_ (Fig. 361 _D_); _Illecebrum_; _Paronychia_ (Fig. 361 _E_); _Herniaria_ (Figs. 361 _F_, 364). =3.= SILENEÆ, PINK OR CARNATION GROUP. This has a _gamosepalous_ calyx and unguiculate, white or red, petals, with _outgrowths_ (_ligule_, _corona_, _paracorolla_) at the throat of the corolla. These structures are not found in the other groups, and are merely outgrowths at the junction of the limb and claw. The corolla, stamens and ovary are frequently raised above the calyx, upon a lengthened internode (_gynophore_). The flower has S5, P5, A5 + 5; fruit a capsule with many seeds. =a.= 5-(rarely 3–4) carpellate ovary.--_Lychnis_ (Campion, Fig. 360). The corolla is longer than the calyx; corona present. The capsule is 10- or 5-toothed, completely 1-chambered or 5-chambered at the base,--the genus has been divided accordingly into several genera: _Melandrium_, _Lychnis_, _Viscaria_. ~Some species are unisexual by the abortion of stamens or carpels (_L. vespertina_, _diurna_).~ _Agrostemma_ (_A. githago_, Corn-cockle, Fig. 361 _A_) has a long-toothed calyx, the teeth exceeding the corolla; corona absent; 5-toothed capsule. [Illustration: FIG. 364.--_Herniaria glabra_: _a^1_ flower; _b^1_ longitudinal section through the flower; _c^1_ stigma with two pollen-grains.] =b.= Tricarpellate.--_Silene_ (Catch-fly). Six-toothed capsule; corona present in the majority.--~_Cucubalus_ has berry-like fruits which finally become dry but do not dehisce.~ =c.= Bicarpellate (2 styles, 4-toothed capsule).--_Dianthus_ (Pink); at the base of the calyx 1–several pairs of floral-leaves are situated; corona absent. The _straight embryo_ is a peculiar exception.--_Gypsophila_ has a campanulate, open calyx, 5-nerved, membranous between the nerves; corona absent; the flowers are generally small and numerous, in a large, paniculate dichasia.--_Saponaria_ (Soapwort) has corona. POLLINATION. _Alsineæ_ has ordinary nectaries at the base of the calyx-stamens (Fig. 336): they are frequently protandrous but may often, in the absence of cross-pollination (in the less conspicuous species) pollinate themselves. Their open flowers are accessible to many kinds of insects (particularly flies and bees). _Gynodiœcious_ flowers are found in several species, and the ☿-flowers are then generally more conspicuous than the ♀-flowers. That the ♀-flowers have descended from ☿-flowers is seen by the large staminodes found in them (Fig. 363). _Arenaria peploides_ is diœcious (Fig. 363). The _Sileneæ_ are as a rule adapted for pollination by insects with long probosces--especially butterflies,--and they are frequently protandrous, so that at first the calyx-stamens open, later on the corolla-stamens, then the stigmas expand. The honey is secreted by a ring-like nectary round the base of the ovary or by nectaries at the base of the stamens. Some only blossom and emit scent at night or in the evening (_Lychnis vespertina_, _Silene nutans_, _Saponaria officinalis_) and, like other night-flowers, are of a white or pale colour. DISTRIBUTION. 1,100 species, especially in temperate climates, fewer in the colder zone, less still in the Tropics. The Paronychieæ are especially found in dry, sandy fields. USES. “Soap-root” (with _Saponin_, forming a lather in water) from _Saponaria officinalis_ was formerly officinal, and _Gypsophila struthium_. The seeds of _Agrostemma githago_ are said to be poisonous.--The following are ornamental plants: species of Pinks (_D. caryophyllus_, garden Pink, often with double flowers; _D. barbatus_, _plumarius_, _etc._). _Lychnis_, _Gypsophila_, _Silene_, _Cerastium_ (_C. tomentosum_ as edging for borders), _Saponaria officinalis_ (often coronate).--_Spergula arvensis_ is sometimes cultivated. Order 2. =Amarantaceæ.= The flowers are essentially the same as in the _Chenopodiaceæ_ and the extremely reduced Caryophyllaceæ (Fig. 361 _F_); they are regular, hypogynous, generally ☿, have 5 free (rarely slightly united) perianth-leaves; in front of these 5 stamens, which _are often united_ at their base into a shorter or longer tube and have stipule-like teeth between them (the division _Gomphreneæ_ has 2-locular anthers, each of which opens longitudinally); and a 2–3 carpellate gynœceum with one loculus and most frequently one, more rarely several ovules; the fruit is a nut, more rarely (in _Celosia_, _Amarantus_, _Gomphrena_) a capsule, dehiscing irregularly, or like a pyxidium. The characters which especially separate them from the allied orders are found in the perianth. The perianth-leaves are not green and herbaceous, but _membranous, dry, and often coloured_; they are frequently produced into a bristle or awn; they have also both subtending floral-leaves and _2 large bracteoles similar to the perianth_; all these dry leaves persist without alteration after the withering of the flower.--The flowers are without scent. They are arranged in spike- or capitulum-like inflorescences; sometimes placed singly, sometimes aggregated in the panicle-like inflorescences; in others, on the contrary, in dichasia. The majority are herbs, some are shrubs. The leaves are scattered, or opposite, but always simple and without stipules; some are smooth, others hairy. 450 species; especially in the Tropics, principally S. Am. and E. Ind.: few are found outside these countries.--Only a few are used; some, chiefly E. Indian species, are cultivated as ornamental plants: _Amaranthus_ (Fox-tail); _Gomphrena globosa_; _Celosia cristata_ (Cock’s-comb) remarkable for its fasciated inflorescence; _Alternanthera_. Some are employed as culinary plants in the Tropics, and in a few of the E. Indian species the seeds are farinaceous, and used for food. Order 3. =Chenopodiaceæ.= Generally herbaceous plants like the Caryophyllaceæ, but the leaves are arranged spirally (except _Salicornia_), and are simple, exstipulate; they are generally fleshy and like the stem “mealy,” that is, covered with small hairs, whose large spherical terminal cell readily falls away; otherwise they are seldom hairy. The inflorescences are generally flower-clusters borne in panicles. Bracteoles generally absent. Flowers generally _unisexual_: with the single exception of _Beta_ the flowers are hypogynous; they are regular, small and inconspicuous, with _single, green_, 5-leaved, but _more or less united_ perianth; 5 stamens opposite the perianth, and a _2–5-carpellate, unilocular_ ovary with 1 basal, curved ovule; but in some genera the number of the perianth-leaves and stamens is reduced to 3–2–1–0. The fruit is generally a _nut_,--thus this flower and fruit are the same as in the reduced Caryophyllaceæ (Fig. 361 _F_). The seed is similar to that generally found in the family (for exceptions see the genera). The floral diagram most frequently present is the same as in Fig. 361 _F_. There is no indication of corolla or of corolla-stamens, which may be supposed to have belonged to the plant, but which are now entirely and completely suppressed. This order appears to have been an offshoot from the Caryophyllaceæ.--The perianth persists after the withering of the flower, and envelopes the nut; it is very variable, and, together with the position of the seed, the form of the embryo, the sex of the flowers, etc., gives the characters of the genera. =1.= CHENOPODIEÆ, GOOSEFOOT GROUP (Fig. 365), has ☿ (or polygamous) flowers, with regular 5-parted perianth (_C_); the embryo is ring-like (_H_). The leaves have the ordinary flat forms.--_Chenopodium_ (Goosefoot). The flower is hypogynous, and the fruit (which is compressed) perfectly free; Mulberry-like collections of fruits are formed in some species (sub-genus _Blitum_) by the perianth becoming finally fleshy and coloured.--_Beta_ (Beet, Mangold, Fig. 365) differs from all genera in the perianth, which finally becomes cartilaginous, being epigynous (_D_). Small, most frequently 2–3-flowered clusters without bracteoles, situated in a long, interrupted axis (_A_, _B_); the flowers and fruits in each cluster are more or less united individually, and fall off together--they are commonly known as seeds (_E_, _F_). The seed lies horizontally.--_Hablitzia_ (_H. tamnoides_). [Illustration: FIG. 365.--_Beta vulgaris._] [Illustration: FIG. 366.--_Salsola soda_: embryo.] =2.= SALSOLEÆ, SALTWORT GROUP, has cylindrical or semi-cylindrical leaves. Perianth as in the preceding group; the fruit is most frequently compressed. The two first mentioned genera differ from most of the others in the order in having a spirally-coiled, and not a ring-like embryo, so that the endosperm is slight or wanting (Fig. 366). These plants are sometimes placed as a group by themselves, SPIROLOBEÆ--in contradistinction to which the others are termed CYCLOLOBEÆ.--_Salsola_ (Saltwort); leaves subulate, with spiny tips; the flowers have 2 spinous bracteoles: during the ripening of the fruit a tough leathery wing is developed transversely to the back of the perianth.--~_Chenopodina_ deviates from _Chenopodium_ chiefly in the embryo and want of endosperm.--_Kochia_ has a somewhat similar perianth to _Salsola_, but a ring-like embryo; it differs from the others in being hairy.~ =3.= SALICORNIEÆ, GLASSWORT GROUP. _Salicornia_ (Glasswort) has a very different appearance. The stems are succulent, jointed, and almost leafless; the leaves opposite, very small, sheath-like and connate; there is a depression in the axil of each leaf, in which a small 3-flowered dichasium without bracteoles is sunk; the flowers have a trimerous perianth, 1–2 stamens and 1 carpel. No endosperm. _S. herbacea_ on clayey beaches. =4.= ATRIPLICEÆ. This group has most frequently unisexual flowers; the ♂-flower has a 4–5 partite perianth, but the ♀-flower differs from it. _Atriplex_ is monœcious or polygamous, the ♀-flower is naked, but has 2 large, herbaceous bracteoles which expand during the ripening of the fruit, and often become warted and fringed, enveloping the _compressed nut_. ~The section _Dichospermum_ has two kinds of ♀-flowers, one like those just described, the other similar to the _Chenopodium_-flowers, which have been deprived of their stamens, and the fruits of which are _depressed_, not pressed together from the sides; some (_e.g. A. hortensis_) have even three kinds of nuts. All the flowers of _Atriplex_, which present vertical fruits, are accessory shoots, which stand beneath the ordinary flower-clusters, a rather singular relation.~--_Spinacia_ (Spinach) is diœcious; ♂-flower: perianth, 4 (-5); stamens, 4 (-5); ♀-flower: tubular, 2–4-partite perianth, hardening during the ripening of the fruit, and uniting with the compressed nut; in _S. oleracea_, it also forms _thorns_; 4 long stigmas.--_Halimus_ has the 2 long bracteoles almost entirely united and ultimately adhering firmly to the fruit. =5.= BASELLEÆ. A somewhat exceptional group with more or less perigynous flowers and 2 bracteoles. _Basella_, _Boussingaultia_, _Ullucus_. The perianth is sepaloid; ovary 1-ovuled. In _Basella_ the perianth is fleshy, enveloping the nut, and the cotyledons are so rolled together that a tranverse cut divides them in two places (as in Spirolobeæ). Herbaceous climbing plants. POLLINATION. Wind-and self-pollination, as far as is known; the insignificant flowers, devoid of honey, appear to exclude insect-pollination.--520 species. Most of them are annual (out of 26 native species only 5 are perennial); inhabiting salt-marshes and salt-steppes, and growing as weeds (most frequently on garden or field soil containing manure) in this country, especially species of _Chenopodium_ and _Atriplex_. The majority are found outside the Tropics, and play a very important part, for example, in the Asiatic salt-steppes. They grow gregariously in large masses. USES. Comparatively few. The only important one is _Beta vulgaris_ (from the Mediterranean basin), with its different varieties, viz. Beet-root, Cattle-beet or Red-beet, Sugar-beet, and others. These are biennial, making in the first year a root which acts as a reservoir of reserve material, with a rosette of leaves, and in the second year using this material in the production of a long stem, leaves and flowers. The primary root has been developed by cultivation into a very thick and fleshy tap-root; its mode of increase in thickness deviates from that of other roots, concentric rings of vascular bundles being formed from a cambial ring developed outside the previous ring. In this way several rings of vascular bundles separated by medullary rays, alternating with rings of parenchyma, may be found in the root of a Beet. Besides _Beta vulgaris_, var. _hortensis_ (Beet-root), the following are also cultivated: var. _cicla_ (Leaf-beet, “Mangold,” or “Roman Spinach ”), _Spinacia oleracea_ and _Atriplex hortensis_ as Spinach; a form of the latter and of Spinach are grown as ornamental plants. The tubers of _Ullucus tuberosus_ are used as potatoes; _Chenopodium quinoa_, in Chili and Peru, is an important farinaceous plant. Soda is made from some (_Salsola kali_, _Chenopodina maritima_ and others). Aromatic properties are rare: _Chenopodium ambrosioides_ and _botrys_. Order 4. =Batidaceæ.= _Batis maritima_, a bushy West Indian maritime plant. Order 5. =Phytolaccaceæ.= The ☿ (sometimes unisexual), regular, sometimes slightly perigynous flowers are inconspicuous and have a single sepaloid or coloured 4–5-leaved perianth (generally united at the base); stamens either in 1 whorl in the spaces between the perianth-leaves or in 1 whorl opposite the perianth-leaves, or in 2, one of which alternates with these; but the number may be increased by the splitting of one or of both the whorls to as many as 10–15–20–25. _Carpels_ sometimes only one, sometimes _many_ (4–10) placed in a whorl, either free or united into a gynœceum with a corresponding number of loculi in the ovary; but in all cases _each carpel bears only its own style and 1 ovule_. The fruit is a _berry_ (or nut, capsule, or schizocarp).--Mostly herbs or herbaceous shrubs, with scattered, simple leaves without stipules (_Petiverieæ_; have stipules). Inflorescences, most frequently _racemes_ or spikes, which in some instances are apparently placed opposite to a leaf, being displaced by a more vigorous growth of the axillary bud. Embryo always bent.--_Petiveria_ has a straight embryo with rolled cotyledons.--_Phytolacca_, _Pircunia_, _Microtea_, _Seguieria_, _Rivina_ (Pr4, A4, G1; berry), and others. The following plant is, with some doubt, placed near this order: _Thelygonum cynocrambe_; monœcious. ♂-flowers: perianth, 2-leaved; stamens indefinite. ♀-flowers: perianth-leaves united, 3-toothed; G1, style gynobasic. Fruit a drupe. An annual plant; Mediterranean. Branching anomalous. About 90 species; in tropical and temperate countries, principally America and Africa.--The red juice in the fruits, especially of _Phytol. decandra_, is used for colouring wine. Order 6. =Portulacaceæ= (=Portulacas=). The flowers are regular (except _Montia_), hypogynous (except _Portulaca_) and ☿. The diagram which applies to the majority of genera is that in Fig. 367, but with all the 5 stamens completely developed: it may be considered as the Chenopodiaceous diagram with the addition of 2 _bracteoles_ in the median line (_m-n_, these by some are considered as sepals), and with a petaloid perianth (usually designated “corolla”). The “petals” fall off very quickly, and are sometimes wanting. Most frequently 5 stamens, situated opposite the “petals,” but in other genera the number varies; _Montia_ has only 3 stamens (by suppression of the two anterior and lateral, Fig. 367), others again have more than 5, some a large and indefinite number. This may be explained partly by the appearance of a second whorl of stamens alternating with the first, and partly by the splitting (dédoublement) of the stamens. Gynœceum most frequently tricarpellate, ovary unilocular with 1–several basal ovules (sometimes on a branched placenta, as in certain _Caryophyllaceæ_). The fruit is a _capsule_, more rarely a nut.--The majority are annual herbaceous plants with scattered, entire leaves, often fleshy and smooth, with or without rudimentary stipules (dry, membranous, modified into hairs). Inflorescence cymose. [Illustration: FIG. 367.--_Montia._ Diagram of flower.] _Portulaca_ (Portulaca): flower, epigynous or semi-epigynous; fruit, a pyxidium. The stamens vary in number, and are most frequently placed in groups (in consequence of splitting) opposite the petals.--_Montia_: the corolla is slightly gamopetalous, but cleft on the posterior side (Fig. 367), and as a consequence of the larger size of the lateral petals, slightly zygomorphic; 3 stamens.--_Calandrinia_; _Talinum_; _Anacampseros_; _Claytonia_. 125 species; mostly in warm and temperate countries, especially the arid parts of S. Am. and the Cape. _Montia fontana_ (Blinks) is a native plant. _Portulaca oleracea_ is cultivated as a pot-herb in the south of Europe. A few species of _Portulaca_ and _Calandrinia_ are ornamental plants. Order 7. =Nyctaginiaceæ.= The characteristic feature of this order is the _single_, regular, _united_, and often petaloid perianth, the lower part of which generally persists after flowering and embraces the fruit as a false pericarp. The upper portion is most frequently _valvate and folded_, or simply valvate in æstivation. The number of stamens varies. The free gynœceum is _unicarpellate_ and has 1 ovule. The fruit is a _nut_, but becomes a _false drupe_, since the lower persistent portion of the perianth becomes fleshy (as in _Neea_, where this fleshy part is almost always crowned by the upper persistent part of the perianth. In the majority of the Mirabileæ the lower part becomes the dry _anthocarp_, while the upper petaloid part falls away after flowering). Finally, a peculiar involucre is formed around the flowers by free or united floral-leaves.--The majority are herbs, some are trees (_Pisonia_, etc.); _Bougainvillea_ is a liane. The stems are often nodose and swollen at the nodes; the leaves are simple, penninerved, scattered, or opposite, without stipules. ~In some, the vascular bundles are scattered; stem anomalous.~ _Mirabilis_; the structure of the stem is abnormal. Dichasial branching with continuation from the second bracteole, thus forming unipared scorpioid cymes. The perianth is petaloid, funnel-shaped, and has a folded and twisted æstivation resembling that of the corolla of the _Convolvulaceæ_; the upper coloured portion falls off after the flowering. Outside, and alternating with it, is a 5-partite, sepaloid involucre of 5 spirally-placed floral-leaves.--_Oxybaphus_; the involucre envelops 1–3 dichasial flowers.--_Bougainvillea_; the involucre is rose-coloured, 3-leaved, and envelops 3 flowers (placed laterally; the terminal flower wanting). The leaves of the involucre in _Boerhaavia_, _Pisonia_, _Neea_, and others are reduced to teeth or scales. 157 species; mostly in tropical countries, and especially S. Am. Species of _Mirabilis_ (Am.) are ornamental plants. Theïn is found in _Neea theïfera_ Oersted (discovered by Lund in Lagoa Santa, Brazil), which may be used as a tea-plant. Order 8. =Aizoaceæ.= Only 3 _whorls_ are found in the flower, which _alternate_ with one another when their leaves are equal in number. The first is sepaloid, the third one the carpels, and the intervening one is either uncleft, in which case it is developed as stamens, or it is divided into a large number of members which then all become stamens (arranged in groups), or the outermost ones become developed as petals. The fruit is most frequently a capsule with several loculi. Most of the species are herbs with thick, fleshy stems, and exstipulate leaves. The structure of the stem is usually anomalous. =1.= AIZOIDEÆ have hypogynous or perigynous flowers with (4–) 5 perianth-leaves; stamens single, or (by splitting) in groups of 2–3, alternating with the perianth-leaves. The gynœceum (with 3–5 carpels) has 3–5 loculi in the ovary, and most frequently numerous ovules in each loculus, borne on the central placenta formed by the edges of the carpels. The fruit is a capsule. The inflorescences are dichasia and unipared scorpioid cymes.--_Aizoon_, _Mollugo_, _Sesuvium_, and others are herbs or bushes, most frequently hairy. =2.= MESEMBRIANTHEMEÆ have semi- or wholly-epigynous flowers.--_Tetragonia._ The perianth is 4 (more rarely 3–5–6)-merous. Stamens single, or (by splitting) in groups alternating with the perianth-leaves. There is an indefinite number of carpels, and each loculus of the ovary contains _only_ 1 pendulous ovule. Fruit a nut or drupe. The flowers arise singly in the leaf-axils, with an accessory foliage-bud below them; in some instances there is also an accessory flower between this bud and the flower. Southern hemisphere, especially at the Cape; _T. expansa_, New Zealand Spinach, is a fleshy plant which is cultivated as a pot-herb (Japan, Austr., S. Am.).--_Mesembrianthemum_: the flowers are 5-merous; the numerous linear petals and the still more numerous stamens all arise by the splitting of 5 or 4 protuberances (primordia) alternating with the sepals. The ovary presents another characteristic peculiarity: the carpels alternating with the 5–4 stamens form an ovary (with several loculi) with the ovules at first borne, as in other cases, on the _inner_ corner of the inwardly-turned carpels; but during the subsequent development the whole ovary is so turned round that the placentæ become parietal and the ovules assume, apparently, a position very rarely met with in the vegetable kingdom: on the dorsal suture of the carpels. Shrubs or under-shrubs, more rarely herbs with fleshy stems and simple, entire, more frequently thick or triangular leaves, containing a quantity of water. The flowers open about noon, and are brightly coloured, generally red or red-violet, but odourless. The capsules dehisce in rainy weather. 300 species, mostly found at the Cape. Some are ornamental plants. _M. crystallinum_ (the Ice-plant) and others are covered with peculiar, bladder-like, sparkling hairs, the cell-sap of which contains salt--these serve as reservoirs of water. Family 8. =Cactifloræ.= The position of this family is very doubtful; but it seems in many respects to approach _Mesembrianthemum_. Some botanists place it near to the Ribesiaceæ; others, again, to the Passifloraceæ. Only 1 order. [Illustration: FIG. 368.--_A Echinocactus_: _a_ position of a leaf-lamina; _b_ a lateral shoot on the displaced axillary bud. _B_ Pereskia: _b_ a foliage-leaf on a small thorny branch which is subtended by a foliage-leaf which has fallen off and left a scar(_a_).] [Illustration: FIG. 369.--_Echinopsis._] Order =Cactaceæ= (=The Cacti=). The flower is epigynous, ☿, regular, and remarkable for its _acyclic_ structure; there are, for instance, a large number of spirally-placed sepals and petals, which gradually pass over into one another, and which in some species, to a certain extent, arise from the walls of the ovary as in _Nymphæa_ (Fig. 383 _A_, _B_). The petals are free; rotate, opening widely in _Opuntia_, _Pereskia_, and _Rhipsalis_; erect and united at their base into a shorter or longer tube in _Cereus_, _Epiphyllum_, _Mammillaria_, _Echinocactus_, _Melocactus_, and others (Fig. 369). _Stamens numerous_, attached to the base of the corolla; gynœceum formed of _many carpels_, with one style, dividing into a number of branches corresponding to the number of carpels; the ovary has _one loculus_ with _many parietal_ placentæ; the ovules are anatropous, on long and curved funicles. Fruit a berry with exendospermous seeds. The fruit-pulp is mainly derived from the funicles.--The external appearance of the Cactaceæ is very peculiar; _Pereskia_, which has thick and fleshy leaves (Fig. 368), deviates the least; foliage-leaves of the usual form are wanting in the other genera, or are usually very small, and quickly fall off and disappear (_Opuntia_), or are modified into thorns; the stem, without normal foliage-leaves,--so characteristic a feature in this order,--makes its appearance after the two normally developed cotyledons. The stems are fleshy, perennial, and may finally become woody. In some they are elongated, globose, pointed, and more or less dichotomously branched, _e.g._ in several of the _Rhipsalis_ species, which live mostly as epiphytes on trees; in others, elongated, branched, globose, or, most frequently, more or less angular (prismatic) or grooved and provided with wings, and either columnar and erect (as much as about 20 metres in height and 1 metre in circumference, as in _C. giganteus_ in New Mexico) or climbing by roots (_Cereus_ and _Rhipsalis_-species); in others again, compressed, more or less leaf-like, often with a ridge in the centre (winged), branched and jointed: _Epiphyllum_, _Phyllocactus_, _Opuntia_, some species of _Rhipsalis_; others are thick, short, spherical or ovoid, unbranched or only slightly branched, and either studded with prominent warts (_mammillæ_) each of which supports a tuft of thorns (Fig. 368 _A_; _Mammillaria_ and others) or with vertical ridges, separated by furrows (rows of mammillæ which have coalesced) in _Melocactus_, _Echinocactus_, _Echinopsis_ (Fig. 369); at the same time the ovary in some is embedded in the stem so that leaves or leaf-scars, with tufts of thorns in their axils, may be observed on the ovary just as on the stem.--The flattened shoots of the Cactaceæ are formed in various ways, either by the compression of cylindrical axes (_Opuntia_) or, as in _Melocactus_, etc., from winged stems in which all the wings are suppressed except two. The thorns are produced directly from the growing points of the axillary buds, and are modified leaves. The axillary bud is united at its base with its subtending leaf, which as a rule is extremely rudimentary; and these together form a kind of leaf-cushion, larger in some genera than in others. This leaf-cushion attains its highest development in _Mammillaria_, in which it is a large, conical wart (see Fig. 368 _A_), bearing on its apex the tuft of thorns and rudimentary lamina.--The _seedlings_ have normal cotyledons and a fleshy hypocotyl. All the species (1,000?) are American (one epiphytic species of _Rhipsalis_ is indigenous in S. Africa, Mauritius and Ceylon), especially from the tropical table-lands (Mexico, etc.). Some species, especially those without thorns, as _Rhipsalis_, are epiphytes. _Opuntia vulgaris_, the fruits of which are edible, is naturalized in the Mediterranean. The cochineal insect (_Coccus cacti_) lives on this and some closely allied species (_O. coccinellifera_, etc.), particularly in Mexico and the Canary Islands. Several are ornamental plants. Family 9. =Polycarpicæ.= The flowers _as a rule are_ ☿, _regular_ and _hypogynous_; however in some orders they are unisexual, _e.g._ in the Myristicaceæ, or zygomorphic (in Monkshood and Larkspur in the Ranunculaceæ); in the Lauraceæ, (Fig. 386) for example, perigynous, and in _Nymphæa_ (Fig. 383) even partially epigynous flowers are typical.--The flowers are acyclic in very many of the genera of the two first orders, if not completely so, at any rate in the numerous stamens and carpels, thus denoting an old type. It is a remarkable characteristic that in the majority of the orders the number 3 prevails in the calyx and corolla; the number 5 also occurs, but the number 2 is seldom met with. Most orders have a double perianth; chorisis does not occur, suppression is rare, and the parts of the flower are developed in acropetal succession. The most characteristic feature in the order is the _free, one-leaved_, as a rule _numerous carpels_ (apocarpous gynœceum). The number of carpels in some of the last mentioned orders dwindles down to 1 (_e.g._ the _Berberideæ_ and _Myristicaceæ_). The carpels in _Nymphæaceæ_ become united into _one pistil_ (syncarpous), a condition which we also find distributed among the other orders. _Endosperm occurs in almost all_ the orders (except _e.g. Lauraceæ_). The nutritive tissue in _Cabombeæ_ and _Nymphæeæ_ is chiefly _perisperm_. [Illustration: FIG. 370.--Diagram of _Aquilegia vulgaris_: _sp_ spur. A cyclic flower.] [Illustration: FIG. 371.--Diagram of a dichasium of _Ranunculus acer_: α_{1}, α^1, and β_{1}, β^1, bracteoles (the buds in the axils of the bracteoles, α and α^1, are continued antidromously). The flower has cyclic calyx and corolla, bub acyclic (8/21) stamens.] [Illustration: FIG. 372.--Diagram of an acyclic Ranunculaceous flower (only 3 stamens are indicated). The spiral of the sepals has a divergence of 3/5; that of the corolla and subsequent leaves 3/8.] Order 1. =Ranunculaceæ.= Nearly all are _herbs_ (except _Clematis_). The leaves are scattered (except _Clematideæ_), they have a large sheath with broad base (no stipules), and are most frequently palminerved with palmate lobes. The flowers are hypogynous, with most frequently a well pronounced convex receptacle (Figs. 374 _B_, 380), ☿, regular (except _Delphinium_ and _Aconitum_); their structure varies very much; in some the leaves are verticillate, in others arranged spirally; in others, again, both modes of arrangement are found. It is a characteristic feature that the various series of leaves (especially calyx and corolla) are not so distinct or so sharply divided as is usual. The leaves of the perianth are free, imbricate (except _Clematideæ_); stamens _numerous_, with most frequently extrorse anthers; gynœceum _free_, _apocarpous_ (except _Nigella_ and partly _Helleborus_), with 1 or several ovules (Figs. 373, 378, 379) borne on the ventral suture. The fruit is either a nut or a follicle (_Actæa_ has berries). The seed has a _large, oil-containing_ endosperm and a small embryo (Fig. 374). The main axis generally terminates in a flower, and the lateral axes branch in a cymose manner (Fig. 371). The flowers show the following differences in construction: VERTICILLATE (EUCYCLIC), _i.e._ constructed all through of alternating whorls: _Aquilegia_ (Fig. 370), _Xanthorhiza_, and sometimes _Eranthis_. SEMIVERTICILLATE (HEMICYCLIC) _i.e._ with sepals and petals in alternate whorls, and the others arranged spirally: _Ranunculus_ (Fig. 371), _Myosurus_, _Pæonia_ and several other genera entirely, or in certain species only. SPIRAL-FLOWERED (ACYCLIC) _i.e._ all the leaves are arranged spirally, so that sepals and petals do not alternate the one with the other, even though they are the same in number: _Adonis_ (Fig. 372), _Aconitum_, _Delphinium_-species, _Nigella_-species, _Helleborus_. The leaves of the calyx are in this instance arranged on a spiral of 2/5; those of the corolla on 2/5, 3/8, 5/13 or 8/21, and stamens and carpels likewise on higher fractions of the same series. The genera _Caltha_, _Anemone_, _Thalictrum_ and _Clematis_ have a _single perianth_, which is most frequently petaloid; it is thus apparent that the sepals are petaloid, and the leaves, which in other genera have developed as petals, are in these instances stamens. The calyx is similarly petaloid in the genera _Helleborus_, _Eranthis_, _Nigella_, _Delphinium_ and _Aconitum_; but the petals are present in these instances in unusual (horn-like) forms, and almost entirely given up to the function of nectaries, a function they already possess in _Ranunculus_. According to a more recent theory the “honey-leaves” are transformed stamens, which have lost the function of reproduction; the perianth is then single, and most frequently petaloid. [Those leaves in the flowers of many Ranunculaceæ which bear nectaries are termed by Prantl honey-leaves, and comprise those leaf-structures of the flower whose essential function lies in the production of nectar, and which, independent of the differentiation of the perianth into calyx and corolla, are derived from the stamens by the loss of their reproductive functions. Clear transitional forms are found between the two series of the perianth (_e.g._ between the sepaloid and petaloid perianth-leaves of _Anemone japonica_, _A. decapetala_, _Trollius_-species) while transitional forms are never found between perianth-and honey-leaves (with the exception of _Aquilegia vulgaris_, var. _stellata_). In _Anemone_ and _Clematis_ the honey-leaves pass gradually into the stamens, and agree with the stamens in the other Ranunculaceæ in their arrangement, development, and scant system of veins (except _Nigella_). In _Delphinium_, sect. _Consolida_, the two honey-leaves placed in front of the unpaired perianth-leaf are united into one, as shown by the veins (twice three veins arranged symmetrically). The honey-leaves of _Aquilegia_, _Callianthemum_, and the majority of the _Ranunculus_-species serve by reason of their large circumference, as organs of attraction, and on this account are considered as petals by other authors.--The same position in the flower which the honey-leaves assume is found occupied by staminodes, without nectar, in some _Coptis_-species, in _Anemonopsis_, _Actæa_ sect. _Euactæa_, (_e.g. A. racemosa_), _Clematis_ sect. _Atragene_; in the last-named they closely surround the stamens, in _Actæa_ they are petaloid.--A perianth, sharply differentiated into calyx and corolla, and destitute of honey-leaves, is found in _Anemone_, sect. _Knowltonia_ (Cape), _Adonis_, _Pæonia_.--The perianth of the Ranunculaceæ is considered by Prantl to be usually petaloid.--The nectaries arise in the Ranunculaceæ (1) on normal stamens (_Clematis_ sect. _Viorna_), (2) on the honey-leaves (this is generally the case), and (3) on the carpels (_Caltha_ and the majority of _Trollius_-species).--As the result of his researches upon the Ranunculaceæ, Prantl does not agree with the view advanced by Drude (Schenk, _Hand. d. Bot._ iii.) that the petals in general have proceeded from the metamorphosis of the stamens (_K_)]. [Illustration: FIG. 373.--Ovaries in longitudinal section: _v_ the ventral suture; _d_ the dorsal suture: _A_, _B Clematis_; _C Ranunculus_; _D Myosurus_.] The most primitive form of fruit is undoubtedly the pod formed by one carpel, on the edges of which (along the ventral suture) two rows of ovules are situated: Pæonieæ, Helleboreæ, Delphinieæ (Fig. 379). In a great many genera the number of ovules has been limited to _one_ perfect one, which is placed in the central plane under the united leaf-edges, and sometimes also some barren ovules above it (Fig. 373). The fruitlets in this case become achenes, and are present in much larger numbers than when there are follicles. [Illustration: FIG. 374.--_Helleborus niger_: _A_ flower; _B_ receptacle; _pet_ petals (honey-leaves); _pi_ stamens and carpels; _C_ seed; _D_ anther (cross section); _alb_ endosperm.] [Illustration: FIG. 375.--_Caltha palustris_: fruit.] The following have FOLLICLES: _Pæonieæ_, _Helleboreæ_ (except _Actæa_) and _Delphinieæ_; ACHENES: _Ranunculeæ_, _Anemoneæ_ and _Clematideæ_. =A. Follicles= (Figs. 375, 379), with many ovules, situated in two rows along the ventral suture. ~_Actæa_ has berries, _Nigella_ has capsules of several loculi.~ =1.= PÆONIEÆ, PEONY GROUP. This has regular, acyclic flowers with a normal, most frequently 5-leaved, imbricate calyx; large, coloured petals, and introrse anthers. Slightly perigynous. Surrounding the base of the carpels a ring-like swelling of the receptacle (“disc”) is present, which is largest in _P. moutan_. The follicles are more or less fleshy or leathery. Mostly herbs, with pinnatisect or decompound leaves and large, solitary flowers; a gradual transition may be traced from the foliage-leaves to the petals. _Pæonia; Hydrastis._ [Illustration: FIG. 376.--_Aquilegia vulgaris._] [Illustration: FIG. 377.--_Caltha palustris_ (nat. size).] [Illustration: FIG. 378.--_Nigella_: _A_, _B_ fruit of _N. damascena_, entire, and cut transversely. _C_ Petal (honey-leaf) of _N. arvensis_. _D_ Petal of _N. damascena_.] =2.= HELLEBOREÆ, HELLEBORE GROUP. This has regular flowers with most frequently a coloured calyx. The petals (honey-leaves) are modified into nectaries; they may be horn-like, provided with a spur, or of a similarly unusual form, or they may be entirely absent. Anthers often extrorse.--_Trollius_ (Globe-flower[36]). The flower is acyclic: many petaloid sepals, succeeding these, most frequently, several _linear_, dark yellow petals, which bear a naked nectary at the base; finally, many stamens and carpels arranged in a spiral (3/8, 8/21).--_Caltha_ (Marsh-marigold, Figs. 375, 377); 5 (-7) yellow sepals, no petals. The foliage-leaves have a large amplexicaul sheath.--_Helleborous_ (Hellebore) has pedate leaves. The flower is acyclic, with 5 large, regular, _persistent_, often petaloid sepals (2/5); small, _horn-like_ petals (honey-leaves; most frequently 13, divergence 8/13) and generally few carpels (Fig. 374).--_Coptis._--_Isopyrum._--_Eranthis_ (Winter Aconite), like _Anemone_, has a 3-leaved involucre and most frequently trimerous flowers, ~6 large petaloid sepals, 6 petals (tubular honey-leaves), 6 oblique rows of stamens, 3–6 carpels~. _Aquilegia_ (Columbine, Fig. 376); the flower is entirely cyclic and has large spurs on all the 5 petals (funnel-shaped honey-leaves); S5 coloured, P5, A5 × (8–12), G5 in regular alternation (Figs. 376, 370); the innermost stamens are often staminodes (Fig. 370).--_Nigella_ (Love-in-the-mist, Fig. 378) has 5 sepals and 8 small, _two-lipped_ petals cleft at the apex (the nectary is covered by the under-lip; Fig. 378 _C_, _D_). The 5 carpels are more or less completely united; and a many-carpellate ovary with free styles is formed in some. Large air-chambers in the external wall of the ovary are formed in _N. damascena_ (Fig. 378).--_Actæa_ (Baneberry) has coloured sepals, either no petals or an indefinite number, and only 1 carpel. The fruit is a berry (or follicle).--~_Cimicifuga_, _Garidella_, _Xanthorhiza_ (S5, P5, A5 + 5, G5).~ =3.= DELPHINIEÆ, LARKSPUR GROUP. Zygomorphic flowers with coloured calyx; the 2 posterior petals (honey-leaves) are transformed into nectaries, the others are small or absent altogether.--_Aconitum_ (Monkshood); 5 sepals, of which the _posterior one_ (Fig. 379 _A_) _is helmet-shaped_; most frequently 8 petals (as in Fig. 372), of which the two posterior ones (honey-leaves) are developed into long-clawed nectaries (Fig. 379 _A_, _k_) enveloped by the helmet-like sepal; the others are small, or are to some extent suppressed. ~Stamens on a spiral of 3/8–5/13; generally 3 carpels.~ Perennial herbs.--_Delphinium_ (Larkspur); very closely allied to _Aconitum_, but the anterior 4 petals are most frequently wanting, and the 2 posterior ones have each a spur, which is enclosed by the _posterior sepal_, the latter being also provided with _a membranous spur_. ~Stamens and carpels arranged on a spiral of 3/8, 5/13, 8/21. In _D. ajacis_ and _consolida_ there is apparently only 1 petal (by the fusion of 4) and 1 carpel.~ [Illustration: FIG. 379.--_Aconitum napellus. A_ Flower in longitudinal section, below are the 2 bracteoles; _a_ half of helmet-like sepal; _b_ and _c_ other sepals; _k_ nectary; _f_ carpels. _B_ Ovary in longitudinal section; _C_ the same transversely; _d_ dorsal suture; _v_ ventral suture.] =B. Fruit achenes.= Many carpels, each with only 1 ascending (Fig. 373 _C_), or pendulous (Fig. 373 _D_), perfect ovule; often also rudimentary ovules above it (Fig. 373 _A_, _B_). Fruit achenes. =4.= RANUNCULEÆ, BUTTERCUP GROUP, has double perianth. _Myosurus_ and _Adonis_ have pendulous ovules as in Anemoneæ (Fig. 373 _D_); ~_Ranunculus_, with _Batrachium_ and _Ficaria_, erect ovules (Fig. 373 _C_) and downwardly-turned radicle.~--_Ranunculus._ Most frequently S5, P5, many spirally-placed stamens and carpels (Figs. 371, 380). The petals (honey-leaves) have a nectary at the base, covered by a small scale. ~_Batrachium_, Water Ranunculus, deviates by the achenes being transversely wrinkled; dimorphic leaves. _Ficaria_ has 3 sepals and 7–8 petals arranged in 2/5–3/8. _F. ranunculoides_ (the only species) has tuberous roots, which spring from the base of the axillary buds, and together with these, serve as organs of reproduction. The embryo has only 1 cotyledon.~--_Myosurus_ (Mouse-tail) has small prolongations from the 5 sepals; 5 narrow petals which bear the nectaries near the apex; sometimes only 5 stamens, and an ultimately very long receptacle, with numerous spirally-arranged achenes (Fig. 381).--_Adonis_ is acyclic (Fig. 372); most frequently 5 sepals with a divergence of 2/5, 8 petals of 3/8, indefinite stamens and carpels of 3/8 or 5/13. The corolla has no nectary. [Illustration: FIG. 380.--Flower of _Ranunculus sceleratus_ in longitudinal section.] [Illustration: FIG. 381.--_Myosurus minimus_: _c_ cotyledons; _m_ the foliage-leaves; _f_ the floral axis with the carpels, and _g_ the same without; _y_ insertion of perianth.] =5.= ANEMONEÆ, ANEMONE GROUP, has a single perianth. ~(Pendulous ovules (Fig. 373 _D_), radicle turned upward).~--_Anemone_ has a single, petaloid, most frequently 5–6-leaved perianth, and beneath the flower most frequently _an involucre of 3 leaves_, placed close together in the form of a whorl. In _A. nemorosa_, _ranunculoides_, etc., the involucral leaves resemble foliage-leaves; in _A. hepatica_ they are situated close under the perianth, and resemble sepals, and in the sub-genus _Pulsatilla_ they stand between the foliage-leaves and floral-leaves. The style of _Pulsatilla_ finally grows out in the form of a feather. ~The main axis of _A. hepatica_ has unlimited growth (it is biaxial), and the flowers are borne laterally in the axils of the scale-leaves; in the others (uniaxial) the flower is terminal, and the rhizome becomes a sympodium after the first flowering.~--_Thalictrum_ (Meadow Rue) has no involucre; 4–5-leaved, greenish perianth. The receptacle is flat. ~The stamens are brightly-coloured and have long filaments; 1–5 accessory flowers may occur in the leaf-axils of the panicle-like inflorescence.~ =6.= CLEMATIDEÆ, CLEMATIS GROUP. This differs from all the others in the _valvate æstivation_ of the calyx and its opposite leaves. There are 4 (-several) petaloid sepals; petals are absent, or linear (_Atragene_). Ovule 1, pendulous. Achenes, often with prolonged, feathery style. The majority of the genera are shrubs, and climb by their sensitive, twining leaf-stalks.--_Clematis; Atragene._ POLLINATION. The flowers are conspicuous either by coloured petals (honey-leaves) (_Ranunculus_, _Pæonia_) or coloured sepals (_Helleborus_, _Anemone_, _Caltha_, etc.), or by both (_Aquilegia_, _Delphinium_), or by the coloured stamens (_Thalictrum_). Some have no honey (_Clematis_, _Anemone_, _Thalictrum_), and are generally visited by insects for the sake of their pollen. Others have nectaries on the corolla (_Ranunculus_, _Trollius_, _Helleborus_, _Nigella_, _Aconitum_, etc.), more rarely on the stamens (_Pulsatilla_, _Clematis_-species), or the carpels (_Caltha_), or the calyx (certain species of _Pæonia_). The honey is readily accessible in the flat, open flowers, and these flowers also may easily pollinate themselves. There is marked protandry where the honey lies deeply hidden, as in _Aquilegia_, _Delphinium_, and _Aconitum_. _Helleborus_ and some _Ranunculus_-species are protogynous. About 680 species; especially in northern temperate climates, and extending to the Polar and Alpine regions. Only the _Clematideæ_ are tropical. The order has an abundance of _acrid_, vesicant properties (_R. acer_, _sceleratus_, etc.), and _poisonous_ alkaloids (_Helleborus niger_ is poisonous). OFFICINAL: _Aconitum napellus_ (aconitine; leaves and tuberous roots); the rhizome of _Hydrastis canadensis_ from N. Am. (the alkaloid hydrastine). The order, however, is best known for its ornamental plants; almost all the genera have species which are cultivated for their beauty. Sweet-scented flowers are absent. Order 2. =Nymphæaceæ (Water Lilies).= WATER PLANTS; generally with large, floating leaves, and large solitary flowers; sepals 3–5, petals 3–∞, stamens 6–∞, carpels 3–∞. The flower is hypogynous, but in the _Nymphæeæ_ different degrees of epigyny are found, and from this fact, as well as from the carpels being united into one pistil, the family forms a lateral offshoot from the Ranunculaceæ, with much greater modification. The seed often has an aril, and, in the majority, a farinaceous nutritive tissue, partly endosperm, partly perisperm (Fig. 383 _C_). The embryo has 2 thick cotyledons and a small hypocotyl; the plumule is well developed, with 2–4 leaves. 1. CABOMBEÆ. 3–4 species (Tropical S. Am.), resembling the Water Ranunculus, with two kinds of leaves, the submerged being dissected and the aerial peltate. The flowers are eucyclic, trimerous, with 2–3 free, epigynous carpels. The ovules are situated _on the central line_ of the carpel--an almost unique circumstance. Endosperm and perisperm. _Cabomba; Brasenia._ 2. NELUMBONEÆ. The leaves are _peltate_, raised on long stalks high above the water. Large, _hypogynous_ flowers (Fig. 382); sepals 4–5; petals numerous; stamens numerous; _carpels several_, _distinct_. The receptacle is very remarkable, being raised above the stamens, and developed into an _inverted conical_ body on the apex of which the nut-like fruits are _embedded in pits_. _Endosperm is wanting_, but the embryo is large and has well developed cotyledons.--~_Nelumbo_, 2 species. _N. lutea_ (N. Am.); _N. speciosa_ (E. Ind.) was sacred amongst the ancient Hindoos and Egyptians, (the Lotus flower); its seeds are used as food.~ 3. NYMPHÆEÆ, WATER LILY GROUP. The carpels are united into _one_, _many-locular ovary_, _whose numerous ovules are situated on the surface of the partition walls_ (as in the Poppies); the stigma is sessile and radiating, the number of rays corresponding to the number of carpels (Fig. 383). The fruit is a spongy _berry_ with many seeds, which have a large perisperm in addition to the endosperm (Fig. 383 _C_). [Illustration: FIG. 382.--_Nelumbo nucifera_: vertical section through the receptacle.] Sepals, petals, and stamens often pass gradually over the one into the other, the petals becoming narrower by degrees, and bearing anthers on each side of the apex, which gradually become larger anthers in proportion to the filament, until the perfect stamen is developed. The long-stalked leaves are floating, and most frequently cordate, elliptical, leathery, with a shiny surface, sometimes (as in _Victoria regia_ and _Euryale ferox_) with strongly projecting thorny ribs on the lower surface. In the intercellular passages of the leaves are some peculiar, stellate cells. _Nuphar_ has 5 sepals, and an _hypogynous_ flower. ~The petals, which are small, have a nectary on the back; the coloured inner side of the sepals functions as petals; the ovate gynœceum is quite free.--_N. luteum_ is a native plant (Yellow Water-Lily), with, most frequently, 13 petals and 10–16 loculi in the ovary. The rhizome is horizontal, as much as 5–6 cm. in thickness, and bears on its under surface a number of roots, which on dying-off leave deep scars; the leaves are borne in spiral lines, and the flowers are solitary in certain leaf-axils. The construction of the rhizome is very peculiar; the vascular bundles are scattered and closed as in a monocotyledonous stem.~ [Illustration: FIG. 383.--_Nymphæa_: _A_ flower in longitudinal section, the most external leaves being removed; _B_ fruit; _C_ seed of _Nuphar_ (longitudinal section); the perisperm at the base, the endosperm at the top surrounding the embryo.] _Nymphæa_ has 4 sepals, and the flower is more or less _epigynous_. Petals and stamens are inserted at different heights on the ovary to just beneath the stigma (Fig. 383). _Nymphæa alba_ (White Water-Lily). _Victoria regia_ from the Amazon, and _Euryale ferox_ from Asia, have entirely epigynous flowers. ~The shield-like leaves of _Victoria_ are as much as 2 metres in diameter, and the edge is bent up to a height of 5–14 cm.; the flowers are 20–40 cm. in diameter, and change in twenty-four hours from white to rose-red. A development of heat, as much as 14°C. above the temperature of the air, together with a strong formation of carbonic acid, has been observed during flowering.~ POLLINATION. _Nymphæa alba_ and other species of the sub-genus _Symphytopleura_ are self-pollinated; the sub-genus _Leptopleura_ is insect-pollinated. _Nuphar_ and _Victoria_ can effect self-fertilisation; _Euryale_ is self-fertilised, often in entirely closed and submerged flowers.--The dissemination of the seeds in _Nuphar luteum_ is effected by the fruit, which rests on the water, becoming detached from its stalk, and dehiscing from the base upwards so that the seeds are set free; while in _Nymphæa alba_ the spirally-twisted stalk draws the fruit under water, and it dehisces by its upper part being thrown off as a hood, and the seeds which are enclosed in air-tight sacs rise to the surface of the water. In this condition they are able to float and can only sink to the bottom when the air has disappeared. 53 species; in fresh water in all parts of the world, but especially in the Tropics.--The rhizomes and seeds of some may be used as food; _Euryale ferox_ is even cultivated. _Nymphæa cœrulea_ and _Lotus_ were sacred among the Egyptians. Order 3. =Ceratophyllaceæ.= About 3 species. Aquatic plants, submerged, rootless; leaves cartilaginous, verticillate, dissected into repeatedly dichotomous branches which are finely toothed; only one of the leaves in a whorl supports a vegetative branch. The flowers are _monœcious_, axillary. Inside the 6–12 perianth-leaves are situated in the ♂-flower 10–20 stamens with thick connective, and in the ♀-flower a gynœceum formed by one carpel, with one orthotropous and pendulous ovule, which has only one integument. Fruit a nut, which, in some species, bears on each side a pointed horn, and at the apex a similar one, formed by the persistent style.--The embryo has an unusually well developed plumule with several whorls of leaves. The plant is rootless throughout its whole life.--_Ceratophyllum_ (Horn-wort). Order 4. =Annonaceæ.= Sepals 3; petals 3+3 (most frequently _valvate_); succeeding these (as in the _Ranunculaceæ_) are _numerous acyclic_ stamens and an _apocarpous gynœceum_; the flowers are hypogynous, regular and ☿, generally very large (2–3 cm. in diameter), and the leaves of the perianth are more or less fleshy or leathery. The majority have syncarps with berry-like fruitlets, but in _Annona_ and some others the carpels fuse together into a large, head-like fruit--a kind of composite berry. The seeds have _ruminate_ endosperm as in _Myristica_.--Trees or shrubs with _alternate_, simple, entire, penninerved leaves without stipules. 450 (700?) species; especially tropical. The best known are _Anona cherimolia_, _squamosa_ and _reticulata_ (all from America) cultivated on account of their large, delicious fruits. Some have acrid and aromatic properties (_Xylopia_, _Cananga_--the flowers of the latter yield Ylang-ylang); _Artabotrys odoratissimus_; _Asimina_ (N. Am.). Order 5. =Magnoliaceæ.= Trees or shrubs with scattered, often leathery, entire leaves, generally with _stipules_, which (as in _Ficus_) are rolled together and form a hood round the younger internodes above them, and are cast off by the unfolding of the next leaf, leaving a ring-like scar. The endosperm is _not ruminate_. Corolla imbricate. Fruit a syncarp. =A.= MAGNOLIEÆ. The flowers are borne singly, and before opening are enveloped in an ochrea-like spathe which corresponds to the stipules of the foliage-leaves. The perianth generally consists of 3 trimerous whorls, the external one of which is sometimes sepaloid (_Liriodendron_, and the majority of _Magnolia_species), sometimes coloured like the others; the perianth is sometimes many-seriate. _Numerous spirally-placed_ stamens and carpels. The latter are situated on the _elongated_, cylindrical receptacle, and are individually more or less united, except in _Liriodendron_, where they are free. This last genus has winged achenes; the fruitlets in _Magnolia_ open along the dorsal and ventral sutures, and the seeds then hang out, suspended by elastic threads formed from the vascular bundles of the funicle and raphe; they are red and drupaceous, the external layer of the shell being fleshy--a very rare occurrence. =B.= ILLICIEÆ has no stipules. The carpels are situated in a whorl on a short receptacle. Follicles, one-seeded. The leaves are dotted by glands containing essential oil. _Illicium; Drimys._ 70 species; in tropical or temperate climates; none in Europe or Africa. They are chiefly used as ornamental plants, _e.g._ the Tulip-tree (_Liriodendron tulipifera_, N. Am.), _Magnolia grandiflora_ (N. Am.), _M. yulan_ and _fuscata_ (China), and others. The remains of _Liriodendron_ occur as fossils in the Cretaceous and Tertiary periods.--The fruits of _Illicium anisatum_ (Star-aniseed from Eastern Asia) are OFFICINAL. The bark of _Drimys winteri_ (S. Am.) is also strongly aromatic. Order 6. =Calycanthaceæ.= These are very closely related to the Magnoliaceæ, but differ in having _perigynous_ flowers with many perianth-leaves, stamens and (about 20) carpels in a continuous _spiral_, seeds _almost devoid of endosperm_ with rolled up, leaf-like cotyledons, and leaves opposite on a square stem.--There are some species in N. America (_Calycanthus florida_, _occidentalis_, etc.) and 1 in Japan (_Chimonanthus præcox_), all strongly aromatic. Order 7. =Monimiaceæ.= Aromatic shrubs with opposite leaves. Perigynous flowers. The anthers dehisce by valves like those of the _Lauraceæ_, and the Monimiaceæ may thus be considered as an apocarpous form of this order. They are also closely related to _Calycanthaceæ_. 150 species, tropical.--_Hedycarya, Mollinedia, Monimia._ [Illustration: FIG. 384.--Diagram of _Berberis_.] [Illustration: FIG. 385.--_Berberis_: carpel with 2 stamens.] Order 8. =Berberidaceæ (Barberries).=--The regular, ☿, hypogynous flowers are dimerous or trimerous and have regularly alternating whorls of free sepals, petals, and stamens and 1 unilocular carpel; the corolla and stamens have each 2 whorls, the calyx at least 2. The anthers open, as in Lauraceæ, by (2) _valves_, but are always introrse (Fig. 384). The pistil has a large, disc-like, almost _sessile_ stigma (Fig. 385), and in the ovary _several_ erect ovules are placed close to the base of the ventral suture. The fruit is most frequently a _berry_. Seeds endospermous.--Shrubs or herbs with scattered, most frequently compound leaves (without stipules), and racemose inflorescences.--~They show a relationship to the Lauraceæ in the number of the parts of the flower and the dehiscence of the anthers.~ _Berberis_ is a shrub; it has sepals 3 + 3, petals 3 + 3, stamens 3 + 3 (Fig. 384). The petals (honey-leaves) bear internally at the base 2 darkish-yellow nectaries. The filaments are sensitive at the base, and suddenly bend inwards if touched at that spot (Fig. 385). ~The racemes often have a terminal, 5-merous flower; they are borne on dwarf-branches. The leaves on the long-branches develope into thorns, but the buds in their axils, in the same year as themselves, develope as the short-branches with simple foliage-leaves, _articulated_ at the base, from which fact some authorities have considered that the leaf is compound with a single, terminal leaflet.~--_Mahonia_ has imparipinnate leaves. The flower has 3 whorls of sepals. Otherwise as in _Berberis_.--~_Epimedium_; herbs with spurred petals; the flowers dimerous; 4–5 whorls of sepals, 2 of petals and stamens. Fruit a capsule. _Leontice_, fruit dry. The anthers of _Podophyllum_ dehisce longitudinally.--_Nandina. Aceranthus._~ 100 species; North temp., especially Asia: fossils in Tertiary. _Berberis vulgaris_ is a native of Europe. This and other species, together with _Mahonia aquifolium_ (N. Am.), _Epimedium alpinum_, etc., are cultivated as ornamental plants. Several have a yellow colouring matter in the root and stem. OFFICINAL: the rhizome of _Podophyllum peltatum_ (from N. Am.) yields podophyllin. Order 9. =Menispermaceæ.= This order has derived its name from the more or less crescent-like fruits and seeds. Diœcious. The flowers are 2–3-merous, most frequently as in _Berberis_ (S3 + 3, P3 + 3, A3 + 3), with the difference that there are 3 _free carpels_, each with 1 ovule; in some genera, however, the number is different. Stamens often united into a bundle (as in _Myristica_); anthers dehiscing longitudinally; fruit a drupe.--The plants (with herbaceous or woody stems) belonging to this order are nearly all _twining_ or _climbing_ plants, and have scattered, palmate or peltate, sometimes lobed leaves without stipules. Structure of stem anomalous. _Cocculus, Menispermum, Cissampelos, Anamirta._ 150 species; Tropical; very rich in bitter and poisonous properties. OFFICINAL: Calumba-root from _Jateorhiza columba_ (E. Africa). The following are cultivated as ornamental plants:--_Menispermum canadense_ (N. Am.) and _M. dahuricum_ (Asia). The fruits of _Anamirta cocculus_ (E. Ind.) are very poisonous (“Grains-of-Paradise”; the poisonous matter is picrotoxine). Order 10. =Lardizabalaceæ.= This order, by the free, apocarpous carpels, belongs to a more primitive type, and by the united stamens to a more developed one. _Akebia_; _Holbœllia_; principally climbing or twining shrubs. About 7 species in S.E. Asia and S. Am. Order 11. =Lauraceæ= (=True Laurels=). Trees or shrubs; the leaves, always without stipules, are simple, most frequently scattered, lanceolate or elliptical, entire, penninerved, finely reticulate (except _Cinnamomum_ with 3–5-veined leaf), leathery and evergreen (except, _e.g. Cinnamomum_); they are frequently studded with clear glands containing _volatile oil_. The flowers are borne in panicles and are small and of a greenish or whitish colour. They are _regular, perigynous_, with most frequently a bowl or cup-shaped receptacle (Fig. 386), usually ☿, and _trimerous_ (rarely dimerous) through all (most frequently 6–7) whorls; viz. most frequently, perianth 2 whorls, stamens 3–4 and carpels 1 (P3 + 3, A3 + 3 + 3 + 3, G3) in regular alternation (Fig. 387). Each of the 2 or 4 loculi of the anthers _open by an upwardly directed valve_ (Fig. 386); of the stamens, the 2 outermost whorls are generally introrse, the others extrorse, or 1–3 whorls are developed as staminodes (Fig. 387 _g_). The gynœceum has 1 loculus with 1 style and 1 pendulous ovule (Fig. 386), and may be considered as formed of 3 carpels. The fruit is a _berry_ (Fig. 388) or _drupe_, which often is surrounded at its base by the persistent receptacle (as an acorn by its cupule), which becomes fleshy and sometimes coloured during the ripening of the fruit. The embryo has 2 thick cotyledons, but _no endosperm_ (Fig. 388). [Illustration: FIG. 386.--Flower of the Cinnamon-tree (_Cinnamomum zeylanicum_) (longitudinal section).] [Illustration: FIG. 387.--Typical diagram of the Lauraceæ: _g_ staminodes.] [Illustration: FIG. 388.--_Laurus nobilis_: longitudinal section of fruit.] The Lauraceæ present affinities with the Polygonaceæ, in which there is found perigyny, as well as a similar number of parts in the flower and a similar gynœceum, but with erect and orthotropous ovule. From their general characters they should be classed among the Polycarpicæ, but stand, however, isolated by the _syncarpous_ gynœceum, if it is in reality formed by 3 carpels and not by 1 only. _Hernandia_, which has epigynous monœcious flowers, deviates most.--_Cassytha_ is a _Cuscuta_-like, herbaceous, slightly green parasite with twining, almost leafless stems. The flower however agrees with the diagram in Fig. 387. Some Lauraceæ have curved veins or palminerved and lobed leaves (often together with entire ones) _e.g. Sassafras_. [Illustration: FIG. 389.--_Myristica_: fruit.] [Illustration: FIG. 390.--Seed with aril entire and in longitudinal section.] There are 1000 species; especially in the forests of tropical S. America and Asia, of which they form the principal part. Only _Laurus nobilis_ is found in Europe, and there is little doubt that its proper home is in Western Asia. They are rare in Africa.--On account of _the volatile oil_ found in all parts of the plant, they are used as _spices_, _e.g._ the false Cinnamon-tree (_Dicypellium caryophyllatum_, in the Brazils). The OFFICINAL ones are--the Cinnamon-tree (_Cinnamomum zeylanicum_ from Ceylon, E. India, Eastern Asia), which is also cultivated; the Camphor-tree (_Cinnamomum camphora_, Eastern Asia). The Laurel-tree (_Laurus nobilis_, Mediterranean), the berries and leaves of which give laurel oil, is medicinal.--Scented wood for furniture, etc., is obtained from _Sassafras officinalis_ (from N. Am.). The wood from its roots is officinal. Pichurim “beans” are the large cotyledons of _Nectandra pichury_, whilst the famous “Greenheart” wood of Demarara is the wood of _Nectandra rodiæi_. The pulp and seeds contain a _fatty oil_. The pear-like fruit of _Persea gratissima_ (Mexico, also cultivated) is very delicious. _Lindera benzoin_ is a garden shrub; _Laurus nobilis_ likewise. Order 12. =Myristicaceæ= (=Nutmegs=). In this order there is only 1 genus, _Myristica_. Trees or shrubs. The leaves agree closely with those of the Lauraceæ, with which this order has many points in common. The majority of the species are aromatic, having in their vegetative parts pellucid glands with volatile oils. The flowers are regular, diœcious, trimerous, and have a single gamophyllous (cupular or campanulate) 3-toothed, fleshy perianth. In the ♂-flowers the anthers vary in number (3–15), and they are extrorse and borne on a centrally-placed column; in the ♀-flower the gynœceum is unilocular, unicarpellary, with 1 ovule. The FRUIT (Fig. 389) has the form of a pear; it is a fleshy, yellow capsule, which opens along the ventral and dorsal sutures, exposing the large seed. This seed has a large, red, irregularly branched aril--the so-called “mace”; the “nutmeg,” on the other hand, is the seed itself with the inner thin portion of the testa, which has pushed its way irregularly into the endosperm, and causes the marbled appearance of the cut seed (Fig. 390); the external, dark brown, hard, and brittle part of the seed-shell is however removed. Mace and nutmeg contain volatile and fatty oils in abundance.--80 species. Tropical. The majority are used on account of their aromatic seeds and aril, the most important being _M. fragrans_ (_moschata_), from the Moluccas. This is cultivated in special plantations, not only in its native home, but in other tropical countries also. Nutmegs were known as commodities in Europe in very ancient times (_e.g._ by the Romans), but it was not until the year 1500 that the tree itself was known. The seed is OFFICINAL. Family 10. =Rhœadinæ.= The plants belonging to this family are almost exclusively herbaceous, with scattered, exstipulate leaves. The flowers are eucyclic di- or tetramerous, with the calyx and corolla deciduous, _hypogynous_, ☿, _regular_, the gynœceum with 2–several carpels (generally 2, transversely placed) (Figs. 391, 392, 393, 397). The ovary is _unilocular with parietal placentæ_, but in _Cruciferæ_ and a few others it becomes bilocular by the development of a _false_, membranous wall between the placentæ. The stigmas in the majority of cases are _commissural_, _i.e._ they stand above the placentæ, and not above the dorsal line of the carpels. The fruit is nearly always a _capsule_, which opens by the middle portions of the carpels detaching themselves as valves, bearing no seed, whilst the placentæ persist as the seed-bearing frame. Endosperm is found in _Papaveraceæ_ and _Fumariaceæ_, but is absent in _Cruciferæ_ and _Capparidaceæ_.--~This family through the Papaveraceæ is related to the Polycarpicæ (the Nymphæaceæ), through the Capparidaceæ to the Resedaceæ in the next family.~ Exceptions to the above are: _Eschscholtzia_, _Subularia_ (Fig. 403) and a few Capparidaceæ, in which perigynous flowers are found. A few Papaveraceæ and Fumariaceæ have trimerous flowers. In _Fumaria_ and certain Cruciferæ, the fruit is a nut. The Fumariaceæ have zygomorphic flowers. Trees and shrubs are almost entirely confined to the Capparidaceæ, in which order stipules also are found. Order 1. =Papaveraceæ= (=Poppies=). Herbaceous plants with stiff hairs and _latex_; flowers _regular_ (Fig. 391) with generally 2 (-3) sepals (which _fall off_ as the flower opens), 2 + 2 petals (imbricate and crumpled in the bud) _without spur, numerous stamens in several alternating whorls_ (generally a multiple of 2); carpels 2–several, united into a unilocular gynœceum. Trimerous flowers also occur. Capsule with very numerous seeds on the parietal placentæ; embryo small, with large, oleaginous _endosperm_ (Fig. 392).--The leaves have no stipules and are generally pinnately lobed. [Illustration: FIG. 391.--A Diagram of the flower of _Glaucium_ and the dichasium (which becomes transformed into a scorpioid cyme). _B Papaver argemone_, transverse section of the ovary with indication of the position of the stigmas.] [Illustration: FIG. 392.--_Papaver somniferum_: _A_ capsule; _st_ the stigma; _v_ valves; _h_ pores; _B_ seed in longitudinal section; _alb_ endosperm; _emb_ embryo.] _Papaver_ (Poppy) has large, solitary, terminal flowers; petals firmly and irregularly folded in æstivation; gynœceum formed by many (4–15) carpels; stigmas velvety, _sessile_ and _stellate_ (the rays stand above the placentæ) (Fig. 391 _B_). The edges of the carpels project deeply into the ovary, but do not meet in the centre, so that it remains unilocular. The capsule opens by pores placed close beneath the stigma, and formed of small valves alternating with the placentæ and the rays of the stigma (Fig. 391). _P. dubium_, _P. argemone_, _P. rhœas_.--_Chelidonium_ (Greater Celandine) has _yellow_ latex, flowers in umbellate cymes (the terminal, central flower opening first) and only 2 carpels; the fruit resembles the siliqua of the Cruciferæ in having two _barren valves_, which are detached from the base upwards, and a _seed-bearing frame_, but there is no partition wall formed between the placentæ. _Ch. majus._--~The majority of the other genera have, like _Chelidonium_, 2 carpels (lateral and alternating with the sepals: Fig. 391 _A_) and siliqua-like fruit, thus: _Eschscholtzia_ (perigynous) with a linear, stigma-bearing prolongation extending as far above the placentæ as above the dorsal suture of the carpels; _Glaucium_ (Horn-Poppy); _G. luteum_, whose extremely long, thin capsule differs from that of _Chelidonium_ by the formation, during ripening, of a thick, spongy (_false_) replum, which persists when the valves are detached; _Sanguinaria_ with red latex, the 2 petals divided into 8–12 small petals (perhaps by dédoublement); _Macleya_ and _Bocconia_ (1-seeded capsule) with 2 sepals and no petals.--Trimerous flowers are found in _Argemone_ and _Platystemon_ (with a curious fruit, carpels free, and transversely divided and constricted into joints which separate as nut-like portions).--_Meconopsis._--_Hypecoum_ (Fig. 393 _C_) has tri-lobed and three cleft petals, 4 free stamens with 4-locular anthers and a jointed siliqua; it presents a transitional form to the Fumariaceæ, with which order it is sometimes included.~ POLLINATION. _Papaver_ and _Chelidonium_ have no honey, and are without doubt only visited by insects for the sake of the pollen. The anthers and stigmas mature about the same time.--There are 80 species; especially from warm climates. OFFICINAL: _Papaver somniferum_ (Opium-Poppy); the latex of its unripe capsules is obtained by incisions, and dried (_opium_); it contains many alkaloids: morphine, papaverine, narcotine, thebaine, etc. The oleaginous seeds are also used in the manufacture of oil. Its home is in the East, where it is extensively cultivated. The petals of the Corn-poppy (_P. rhœas_) are also officinal. Several species are cultivated as ornamental plants. Order 2. =Fumariacæ= (=Fumitories=). This order differs from the closely allied Papaveraceæ in the absence of latex, a poorer flower, generally _transversely zygomorphic_ (Fig. 393 _B_), in which case one or both of the outer lateral petals are gibbous, or prolonged into a spur; the stamens are especially anomalous. Sepals =2=, caducous; petals 2 + 2; stamens 2, _tripartite_; each lateral anther is _bilocular_ (Figs. 393 _A_, _B_; 395); gynœceum bicarpellate. The fruit is a nut or siliqua-like capsule. _Endosperm._--_Herbs_ with scattered, repeatedly pinnately-divided leaves without stipules, generally quite glabrous and glaucous; the flowers are arranged in racemes with subtending bracts, but the bracteoles are sometimes suppressed. _Dicentra_ (syn. _Dielytra_) and _Adlumia_ have a doubly symmetrical flower, with a spur or gibbous swelling at the base of _each_ of the laterally-placed petals (Figs. 393 _A_, 394). _Corydalis_ has a zygomorphic flower, _only one of_ the lateral petals _having a spur_, and consequently there is only one nectary at the base of the bundle of stamens, which stands right in front of the spur (Fig. 393 _B_, 395, 396). The fruit is a many-seeded siliqua-like capsule. ~A peculiarity of the flower is that the plane of symmetry passes _transversely_ through the flowers, whilst in nearly all other zygomorphic flowers it lies in the median line. Moreover, the flower is turned, so that the plane of symmetry ultimately becomes nearly vertical, and the spur is directed backwards.--Many species have subterranean tubers; in these the embryo germinates with _one cotyledon_, which is lanceolate and resembles a foliage-leaf. The tuber is in some the swollen hypocotyl (_C. cava_), in others a swollen root (_C. fabacea_, etc.), which grows down through the precisely similar swollen root of the mother-plant. The sub-genus _Ceratocapnos_ has dimorphic fruits (nuts and capsules) in the same raceme.~ _Fumaria_ differs from _Corydalis_ only by its almost drupaceous, one-seeded nut (Fig. 395). [Illustration: FIG. 393.--Diagram of _Dicentra_ (_A_), _Corydalis_ (_B_), and _Hypecoum_ (_C_).] [Illustration: FIG. 394.--_Dicentra spectabilis_: _A_ flower (2/5); _B_ the same, after removal of half of one outer petal; the cap, formed by the inner petals, is moved away from the anthers and stigma; the insect does this with the lower side of its abdomen, and thus rubs the stigma on the hairs of its ventral surface; the dotted line at _e_ indicates the direction of the proboscis; _C_ andrœcium and gynœceum; _D_ stigma.] THE STRUCTURE OF THE FLOWER. _Hypecoum_ among the Papaveraceæ is the connecting link with the Fumariaceæ. The diagram (Fig. 393 _C_) corresponds both in number and in the relative position of its members with that of most of the other Papaveraceæ (Fig. 391), except that there are only four stamens (with extrorse anthers). In _Dicentra_ (Fig. 393 _A_), the two central (uppermost) stamens are absent, but each of the two lateral ones are divided into three filaments, of which the central one bears a four-locular anther, and each of the others a two-locular (half) anther. _Corydalis_ and _Fumaria_ stand alone in the symmetry of the flower, differing from _Dicentra_ in having only one of the lateral petals (Fig. 393 _B_, _sp_) prolonged into a spur, while in _Dicentra_ both the petals are spurred. This structure has been interpreted in various ways. According to Asa Gray the median stamens are absent in the last-named genera, and the lateral ones are split in a similar manner to the petals of _Hypecoum_. Another, and no doubt the most reasonable theory (adduced by De Candolle), is: that two median stamens are split, the two parts move laterally, each to their respective sides and become united with the two lateral stamens; this affords a natural explanation of the two half-anthers, and establishes a close relationship to the Cruciferæ. A third interpretation, held by Eichler and others, is as follows: the median stamens are _always_ wanting; when they appear to be present, as in _Hypecoum_, it is due to the fact that the side portions of the lateral stamens _approach each other_ (as interpetiolar stipules) and coalesce into an apparently single stamen. [Illustration: FIG. 395.--_Fumaria officinalis_: _A_ the flower in longitudinal section; _B_ the andrœcium and gynœceum; nectary to the right.] [Illustration: FIG. 396.--_Corydalis cava_: _a_ a flower (lateral view); _b_ the anthers lying round the stigma; _c_ the anthers shortly before the opening of the flower; _d_ the head of the stigma; _e_ relative position of the parts of the flower during the visit of an insect.] 130 species; mostly from the northern temperatures. POLLINATION. _Fumaria_, with its inconspicuous flowers, has to a great extent to resort to self-pollination. _Corydalis_, on the other hand, is dependent on cross-pollination; _C. cava_ is even absolutely sterile with its own pollen. _Corydalis_ is pollinated by insects with long probosces (humble-bees, bees), which are able to reach the honey secreted in the spur; as they alight on the flowers they press the exterior petals on one side (Fig. 396 _e_), so that the stigma, surrounded by the anthers, projects forward; the proboscis is introduced in the direction of the arrow in the figure, and during this act the under-surface of the insect is covered with pollen, which is transferred by similar movements to the stigma of another (older) flower.--Ornamental plants; _Dicentra_ (_spectabilis_ and _eximia_), _Adlumia_, _Corydalis_. Order 3. =Cruciferæ (Crucifers).= The flowers are _regular_, ☿; sepals 4, free (2 + 2), deciduous; petals 4, free, deciduous, unguiculate, placed _diagonally_ in one whorl, and alternating with the sepals; stamens 6; the 2 _outer_ are _short_, the 4 _inner_ (in reality the two median split to the base) _longer_, placed in pairs (tetradynamia of Linnæus); gynœceum syncarpous formed by 2 (as in the previous order, lateral) carpels, with 2 parietal placentæ, but divided into two loculi by a _spurious_ membranous dissepiment (_replum_) (Fig. 397). Style single, with a capitate, usually two-lobed stigma, generally commisural, that is, placed above the parietal placentæ (Fig. 397), but it may also be placed above the dorsal suture, or remain undivided. Ovules _curved_. The fruit is generally a bivalvular _siliqua_ (Fig. 398 _B_, _C_), the valves separating from below upwards, and leaving the placentæ attached to the replum; other forms of fruits are described below. The oily seeds _have no endosperm_ (endosperm is present in the two previous orders); the _embryo is curved_ (Figs. 398 _E_, _F_; 399, 400).--In general they are _herbaceous_ plants, without latex, with scattered, penninerved leaves, without stipules; the inflorescence is very characteristic, namely, a raceme with the flowers aggregated together at the time of flowering into a corymb, and _destitute of both bracts and bracteoles_. [Illustration: FIG. 397.--Diagram of a Cruciferous flower.] [Illustration: FIG. 398.--_Brassica oleracea_: _A_ raceme; _B_, _C_ siliqua; _D_ seed; _E_ embryo; _F_ transverse section of seed.] [Illustration: FIG. 399.--Transverse section of seed and embryo of _Cheiranthus cheiri_.] [Illustration: FIG. 400.--Transverse section of seed of _Sisymbrium alliaria_.] Many are biennial, forming in the first year a close leaf-rosette. By cultivation the tap-root can readily be induced to swell out into the form of a tuber (Turnips, Swedes, etc.). _Stipules_ are found indicated by small glands on the very young leaves; in _Cochlearia armoracia_ they are fairly large triangular scales. _Stellate hairs_ often occur. _Floral-leaves_ are occasionally developed. Terminal flowers are never found in the inflorescences. _Iberis_ and _Teesdalia_ have _zygomorphic_ flowers. _Subularia_ (Fig. 403) is perigynous. The 2 external sepals (Fig. 397) stand in the median plane; it may therefore be supposed that there are two bracteoles outside these which, however, are suppressed, and can only in a few instances be traced in the young flower; the two lateral sepals are often gibbous at the base, and serve as reservoirs for the nectar secreted by the glands placed above them; they correspond in position to the external petals of the Fumariaceæ. The 4 petals which follow next arise simultaneously, and alternate with the 4 sepals; if it could be shown that these are merely 2 median petals, which have been deeply cleft and the two parts separated from each other and displaced to the diagonal position, there would be a perfect correspondence with the Fumariaceous flower; then the petals would be followed in regular alternation by the 2 lateral small stamens, the 2 median long stamens, which it has been proved are split into 4 and placed in couples, and the 2 laterally-placed carpels,--in all 6 dimerous whorls. But the formation of the corolla by the splitting of 2 petals does not agree with the development of the flower or bear comparison, and hence the only fact in favour of this theory is the otherwise prevailing correspondence with the Fumariaceæ. Yet it may be observed that in special cases each pair of long stamens clearly enough arises from one protuberance and even later on may be considerably united or entirely undivided (_e.g._ _Vella_); in other instances they are quite distinct from the beginning, and it is possible that this latter condition has become constant in the corolla. _Lepidium ruderale_ and others have no corolla. _Senebiera didyma_ has only 2 median stamens. _Megacarpæa_ has several stamens, no doubt by dédoublement, as in Capparidaceæ.--The _number of carpels_ may also be abnormally increased; _Tetrapoma barbareifolium_ has normally 4 carpels with an equal number of placentæ and repla. It is supposed to be a variety of _Nasturtium palustre_.--The 2–4–8–10 greenish _glands_, which are found at the base of the stamens, are nectaries, morphologically emergences, and not rudimentary stamens. The forms of _fruits_ are of great systematic significance, see the genera. In some species dimorphic fruits are present, _e.g. Cardamine chenopodiifolia_ which has both ordinary _Cardamine_-siliquas and 1-seeded siliculas. The _curved embryo_ appears in five forms, which have systematic importance: 1. To the PLEURORHIZÆ belong those genera whose radicle (with the hypocotyl) lies bent upwards along the _edge_ of the _flat_ cotyledons (Fig. 399); to this group belong _Cardamine_, _Nasturtium_, _Cheiranthus_, _Matthiola_, _Cochlearia_, _Draba_, _Iberis_, _Thlaspi_, etc.; diagrammatic transverse section: ◯=.--2. To NOTORHIZÆ belong those whose radicle lies in an upward direction along the _back_ of one of the _flat_ cotyledons (Figs. 400, 413); _e.g._ _Hesperis_, _Sisymbrium_, _Lepidium_, _Capsella_, _Camelina_: ◯‖.--3. ORTHOPLOCEÆ differ from the Notorhizeæ in having the cotyledons folded (not flat) (Fig. 398 _E_, _F_); to this belong _Brassica_, _Sinapis_, _Raphanus_, _Crambe_, etc.: ◯>>.--4. SPIROLOBEÆ: the radicle lies as in the Notorhizæ, but the cotyledons are so rolled together that a transverse section of the seed cuts them twice; _Bunias_: ◯‖‖.--5. DIPLECOLOBEÆ: the cotyledons are folded forward and backward so that a transverse section cuts them several times; _Subularia_, _Senebiera_: ◯‖‖‖. On _germination_ the cotyledons appear above the ground as green leaves; in the Orthoploceæ they are bilobed, in the _Lepidium_-species divided. 1. =Silicula, broad replum= (Siliculosæ latiseptæ), valves flat or slightly vaulted, and the replum extends through the greatest width of the silicula (Fig. 404). The seeds are situated in two rows. ◯=: _Cochlearia_ (Horse-radish): the siliqua is nearly spheroid; glabrous herbs, generally with fleshy, stalked leaves, and white flowers.--_Draba_ has an oblong, lanceolate, somewhat compressed silicula; herbs with small rosettes of leaves, most frequently with stellate and long-stalked racemes.--_Alyssum_ and _Berteroa_ are whitish, on account of the stellate hairs; they have a more compressed and round or elliptical silicula. _Vesicaria_; _Aubrietia_. _Lunaria_ (Honesty, Fig. 401): very broad and flat silicula with long stalk (the receptacle as in Capparidaceæ). ◯‖: _Camelina_ (Gold-of-pleasure) has a spheroid, pear-shaped siliqua with a small rim passing right round (Fig. 402). _Subularia_ (Awlwort), an aquatic plant with _perigynous_ flower (Fig. 403) and folded cotyledons. 2. =Silicula, narrow replum= (Siliculosæ angustiseptæ), _i.e._ the replum is much shorter than the arched, more or less boat-shaped valves (Figs. 405, 406, 407). [Illustration: FIG. 401.--_Lunaria biennis._ Fruit, the valves of which have fallen off.] [Illustration: FIG. 402.--_Camelina sativa._ Fruit.] [Illustration: FIG. 403.--_Subularia aquatica._ Longitudinal section through the flower.] ◯=: _Thlaspi_ (Penny-Cress) has a flat, almost circular silicula, emarginate or cordate, with a well-developed wing round the edge (Fig. 406). _Iberis_ and _Teesdalia_: the racemes during flowering are especially corymbose, and the most external petals of the outer flowers project radially and are much larger than the other two (the flower is _zygomorphic_).--_Biscutella_, _Megacarpæa_. ◯‖: _Capsella_ (Shepherd’s-Purse) has a wingless, obcordate or triangular silicula (Fig. 407). _Lepidium_ (Pepperwort) has a few–(2–4) seeded, slightly winged, oval silicula. _Senebiera_ has a silicula splitting longitudinally into two nut-like portions; its cotyledons are folded.--~_Anastatica hierochuntica_ (“Rose of Jericho”) is an annual, silicula-fruited, desert plant (Arabia, Syria, N. Africa). After the flowering all its then leafless branches bend together upwards, forming a kind of ball; this spreads out again on coming in contact with water, and the fruits then disseminate their seeds, which germinate very quickly, often in the fruit.~ 3. =Siliqua= (Siliquosæ). The fruit is a true siliqua, several times longer than broad. The seeds in most are borne apparently in one row. [Illustration: FIG. 404.--Transverse section of a silicula with broad replum: _s_ replum; _k_ the valves.] [Illustration: FIG. 405.--Transverse section of a silicula with narrow replum.] ◯>>: _Brassica_ (Cabbage). The seeds are placed apparently in one row in each loculus (Fig. 398 _C_); the style is long and round; the valves have only 1 strong, longitudinal rib.--_Melanosinapis_ (_M. nigra_, Black-mustard); the style is compressed, two-edged; the valves of the siliqua are one ribbed.--_Sinapis_ (Mustard); quadrangular or flat style (in which in most cases there is a seed) and 3–5 strong, longitudinal ribs on the valves.--_Eruca_ differs from _Brassica_ by the shorter siliqua, broad, sword-like “beak” and seeds in two rows. ◯= (Fig. 399): _Cardamine_ (Bitter Cress) has a long, linear siliqua, with flat, unribbed, _elastic_ valves. The leaves are most frequently pinnatifid or pinnate. ~_C. pratensis_ reproduces by buds formed in the axils of the leaves.~--_Arabis_ (Rock Cress); _Matthiola_ (Stock); _Cheiranthus cheiri_ (Wallflower); _Barbarea_ (Winter Cress) (double-edged, quadrangular siliqua); _Nasturtium_ (_N. officinale_, Water-cress); the siliqua of the latter genus is in some species short, in others long. [Illustration: FIG. 406.--_Thlaspi arvense._] [Illustration: FIG. 407.--Silicula of _Capsella bursa-pastoris_.] ◯‖ (Fig.400): _Sisymbrium_ (Hedge Mustard) the valves of the siliqua are 3-ribbed.--_Erysimum_; _Hesperis_; _Schizopetalum_ (with fimbriate petals). 4. =Fruit jointed= (Lomentaceæ). The fruit is divided by transverse walls into as many spaces as there are seeds, and dehisces at maturity, generally _transversely_, into a corresponding number of nut-like joints (“articulate-siliqua.”) ◯=: _Crambe_ (Kale, Fig. 408). The fruit has only 2 joints. The lower one resembles a short, thick stalk, and is barren, the upper one is spherical, and has 1 seed.--_Cakile_ (_C. maritima_, Sea-kale); the lower node is triangular, 1-locular, the upper one more ensiform, 1-locular (Fig. 409). [Illustration: FIG. 408.--Fruit of _Crambe maritima_.] [Illustration: FIG. 409.--_Cakile maritima._ Fruit (2/1).] [Illustration: FIG. 410.--_Raphanus raphanistrum._] [Illustration: FIG. 411.--_Raphanus sativus._] ◯>>: _Raphanus_ has a long siliqua, which, in the garden Radish (_R. sativus_), is spongy and slightly abstricted (Fig. 411), but neither opens nor divides transversely (a kind of dry berry), and which in the Wild Radish (_R. raphanistrum_) (Fig. 410) is abstricted in the form of a string of pearls, and separates into many joints. ~_R. sativus_; the “Radish” is formed by the hypocotyl, after the bursting of its external, cortical portions (of which there are generally two patches at the top of the Radish).~ 5. =Siliqua indehiscent= (Nucumentaceæ). The fruit is a short, _unjointed_, unilocular and 1-seeded nut, and the fruit-stalks are often long, slender, and drooping. (Sometimes a thin endosperm is present).--_Isatis_ (Woad) has most frequently an oblong, small-winged nut; ◯‖ (Figs. 412, 413).--_Bunias_; _Neslia_. [The systematic division of this order given above is founded upon that of A. P. de Candolle. Prantl (_Engler and Prantl, Nat. Fam._), 1891, adopts a somewhat different system, which may briefly be summarised as follows:-- _A._ Hairs unbranched or absent; no glandular hairs. 1. THELYPODIEÆ. Stigma equally developed on all sides; style undivided or prolonged above the middle of the carpels, or turned back.--_Stanleyinæ_; _Heliophilinæ_. 2. SINAPEÆ. Stigma strongly developed above the placenta; style beaked or two-lobed. _a._ Cotyledons arising behind the bend of the embryo.--_Lepidiinæ._ _b._ Cotyledons arising at the bend of the embryo. α. Only lateral nectaries. Generally a silicula or indehiscent fruit.--_Cochleariinæ._ β. Generally a siliqua, more rarely a silicula or transversely-divided or indehiscent fruit. Nectaries generally lateral and median.--_Alliariinæ_; _Sisymbriinæ_; _Vellinæ_; _Brassicinæ_; _Cardamininæ_. _B._ Hairs collectively or partially branched, very rarely entirely absent; glandular hairs are sometimes also present. 1. SCHIZOPETALEÆ. 2. HESPERIDEÆ. Stigma strongly developed above the placenta; style undivided or prolonged above the placentæ into shorter or longer lobes. _a._ Surface cells of the replum, not divided diagonally.--_Capsellinæ_; _Turritinæ_; _Erysiminæ_; _Alyssinæ_. _b._ Surface cells of the replum divided diagonally.--_Malcolmiinæ_; _Hesperidinæ_; _Moricandiinæ_.] [Illustration: FIG. 412.--_Isatis tinctoria._ Fruit (Fig. 412); and in longitudinal section (Fig. 413). (Mag.)] POLLINATION. Honey is secreted by the nectaries mentioned above; but the position of the stamens is not always the most favourable for pollination by insects (in these flowers the honey-seeking insect must touch the anthers with one of its sides and the stigma with the other), and self-fertilisation is common. In some species (_Cardamine pratensis_) the long stamens turn their anthers outwards towards the small stamens, so that 3 anthers surround each of the two large entrances to the nectaries. 1200 species (180 genera), especially in the cold and temperate parts of the Old World (Europe, W. Asia). Many are _weeds_ in this country, _e.g._ Wild Cabbage (_Brassica campestris_), Charlock (_Sinapis arvensis_), Wild Radish (_Raphanus raphanistrum_) and others.--The order is acrid and oleaginous. Oil is obtained from many of the oil-containing seeds, especially of the Rape (_Brassica napus_), Summer-Rape (the oil-yielding cultivated form of the Field-Cabbage) and _Camelina_. Several are pot-herbs or fodder plants, _e.g._ Cabbage (_Brassica oleracea_) with its numerous varieties: Cauliflower (var. _botrytis_; the entire inflorescence is abnormally branched and fleshy), Kohlrabi (var. _gongylodes_, with swollen, tuberous stem), Kale, Red-Cabbage, White-Cabbage, etc.; _B. campestris_, var. _rapifera_ (Turnip); _B. napus_, var. _rapifera_ (Swede); _Raphanus sativus_ (Radish from W. Asia), _R. caudatus_ (long Radish); _Nasturtium officinale_ (Water Cress), _Lepidium sativum_ (Garden Cress), and _Barbarea præcox_ (Early Cress); _Crambe maritima_ (Sea-Kkale). The seeds of the following are especially used as spices: (the flour of) _Melanosinapis_ (Black-mustard), and _Sinapis alba_ (White-mustard), which are _officinal_ like the root of _Cochlearia armoracia_ (Horse-radish, E. Eur.). The herbaceous parts of _Cochlearia officinalis_ and _danica_ are medicinal.--A blue dye (woad) is extracted from _Isatis_.--Ornamental plants: _Cheiranthus cheiri_ (Wallflower), _Matthiola_ (Stock), _Iberis_, _Hesperis_, _Lunaria_, and others (especially from S. Eur.). Sweet-scented flowers are rare. [Illustration: FIG. 414.--_Gynandropsis pentaphylla._] [Illustration: FIG. 415.--_Capparis spinosa._] Order 4. =Capparidaceæ= (=Capers=). The relationship with the Cruciferæ is so close that certain forms are with difficulty distinguished from them. The diagram of the flower is the same in the number and position of its parts, but it differs in the modifications which occur in the development of the stamens. In some genera all 4 stamens are undivided; in others both the 2 median ones are divided as in the Cruciferæ (6 stamens, but _not tetradynamous_) (Fig. 414); in other genera only 1 of these; in other instances again they are divided into more than 2; and finally the 2 lateral ones also may be found divided, so that _indefinite stamens_ occur (Fig. 415). The bicarpellate gynœceum is _unilocular_ (without replum), but more than 2 carpels may occur. The ovary is elevated on a _stalk_ (sometimes as much as 1 foot in length); also between the stamens and corolla a similar stalk may be found (Fig. 414). The fruit is long and siliquose (_Cleome_, _Polanisia_, _Gynandropsis_), or a berry (_Capparis_). Endosperm absent. Some have zygomorphic flowers. Gamosepalous calyx and perigynous flowers also occur.--350 species; especially in the Tropics. The majority are trees and shrubs, and they differ also from the Cruciferæ in having distinct stipules present in some species. “Capers” are the flower buds of the climbing, thorny shrub, _Capparis spinosa_ (Fig. 415), which grows in the Mediterranean. Family 11. =Cistifloræ.= The flowers in this family are perfect, regular (except _Resedaceæ, Violaceæ_), hypogynous, the perianth-leaves free (a few have them slightly united), æstivation most frequently imbricate; they are eucyclic in the andrœcium, and most frequently in the other parts, and generally 5-merous with S5, P5, A5 + 5, G3, but other numbers also occur; several have _indefinite stamens_, but the stamens arise (where the development is known) in _centrifugal order_ and are arranged, often very distinctly, _in bundles_; in other words, the large number of stamens is formed by the splitting of a small number (most frequently 5); a true spiral arrangement is never found. Gynœceum syncarpous, multicarpellary (_Dilleniaceæ_ and a few _Resedaceæ_ are apocarpous), most frequently the number of carpels is 3, forming a _unilocular ovary_ with _parietal placentæ_, but parallel with this, multilocular ovaries, with the ovules placed in the inner angle of the loculi, are also found, and a few genera have a free, centrally-placed placenta. The fruit is most frequently a capsule. The dehiscence is never with a “replum,” _i.e._ the persistent frame of the placenta, as in the family Rhœadinæ. One half of the orders has endosperm (_Violaceæ_, _Cistaceæ_, _Droseraceæ_, _Bixaceæ_, _Ternstrœmiaceæ_, etc.), the other has no endosperm (_Resedaceæ_, _Hypericaceæ_, _Elatinaceæ_, _Tamaricaceæ_, etc.); some have a curved, the majority a straight embryo. ~The family is scarcely quite natural; in the future the orders will probably be arranged differently.~ Order 1. =Resedaceæ (Mignonettes).=--Herbs or small shrubs with spirally-placed leaves and very small, gland-like stipules (as in Cruciferæ); the ☿, hypogynous flowers are _zygomorphic_, and arranged in racemes or spikes typically without bracteoles. The zygomorphic structure is produced by the _greater development of the posterior side of the flower_, especially the petals and the nectary (“disc,” in Fig. 416 _d_) which is situated between the petals and stamens; in general there are 5–8 free sepals and petals, the latter consisting of a large scale-like _sheath_ with a fimbriated blade (see Fig. 416); stamens numerous; carpels 6–2 united together; ovary unilocular with parietal placentæ, but _the cavity of the ovary is not closed_ at the top. In _Astrocarpus_ the gynœceum is apocarpous. The fruit is most frequently a capsule; the seeds are reniform, without endosperm, and the embryo is _curved_. This order connects the Rhœadinæ with the Cistifloræ. It is closely allied to the Rhœadinæ by its external appearance, even by the smell and taste, the parietal placentation, structure of the seeds, the inflorescences, etc., whilst by the irregular flowers and the disc placed at the posterior side of the flower, _it is allied to Capparidaceæ_, but differs from this order in not having its characteristic number (2–4) and by the very different mode of dehiscence of the fruit, etc. It differs from the other orders of this family chiefly in the fact that the number of the perianth-leaves is not constantly 5. In _Reseda luteola_ both the calyx and corolla appear to be 4-leaved, because the posterior sepal is suppressed, and the 2 posterior petals are united. Where there are 10 stamens, they stand in 2 whorls, _i.e._ in front of the sepals and petals; if there are several, their position depends upon the splitting.--_Astrocarpus_ is remarkable for its apocarpous fruit and the position of the ovules on the _dorsal_ suture of the carpel. The yellow, flat disc at the back of the flower serves as a nectary, the honey being protected by the lobes of the petals. If pollination by insects is not effected, then self-pollination may take place, at all events in _R. odorata_. 45 species; the majority in the Mediterranean and in Persia. _Reseda odorata_ (from Egypt) is cultivated on account of its sweet scent; _R. luteola_ (“Dyer’s Weed”) yields a yellow dye. [Illustration: FIG. 416.--Diagram of _Reseda odorata_.] Order 2. =Droseraceæ (Sundews).= Herbs, chiefly living on moors or in water, and whose leaves are adapted to catch and digest small animals. With regard to the flower, they are closely allied to the Violaceæ, especially to those with regular flowers. _Drosera_ (Sundew) has a long-stalked scorpioid cyme with regular, ☿, hypogynous flowers, 5-merous as in _Viola_. S5, P5, A5, G3 (in a syncarpous gynœceum, with free, bifid styles and basal or parietally-placed ovules in the unilocular ovaries). The capsule opens also as in _Viola_, but, among other differences, the styles are free, the seeds very small, and surrounded by a loosely lying, thin shell. ~_Drosera_ has radical, long-stalked leaves with the blade (Fig. 417) covered by numerous strong glandular hairs, placed on the edge and in the middle; when small animals are caught by these hairs, the latter and the entire blade close slowly over them dissolving and absorbing all the digestible matter as nourishment.~ [Illustration: FIG. 417.--Leaf-rosette of _Drosera rotundifolia_ (nat. size), and a leaf (magnified).] _Dionæa muscipula_ (Fly-trap; N. Am.) has the same appearance as _Drosera_, but the leaves are constructed as in Fig. 418. The stalk is flat and winged, the blade small, circular, with powerful, pointed teeth along the edge, and on its surface are 6 small bristles (_A_), which are very sensitive. When these are touched the blade quickly closes, folding along the midrib (_B_, _C_) and imprisoning the irritating object, the teeth round the edges fitting like the teeth of a trap. If it happens to be an insect or similar body, a digestive fluid is secreted which, like the gastric juice, dissolves the digestible portions. _Aldrovandia vesiculosa_ (Central and S. Europe) captures small aquatic animals in a similar manner; it is a floating, aquatic plant, the two halves of its leaves also close together when irritated (Fig. 419).--_Drosophyllum._ About 110 species; most of them in the temperate regions. [Illustration: FIG. 418.--_Dionæa muscipula._ Leaves (nat. size).] Orders 3 and 4. =Sarraceniaceæ and Nepenthaceæ.= These two orders are perhaps most closely allied to the Droseraceæ and agree with these, among other things, in the manner of taking nourishment. Like the Droseraceæ they absorb nitrogenous food from dissolved animal matter by means of their leaves, which are specially constructed both to catch, to retain, and to digest any small animals which may be caught. The SARRACENIACEÆ are North American marsh-plants (10 species) which have pitcher-like leaf-stalks, in the cavity of which a fluid (with properties approaching those of gastric juice) is secreted, and which bear at the apex a small, lid-like blade; these leaf-stalks are the catching and digestive organs.--_Sarracenia, Darlingtonia._ [Illustration: FIG. 419.--_Aldrovandia vesiculosa_: _A_ a plant (nat. size). _B_ Leaf (mag.); the blade is closed; the winged stalk is prolonged into 4–6 irritable bristles.] [Illustration: FIG. 420.--_Nepenthes_ (reduced).] NEPENTHACEÆ has only 1 genus, _Nepenthes_ (the Pitcher-plant; about 35 species), especially found in tropical E. Asia; the majority are climbing shrubs. The leaf-stalks are twining organs, and terminate either simply in a tendril, or in addition to this, with a pitcher-shaped body (which in some species may be as much as a foot in length) on whose upper edge a lid-like structure is found (Fig. 420). In this pitcher, as among the Sarraceniaceæ, a fluid is secreted which is able to digest the animals captured (sometimes rather large) and which corresponds in some degree to the gastric juice. Order 5. =Violaceæ (Violets).= The flowers are ☿, and generally zygomorphic, hypogynous, with S5, P5, A5, G3 (Fig. 421). The stamens are closely applied to the ovary, they have a very short filament, and at their summit generally a membranous appendage formed by the prolongation of the connective (Fig. 422 _g_). The ovary is unilocular with 3 parietal placentæ; style undivided (Fig. 422 _B_). The fruit is usually a 3-valved capsule, opening along the dorsal sutures (Fig. 423). Embryo straight; endosperm fleshy (Fig. 425).--Many are herbaceous plants (_e.g. Viola_), but in the Tropics shrubs are also found (_e.g. Ionidium_); a few are lianes; the leaves are scattered, with stipules, and involute in the bud. [Illustration: FIG. 421.--Diagram of _Viola_.] [Illustration: FIG. 422.--The large-flowered form of _Viola tricolor_: _A_ the flower in median longitudinal section; _B_ the gynœceum.] _Viola._ The sepals are prolonged backwards beyond the point of insertion (appendiculate); the corolla is polypetalous, descending imbricate, and zygomorphic, its anterior petal being larger than the others and provided with a spur (Fig. 421). The 2 anterior of the 5 almost sessile stamens are provided with a spur-like nectary, which protrudes a considerable distance into the petaloid spur (Figs. 421, 422 _n_, _sp_). The style is club-like, and bears the stigma in a groove on the anterior side (Fig. 422 _st_). ~Herbs with rhizomes, or annuals; flowers solitary. _V. odorata_, _canina_, etc., have cleistogamic flowers which produce fruit in addition to the large, coloured (violet) flowers. The Pansy (_V. tricolor_) has large flowers adapted for insect-pollination, and also smaller, less conspicuous ones designed for self-pollination. The stigma, as in Fig. 422 _A_, _st_, and _B_, is situated on the anterior side of the stylar-head, immediately in front of the channel leading down to the spur (_sp_); below it is situated a valve, easily covered with pollen when the proboscis of an insect is introduced into the spur, but which closes upon its withdrawal; cross-pollination is thus secured.--The sweet-scented _V. odorata_ is visited by the honey-bee, which insures cross-pollination, and in the absence of insect visits it effects self-fertilisation by cleistogamic flowers. The conspicuous but scentless _V. tricolor_, var. _vulgaris_, is less frequently visited by insects (humble-bees). In _V. silvatica_ and _V. canina_ the pollen is carried on the head or proboscis of the honey-sucking bee.--The fruits of _V. odorata_ bury themselves slightly in the soil. In the others the fruits are raised above the ground; the 3 boat-shaped valves close together along the central line, and eject the seeds, one by one, with much violence, so that they are thrown to a great distance.~ [Illustration: FIGS. 423–425.--_Viola Tricolor._ FIG. 423.--Capsule after dehiscence (nat. size). FIG. 424.--External view of the seed. FIG. 425.--Seed in longitudinal section.] The _Alsodeia_-group has regular or almost regular flowers. Gamopetalous corollas are found in _Paypayroleæ_. _Sauvagesieæ_ differs the most by its regular corolla, and 5–∞ free or united staminodes. 250 species; especially in the Tropics.--The _Ionidium_-species are used as ipecacuanha. A number of _Viola_-species are cultivated as garden plants, especially _V. odorata_ (sweet-scented Violet) and _V. tricolor_, which have a large number of varieties. Order 6. =Frankeniaceæ.= A small order with doubtful relationships. Perennial herbs or shrubs; beach plants with nodose stem. Sepals united, petals free. Unilocular ovary, with 3–4 parietal placentæ. Fruit a capsule. Embryo straight, endospermous. Especially in S. Europe, Africa, on the shores of the Mediterranean and Atlantic. Order 7. =Tamaricaceæ (Tamarisks).= To this order belong only _Tamarix_ and _Myricaria_. They are shrubs of a cypress- or heather-like appearance, as the scattered leaves are very small, sessile, scale-like or linear, adpressed, entire, and usually glaucous, and the branches are slender and whip-like. The flowers are borne in small spikes or racemes, and are small, reddish or whitish, regular, ☿, hypogynous and polypetalous; formula S5, P5, A5 + 0 (_Tamarix_, which often has stipular teeth at the base of the filaments), or A5 + 5 (_Myricaria_, in which the stamens are united at the base); the number 4 may appear instead of 5, but in either case there is usually a tricarpellate gynœceum, which is _unilocular_ and has either parietal placentæ (_Myricaria_) or a small basal placenta (_Tamarix_); 1 trifid style, or 3 styles. Capsule dehiscing along the dorsal suture, and resembling the Willows in having a unilocular ovary with numerous _woolly_ seeds; but the seed-wool in this case is borne on the chalaza, and may be attached to a long stalk.--Some _Tamarix_-species shed part of their branches in the winter.--40 species; North Temperate, on the sea-shores or steppes, especially in Asia. Ornamental shrubs: _Myricaria germanica_, and _Tamarix gallica_. Order 8. =Cistaceæ.= Shrubs or herbs, natives especially of the Mediterranean region. Flowers generally in raceme-like scorpioid cymes, regular, ☿, hypogynous; sepals 5, free, _twisted_ in the bud, of which the two outer are generally much smaller than the others; petals 5, free, _twisted_ in the bud (in the direction _opposite_ to the sepals), fugacious; stamens _numerous_; gynœceum syncarpous, carpels usually 3–5, style simple, ovary unilocular, with parietal placentation (seldom divided into loculi, with axile placentation). The ovules are _orthotropous_ in opposition to some of the other orders of this family. The capsule dehisces along the dorsal sutures; embyro _curved_. The leaves are simple, undivided, generally opposite and stipulate.--~They are Violaceæ with regular flowers, numerous stamens, and curved embryo. The numerous stamens are in reality only one or two 5-merous whorls, divided into a large number of stamens; these are formed, therefore, in descending order, like the lobes of many compound foliage-leaves.~ _Helianthemum_ (Rock-Rose), has 3 carpels.--_Cistus_ has 5 (-10) carpels. About 70 species; temperate climates, especially about the Mediterranean. The resin of the _Cistus_-species has been used medicinally (ladanum). Order 9. =Bixaceæ.= This order is closely allied to the Cistaceæ and Ternstrœmiaceæ; like these it has regular, 5-merous, hypogynous flowers with numerous stamens, unilocular ovary and _parietal_ placentæ; sometimes unisexual flowers; it differs in having anatropous ovules, in the æstivation of the sepals, etc. All species (about 180) are trees or shrubs, with scattered, simple leaves, which usually have stipules, and are occasionally dotted with pellucid oil-glands.--_Bixa orellana_ (Trop. Am.) is the best known species; it has a 2-valved capsule; the seeds are enclosed in a shiny _red, fleshy testa_, which contains the well-known orange or yellow dye, annatto. Order 10. =Dilleniaceæ.= Gynœceum usually apocarpous, seed arillate. The flower has most frequently S5, P5, and compound stamens (one or more bundles); sometimes irregular. 200 species; Tropical; woody plants, many lianes.--_Dillenia_, _Candollea_, _Pleurandra_, _Davilla_, etc. Order 11. =Elatinaceæ= (=Water-worts=). About 25 species belong to this order; especially in temperate climates. They are small, creeping, rooted, aquatic plants, with opposite or verticillate leaves and _stipules_. The flowers are solitary or situated in small dichasia in the leaf-axils, they are small, regular, ☿, hypogynous, with free petals, the same number in all 5 whorls (Sn, Pn, An + n, Gn), 3-merous (_e.g. Elatine hexandra_), 4-merous (_e.g. E. hydropiper_), or 5-merous (_Bergia_); the corolla-stamens are sometimes suppressed; petals imbricate without being twisted; the ovary is 3–4–5-locular, with 3–4–5 _free styles_; the capsule dehisces septicidally. The seeds are orthotropous or curved, often transversely ribbed, endosperm wanting. The order is most nearly allied to Hypericaceæ, whose primitive form it appears to represent. [Illustration: FIG. 426.--Diagram of _Hypericum quadrangulum_: _S_ indicates the bud of the helicoid cyme in the axil of the bracteole β.] [Illustration: FIG. 427.--_Hypericum._ Flower with three bundles of stamens.] Order 12. =Hypericaceæ= (=St. John’s-worts=). This order is recognised by its always _opposite_ or _verticillate_, _simple_, and entire, penninerved leaves, without stipules, and usually dotted with _pellucid_ glands; by the always ☿, regular, hypogynous flowers in a cymose inflorescence; the generally 5-merous calyx and corolla, with sepals and petals free; the stamens 3–5, numerously branched (Figs. 426, 427); and the gynœceum, 3–5-carpellate, styles usually _free_. The ovary is 3–5-locular, or unilocular with 3–5 parietal placentæ. Fruit a capsule (dehiscing septicidally) or berry. Endosperm absent. The inflorescence is a _dichasium_ or _helicoid cyme_. The structure of the flowers is the same as that of the foregoing orders: S5, P5; succeeding these in some cases are two 5-merous whorls of stamens in regular alternation, of which the inner is epipetalous; but the outer whorl is only represented by 5 small scales (Fig. 427), or is altogether absent (_Hypericum calycinum_, _H. hircinum_), and the inner divided into numerous stamens, that is, these 5 stamens are so deeply divided that 5 _epipetalous_ groups bearing anthers are found (as in the Cistaceæ); in other cases the flower becomes _3-merous after the petals_, stamens 3 + 3 following in regular alternation (Figs. 426, 427), the outer whorl of stamens in these cases is also present as staminodes (Fig. 427), or may be altogether suppressed. Carpels 3–5. _The petals are often twisted_ in the bud, and are then oblique. _Hypericum._ Some species have a square stem; in these cases the leaves are placed opposite the edges. Fruit a capsule.--_Vismia_ has a berry.--~The flowers of _Hypericum_ have no honey, and supply only pollen; self-pollination often takes place.~ About 240 species; the tropical ones being often shrubs or trees; the others generally perennial shrubs.--_Hypericum_, St. John’s-wort, contains a resinous, red matter, which can be extracted with alcohol. The American gamboge is the dried sap of species of _Vismia_. Order 13. =Guttiferæ=, or =Clusiaceæ=. Closely allied to the Hypericaceæ and Ternstrœmiaceæ. Leaves opposite or verticillate. The flowers are often unisexual; stamens united; the gynœceum has most frequently a sessile, radiating or shield-like stigma. 370 species; chiefly in the Tropics (Am.). They are principally woody plants and their bark contains a yellow gum resin, “gamboge,” which is extracted from _Garcinia morella_ (E. Ind.) and others. Mangosteen (_Garcinia mangostana_ S.E. Asia), and _Mammea americana_ (W. Ind.), have very delicious fruits. To this order also belong _Platonia insignis_, _Pentadesma butyracea_ (the Butter-tree), _Clusia_, _Calophyllum_, _Cataba_, etc. Order 14. =Ternstrœmiaceæ.= Trees and shrubs with scattered, simple, and often more or less leathery, evergreen, penninerved leaves, without stipules (Fig. 428). The two most important genera are: _Camellia_ and the closely allied _Thea_ (by some authorities these are united into one genus). The flowers are regular, hypogynous, and situated singly on very short stalks. A number of green floral-leaves are placed below the calyx and gradually pass over into the sepals, and the leaves (5–6) of the calyx again gradually pass over into the corolla (this being especially marked in _Camellia_), of which the number of leaves varies (5, 6, 7 and upwards); the calyx and the corolla are _acyclic_ or _eucyclic_; the petals are slightly united at the base; stamens _numerous_ in many whorls, the external ones are arranged in bundles and united with the petals as in the Columniferæ; gynœceum syncarpous; styles often _free_ nearly to the base; ovary 3–5-locular, ovules numerous in each loculus. The fruit is a woody capsule.--~Other genera show more distinctly than these the same structure as in the preceding orders, namely: S5, P5, A5 + 5, of which the calyx-stamens are often suppressed, and the petal-stamens divided into numerous stamens.--_Kielmeyera_ (S. Am.)~ 260 species; especially in the Tropics (E. Asia, Am.) The leaves of _Thea chinensis_ (or _Camellia thea_), the Tea-tree (E. Asia), are cultivated for the well-known “tea,” and contain theine: the best are the young, still hairy leaves, of greyish colour; there are many varieties. Ornamental plants, _Camellia japonica_ and _Actinidia_. [Illustration: FIG. 428.--_Thea chinensis_ (reduced).] Closely allied to this order are: Order 15. =Rhizoboleæ= (with enormously large hypocotyl--hence the name), and Order 16. =Marcgraviaceæ= (partly epiphytes, with dimorphic leaves and cup- or helmet-like, coloured, honey-secreting floral-leaves, which serve to attract insects). Order 17. =Dipterocarpaceæ.= This order has taken its name from the large wings attached to the fruits in _Dipterocarpus_ (the wings being largely developed sepals); trees and shrubs from Trop. Asia. 180 species. Camphor ready prepared is found in the stem of _Dryobalanops camphora_. _Hopea_; _Vateria_. Family 12. =Gruinales.= The flowers are hypogynous, ☿, polypetalous, usually regular (except _Pelargonium_, _Tropæolaceæ_, _Balsaminaceæ_) and _throughout 5-merous_: S5, P5, A5 + 5, or 5 + 0, G5 (_epipetalous_). The stamens soon fall off and are _obdiplostemonous_, often united at the base (_monadelphous_); the corolla-stamens are in some completely suppressed (_e.g. Balsaminaceæ_, Fig. 438), in others reduced to teeth (_Linum_, Fig. 431; _Erodium_). The _Tropæolaceæ_ have 3 carpels and only 8 stamens (Fig. 437). Ring-like nectaries are not present, but at most only glandular bodies, borne outside the base of the stamens. Ovaries many-locular. The ovules as a rule are pendulous, with the micropyle directed outwards (Fig. 431, B), and the radicle therefore also points outwards. Usually _herbs_. Related to the Columniferæ. Order 1. =Oxalidaceæ.= Most of the species are herbs with rhizomes; the leaves are stalked, _compound_, with entire leaflets which are folded and bent backwards in the bud (and in the sleep position), exstipulate; some species have sensitive leaves. The flowers (Fig. 429) are regular, and have S5, P5, which are _twisted_ to the left or right in æstivation, A5 + 5, all united at the base (monadelphous), gynœceum 5-carpellate, _styles 5 free_, stigmas capitate, ovary 5-locular, ovules numerous. The fruit is a _capsule opening_ with clefts _on the dorsal sutures_ through which the seeds are ejected, while the _fleshy, external layer of the testa_ springs off elastically. Embryo straight. Endosperm. [Illustration: FIG. 429.--Diagram of _Oxal’s acetosella_.] _Oxalis_ (Wood-Sorrel). Leaves digitate. Species also occur with phyllodia, _i.e._ leaf-like petioles placed vertically without lamina; a few have pinnate leaves. The flowers are situated singly or in dichasia, and unipared scorpioid cymes. The pollination is effected by insects. Some species are trimorphic (long-, short-, medium-styled flowers) and some, _e.g. O. acetosella_, have cleistogamic flowers in addition to the ordinary ones. Glands are found on the outer side of the corolla-stamens or of all the stamens. _O. tetraphylla_ and others have adventitious edible roots, resembling tap-roots.--_Averrhoa_ is a tropical tree, with berries and pinnate leaves. 235 species (205 belong to _Oxalis_); chiefly in S. Africa and Trop. America.--Oxalate of potash is contained in the leaves of _Oxalis_. Order 2. =Linaceæ.= Herbs with scattered or opposite, sessile, _simple_, small, entire leaves, without (rarely with small) stipules. The flowers (Fig. 430) are regular, 5- or 4-merous. Petals are free, _twisted_, quickly falling off. Stamens united at the base; the petal-stamens _are either reduced to teeth_ (Fig. 431 _A_, _m_) _or entirely suppressed_. _Styles free._ The (5–4) epipetalous loculi of the ovary are incompletely halved by _false divisional walls_, each half contains one ovule (Fig. 431 _C_). The fruit is a spherical _capsule, dehiscing along the divisional wall_ (Fig. 432); the 10 (-8) seeds have a straight embryo and very slight endosperm (Fig. 433). [Illustration: FIGS. 430–433.--_Linum usitatissimum._ Fig. 430.--The Flax plant. Fig. 431.--_A_ Flower after removal of sepals and petals; _m_ petal-stamens reduced to teeth. _B_ Longitudinal section of ovary. _C_ Transverse section of capsule. Fig. 432.--Capsule (nat. size). Fig. 433.--Transverse and longitudinal section of seed: _bl_ the cotyledons; _k_ the plumule; _R_ the radicle; _fr_ the endosperm; _sk_ the testa.] _Linum_ (Flax) has 5-merous flowers. ~The main axis terminates in a flower; and the succeeding branching is cymose, or unipared scorpioid branching by unilateral development, and the flowers in consequence of the vigorous sympodial development of the lateral axis (and also by the leaves being displaced and pushed aside), assume a position apparently lateral (_i.e._ racemose) without bracts; each branch of the sympodium generally has 2 leaves. The testa is shining and smooth when dry, but its external cellular layer becomes mucilaginous in water.~--_Radiola_ has a 4-merous flower. It is a small herb with opposite leaves, and regular, dichasial branching. The anthers and stigmas in _L. catharticum_ and _usitatissimum_ develop simultaneously, and cross-pollination as well as self-pollination takes place. _L. grandiflorum_, _perenne_, and others, are dimorphic (short-and long-styled). There are 5 nectaries outside the stamens. 130 species; _Linum_ and _Radiola_ are native genera.--_L. usitatissimum_ is extensively cultivated in Europe (especially in Russia and Belgium), N. America and elsewhere (its home no doubt being Asia), partly on account of the oil (linseed oil) which is extracted from the seeds, and partly on account of the bast of the stem, which has very thick-walled cells. The seeds and oil are OFFICINAL. The species cultivated in ancient times was _L. angustifolium_. Several species are cultivated as ornamental plants. Order 3. =Geraniaceæ.= The majority are herbs with dichasial branching, and scattered or opposite, stalked, _palminerved_ (rarely penninerved) leaves with small _stipules_. The flowers are regular (except _Pelargonium_) and 5-merous, with 10 or 5 stamens, which are slightly united at the base. Nectaries alternate with the corolla-stamens. The ovary is most frequently 5-locular, deeply 5-grooved, and bears 1 _well developed style_ (“beak”), which towards the apex divides into 5 branches bearing stigmas; ovules 1 in each loculus, pendulous or ascending. _The 5 carpels become detached from one another when ripe_, and bend or _roll back_ (Fig. 434) or become _spirally twisted_ in the upper “beak-like” part (Figs. 435, 436), whilst a _central column_ (septal column) persists; each carpel, in consequence, remains either closed, and the fruit is a 5-merous _schizocarp_ whose nut-like lower portion, containing the seed, is forced into the ground, thus burying the seed by the movements of the spirally-twisted, hygroscopic “beak” (Figs. 435, 436); or it opens along the ventral suture, so that the seeds may fall out, and it is then a 5-valved _capsule_, with septicidal dehiscence (Fig. 434) and the rolling up often takes place so suddenly and violently that the seeds are shot out to considerable distances. The embryo is usually green and _curved_, and the _cotyledons are folded_; endosperm is wanting. _Geranium_ (Crane’s-bill) has 5 + 5 stamens,and a septicidal capsule; the carpels most frequently remain suspended from the apex of the column (Fig. 434). The leaves are most frequently palminerved. The flowers are situated solitarily or 2 together (2-flowered scorpioid cyme).--_Erodium_ (Stork’s-bill); inflorescence a many-flowered unipared scorpioid cyme, stamens 5 + 0 (petal-stamens are wanting), and fruit a schizocarp whose carpels become detached; their beaks are hairy on the internal surface and _twist themselves spirally_ (Fig. 436). The umbellate inflorescences are composed of multiflowered scorpioid cymes. The leaves are often penninerved.--~The most primitive type is represented by _Biebersteinia_: S5, P5, A5 + 5, G5 (ovaries _free_, and styles united above); fruit 5 small nuts. The most advanced type is _Pelargonium_, which has _zygomorphic_ flowers, the posterior sepal being prolonged into a spur which becomes adnate to the peduncle; the petals are unequal in size; some of the petal-stamens are often wanting. (_Erodium_ may be slightly zygomorphic).~ [Illustration: FIG. 434.--_Geranium sanguineum._ Fruit (3/1).] [Illustration: FIG. 435.--_Pelargonium._] [Illustration: FIG. 436.--_Erodium cicutarium_, detached carpel.] POLLINATION. The large-flowered _Geranium_-species are protandrous, _e.g. G. pratense_ (one whorl of stamens opens first, and then the other, and succeeding these the stigmas, after shedding the pollen the stamens bend outwards); the small-flowered are also adapted, with various modifications, for self-pollination.--470 species; moderately hot climates, especially S. Africa.--Several _Pelargonium_-species, with numerous varieties, are ornamental plants (from S. Africa). Order 4. =Tropæolaceæ.= Herbaceous, juicy plants which have scattered, long-stalked, peltate leaves without stipules, and often climb by their sensitive petioles. The flowers are situated singly in the axils of the foliage-leaves on long stalks, and are _zygomorphic_, the receptacle under the posterior sepal being prolonged _into a spur_; there are also differences between the posterior and anterior petals, the 2 posterior petals situated on the border of the spur being _perigynous_, and the edge of the anterior petals adjoining the claw fringed. After the 5 sepals (which are more or less coloured) and the 5 petals, follow 8 _stamens_ (as the 2 median ones are suppressed, one from each whorl) and a gynœceum formed of 3 carpels; in each of the 3 loculi of the 3-grooved ovary is 1 ovule. The fruit is a _schizocarp_ and divides into 3 1-seeded, _drupe-like_ fruitlets, which do not (as in the Geraniaceæ) leave any pronounced column between them. Endosperm is wanting. The cotyledons are thick and sometimes slightly coalescent. ~Tubers often occur.~ [Illustration: FIG. 437.--Diagram of _Tropæolum_: _sp_, spur.] _Tropæolum._--About 40 species; all from America. POLLINATION.--The spur is the receptacle for the nectar; the flowers are protandrous; the anthers open first, and one by one take up a position in front of the entrance to the spur, resuming their original position when the pollen is shed; the stigma finally takes their place after the filaments have bent backwards.--These plants have an acrid taste (hence the name “Nasturtium,” “Indian Cress”), on which account the flower-buds and young fruits of _T. majus_ are used as capers. Some species are ornamental plants. Order 5. =Balsaminaceæ.= Herbaceous, chiefly annual plants with juicy, brittle stems, so transparent that the vascular bundles may be distinctly seen. The leaves are simple, usually scattered, penninerved and dentate; stipules are wanting, but sometimes large glands are present in their place at the base of the petioles. The flowers are strongly zygomorphic; of their five 5-merous whorls the petal-stamens are suppressed (S5, P5, A5 + 0, G5); the sepals are _coloured_, the 2 _anterior ones_ (Fig. 438 _3_, _5_) _are very small_ or entirely suppressed, _the posterior one_ is very large and _elongated into a spur_, and the 2 lateral ones pushed forward; sometimes the weight of the spur turns the flower completely round, so that the posterior leaves assume an anterior position; apparently only 3 petals, since the lateral and the posterior petals become united in pairs, and the anterior is larger and differently shaped; the 5 stamens have very short and thick filaments united at the base, and their anthers finally adhere together and remain in this condition, covering over the gynœceum; the filaments ultimately rupture at the base, and the entire anthers are raised on the apex of the gynœceum as it grows up. The gynœceum has a _sessile stigma_ and a 5-locular ovary. The fruit is a capsule which, on maturity, opens suddenly when irritated, dividing into valves from the base upwards, and as the 5 valves roll up elastically, the seeds are shot out on all sides to considerable distances; a central column persists (Fig. 439). The embryo is straight, and without endosperm. [Illustration: FIG. 438.--Diagram of _Impatiens glanduligera_.] [Illustration: FIG. 439.--Fruit of _Impatiens_.] _Impatiens_; in Europe only _I. noli-me-tangere_. 225 species; especially from Asia. Several species have two kinds of flowers: small, cleistogamic, but fertile; and large, coloured flowers, which in _I. balsamine_ (ornamental plant, E. Ind.) are protandrous and pollinated by hive-and humble-bees, as they suck the honey from the spur. Order 6. =Limnanthaceæ.= The flowers are regular and differ from all the other orders in the family by having the carpels not in front of the petals, but _in front of the sepals_ (which are _valvate_), and further, the loculi are nearly _free individually_, but with a _common gynobasic_ style; the ovules are _ascending_ and _apotropous_ (anatropous with ventral raphe). The fruit is a schizocarp, with nut-like cocci.--_Limnanthes_ (4 species; N. Am.) perhaps belongs to another family. Order 7. =Humiriaceæ.= Trees and shrubs; about 20 species; Trop. Am. Family 13. =Columniferæ.= The chief characteristics of the orders belonging to this family are the ☿, regular, generally 5-merous, _hypogynous_ flowers with 5-merous _calyx_, sepals united and _valvate_ in the bud; petals 5, free (often _twisted_ in the bud); stamens ∞ _e.g._: 10, in two whorls, but one of these is more or less suppressed, often altogether wanting, or replaced by 5 staminodes, while _the other_ (inner whorl) _is generally divided more or less deeply_ into a large number of anther-bearing filaments. The filaments too (except _Tiliaceæ_) are _united into a tube_, which, especially in the _Malvaceæ_, forms a long column in the centre of the flower, surrounding the gynœceum (Figs. 445, 448); in this case, which is the most pronounced, the filaments are united into one bundle (_monadelphous_), in other instances, _polyadelphous_. The number of carpels varies greatly (2 to about 50), but they are nearly always united and form a syncarpous multilocular gynœceum.--The vegetative characters also closely agree, the leaves _are always scattered and generally stipulate_; all the green portions very often bear _stellate hairs_, and the bark in all the 3 orders is _rich in tough bast_. Mucilage is often present in cells or passages.--This family is connected with the _Ternstrœmiaceæ_, from which it is very hard to draw a sharp line of demarcation, and it is also allied to the _Cistaceæ_ and to the _Gruinales_. Order 1. =Sterculiaceæ= (including Buettneriaceæ). This is, no doubt, the least modified order, and one in which the stamens occur undivided. Obdiplostemonous. The 10 stamens in two whorls are most frequently united at the base into a short tube, and have _4-locular, extrorse_ anthers. The calyx-stamens are nearly always simple, tooth-like staminodes, situated on the edge of the tube, or are entirely suppressed. The same relation is found, for instance, in the Ampelidaceæ and Rhamnaceæ, namely _5 stamens in front of the 5 petals_; not infrequently the 5 stamens are doubled (Fig. 441). Unisexual flowers are found in _Sterculia_, _Cola_, _Heritiera_. The corolla is often wanting, or developed in an unusual manner. Each loculus of the ovary (generally 5) always contains more than one ovule. Fruit a capsule. Androgynophore often present (_Helicteres_; _Sterculia_, etc.). _Hermannia_, _Mahernia_, _Melochia_, etc., have flat petals with twisted æstivation; 5 undivided stamens, which usually are but slightly united at the base, and most frequently, without staminodes. _Thomasia_; _Helicteres_; _Sterculia_ (free follicles).--_Theobroma_, _Rulingia_, _Buettneria_, _Commersonia_, _Guazuma_, etc., have petals concave at the base, and terminating in a limb abruptly bent back, and at the boundary between them most frequently ligular outgrowths, as in certain genera of the Caryophyllaceæ; stamens 5–15–∞, anthers at the edge of a short tube and 5 linear staminodes (Fig. 441).--The Cocoa-tree (_Theobroma_), (Fig. 440) bears large, reddish-yellow, berry-like fruits, resembling short cucumbers, but ultimately becoming leathery to woody; in each of the 5 loculi are 2 (apparently only 1) rows of horizontal, oily seeds, as large as almonds. Cotyledons large, thick, and irregularly folded. Endosperm absent (Fig. 442). 49 genera, with about 750 species; almost entirely confined to the Tropics; none in Europe or in N. Asia.--The seeds of the Cocoa-tree (_T. cacao_, _bicolor_, _glaucum_, etc., natives of Trop. Am., especially north of the Equator) are used for chocolate and are also _officinal_ (“Cocoa-beans,” “Cocoa-butter,” “Oil of Theobroma”). Theobromine. _Cola acuminata_, Africa. [Illustration: FIG. 440.--_Theobroma cacao._ Branch with flowers and fruits (⅙).] [Illustration: FIGS. 441–442.--_Theobroma cacao._ FIG. 441.--Diagram of the flower: _st_ barren stamens. FIG. 442.--_B_ Seed in transverse section: _n_ hilum. _A_ Embryo after the removal of one of the cotyledons.] Order 2. =Tiliaceæ.= This differs from the other orders of the Columniferæ chiefly in the stamens being entirely _free_ from each other, and also _divided_ into many filaments, _as far as the base_, or at all events very far down, so that the _flower appears to have numerous stamens_ or to be _slightly_ polyadelphous (Fig. 443); in addition to this, it may be observed that the anthers are _4-locular_ and _introrse_. In _Luehea_ the groups of stamens alternate with the petals. In a few genera (_Corchorus_, _Triumfetta_) 10 free and single stamens are found in 2 whorls; but, in the majority, groups of free stamens in separate bundles. The stamens are more or less united in _Apeiba, Luehea_. Style simple. Ovary 2-locular. The ovules are pendulous; raphe turned inwards. The calyx readily falls off; the æstivation of the entirely free petals is slightly imbricate (_not twisted_). [Illustration: FIG. 443.--Inflorescence of _Tilia_, with its winged bracteole (_h_); _a_, _a_ axis of the shoot; the vegetative bud is seen between the inflorescence and the axis of the shoot; _b_ petiole of foliage-leaf.] _Tilia_ (Figs. 443, 444). Calyx and corolla 5-merous; the 5 staminal leaves (opposite the petals) divided as far as the base into a large number of stamens which are free or united into groups; gynœceum with 5 loculi in the ovary (opposite the sepals); there are 2 ovules in each loculus, though the ovary ripens into a 1-seeded nut, which is not detached from the axis of the inflorescence, but is carried away by the wind, whirling round and round, its large-winged bracteole serving as a parachute (Fig. 443).--~Only trees, with alternate, obliquely heart-shaped and dentate leaves; stellate hairs, as in the other Columniferæ, are often present. The terminal bud of the branch always fails to develop, and the growth is then continued sympodially by the uppermost axillary buds. The INFLORESCENCE (Figs. 443, 444) is a 3–7-flowered dichasium (Fig. 444 _t_, _d_, _e_), which is developed in the axil of a foliage-leaf (Fig. 444). The first of its 2 bracteoles (_a_) is large, thin, leaf-like, and united with the inflorescence, the lower portion of which forms a broad wing, its so-called “bract”; the second bracteole (_b_), on the other hand, remains scale-like, and supports a winter foliage-bud covered with bud-scales which thus is situated at the base of the inflorescence, and is a bud of the 2nd order, in relation to the vegetative shoot. This bud is always found beneath the inflorescence on the branch placed horizontally, and the winged bracteole is always found above it, a relation which is connected with the fact that the 2 rows of shoots on the sides of a branch are _antidromous_ with regard to each other.--The dichasium itself (Fig. 444) terminates with the flower (_t_); it has 3 floral-leaves (_c_, _d_, _e_), which soon fall off; _c_ is barren: the other two bear flowers, or few-flowered dichasia, or unipared scorpioid cymes (indicated in the figure).--The foliage-leaves are folded in the bud upon the median line (1, 2, 3 in Fig. 444 are foliage-leaves with their 2 stipules), the inner half is broader than the outer, and after unfolding is turned away from the mother-axis (the position of the new inflorescences and vegetative buds is indicated in their axils on the figure).--The cotyledons on germination appear above the ground as large, _lobed_ leaves.~ Of the other genera some have a bell-shaped, gamosepalous calyx, some have no corolla, the anthers of some open at the apex (_Aristotelia_, _Elæocarpus_, etc.), the majority have a capsule, some have berries, or drupes, some separate into fruitlets, etc.--_Corchorus_, _Triumfetta_ (nut, with hooked bristles), _Luehea_, _Apeiba_, etc. _Sparmannia_ is an African genus; 4-merous flowers; fruit a warted capsule; filaments numerous and sensitive to touch, the external ones are without anthers and moniliform above. The plant is covered with numerous soft and stellate hairs, and at the apex of the branches bears several cymose umbels. [Illustration: FIG. 444.--Diagram of the inflorescence of _Tilia_ and the vegetative bud; the position of the leaves is indicated, and also the position of the inflorescences, which develop from their axils in the following year.] POLLINATION in _Tilia_ is effected by insects, especially bees and Diptera, which swarm round the tree tops, allured by the numerous strongly-scented flowers and the easily accessible honey (formed in the hollow sepals). As the flowers are pendulous, the nectar is protected from ruin; and, in addition, the inflorescence is more or less concealed beneath the foliage-leaf. Self-pollination is impossible, on account of protandry.--About 470 species (nearly all trees and shrubs); especially in the Tropics, only a few being found in the temperate, none in the polar regions, or in high mountainous districts.--The inflorescence of the native species of _Tilia_ is medicinal. The wood is used for charcoal.--The majority are used for timber, and for the sake of the bast (“Bast,” “Jute,” the bast of _Corchorus textilis_, _Luehea_, and others). Order 3. =Malvaceæ= (=Mallows=). The plants are easily recognised by the scattered, simple, _palminerved_, most frequently lobed, stipulate _leaves_, folded in the bud; the perfect, regular, hypogynous flowers, with _gamosepalous_, persistent, 5-merous calyx with _valvate_ æstivation; the 5 _petals twisted_ in the bud and united with one another at the base, and by the 5 _apparently numerous stamens_ (Figs. 445, 448), with the filaments _united into a tube_, with _reniform bilocular anthers_ opening by a crescentic slit (in 2 valves). Carpels 3–∞ united into one gynœceum; the _embryo is curved and the cotyledons are folded_ (Figs. 447, 451); endosperm scanty, often mucilaginous.--Most of the plants belonging to this order are herbs, often closely studded with _stellate hairs_. The leaves are most frequently palmatifid or palmatisect. [Illustration: FIG. 445.--Longitudinal section through the flower of _Malva silvestris_.] [Illustration: FIG. 446.--Diagram of _Althæa rosea_: _i_ the epicalyx.] An _epicalyx_ is often found formed by _floral-leaves_ placed close beneath the calyx, in some 3, in others several. The median sepal is posterior in the species without epicalyx, often anterior in those which have an epicalyx.--The petals are _twisted either to the right or to the left_ in accordance with the spiral of the calyx; they are most frequently oblique, as in the other plants with twisted corollas, so that the portion covered in the æstivation is the most developed. The corolla drops off as a whole, united with the staminal tube.--Only the 5 petal-stamens are developed, but they are divided into a number of stamens, placed in 2 rows, and provided only with _half_-anthers (leaf-segments, see Fig. 446; the sepal-stamens are completely suppressed); these 5 staminal leaves are then united into a tube, frequently 5-dentate at the top, and bearing the anthers on its external side. The pollen-grains are specially large, spherical and spiny. There are from 3 to about 50 carpels united into one gynœceum and placed round the summit of the axis which most frequently projects between them. There is only 1 style, which is generally divided into as many stigma-bearing branches as there are carpels (Figs. 445, 448). The fruit is a schizocarp or capsule. Endosperm (Figs. 447 A, 451) scanty, often mucilaginous round the _embryo_, which is rich in oil. The order is the most advanced type of Columniferæ; it stands especially near to the Sterculiaceæ, but is separated from these and from the Tiliaceæ, among other characters, by its 2-locular (ultimately 1-chambered) anthers. The sub-orders may be arranged as follows:-- I. Carpels in one whorl. =A.= =The fruit a capsule=, ~most frequently with loculicidal dehiscence, and many seeds in each loculus~. =1.= GOSSYPIEÆ. The staminal-column is naked at the apex, blunted, or 5-dentate.--_Gossypium_ (the Cotton plant) has an epicalyx of 3 large ovate-cordate leaves, an almost entire, low and compressed calyx. Solitary flowers. Large, most frequently yellow, corollas. A 3–5-valved capsule with many spherical seeds. “Cotton” is the seed-hairs developed upon the entire surface of the seeds (Fig. 447), and consists of long, 1-cellular hairs, filled with air (and therefore white); these are thin-walled, with a large lumen, and during drying twist spirally, and come together more or less in the form of bands. They consist of cellulose, and have a cuticle.--_Hibiscus_ has several, most frequently narrow, epicalyx-leaves, a distinct 5-toothed or 5-partite calyx.--_Abutilon_; _Modiola_. [Illustration: FIG. 447.--_A_ Seed of _Gossypium_ with hairs; _B_ the same in longitudinal section.] =2.= BOMBACEÆ. The staminal tube is more or less deeply cleft into bundles, sometimes almost to the base; pollen smooth, style simple with capitate, lobed stigma. Almost all plants belonging to this group are trees, and in many instances have large barrel-shaped stems, that is, swollen in the centre, and sometimes covered with large warts. The wood is exceptionally light and soft. The flowers are often enormously large, and have beautiful petals; in some they unfold before the leaves. The capsule-wall is sometimes closely covered on its inner service with long, silky, woolly hairs, while the seeds themselves are generally without hairs. These hairs, however, on account of their brittle nature, cannot be used like those of the Cotton-plant. Digitate leaves are found in the _Baobab-tree_ (_Adansonia_) from Africa, noted for its enormously thick, but short stem, and in the American _Silk-cotton trees_ (_Bombax_, _Eriodendron_, _Chorisia_). _Ochroma_, _Cheirostemon_, _Durio_, and others also belong to this group. _Durio_ is noted for its delicious fruits, which have a most unpleasant smell. [_Bombax malabaricum_ is diplostemonous; the five sepal-stamens repeatedly branch, and the filaments bear unilocular anthers; the five petal-stamens bear bilocular anthers.] =B.= =Schizocarps=, with 1-seeded fruitlets, most frequently nut-like and reniform (Figs. 449, 451). =3.= MALVEÆ, MALLOW GROUP. The carpels are arranged in one whorl (Fig. 449); the number of stylar-branches equals that of the carpels; fruitlets 1-seeded, reniform, indehiscent, but detaching themselves from one another and from the persistent central column (Figs. 450, 451).--~_Malva_ has an _epicalyx of 3 free leaves_. ~A flower with 2 suppressed bracteoles is situated in the axil of the foliage-leaves; one of these supports a homodromous foliage-shoot which forms a repetition of the main axis, the other an antidromous flower which continues the branching as a unipared scorpioid cyme.~--_Althæa_, Rose Mallow, has an _epicalyx of 6–9 leaves united at the base_.--~_Lavatera_, _Sida_, _Anoda_, _Bastardia_, etc., have no epicalyx.~ [Illustration: FIGS. 448–451.--_Malva silvestris._] [Illustration: FIG. 448.--The flower after removal of the perianth (5/1).] [Illustration: FIG. 449.--The fruit (5/1).] [Illustration: FIG. 450.--A fruitlet (5/1).] [Illustration: FIG. 451.--The same in longitudinal section.] =4.= URENEÆ, have always only 5 carpels arranged in 1 whorl, with 1 ovule in each loculus, and the fruit a schizocarp, generally with nut-like fruitlets provided with warts and hooks; but in some they dehisce by 2 valves (capsule). They differ principally from the other groups _in having twice as many stylar-branches as carpels_; the staminal tube is naked at the point, blunt or 5 toothed.--The genera _Urena_, _Pavonia_, _Malachra_, _Malvaviscus_ (with _berry-like fruits_) belong to this group. II. Carpels arranged in a spherical head in five groups opposite to the petals. =5.= MALOPEÆ, differ from all the others in having a large number of fruitlets arranged irregularly in a round head, and separating considerably from each other even before maturity; there is, however, only 1 style, divided into a corresponding number of branches (this condition may be considered to have arisen from the branching [dédoublement] of 5 _carpels_). _Malope_ has 3 large, heart-shaped (_Kitaibelia_ 6–9) epicalyx-leaves, united at the base. _Palava_ has no epicalyx. POLLINATION. The majority have protandrous flowers, and are pollinated by insects. Between the basal portions of the 5 petals, there are 5 nectaries, protected from the rain by hairs, _e.g._ in _Malva silvestris_. When the flower first opens the numerous anthers occupy the centre of the flower, and the still undeveloped stigmas are concealed in the staminal tube; in the next stage the anthers are withered and empty, and the stigmas protrude and assume their places (Fig. 452). The large-flowered forms, it appears, are pollinated only by insects; but self-pollination takes place in small-flowered forms, as, for example, in _Malva rotundifolia_, in which the stylar-branches, twisting themselves, place the stigmas in between the undeveloped anthers. [Illustration: FIG. 452.--_Anoda hastata_: _a_ the bud just opened, the stigmas are concealed by the anthers; _b_ fully opened flower in ♂-stage; the upper stamens are developed first, and then the others in descending order; the stylar-branches are now visible, and lie bent back on the staminal column; _c_ all the stamens project upwards, and all the anthers are open, but the stylar-branches are still bent back; d the anthers are emptied and the filaments shrunk together, but the styles have now straightened themselves upwards, and the stigmas are in the receptive condition.] DISTRIBUTION. 800 species (63 genera), most of which are natives of the Tropics, especially America. _Althæa_ and some of the species of _Malva_ are natives of the temperate regions of the Old World, the latter is also found in North America. _Gossypium_ is tropical, no doubt especially Asiatic (_G. herbaceum_ from India; _G. arboreum_ from Upper Egypt). Cotton was introduced into Greece in the time of Herodotus, and was cultivated in America before the arrival of the Europeans. USES. Pungent and poisonous properties are entirely wanting; _mucilage_, on the other hand, is found in abundance in all parts of the plant. Medicinal: the root of _Althæa officinalis_, leaves and flowers of _Malva_-species (_M. silvestris vulgaris_ and _borealis_) and _Gossypium_.--The seeds contain a large quantity of _fatty oil_, which is in some cases extracted (Cotton-seeds and others). _The seed-hairs of the Cotton plant_ are the most important product of the order. The cultivated forms of Cotton belong to several species: _G. barbadense_, _herbaceum_, _religiosum_, _arboreum_ (Nankin), _hirsutum_, and others. According to other botanists, there are only 3 species. _Bast_ is obtained from _e.g. Hibiscus cannabinus_ (Gambo-hemp, Africa), _Paritium tiliaceum_ and _Sida retusa_. The fruits of certain species of _Hibiscus_ (_e.g. H. esculentus_, from Tropical Africa) are used in tropical countries as a vegetable before they are ripe.--_The colouring matter_ in the flowers of _Althæa rosea_, var. _nigra_, is used for colouring wines, and hence is extensively cultivated in certain parts of Europe.--_Ethereal oils and sweet-scented flowers_ are rare; but several species possess a peculiar musk-like odour (_Malva moschata_, _Hibiscus abelmoschus_, and others).--Many are cultivated as _ornamental plants_ on account of the large flowers, _e.g._ Hollyhock (_A. rosea_, etc.), _Lavatera trimestris_, _Malope grandiflora_ and _trifida_, _Malva_-species, _Hibiscus rosa sinensis_, _syriaca_; _Sphæralcea_, etc. Family 14. =Tricoccæ.= The very large order _Euphorbiaceæ_ and three smaller ones belong to this family. They have in common: _unisexual_, hypogynous, frequently regular flowers, the perianth most frequently single, rarely double, or entirely wanting; there is such a great variety in the structure and parts of the flower that one only can be cited as the _rule_: viz. the simple gynœceum composed of 3 carpels forming a 3-locular ovary, which is frequently more or less deeply grooved (hence the name, _Tricoccæ_); in the inner angles of the loculi are found 1 or 2 (never several) pendulous (except _Empetraceæ_), anatropous ovules, with upward and outwardly turned, frequently swollen, micropyle (Fig. 455). The seed most frequently has a large endosperm and a straight embryo (Figs. 455 _B_, 464).--~The family approaches the nearest to the Gruinales and Columniferæ; it may perhaps be regarded as an offshoot from the Sterculiaceæ.~ Order 1. =Euphorbiaceæ.= Flowers unisexual. In each of the loculi of the ovary, generally 3, there are 1 or 2 pendulous ovules with upward and outwardly turned micropyle. The placenta protrudes above the ovules (Figs. 454, 461 _B_). On the ripening of the capsule the 3 carpels separate septicidally, frequently with great violence, ejecting the seeds and leaving a central column. Endosperm copious.--For the rest, the flowers present all stages, from genera with calyx and corolla, to those which are the most reduced in Nature, namely the naked, 1-stamened flowers of _Euphorbia_. The same variety which is found in the flower is also present in the vegetative parts. Some are herbs, as our Spurges, others are shrubs and trees; some African _Euphorbia_-species even resemble the habit of a Cactus. Leaf-like branches with rudimentary leaves are found in _Phyllanthus_ (sub-genus _Xylophylla_) (Fig. 456). The leaves are scattered or opposite, often stipulate; they are nearly always simple. Large, highly-branched cells containing a great quantity of pungent latex are found in many, and watery juice in others. Glands and glandular hairs are general.--Only a few genera can be considered in this book. As an example of the most perfect flowers (which partly reproduce the Geraniaceous type) may be mentioned, _Croton_, _Manihot_, and _Jatropha_; 5 sepals, 5 petals, sometimes gamopetalous, andrœcium diplostemonous, or many-stamened, often monodelphous. [Illustration: FIGS. 453–455.--_Ricinus communis._ FIG. 453.--♂-flower (magnified). FIG. 454.--♀-flower in longitudinal section. FIG. 455.--_A_ seed entire; _B_ in longitudinal section.] _Ricinus_ (Castor-oil) (Figs. 453–455); monœcious; the ♂-flowers, situated in the lower portion of the inflorescence, have 5 perianth-leaves and a large number of branched stamens; the ♀-flower has 3–5 perianth-leaves; 3 bifid styles. Leaves peltate, palmately lobed. The seeds (Fig. 455) contain an abundance of fatty oil and large aleurone grains.--_Mercurialis_ (Mercury): the perianth is most frequently 3-merous; in the ♂-flowers 9–12 stamens; in the ♀-flowers most frequently a _2-locular_ gynœceum.--_Phyllanthus_: Pr3 + 3, A3, united in some and forming a column in the centre of the flower (Figs. 457, 458); _Xylophylla_ is a section of this genus.-- _Hura crepitans_ (Sand-box tree) has a many-carpellate gynœceum, which separates with great violence when ripe.--A drupe is found in _Hippomane mancinella_ (the Mancinil-tree, W. Ind.)--_Alchornea (Coelebogyne) ilicifolia_ is well known on account of its “parthenogenesis”; only the ♀-plant has been introduced into Europe, but it nevertheless produces seeds capable of germination; these have generally several embryos. [Illustration: FIGS. 456–458.--_Phyllanthus (Xylophylla) angustifolius._ FIG. 456.--Leaf-like branch with flowers (nat. size). FIG. 457.--♂-flower; and FIG. 458, ♀-flower (mag.).] _Euphorbia_ (Spurge) has the most reduced flowers, which are borne in a very complicated inflorescence. Each ♂-flower (Fig. 460 _B_) is naked, and consists of one stamen only (terminal on the axis). In the closely allied genus _Anthostema_, a small perianth is situated at the place where, in _Euphorbia_, there is a joint in the “filament,” (Fig. 461 _A_). The ♀-flowers (Fig. 460) are naked, with a 3-locular ovary and 3 bifid styles. (_Anthostema_ has a distinct perianth (Fig. 461 _B_); in a few Euphorbias traces of a perianth are present). In _Euphorbia_ the ♂-and ♀-flowers are grouped into flower-like inflorescences termed “cyathia.” Each cyathium consists of a centrally placed ♀-flower which is first developed, surrounded by 5 groups of ♂-flowers (stamens) placed in a zig-zag, with a centrifugal order of development (Figs. 459, 460 _B_), that is, in unipared scorpioid cymes; these flowers are surrounded by an _involucre_ of 5 leaves united into a _bell-shaped structure_ (Fig. 459, 1–5) (resembling a calyx); on its edge are placed 4, generally crescent-like, yellow glands, one in each of the intervals, except one, between the lobes of the involucre (shaded in Fig. 459; see also Fig. 460 _A_). Scale-like thin structures (floral-leaves?) are situated between the ♂-flowers. The ♀-flower has a long stalk, and finally bends down on one side, namely to the place on the edge of the involucre where the gland is not developed. These cyathia are again arranged in an inflorescence which commences as a 3–5-rayed umbellate cyme (pleiochasium), the branches of which ramify dichasially and finally as scorpioid cymes.--Latex, with peculiar-shaped starch-grains, is found in laticiferous _cells_ (especially in the Cactus-like, leafless species.) [Illustration: FIG. 459.--Diagram of an inflorescence (cyathium) of _Euphorbia_ with 3 floral-leaves, _m_, _n_, _o_, supporting other cyathia which are subtended by 2 floral-leaves (bracteoles; _m_, _n_). 1–5, the involucral leaves in their order of development; the shaded portions are the crescentic glands.] [Illustration: FIG. 460.--_Euphorbia lathyris_: _A_ an (entire) inflorescence (cyathium); _B_ the same after the removal of the involucre.] [Illustration: FIG. 461.--_Anthostema_: ♂- (_A_) and ♀-(_B_) flowers; _p_ the perianth; _ar_ the node; _o_ the ovule.] 205 genera; more than 3,000 species; especially in the Tropics.--Many are used on account of the oil, and of the pungent (aperient, poisonous, anthelmintic, etc.) properties in the latex or the seeds. OFFICINAL: “Cascarilla-bark” of _Croton eluteria_; the fatty oil of the seeds of _Croton tiglium_ (Trop. Asia); “Castor oil” from _Ricinus communis_ (Africa, and cultivated in all warm climates throughout the world); the glandular hairs of _Mallotus philippinensis_ (“Kamala”); this also yields a red dye. Gum “Euphorbium” is the hardened (resinous) latex of the _Cactus_-like _Euphorbia resinifera_ (Morocco).--NUTRITIVE plants: _Manihot utilissima_ and other species (Maniok, Am.). Their large, farinaceous roots form a very important article of food in the Tropics (Cassava-flour, Tapioca or Brazilian arrowroot). The fresh latex of the root in some species is a powerful poison; but the poisonous properties are diminished by roasting or cooking. _Caoutchouc_ is obtained from _Siphonia elastica_ (Trop. S. Am.). The vegetable tallow of the Chinese tallow-tree (_Stillingia sebifera_) is used in large quantities in soap factories. An indigo-like _dye_ is obtained from _Crozophora tinctoria_, and is also found in _Mercurialis perennis_. Shellac is obtained from _Aleurites laccifera_. ORNAMENTAL plants: _Acalypha_, _Croton_, _Dalechampia_.--_Hippomane_ is poisonous. Order 2. =Buxaceæ.= This order differs from the Euphorbiaceæ in having the micropyle turned inwards; the ♂-flower has a 4-partite perianth and 4 stamens; the ♀-flower a 6-partite perianth and 3 carpels. Capsule with loculicidal dehiscence, the inner layer being detached elastically from the outer.--30 species. Shrubs without latex and with evergreen leaves.--_Buxus sempervirens_ (Box) is an ornamental shrub (poisonous); it has a very hard and valuable wood which is used for wood-engraving and carving. [Illustration: FIGS. 462–464. _Callitriche stagnalis._ FIG. 462.--♂-flower with the 2 bracteoles and the solitary stamen. FIG. 463.--♀-flower. FIG. 464.--Longitudinal section of the ripe fruit.] Order 3. =Callitrichaceæ.= Aquatic plants, growing at the bottom of shallow water, with opposite, simple, undivided, entire, exstipulate leaves, which are generally crowded and form a rosette in the apex of the branches. The flowers are unisexual (monœcious) and borne singly in the leaf-axils; they have no perianth, but are provided with two delicate bracteoles; the ♂-flowers consist of only _1 terminal stamen_ (Fig. 462); the ♀-flowers of a bicarpellate gynœceum (Fig. 463) which is originally 2-locular, but later on becomes 4-locular, as in the case of the gynœceum of the Labiatæ, by the formation of a false partition-wall; in each loculus there is 1 pendulous ovule with the micropyle turned outwards. Fruit a _4-partite schizocarp_ (Fig. 464). 25 species.--_Callitriche._ Order 4 (?). =Empetraceæ.= 4 species. _Empetrum_; _E. nigrum_ (Crowberry) is a heather-like, moorland, evergreen undershrub with linear leaves, having a deep groove closed with hairs, on the under side. The _erect ovules_ show the greatest deviation from the Euphorbiaceæ. Diœcious (and ☿); S3, P3; in the ♂-flower, 3 stamens; in the ♀-flower, a 6–9-locular ovary. Fruit a _drupe_. Family 15. =Terebinthinæ.= The diagram of the flower (Figs. 465–467) is the same as in the Gruinales, namely S, P, A2 and G in whorls of 5 (less frequently 3, 4, 6, 8), and the same modifications also occur with the suppression of the petal-stamens, etc. But a _ring_ or sometimes _cup-like glandular structure_ (_disc_) is found _between_ the andrœcium and the gynœceum (Figs. 465, 466). The flowers similarly are regular, _hypogynous_, ☿ and polypetalous, though exceptions are found to all these characters: thus, for example, united sepals and petals frequently occur, and, in some orders, unisexual flowers by the suppression of one sex. In most cases the flowers are small, greenish-yellow, and arranged in paniculate inflorescences. The carpels (most frequently 5) are free in a few, but generally united into a multilocular gynœceum; rarely more than 1 or 2 ovules in each loculus. The gynœceum in the Anacardiaceæ is so reduced that it has only 1 fertile loculus with 1 ovule.--The _ovules are epitropous_, _i.e._ anatropous with outward-turned raphe (except the Anacardiaceæ).--The majority of the species are trees and shrubs with scattered, often _compound (pinnate) leaves_ without stipules, and as in addition they frequently contain _aromatic, especially turpentine-like substances_, they assume a certain resemblance to the Walnut trees, and were formerly classed with them mainly on this account. In a series of genera the volatile, scented oils are found in special glands in the bark of the branches and in the leaves, in the latter case appearing as _pellucid dots_. This family includes several orders which are somewhat difficult to distinguish from each other. Order 1. =Connaraceæ.= This order forms the connecting link between Terebinthinæ and Rosifloræ (_Spiræa_) as well as Leguminosæ, with which they are sometimes classed. The flowers have 5 5-merous whorls; 2 ovules in each loculus; micropyle turned upwards. Fruit a _follicle_, rarely a collection of follicles. Seed with aril. Shrubs with scattered (most frequently pinnate) leaves, without stipules. 170 species. Tropical. Order 2. =Meliaceæ.= Trees and shrubs with scattered, often pinnate leaves without pellucid dots and exstipulate; the leaflets are nearly always entire. Flowers small in paniculate inflorescences. Calyx and corolla 4–5-merous; 2 whorls of stamens; 3–5 carpels in the gynœceum. A very characteristic feature is the union of the filaments into a tube, on the edge of which stipule-like teeth are often found. There are most frequently 2 ovules in the loculi; fruit a capsule with many winged seeds in _Swietenia_ (Mahogany tree; Trop. Am.), _Cedrela_, etc.; berries in others. The wood of _Cedrela_ is used for making cigar boxes. 550 species; tropical. Order 3. =Rutaceæ.= Leaves glandular with pellucid dots. The type is the same as that of the family. Flowers 4–5-merous. The ovary is most frequently 4–5-grooved. Disc well pronounced, often appearing as a “gynophore.” The majority are shrubs with alternate or opposite, compound, more rarely simple, leaves. =A.= The ovary is deeply 2–5-cleft with basal styles which are more or less united; the carpels in some genera are entirely free (groups 1, 2). The fruit is capsular and most frequently dehisces like follicles along the ventral suture or septicidally, so that a horn-like internal layer (endocarp) separates elastically from the external layer. =1.= ZANTHOXYLEÆ. _Zanthoxylum_; _Choisya_; _Evodia_. =2.= BORONIEÆ. Australia.--_Correa._ =3.= DIOSMEÆ. Heather-like shrubs; Africa.--_Diosma_, _Coleonema_, _Empleurum_ and _Barosma_. OFFICINAL: _Barosma crenulata_ and _betulina_, “broad Buchu leaves” (_B. serratifolia_ and _Empleurum serrulatum_, “narrow Buchu-leaves”). [Illustration: FIG. 465.--_Ruta._ Flower (mag.).] [Illustration: FIG. 466.--_Ruta._ Longitudinal section of flower.] [Illustration: FIG. 467.--_Ruta._ Floral diagram.] =4.= RUTEÆ. _Ruta_ (Figs. 465–467) _graveolens_ is an herbaceous, glaucous, strongly smelling plant with bipinnate leaves and yellow flowers; the terminal flower is 5-merous, the others 4-merous (S. Eur.).--_Dictamnus_; zygomorphic flower. ~The individual carpels of the fruit separate from each other, and dehisce like follicles, upon which the internal layer is detached elastically and springs out, carrying the seeds with it. Several species are ornamental plants.~ =5.= CUSPARIEÆ. American. Flowers often zygomorphic with gamopetalous corolla; stamens 5.--_Ticorea_; _Galipea_ (_G. officinalis_; S. Am.; “Cortex angosturæ”); _Cusparia_; _Almeidea_. =B.= The ovary is entire or only slightly grooved; the style is terminal, undivided. The fruit is most frequently a drupe or berry. =6.= TODDALIEÆ. _Ptelea_; winged fruit. The buds are enclosed in the leaf-sheath. _Skimmia_; _Phellodendron_. [Illustration: FIGS. 468–470.--_Citrus vulgaris._ FIG. 468.--Branch with compound leaves. FIG. 469.--Transverse section of fruit. FIG. 470.--Flowers (after the removal of the petals).] =7.= AURANTIEÆ, ORANGE GROUP. Fruit a berry with a leathery external layer.--The most typical flower is found for example in _Limonia_: S5, P5, A5 + 5, G5 (2–5).--_Citrus_ has 4–5–8-merous flowers, a gamosepalous, dentate calyx, free petals, one whorl of stamens which are split irregularly into several bundles (Fig. 470). The fruit is a _multilocular berry_ provided with a thick, tough, outer layer. The juicy pulp, which fills up the loculi and envelopes the seeds, is formed from many large-celled, juicy hair-structures which arise on the inner side of the walls of the loculi and by degrees entirely fill them up; the dissepiments remain thin, and form the partitions so easily separating from each other (Fig. 469). The seeds in many instances are remarkable for containing several embryos. The blade of the leaf is separated from the frequently winged stalk by a _node_ (and hence is a compound leaf with only the terminal leaflet developed?) (Fig. 468); in other genera, as _Triphasia_, there is a fully developed trifoliate leaf. Thorns are frequently developed.--~The species of this genus, which is a native of the warmer parts of S. E. Asia, are very hard to separate. The differences are found in the forms of the fruit, the leaves and the leaf-stalks, and in the number of stamens. _Citrus medica_, “Cedrat” (Ind.); _C. limonum_, “Citron,” “Lemon” (introduced into Italy in the 3rd to 4th century). OFFICINAL: the fruits and essential oil of Lemon. _C. aurantium_ from E. Asia, the Orange (introduced into Italy in the 14th century). _C. vulgaris_ (Fig. 468), Bitter Orange (introduced into Europe at the time of the Crusades); the unripe Bitter Oranges, and peel of the Bitter Orange is officinal; it is from the flowers of this species especially that the essence of Neroli is made. _C. limetta_, _C. bergamia_, Bergamot; essence of Bergamot is officinal. _C. decumana_, Pomalo, a native of the Islands of the Pacific. About 780 species; chiefly tropical.~ Order 4. =Burseraceæ.= Fruit a drupe; 1–5 stones. The bark, as well as the other parts, contain strong aromatic resins and balsams, and hence several species are used: the Myrrh tree, _Commiphora_ (_Balsamodendron_) from Arabia and Africa; OFFICINAL: Myrrha (_Commiphora myrrha_). Mecca-balsam from _C. opobalsamum_, Arabia; E. Africa. The Incense-tree (_Boswellia_) from the same parts of the globe and E. India. The incense of _B. carteri_ is medicinal (Frankincense). The resin (Elemi) of _Protium_-species is officinal, and is used technically for varnish (S. Am.). Takamahaka-resin from _Elaphrium_ (S. Am.) _Protium_ (_Icica_); _Amyris_ (1 carpel). 270 species; tropical. Order 5. =Zygophyllaceæ.= The majority have opposite, pinnate leaves with stipules. _Leaves without pellucid dots._ The filaments have a scale on the inner side. The most important is _Guaiacum officinale_ (West India), the wood (Lignum Vitæ) of which is very hard and heavy, this wood and Gum-guaiacum are officinal. Others have a peculiar repulsive smell and taste: the Creosote shrub (_Larrea mexicana_) and _Zygophyllum simplex_. _Tribulus terrester_ is a common weed in S. Europe. _Fagonia._ _Peganum harmala_ (South of Russia) yields a red dye.--110 species; especially in the Tropics; several species in sandy deserts. _Nitraria._ Order 6. =Simarubaceæ.= This order is distinguished by the abundance of _bitter_ substances which it contains (Quassine) especially in the bark and the wood. The wood of _Quassia amara_ (Guiana, Antilles) is officinal; _Picraena excelsa_ yields Jamaica Quassia; the bark of _Simaruba_, _Simaba_-species and others is used. _Ailanthus glandulosa_ is a garden plant (pinnate leaves, winged fruit).--110 species. Tropical. Order 7. =Ochnaceæ.= Flowers diplostemonous, 5-merous. The unilocular ovaries, which are individually free, project considerably into the air around the gynobasic style; 1 ovule in each loculus; the fruitlets are drupes. Shrubs; leaves alternate, with stipules. _Ochna_; _Ouratea_.--160 species; tropical; especially American. Order 8. =Anacardiaceæ.= The ovary rarely contains more than 1 ovule, even though there be several loculi and several carpels; in _Anacardium_ all the 10 stamens except one become suppressed. Resin passages.--_Anacardium._ The most peculiar feature is the development of the flower-stalk into a fleshy body about the form and size of a pear (_A. occidentale_ from Trop. Am. and _A. orientale_ from E. Ind.) which bears the kidney-shaped nut (the so-called “Cashew-nut”) on its apex. _Mangifera indica_ (the Mango-tree, from E. Ind.) is cultivated in several tropical countries on account of its delicious drupe. Similarly, species of _Spondias_ (_S. dulcis_, Pacific Islands, _S. lutea_). Several species of _Rhus_ are ornamental shrubs in this country, for instance, _R. typhina_ (N. Am.), _R. cotinus_ (the Wig-tree, the _barren_ flower-stalks of the panicles being feather-like and hairy); _R. toxicodendron_ (Poisonous Sumach, from N. Am.) is poisonous. Chinese galls are produced by the sting of a leaf-louse (_Aphis chinensis_) on _R. semialata_ (China), and Japanese wax is from the seeds of _R. succedanea_ (Japan). Considerable quantities of Sumach (_R. coriaria_) are used in tanning and as a black dye. OFFICINAL: the mastic resin of _Pistacia lentiscus_ (the Mastic-tree, from the Mediterranean). The fruits of _Pistacia vera_ (Syria) are edible; _P. terebinthus_ and others yield turpentine.--450 species; tropical. Order 9. =Icacinaceæ.= Flowers 4–5-merous; haplostemonous; receptacle convex or cup-like surrounding the gynœceum; in the (single) loculus of the ovary, 2 anatropous, pendulous ovules.--200 species; tropical. Family 16. =Aesculinæ.= The essential characters of this family are in the main the same as those of the Terebinthinæ and Gruinales. The flowers are hypogynous, perfect, with free petals, 5-merous (S5, P5, typically A5 + 5, all of which, however, are not generally developed; in our native orders there are only 7–8 stamens), and most frequently a _3-merous, 3-locular gynœceum_ (less frequently 2 or 5 carpels with as many loculi). In each loculus there are usually only 1–2 ovules. A deviation from the preceding families is the frequent _zygomorphy_ of the flower, with, as a rule an _oblique_ plane of symmetry (Fig. 471). When a _disc_ is developed it is placed _outside_ the stamens. The majority have no endosperm (Fig. 473).--The members of the family are nearly all trees. The family is closely allied to the Terebinthinæ, but unlike this it never has aromatic properties, and differs also in the position of the nectary, in the flowers, which are often irregular with a reduction in the number of stamens, and in the ovule which is usually ascending with micropyle pointing downwards (the Terebinthinæ having the micropyle turned upwards), etc. It is also related to Frangulinæ, the Staphyleaceæ being the chief connecting link; but the Æsculinæ generally have compound leaves. Order 1. =Staphyleaceæ.= Leaves opposite, often compound. Flowers regular, ☿, 5-merous in calyx and corolla, 5-stamened. The stamens are placed _outside_ the nectary. Ovary syncarpous or 2–3-partite with free styles. The capsule is thin, bladder-like, 2–3-locular, opening at the apex, and has several very hard seeds with a shining testa without aril. Endosperm. _Staphylea pinnata_ (S. Europe) and _trifoliata_ (N. Am.) are cultivated in gardens; they have white flowers in pendulous, axillary racemes or panicles.--16 species.--_Staphylea_ is found in the Tertiary of N. America. Order 2. =Melianthaceæ.= Glaucous shrubs with scattered, pinnate leaves, and large stipules. _Melianthus._--8 species; S. Africa. Order 3. =Sapindaceæ.= Trees or shrubs, often climbing by tendrils (lianes with anomalous structure of the stem) and with compound leaves. The flowers, in most cases, are small, insignificant, and without scent, and in some polygamous and zygomorphic. S4–5, P4–5, A8 (less frequently 5–10) inside the nectary (disc); ovary generally 3-locular, with 1–2 ovules in each loculus (raphe ventral, micropyle turned downwards). Seed without endosperm, often with an aril. The embryo is often thick and curved (Fig. 473). [Illustration: FIGS. 471–473.--_Æsculus hippocastanum._ FIG. 471.--Diagram of the flower and of a scorpioid cyme. FIG. 472.--Flower in longitudinal section. FIG. 473.--Seed in longitudinal section.] _Æsculus_ (Horse-Chestnut). Trees with opposite, digitate, dentate leaves without stipules; the inflorescence is composed of unipared scorpioid cymes arranged in a pyramidal panicle (termed a thyrsus). The flowers are irregular, with an _oblique plane of symmetry_ (through the 4th sepal, Fig. 471); there are 5 sepals, 5 free petals, of which the one lying between S^3 and S^5 is the smallest (see Fig. 471) and may be absent; stamens 7 (5 + 2), three being suppressed; gynœceum simple, 3-carpellary and 3-locular, with single style; of the two ovules one is ascending, the other descending (Fig. 472).--The fruit is a 3-valvate, sometimes spiny, capsule, with loculicidal dehiscence, the seed having a large hilum, a curved embryo without endosperm and united cotyledons (the radicle lies in a fold of the testa, Fig. 473). _Æ. hippocastanum_ (Greece, Asia), introduced into cultivation about 300 years ago; the majority of the other species, _e.g. Æ. pavia_, etc., several of which are frequently cultivated in gardens, are from N. America. ~The flower of the Horse-Chestnut is adapted for bees, whose abdomen touches the anthers or style when visiting the flower. The flowers are protogynous.~ The other Sapindaceæ have most frequently 4 sepals, 8 stamens, various fruits (septicidal capsule, nuts with or without wings, schizocarp), etc. _Serjania_, _Cardiospermum_, _Sapindus_, _Koelreuteria_, etc. (about 118 genera, 970 species). The seeds of _Paullinia sorbilis_ contain caffeine, and are used as “Pasta guaranà,” in the North Western Brazils in the manufacture of a common drink. _Nephelium_ (or _Euphoria_) _litchi_ (with edible aril), and other species, from Asia. [Illustration: FIG. 474.--Samara of _Acer platanoides_.] Order 4. =Aceraceæ.= This order is so closely allied to the Sapindaceæ, that some authorities have classed it with them. The main difference is in the _regularity_ of the flowers, and the =2=-merous gynœceum (in abnormal cases several carpels occur).--They are trees, and, like the Horse-Chestnuts, have opposite leaves without stipules; in _Acer_ the leaves are palminerved, but imparipinnate in _Negundo_, a plant frequently cultivated in gardens. The flowers are often unisexual, polygamous (some species have ☿-, ♂-and ♀-flowers); sepals 5, petals 5 free, =stamens 8= (that is, 5 + 5, but the two median ones are absent) inside a large disc. Fruit a samara (schizocarp) with 2 _winged, nut-like_ fruitlets (Fig. 474). In each of the 2 loculi of the ovary are 2 ovules. Embryo _curved_, with thin, _folded_ cotyledons. Endosperm absent.--~The inflorescences are racemes with a more or less elongated main axis and terminal flower (which sometimes has 10 stamens); when the lateral branches are developed they are similar to the main axis. In some species both corolla and petal-stamens are suppressed. _Acer_ is pollinated by insects, _Negundo_ by the wind.--88 species; North Temperate zone. _Acer_ in the Tertiary from the Oligocene. The following are native plants: Maple (_Acer campestre_), Sycamore (_A. pseudoplatanus_, doubtful native). Important as avenue trees and timber. Sugar is obtained from the spring sap of the Sugar Maple (N. Am.).~ Order 5. =Malpighiaceæ.= A tropical (especially American) order closely related to the Aceraceæ, having often the same form of fruit (but 3-partite). Some species are lianes with anomalous stem-structure. Leaves opposite. The flowers are regular or obliquely zygomorphic (the plane of symmetry passing through sepal 3), with S5, P5, A5 + 5, G3; 1 pendulous ovule in each loculus. Important characteristics for identification are the numerous grandular structures on the sepals. Peculiar 2-spined hairs are found in some. _Malpighia_, _Bunchosia_, _Galphimia_, _Tetrapterys_, _Heteropterys_, etc.--About 600 species. Order 6. =Erythroxylaceæ.= Sepals 5, petals 5 (with a ligular corona), 10 stamens in one bundle. Gynœceum 3-locular. Fruit a drupe. Tropical (especially American) trees and shrubs, the _Coca-plant_ (_Erythroxylon coca_) being best known. Its leaves are considered by the inhabitants of Chile and Peru to be one of the indispensable necessaries of life; they are chewed, and possess intoxicating, exhilarating properties, and contain the alkaloid cocaine, which is frequently employed as a local anæsthetic.--103 species; chiefly in America. Order 7. =Vochysiaceæ.= Trees; Trop. Am. 1 stamen.--140 species. Order 8. =Trigoniaceæ.= Shrubs; Trop. Am.--30 species. Order 9. =Tremandraceæ.= Polygalaceæ with regular flowers.--27 species. Australia. [Illustration: FIG. 475.--Diagram of _Polygala_: _d_ a gland in the posterior side of the flower; α and β the two caducous bracteoles.] Order 10. =Polygalaceæ.= Herbs or shrubs (some tropical species are lianes) with scattered (rarely opposite), simple and most frequently quite entire leaves, without stipules. The flowers are usually borne in terminal spikes or racemes, and are strongly zygomorphic (_the plane of symmetry being median_); they have 5 free sepals, the 2 _lateral ones_ of which (4 and 5 in Figs. 475, 476) are very large, _petaloid_, and frequently project on each side like the “wings” of a Pea-flower; petals 5, of which the two lateral ones are wanting or rudimentary (dotted on Fig. 475), and the _anterior_ “the _keel_” (Fig. 476 _c_) is large, hollow and boat-shaped, and frequently with a lobed or fimbriated edge (Fig. 476 _A_ and _B_, _c_); stamens 8, the two median ones being absent, all _united_ into a tube split along the back, which is also slightly united to the keel (the anthers, often 2 locular, _open by pores_, Fig. 476 _B_, _st_); the 2 median carpels form a bilocular ovary. 1 pendulous ovule in each loculus (Figs. 476 _C_, 475); capsule compressed with loculicidal dehiscence, rarely a nut. _Polygala_ (Milk-wort). 470 species; distributed over the whole globe (none Arctic). OFFICINAL: the root of _P. senega_, from N. Am. Some are used as ornamental plants. POLLINATION. The flowers of _Polygala_ are pollinated by insects (chiefly bees). The fimbriated processes of the anterior petal support the insect when it alights. The anthers lie on each side of the stigma in the pouch of the anterior petal; the apex of the style is spoon-shaped, and immediately behind it is a viscid stigmatic lobe. In reaching the honey the proboscis of the insect must come in contact with the pollen and the viscid stigma, by which it is rendered sticky; this ensures the pollen adhering to the proboscis and so being carried to other flowers. [Illustration: FIG. 476.--_Polygala amara._ Parts of the flower (mag.) _A_ Flower from side, 1-5 sepals: _c_ keel; _B_ flower from above spread out: _st_ the 8 stamens; _c_ fimbriated edge of “keel”; _C_ ovary with style and stigma.] Family 17. =Frangulinæ.= The plants belonging to this family, with very few exceptions, are trees or shrubs. The leaves are usually simple; stipules may be absent or present. The flowers in almost all the orders are _small, green or whitish_; they are _always regular_, 4-_or_ 5-_merous_ with 2–5 _carpels_, but never have more than 1 _whorl of stamens_, which in _Rhamnaceæ_ and _Ampelidaceæ_ are placed _opposite_ the petals (typically 5 + 5 or 4 + 4 stamens, of which however either the external or internal whorl is always wanting); hypogynous or slightly perigynous, in _Rhamnaceæ_ only strongly perigynous or epigynous; generally ☿; the calyx is inconspicuous; petals free or slightly united. Gynœceum simple; _ovary generally multilocular_; style short or entirely wanting. A _disc_ is nearly always developed in the flower, but is found sometimes inside the staminal whorl, sometimes outside it or between the stamens. The ovules are apotropous (anatropous with dorsal or ventral raphe). Order 1. =Celastraceæ.= _Euonymus europæa_ (Spindle-tree) may be chosen as a type. It is a shrub with simple, opposite leaves and small caducous stipules. The small, greenish-yellow flowers, borne in regularly-branched dichasia, are regular, ☿, with 4 whorls, 4-(or 5-) merous in regular alternation. There is a _thick disc_ upon which the polypetalous corolla (imbricate in the bud) and the stamens are borne, with a slightly perigynous insertion. The style is short and thick; the ovary has 2 _erect_ ovules in each loculus. The fruit is a red, 4-valvate capsule with loculicidal dehiscence; the seeds are few in number, and have a large, red-yellow _aril_ (developed from the micropyle). Embryo green, in a large, fleshy, white endosperm. ~The dingy yellow flowers are generally visited only by flies and ants for the sake of the honey secreted by the disc, and while they run about on the flowers they touch the anthers and stigmas, now with one part of the body, now with another. The flower is protandrous. The stigmas are not developed till several days after the opening of the anthers.--_Celastrus_, _Cassine_, _Catha_, etc.~ 38 genera; 300 species. Distributed over the entire globe, with the exception of the colder districts, and especially in the Tropics. Some are ornamental bushes (_Euonymus japonica_). The leaves of _Catha edulis_ are used by the Arabs and Abyssinians in the same way as those of _Coca_ by the Peruvians. Order 2. =Hippocrateaceæ.= 150 species; tropical; chiefly lianes. S5, P5, A3, G3. Anthers extrorse. [Illustration: FIG. 477.--_Ilex aquifolium_: magnified flower.] Order 3. =Aquifoliaceæ (Hollies).= The genus _Ilex_ forms almost the entire order. (175 species out of 180; especially from S. Am.) They are shrubs or trees with scattered, leathery, simple leaves (in _Ilex aquifolium_, spiny) with very small stipules. The flowers are small, white, and borne in few-flowered inflorescences in the axils of the foliage-leaves; they are most frequently unisexual and diœcious. There are 4–5 sepals, petals, stamens and carpels in regular alternation; the calyx and _corolla_ have their leaves _slightly_ connate; stamens slightly adnate to the corolla; the ovary is generally almost spherical with a thick, sessile stigma (Fig. 477). This order deviates especially from _Celastraceæ_ in the _absence of the disc_ and in having only 1 (_pendulous_) ovule in each of the 4 loculi of the ovary, and in having a _drupe_ with generally 4 stones. Embryo extremely small, at the apex of the large endosperm, with the radicle directed upwards.--~3 genera.--_I. aquifolium_ (Holly) principally on the coasts of European countries; from Norway to W. Denmark, and further westward. It is a common garden shrub with stiff, shining leaves and red fruits. Several South American species contain so much _caffeine_ that they may be used as a beverage in the place of tea (_I. paraguayensis_, Paraguay tea, or Maté). The Holly does not contain caffeine.~ Order 4. =Ampelidaceæ (Vines).= Shrubs with the stem swollen at the insertion of the petioles and climbing by _tendrils borne opposite the leaves_ (Figs. 478, 479). The leaves are scattered (generally 1/2), stalked, stipulate, frequently palminerved and lobed, divided or compound. The small, greenish flowers are generally borne in paniculate _inflorescences, whose position is the same as that of the tendrils_ (Fig. 478); they are hypogynous or slightly perigynous, ☿, with 4–5 sepals, petals, stamens (which, as in the Rhamneæ, are _opposite the petals_; Fig. 480 _A_, _B_) and 2 carpels. The calyx is very small, entire, or slightly dentate; corolla _valvate_, and in some falling off as a hood, since the individual parts remain united at the summit (Fig. 480 _A_). Between the stamens and gynœceum is situated an hypogynous _disc_, with 5 lobes alternating with the stamens (Fig. 480 _A_, _B_, _E_). In each loculus of the 2-locular ovary there are 2 _erect_ ovules (_E_); the style is short or wanting. The fruit is a _berry_. The embryo is small and lies in a horny, sometimes slightly folded (ruminate) endosperm (Fig. 480 _C_, _D_). [Illustration: FIGS. 478–481.--_Vitis vinifera._ FIG. 478.--Branch with bunch of grapes. FIG. 479.--Diagram of the position of leaf and tendrils. The branch is divided into sections on the sympodial theory (the successive generations, I, II, III, IV, are alternately white and shaded); _k_ buds. FIG. 480.--A Flower throwing off the corolla; _B_ flower after the removal of the corolla; _C_, _D_ longitudinal and transverse section of seed; _E_ longitudinal section of gynœceum; _s_ calyx. FIG. 481.--Diagram of branch and position of leaves; _sl_ tendril; _lt_ the main axis; _ax_ stipules of the foliage-leaf shown below; _g_ axillary-bud (the dwarf-branch); _v_ its fore-leaf; _l_{1} l_{2}_ its first two foliage-leaves with their stipules; _lt_{1}_ long-branch in the axil of _v_ (everything appertaining to this branch is entirely black); _v_{1}_ the first leaf of this branch.] _Vitis_ and _Ampelopsis_ (5-merous flowers); _Cissus_ (4-merous flower); _Leea_ (without stipules, corolla gamopetalous). The inflorescence in _Pterisanthes_ (E. Ind.) has a peculiar, flat, leaf-like axis, on the edges of which ♂-flowers are borne, and on the surface ♀-flowers. The TENDRILS in Ampelidaceæ are modified branches, since they bear leaves and may be abnormally developed as branches with foliage-leaves, and finally the inflorescences are borne in the position of the tendrils, and tendrils are met with which are partly inflorescences. The explanation of the position of the tendril, namely, right opposite the foliage-leaf but without a subtending-leaf, has been much disputed. The relative positions are as follows: in _Vitis vinifera_ the following two kinds of shoots and relative positions are found (the other species deviate in one or other particular), (_a_) LONG-BRANCHES, which have 2 scale-leaves and a large number of foliage-leaves with a divergence of 1/2; opposite the lowest 3–5 foliage-leaves no tendrils are found, then follow: 2 foliage-leaves with tendrils, 1 without a tendril, 2 with and 1 without, etc., with great regularity. Buds are developed in the axils of the foliage-leaves (Fig. 479): these develop into (_b_) DWARF-BRANCHES, which commence with 1 laterally-placed scale-leaf (fore-leaf; Fig. 481 _v_) succeeded by several foliage-leaves with a divergence of 1/2 (in a plane at right angles to that of the mother-shoot), but the whole shoot is extremely small, and often dries up and drops off in the autumn, so that only the scale-leaf, _v_, with the bud (Fig. 481 _lt_{1}_) in its axil remains. This bud in the following year developes into a new long-branch, and since its leaves lie in a plane at right angles to that of the dwarf-branch, their plane coincides with that of the long-branch from which it is developed (the grandmother axis).--The tendrils no doubt may most correctly be regarded as the modified main axis which has been pushed aside by a lateral branch. The branches are then sympodia, whose successive shoots bear alternately 1 and 2 foliage-leaves: thus, on the figure there are portions altogether of 5 shoots (I.-V.), the 1-leaved ones are shaded, the 2-leaved ones are white. The following facts however are adverse to this theory: (1) the first leaf on an axillary bud is then situated 180° from the subtending leaf (_e.g._ the lowermost shaded leaf, Fig. 479, 180° from the lowermost white leaf), whilst the rule in the Dicotyledons is that it is placed only about 90° to one side. (2) The buds (Fig. 479 _K_) from which the dwarf-branches develop, must then be accessory and sister-buds to the sympodial shoots, but their first leaves have a different relative position to this, which is very peculiar, and a still more remarkable fact is that the buds, _K_, etc. are similar in structure and present in _all the axils_; thus we _only_ find accessory buds in the cases where no tendrils are opposite to the leaves, and the main bud must then be considered to be suppressed. (3) The development proves that the tendrils arise on the side of a vigorous growing-point of the stem or by its division, and do not develop, as might be expected, from the apex of the shoot. But these relations however, find their analogues and are all capable of explanation, whereas other less natural modes of explanation are opposed to them. 435 species; especially in the Tropics; they are rarer in America. In N. Am. some _Vitis_-species and _Ampelopsis quinquefolia_ are found. _Vitis vinifera_ is supposed to have originated in the districts East and South of the Caspian Sea. Wine is obtained from _Vitis_-species, especially _V. vinifera_, and “raisins,”--(the name “currants,” given to a special variety with small, seedless fruits, is derived from Corinth).--The species of _Ampelopsis_ (Virginian Creeper) are cultivated as ornamental plants. Order 5. =Rhamnaceæ.= _The stamens are placed opposite the petals_ as in the Ampelidaceæ (Fig. 482), but the flowers are _much more perigynous or entirely epigynous_. The trees and shrubs belonging to this order have simple, most frequently penninerved leaves with stipules; frequently thorny (modified branches). The flowers are inconspicuous, sometimes unisexual (Fig. 482), and have 5 (-4) sepals, petals, stamens, and generally 3 (2–5) carpels. The calyx has _valvate_ æstivation. The petals are very _small_ (generally less than the sepals), often spoon-like, hollow, and embracing the stamens; _a disc covers the inner surface of the thalamus_ or the base of the style in the epigynous flower; gynœceum simple, with one style and one _erect ovule in each loculus_. The fruit is most frequently a _drupe_. The embryo is large, often green or yellow, with endosperm. _Rhamnus_ (Buckthorn) has a juicy drupe with 3 (2–4) stones, surrounded at the base by the persistent portion of the receptacle; the disc is thin. _R. cathartica_ (common Buckthorn): diœcious, with opposite, serrate leaves. _R. frangula_ (Alder Buckthorn): flowers ☿, with scattered, entire leaves.--~_Ceanothus_ (N. Am., with richly-flowered inflorescences and a fruit closely resembling that of the Euphorbias). _Phylica_, _Pomaderris_ (Austr., fruit a capsule). _Zizyphus_, _Paliurus_, _Colletia_ (S. Am.) are thorny shrubs; _C. spinosa_ has thorny shoots with small, caducous leaves; the seedling has normal foliage-leaves. Others climb by tendrils as in the Ampelidaceæ, _e.g._ _Gouania_.~ [Illustration: FIG. 482.--_Rhamnus cathartica_: _A_ long-styled ♂-flower; _pet_ petals; _B_ short-styled ♂-flower; _C_ long-styled ♀-flower; _D_ short-styled ♀-flower (after Darwin).] 475 species, 40 genera; chiefly in temperate and tropical climes. Some are medicinal plants, the bark and fruit having purgative properties (the bark of _Rhamnus frangula_ and “Cascara Sagrada” from the bark of _R. purshiana_ are officinal). The fruits and seeds of others are edible, for example, the fruits of _Zizyphus lotus_, _Z. vulgaris_, _Z. spina Christi_, etc. Green and yellow _dyes_ are obtained from the fruit of _R. cathartica_, _infectoria_ and others (Avignon grain). _Ceanothus-_, _Rhamnus-_ and evergreen _Phylica_-species are ornamental shrubs. Family 18. =Thymelæinæ.= Exclusively trees or shrubs with simple, entire, scattered leaves without stipules. They have a _strongly perigynous_, regular, _4-merous_ flower. The receptacle (often coloured) envelopes a simple gynœceum formed of =1= _carpel_ and with, in most cases, =1= ovule, bearing on its edge 4 (or 5) petaloid sepals and, but rarely at the same time, small, scale-like petals. The corolla is most frequently entirely wanting (and hence these plants were formerly reckoned among the Monochlamydeæ); frequently only one of the 2 whorls of stamens, which are situated on the inner side of the edge of the receptacle, is developed. The fruit is most frequently a _1-seeded_ berry or drupe, or a nut which may be falsely berry-like, the partly persistent receptacle being fleshy and enveloping it. This family appears the most nearly allied to the Frangulinæ, especially the Rhamnaceæ, and may be considered as a further development of these in the direction of the petaloid development of the receptacle and reduction of the corolla and gynœceum, which in this instance only consists of one carpel. Another deviation is that both the whorls of stamens are present, while one of these is always wanting in Frangulinæ. They also appear to be related to the Lauraceæ (see page 391). Order 1. =Thymelæaceæ.= The flowers are most frequently ☿ (Fig. 483). The receptacle is high, generally tubular, coloured, and bears on its edge the 4-(or 5)-merous calyx, with imbricate æstivation. The corolla is wanting or is represented by small scales. The stamens are situated on the inside of the receptacle, and number 4 + 4 (or 5 + 5); stigma capitate. 1 _pendulous ovule_ (Fig. 483 _B_), the _radicle pointing upwards_. The fruit is most frequently a berry. ~A disc is sometimes developed. Endosperm wanting or very slight.~ [Illustration: FIG. 483.--_Daphne mezereum_: _A_ flower; _B_ longitudinal section of pistil.] _Daphne_ (Spurge-Laurel, Fig. 483) has a deciduous receptacle, often coloured; sepals 4; petals absent; stamens 4 + 4. Berry.--_Gnidia_ (corolla); _Pimelea_ (2 stamens); _Thymelæa_; _Passerina_ and others. 400 species; chiefly in the warm, sub-tropical zone, especially the Cape and Australia. Only _Daphne_ and _Thymelæa_ in Europe. In the fruit and bark of some, for example _Daphne_, pungent, burning and poisonous properties are found. The bark of _D. mezereum_ (native and cultivated) and _D. laureola_ is officinal. A specially tough bast is found in some species, for example _Lagetta lintearia_ (Lace-tree, Jamaica), which is used in weaving. Some are cultivated in gardens as ornamental shrubs, especially species of _Daphne_. Order 2. =Elæagnaceæ.= Shrubs or trees, which are easily recognised by the covering of _peltate hairs_ found upon almost all parts of the plant, causing them to assume a _silvery_ or rusty-brown appearance. Stipules are absent; the leaves are simple, most frequently scattered. Flowers (Figs. 484, 485) frequently unisexual. The sepals are valvate, 2-4; the _corolla is wanting_; _stamens_ 4 + 4 or 0 + 4. The ovule is _erect_ and _the radicle turned downwards_ (Fig. 486). The fruit is a _nut_, but becomes _a false fruit_, being surrounded by the persistent receptacle or the lower part of it, and thus assuming a berry- or drupe-like appearance (Fig. 486). Endosperm insignificant.--_Shepherdia_ (opposite leaves) has 4 sepals, 4+4 stamens, as in _Daphne_. Diœcious.--_Elæagnus_ (Silver-leaf) is ☿, has 4–6 sepals, and 4–6 stamens alternating with them. _Hippophaë_ is diœcious; it has 2 sepals and 4 stamens in the ♂-flower (perhaps properly speaking 2+2 stamens); thorny (stem-structures). 16 species; especially ornamental shrubs, _e.g. Elæagnus argentea_, _angustifolia_; _Hippophaë rhamnoides_ and _Shepherdia canadensis_. Northern Temp. [Illustration: FIGS. 484–486.--_Elæagnus angustifolia._ FIG. 484.--Floral diagram. FIG. 485.--Longitudinal section through the flower. FIG. 486.--Longitudinal section through the fruit.] Order 3 (?). =Proteaceæ.= This order has its chief centre in the dry regions of Australia (6/10–7/10 of about 1,000 species), a smaller number in S. Africa (2/10–3/10). a few species in S. Am. Trees or shrubs, leaves generally scattered, without stipules, and more or less dry, leathery, evergreen, and often of very different forms on the same plant (undivided, compound, etc.) The flowers are ☿ (rarely unisexual), and _4-merous_ in the single, petaloid perianth and in the staminal whorl; 1 carpel; sometimes zygomorphic. The perianth-leaves are generally almost free, with _valvate_, æstivation, often leathery. Small scales alternating with the perianth are often found at the base of the ovary. The stamens generally have extremely short filaments, and are situated opposite, sometimes quite on the tip of the perianth-leaves, in a spoon-like groove. The gynœceum is 1-locular, has 1–several ovules, and is often raised on a stalk-like internode. The fruit is a follicle or nut. The seeds, most frequently winged, have no endosperm.--_Protea_, _Manglesia_, _Hakea_, _Banksia_, _Grevillea_, etc. 50 genera; about 1,000 species. Several species are cultivated in our conservatories for the sake of the flowers, which are beautifully coloured and arranged in crowded inflorescences. Protandrous. It is doubtful whether they were existent in Europe in the Tertiary Period. The true systematic position of the order is doubtful. They are related to the Leguminosæ and Rosifloræ, but more closely no doubt to the two preceding orders. Family 19. =Saxifraginæ.= The flower is generally perfect, regular and polypetalous, usually _perigynous_ or _epigynous_, _eucyclic_ and 5-merous; most frequently S5, P5, A5 + 5 or 5 + 0 and G=2=-5, but other numbers are found, especially 4; the flowers are very frequently obdiplostemonous. The calyx is sometimes large and the corolla small; the carpels in some are entirely free, in others more or less united. Endosperm is found in the majority. ~The hypogynous forms approach the Cistifloræ, the others the following families, especially the Rosifloræ. This family is not, upon the whole, so well defined and natural as most of the others. The Saxifragaceæ proper, approach very near to the Rosaceæ, especially _Spiræa_, and form a transition to it. The forms with opposite leaves, as _Philadelphus_, etc., approach the Myrtifloræ, just as the Escalloniæ appear to be closely allied to Bicornes, especially _Vacciniaceæ_. Finally through _Pittosporaceæ_, they pass over to the Frangulinæ. The family terminates in very reduced forms, on the one hand in the arborescent orders with crowded inflorescences, on the other perhaps in the very remarkable order _Podostemaceæ_.~ [Illustration: FIG. 487.--Diagram of a 6-merous flower (_Sedum hispanicum_): _w_ branch of scorpioid cyme in the axil of the bracteole β.] Order 1. =Crassulaceæ.= Nearly all are herbs or small shrubs with round, succulent branches and scattered, _fleshy_, often more or less round leaves, which are very rarely incised, and never have stipules. The flowers are generally borne in dichasia or unipared scorpioid cymes, which again may be arranged in racemes, umbels, etc.; they are regular, ☿, hypogynous or perigynous, and most frequently have free sepals and petals (gamopetalous corollas with sessile stamens are found in _Cotyledon_, _Bryophyllum_, _Echeveria_, and others); the floral formula is Sn, Pn, An + n, Gn, where n may have very different values, partly depending upon the size of the flower (_e.g._ 4–7 in _Sedum_, Fig. 487; 6–30 in _Sempervivum_; 4 in _Rhodiola_, _Bryophyllum_, and _Kalanchoë_; 5 in _Echeveria_, _Umbilicus_, _Cotyledon_). The carpels are _free_ and are _placed opposite the petals_ (Fig. 487). Fruit a _syncarp composed of follicles_ containing many, small seeds without endosperm. Outside each carpel is found a small, nectariferous scale (Fig. 487). ~The northern genus, _Rhodiola_, is diœcious. The petal-stamens are wanting in some (_Crassula_, _Bulliarda_, and others). The floral-leaves are very often displaced upon their axillary branches. A multicarpellary gynœceum also occurs.~ _Sedum_ (Stonecrop) is generally 5-merous with 10 stamens; _Sempervivum tectorum_ (House-leek), 12-merous, and with 24 stamens. ~The leaves of _Bryophyllum calycinum_ very readily form buds, and also frequently exude water from the edges.~ 485 species; especially Temp. (Cape, Europe). Principally used as ornamental plants. Order 2. =Saxifragaceæ.= The flowers are 4–5-merous with =2= (-3) carpels, most frequently: S5, P5, A5 + 5 (obdiplostemonous), G2. They are regular, ☿, polypetalous, hypogynous, perigynous or most frequently _more or less epigynous_ (Fig. 488). The carpels may be individually quite free, but are more frequently united at the base, or the entire portion enclosing the ovules is united into a 1- or 2-locular ovary, the styles, however, are always free. _Fruit a capsule_ with many seeds; endosperm present.--They are herbs, most frequently with _scattered_ leaves without stipules; but the leaf-base is broad. The inflorescences are most frequently cymose, and a displacement of the floral-leaves is frequent (_e.g._ _Chrysosplenium_).--~Some _Saxifraga_-species, _e.g._ _S. sarmentosa_, have irregular flower with an _oblique_ plane of symmetry. The petal-stamens in some may be wanting: _Heuchera_, species of _Saxifraga_ and _Mitella_. The corolla is wanting in others.~ _Saxifraga_ (Saxifrage): S5, P5, A5 + 5, G2 (Fig. 488); capsule bilocular, opening along the ventral suture between the 2 persistent styles. ~_S. granulata_ has small tubers at the base of the stem.~--_Chrysosplenium_ (Golden Saxifrage): 4 sepals, _no corolla_, 4 + 4 stamens; 1-locular capsule. Protandry is most frequently found in _Saxifraga_, with the stamens successively bending towards the gynœceum; protogyny is more rare. In other genera there is protogyny without any movement of the stamens; _Chrysosplenium_ is homogamous.--About 300 species; mostly in temperate climates. _Saxifraga_ is especially Alpine. _S. crassifolia_ and other species, _Hoteia japonica_, _Tellima_, etc., are ornamental plants. [Illustration: FIG. 488.--_Saxifraga granulata._ Longitudinal section of flower.] The following genera are allied to the Saxifragaceæ:-- =1.= _Parnassia_ (about 14 species; _P. palustris_, Grass of Parnassus). The flower is slightly perigynous, and has S5, P5, 5 fertile sepal-stamens, and 5 petal-stamens, which are developed as barren staminodes, palmately-lobed, and (3–) 4 carpels united in a 1-locular ovary with (3–) 4 parietal placentæ. Capsule.--~Protandrous. The flower has a slightly oblique plane of symmetry, which is especially shown during its development and in the order of sequence in which the anthers dehisce: originally they lie closely round the gynœceum; the anthers dehisce extrorsely, first the one which is placed opposite the most external sepal (the 2/5 arrangement is very distinct in the calyx), the filament elongating so that the anther lies over the ovary, and this is followed successively by the 4 others in a zig-zag line; the filaments bend backwards after the pollen is shed and the anthers drop off, and the stigmas are not developed until this is completed. The barren stamens are palmately divided into an uneven number (7, 9, 11) of lobes, tapering from the centre towards the edge, and bearing apparently glandular tips; their gland-like appearance is supposed to allure flies to visit the flower, or they may act as a kind of fence which compels the insects to enter the flower in a certain way, and thus effect pollination; the honey is secreted on their inner side, and not by the gland-like tips.~ [Illustration: FIG. 489.--Portion of _Cephalotus follicularis_: _k_ pitcher-like leaf with thick corrugated edge (_m_) and lid (_l_); _b_ foliage-leaf of the ordinary form.] =2.= _Adoxa moschatellina_ (Moschatel). This is a perennial, creeping herb; the horizontal rhizome has an unlimited growth, and bears, in a _scattered_ arrangement, both foliage-leaves, and white, fleshy scale-leaves. The aerial stem bears 2 opposite foliage-leaves and a capitate inflorescence of 5 flowers, 4 placed laterally (in opposite pairs) and 1 terminally. The flower is semi-epigynous, the calyx gamosepalous, corolla absent. The stamens are divided to the base, so that each filament bears a bilocular anther. The style is free, deeply cleft. The _terminal_ flower has 2 bracteoles, 4 sepals, 4 stamens, cleft to the base, and a 4-locular ovary. The bracts of the _lateral_ flowers are displaced on the flower-stalk, as in _Chrysosplenium_, and united with the 2 bracteoles into a kind of 3-leaved involucre; these flowers have 5 sepals, 5 split stamens with 2-locular anthers, and a 5-locular ovary. 1 pendulous ovule in each loculus. Fruit a _drupe_, green-coloured, with 1–5 stones.--This plant, which would perhaps be best placed in a special order, has also been classed with the Araliaceæ and Caprifoliaceæ. The following are also allied to this order: _Escalloniaceæ_ (arborescent plants with simple, scattered, leathery leaves), _Cunoniaceæ_ (arborescent with opposite leaves), _Cephalotaceæ_ (with pitcher-like, insect-catching leaves; Australia; Fig. 489) and _Francoaceæ_. These have respectively 85, 107, 1 and 3 species. [Illustration: FIGS. 490–492.--_Ribes rubrum._ FIG. 490.--Floral diagram. FIG. 491.--Flower in longitudinal section. FIG. 492.--Seeds in longitudinal section.] Order 3. =Ribesiaceæ= (=Currants=). 5-stamened Saxifragaceæ with epigynous flowers.--Moderately sized shrubs with _scattered_, stalked and palminerved, and generally palmilobed leaves, with a large leaf-sheath. The flowers (Figs. 490, 491), most frequently borne in _racemes_, are regular, _epigynous_, and have often, _above the ovary_, a cup- or bell-shaped, or tubular prolongation of the receptacle, on which the sepals, petals and stamens are situated; they have 5 sepals (often large, coloured), 5 _small_, free petals, only =5= stamens (opposite the sepals) and a =2=-carpellate gynœceum with a _unilocular_ ovary and 2 _parietal_ placentæ bearing many ovules. The fruit is a _berry_, whose seeds have a fleshy and juicy outer covering (Fig. 492). ~In some species, for example _Ribes grossularia_, there is found an unbranched, or a 3–5-branched spine, very closely resembling the spiny leaves of the _Berberis_, but which, however, are emergences springing from the base of the petiole. _Ribes_ has two kinds of branches: long-branches and dwarf-branches, the latter alone bearing the flowers.~--_Ribes_ (Figs. 490–492). The blades of the leaf are folded or rolled together in vernation. _R. alpinum_ is diœcious. 75 species; especially from the N. Temp. regions (especially N. Am.).--The receptacle secretes honey on its inner surface. The Gooseberry-flower is slightly protandrous, others are homogamous; insect-and self-pollination are found. The following are FRUIT BUSHES: _R. nigrum_ (Black Currant), _R. rubrum_ (Red Currant), _R. grossularia_ (Gooseberry), originating in Northern Europe and Asia. ORNAMENTAL BUSHES: the North American _R. aureum_ (Golden Currant) and _R. sanguineum_ (Blood-red Currant), etc. [Illustration: FIG. 493.--_Deutzia crenata._ Longitudinal section of flower.] Order 4. =Hydrangeaceæ.= Shrubs, with simple, opposite leaves, without stipules; flowers generally epigynous, 4–5-merous (Fig. 493).--_Hydrangea_ (_H. hortensia_, etc.). Shrubs from N. Am. and E. Asia; corolla often valvate. The inflorescence, as in the case of the inflorescence of _Viburnum opulus_ (Guelder Rose), has often irregular, large, but barren flowers at the circumference, whilst the others are much smaller, regular and ☿; the barren flowers are mostly 4-merous; in these cases it is the calyx which is large and petaloid, while the other parts of the flower are more or less suppressed. The branches of the inflorescence appear to be partially devoid of floral-leaves, since they are displaced upon the main axis.--_Philadelphus_; racemes (with terminal flower), sepals 4 (valvate), petals 4 (twisted), stamens many, and carpels 4 (opposite the petals), forming a 4-locular ovary. The numerous stamens (20–30) occur by the splitting of the sepal-stamens and are often therefore placed in distinct bundles. Fruit a capsule. _Ph. coronaria_ (Syringa, Mock Orange-blossom), from S. Eur., is a common ornamental shrub, as also is _Deutzia_ (Fig. 493) from N. Am. and E. Asia. The latter has S5, P5, A5 + 5, G3.--About 70 species. Order 5 (?). =Pittosporaceæ.= This order has its home especially in Australia (90 species). The flower has S5, P5, A5 (episepalous), G2 (3–5), most frequently a unilocular ovary with many ovules in 2 rows, borne on 2 parietal placentæ, or a bilocular ovary. Some have berries, others capsules. _Pittosporum, Citriobatus, Sollya, Billardiera._ Order 6. =Hamamelidaceæ.= Flowers more or less epigynous, with S4, P0 or 4, 4 fertile sepal-stamens, and 4 barren petal-stamens, bilocular ovary with 1–2 ovules in each loculus. Fruit a capsule. _Hamamelis_: one species in Japan and one in N. Am. _Fothergilla._ _Liquidambar_: monœcious; flowers in capitula or spikes; ♂-flowers without perianth, stamens indefinite; ♀-flower: slight perianth, 2-locular ovary with many ovules. OFFICINAL: “Styrax-balsam,” which is obtained by boiling the bark of _Liq. orientalis_, from Asia Minor. _Liquidambar_ and _Parrotia_ are found as fossils in the Upper Oligocene; _Hamamelis_ perhaps in the Chalk. Finally two orders with very reduced flowers are included in this family. Order 7. =Platanaceæ.= Trees, with large, scattered, palminerved and lobed leaves, and ochreate stipules; the buds are concealed in a hollow at the base of the petiole. The bark falls off in large scales. ♂-and ♀-flowers (monœcious) in crowded, spherical inflorescences which are placed at wide intervals on a terminal, thin, and pendulous axis. The flowers have an insignificant calyx and corolla; the ♂-flower has few stamens; ♀-flower, perigynous, with 4 free carpels, 1 _pendulous_, _orthotropous_ ovule in each. Fruit a nut; endosperm absent. 5 species; frequently grown in avenues and parks. _P. occidentalis_ (N. Am.); _P. orientalis_ (W. Asia.). Order 8. =Podostemaceæ.= Aquatic plants, especially in swiftly running water, with somewhat of an Alga-like, Moss-like, or thalloid appearance; they show themselves in many ways to be adapted to their mode of life and situations (having a dorsiventral creeping stem, the flowers sunk in hollows, a formation of haptera upon the roots, and thalloid assimilating roots and thalloid stems, etc.). Tropical; 100 species. Family 20. =Rosifloræ.= The leaves are scattered, stipulate, or have at least a well developed sheath, which is generally prolonged on each side into a free portion (“adnate stipules”). The flowers are regular, _perigynous_ or _epigynous_. Calyx and corolla 5 (-4)-_merous_ with the usual position. The corolla is always polypetalous. The stamens are present in very varying numbers (5–∞) and position, but _always_ placed in 5-_or_ 10-_merous whorls_; they _are frequently_ 20 in 3 whorls (10 + 5 + 5; see Figs. 494, 502, 505); the nearer they are placed to the circumference, the longer they are; they are generally _incurved in the bud, or even rolled up_. The number of the carpels is from 1–∞; in most cases all are _individually free_ (syncarp), and when they are united it is in every case with the ovaries only, whilst the _styles_ remain more or less _free_ (_Pomaceæ_, species of _Spiræa_). The _seeds_ have a straight embryo, and usually no endosperm. The perianth and stamens are most frequently _perigynous_ on the edge of the widened receptacle; its form varies between a flat cupule and a long tube or a cup (Figs. 495, 496, 498, 499, 500); the carpels are situated on its base or inner surface, in some instances on a central conical elongation of the floral axis (Fig. 496). The carpels in _Pomaceæ_ also unite more or less with the hollow receptacle, or this grows in and fills up the space between the carpels, so that a more or less epigynous flower is formed (Fig. 504).--The following numbers of _stamens_ occur: 5, 10 (in 1 whorl), 15 (10 + 5), 20 (10 + 5 + 5), 25 (10 + 10 + 5), 30-50 (in 10-merous whorls)--compare the diagrams. The theoretical explanation of this relation of the 10-merous whorls and their alternation with the 5-merous whorls is not definitely determined; a splitting of the members of the 5-merous whorls may be supposed, but the development shows no indication of this, and it is not supported in any other way. Several genera have “_gynobasic_” styles, that is, the style springs from the base of the ovary (Fig. 497 _A_, _B_). The Rosifloræ are on one side closely related to the Saxifragaceæ (especially through _Spiræa_) from which it is difficult to separate them, and to the Myrtifloræ; on the other side they are allied, through the Mimosaceæ with the large number of stamens, and through the Amygdalaceæ with its single carpel, to the Leguminosæ. The family begins with forms which have many-seeded follicles, and passes on the one side to forms with nuts and drupes in perigynous flowers, and on the other side to the Pomaceæ. Order 1. =Rosaceæ.= Herbs or shrubs, generally with compound leaves and persistent (adnate) stipules, flower _perigynous_, _gynœceum formed of many free_ (therefore oblique) _carpels, syncarps_ with fruitlets of various kinds. The exceptions are noted under the genera. [Illustration: FIG. 494.--Diagram of _Comarum palustre_.] [Illustration: FIG. 495.--Flower of _Spiræa lanceolata_.] =1.= SPIRÆEÆ (Fig. 495) has 2–many ovules in each ovary, while in the other groups there is generally only 1, and never more than 2 ovules in each loculus. There are generally 5 _cyclic_ carpels and the fruit is 5 _follicles_, which are not enclosed by the receptacle. The majority are shrubs. Stipules are often wanting.--_Spiræa_ (Meadow-Sweet). The flowers are generally borne in richly flowered inflorescences of various forms. The carpels, in some species, unite together and form a _simple_ gynœceum with free styles (an approach to the _Pomaceæ_).--~Closely allied to _Spiræa_ are the East Asiatic shrubs: _Kerria japonica_, which has solitary flowers, in this country nearly always double (the fruit a nut), and _Rhodotypos kerrioides_ which has opposite leaves, a remarkable feature among the Rosifloræ; it has a 4-merous flower, a well developed disc inside the andrœcium, and a drupe. Closely allied also is _Gillenia_ (N. Am.) differing chiefly in the ascending ovules, _Spiræa_ having pendulous ovules, and a more tubular receptacle.~ The groups _Quillajeæ_ and _Neuradeæ_ form a transition from _Spiræa_ to _Pomaceæ_. In the first group, which contains only trees or shrubs with generally simple leaves, the carpels are either free or united (into a capsule); in the second the receptacle unites with the carpels, which are themselves often united together; in this case, too, the fruit is a capsule. _Quillaja_ (S. Am.); _Exochorda_ (China). =2.= POTENTILLEÆ (Figs. 494, 496, 497). The flower has an “_epicalyx_” (Fig. 494 _C_) alternating with the sepals and formed by their stipules which are united in pairs, and hence its leaves are often more or less deeply bifid. The receptacle is cupular and often quite insignificant. The sepals are valvate in the bud. The large number of fruitlets are _achenes_, borne on a well-developed convex portion of the receptacle (~the Ranunculeæ resemble the Potentilleæ, but have no epicalyx, no enlarged receptacle, and spirally-placed stamens~). Most of the species are herbs with dichasial inflorescences, often arranged in racemes.--_Potentilla_ (Cinquefoil). The achenes are borne on a _dry_, hairy receptacle; the style is situated towards the apex of the ovary, and is not prolonged after flowering. Herbs with digitate, in some, however, pinnate leaves, and generally yellow flowers.--_Comarum_ (Fig. 494) (Marsh Cinquefoil) forms, by its fleshy-spongy receptacle, a transition to the next genus.--_Fragaria_ (Strawberry) (Fig. 496). The receptacle becomes finally fleshy, coloured, and falls off (biologically it is a berry); the numerous fruitlets (drupes with thin pericarp) have basal styles (Fig. 497); leaves trifoliate; long, creeping runners.--_Geum_ (Avens) has a terminal style which after flowering elongates into a long beak, with the apex (after the uppermost part has been thrown off) bent back into a hook, thus furnishing a means of distribution for the fruits. Leaves pinnate.--~_Dryas_ comprises 3 Arctic or Alpine species with simple leaves and solitary flowers, the calyx and corolla 8–9-merous, the fruit resembles that of _Geum_, but the styles become still longer and feather-like (a flying apparatus).~ [Illustration: FIGS. 496, 497.--_Fragaria vesca._ FIG. 496.--Longitudinal section of flower. FIG. 497.--A carpel, entire, and in longitudinal section.] =3.= RUBEÆ. _Rubus_ (Bramble) has the same form of receptacle as the _Potentilleæ_, but _no epicalyx_; _the fruitlets are drupes_, not enclosed by the persistent calyx. Most frequently shrubs or undershrubs with prickles (emergences), glandular bristles and compound leaves. In the Raspberry (_R. idæus_) the fruitlets unite together and detach themselves from the receptacle. =4.= ROSEÆ. _Rosa_; the receptacle is hollow, ovoid and contracted beneath the insertion of the calyx (Fig. 498), ultimately _fleshy_ and _coloured_; it encloses a large number of fruitlets which are achenes as hard as stones (“hip,” biologically a berry).--Shrubs with imparipinnate leaves and adnate stipules. ~The sepals show clearly the order of their development (a divergence of 2/5), the two outer ones on both sides are lobed, the third one on one side only, and the two last, whose edges are covered by the others, are not lobed at all. _Prickles_ (emergences) are generally present and in some species are placed in regular order, being found immediately below each leaf (usually two) although at somewhat varying heights.~ [Illustration: FIG. 498.--Longitudinal section of flower of _Rosa_.] [Illustration: FIGS. 499, 500.--_Agrimonia eupatoria._ FIG. 499.--Flower in longitudinal section. FIG. 500.--Fruit and receptacle in longitudinal section.] =5.= AGRIMONIEÆ. The receptacle is more or less cup- or bell-shaped, and almost closed at the mouth; it is persistent and envelopes the _nut-like fruitlets_, but is _dry_, and in some species hard, the fruitlets being firmly attached to it. In biological connection with this the number of the carpels is generally only 1 or 2, and the whole becomes a _false nut_ (Fig. 500). Herbs.--_Agrimonia_ (Agrimony; Figs. 499, 500); the perianth is 5-merous, stamens 5–20. The receptacle bears externally, on the upper surface, a number of hooked bristles which serve as a means of distribution for the 1–2 achenes which are enclosed in it, and hence the entire flower finally falls off. The inflorescence is a long upright raceme. ~These bristles are arranged in whorls of 5 and 10, of which the uppermost alternate with the sepals.~--_Alchemilla_ (Ladies-mantle; Fig. 501) has 8 green perianth-leaves in two whorls (some authorities consider the four outer as an epicalyx, and the flower therefore apetalous), and 4 stamens _alternating with the innermost whorl_. There is only one carpel with a _basal_ style and capitate stigma. The flowers are small and greenish, the filaments jointed. The anthers open by one extrorse cleft. The leaf-sheath entirely envelops the stem; the leaves are palminerved. _A. aphanes_ has often only 1–2 stamens. ~The following genera, with 4-merous flowers borne in short spikes or capitula, are allied to this group. _Sanguisorba_ has entomophilous, ☿-flowers with 4(-20) stamens, 1 carpel; stigma papillose.--_Poterium_; spike or capitulum, the uppermost flowers are ♀, the lowermost ♂, and some intermediate ones ☿ (the order of opening is not always centripetal); S4, P0, A20–30, G2, the long styles having brush-like stigmas (wind-pollination). Leaves imparipinnate.~ [Illustration: FIG. 501.--Flower of _Alchemilla_ in longitudinal section.] POLLINATION. A yellow ring on the inner side of the receptacle, inside the stamens, serves as a nectary when any honey is formed; this, for instance, is not the case in _Rosa, Agrimonia_, _Spiræa ulmaria_, _S. filipendula_, _S. aruncus_, etc., to which the insects (especially flies and bees) are allured by the quantity of pollen. Homogamy and slight protogyny are frequent, in many instances self-pollination also is finally possible. _Poterium_, with the long-haired stigma, is wind-pollinated.--About 550 (1100?) species, especially in northern temperate regions.--USES. OFFICINAL: the petals of _Rosa centifolia_ and _gallica_, the fruits of the Raspberry (_Rubus idæus_), the rhizome of _Geum urbanum_, the flowers of the Koso-tree (_Hagenia abyssinica_ or _Brayera anthelmintica_).--The bark of _Quillaja saponaria_ (Chili) is used as soap and contains _saponin_. “Attar of Roses” from _Rosa damascena_, _centifolia_ and other species, especially from the southern slopes of the Balkans. Many species and varieties of Roses are ORNAMENTAL plants: from S. Europe, _Rosa lutea_ (the Yellow Rose), _R. gallica_ (the French Rose) and _R. rubrifolia_; from W. Asia, _R. centifolia_, of which the Moss Roses (_R. muscosa_ and _cristata_) are varieties, and _R. damascena_; from India and N. Africa, _R. moschata_ (the Musk Rose); from China, _R. indica_ (Tea Rose) etc., besides the native species and the varieties which have been derived from them. In addition, _Kerria japonica_, species of _Potentilla_, _Rubus odoratus_ from N. Am., and many species of _Spiræa_ from South-eastern Europe and N. Am. ESCULENT: the “hips” of _R. mollissima_, _R. pomifera_, etc.; the fruits of _Rubus_-species: Raspberry (_R. idæus_), Cloudberry (_R. chamæmorus_), Blackberry (_R. fruticosus_), etc.; of _Fragaria_-species (_F. vesca_, _collina_, _grandiflora_, etc). Order 2. =Amygdalaceæ.= Trees or shrubs with rosaceous flowers; leaves simple with caducous stipules; a regular, _perigynous_ flower, the receptacle being partly thrown off by a circular slit; sepals 5, petals 5, stamens 20–30; _gynœceum simple, formed of 1 carpel_ (hence oblique, Fig. 502), with terminal style and 2 pendulous ovules, ripening into a _drupe_ (Fig. 503).--The leaves are penninerved and frequently have _glands_ on the stalks and edges; _thorns_ (modified branches) often occur, _i.e._ dwarf-branches, which, after producing a few leaves, terminate their growth in a thorn (_e.g._ _Prunus spinosa_). ~The vernation of the _foliage-leaves_ varies in the different genera; in the Almond, Peach, Cherry, and Bird-Cherry they are folded; in the Apricot, Plum, Sloe and Bullace, rolled together. In some the flowers unfold before the leaves (_Amygdalus_, _Armeniaca_). That the gynœceum is formed of 1 carpel is evident in this as in other instances (_e.g._ in the Leguminosæ, which are closely related to this order), from the fact that the carpel is oblique, and has only one plane of symmetry, and similarly in the fruit there is a longitudinal groove on one side which indicates the ventral suture. It is only exceptionally that both ovules are developed. In abnormal instances more than 1 carpel is developed.~ [Illustration: FIG. 502.--Diagram of _Prunus virginiana_.] =A.= FRUIT HAIRY: _Amygdalus_ (_A. communis_, Almond-tree) has a dry pulp which is detached irregularly, when ripe, from the wrinkled, grooved, ovoid and somewhat compressed stone.--_Persica_ (_P. vulgaris_, Peach-tree) differs from the Almond in having a juicy pulp, not detachable from the stone, which is deeply grooved and has pits in the grooves (Fig. 503). (~The name of the genus is derived from Persia, though it is a native of China.~).--_Armeniaca_ (_A. vulgaris_, Apricot) has a hairy, velvety fruit, but the stone is smooth and has two ribs along one of the edges; the pulp is juicy. (~The generic name has been given on the incorrect assumption that it was a native of Armenia; its home is China.~) [Illustration: FIG. 503.--Fruit of the Peach. The pulp is cut through so that the stone is visible.] =B.= FRUIT GLABROUS (_i.e._ without hairs): _Prunus_ (Plum) has a glabrous fruit with bluish bloom; the stone is compressed, smooth or wrinkled. The flowers are borne solitarily or in couples, and open before or at the same time as the leaves; they are borne on shoots without foliage-leaves.--_Cerasus_ (Cherry) has a glabrous, spherical fruit, without bloom, and a spherical stone. The flowers are situated in 2–many-flowered umbels or racemes, and open at the same time as the leaves or a little before them. ~_Long-stalked_ flowers in _umbels_ are found in _C. avium_ (Wild Cherry), _C. vulgaris_ (the cultivated Cherry, from Western Asia); _racemes_ at the apex of leaf-bearing branches and small spherical fruits are found in _C. padus_ (Bird Cherry), _C. virginiana_, _C. laurocerasus_ (Cherry-laurel), _C. mahaleb_.~ POLLINATION. _Prunus spinosa_ (Sloe, Blackthorn) is protogynous, but the stamens are developed before the stigma withers. Honey is secreted by the receptacle. _Cerasus padus_ (Bird-Cherry) agrees in some measure with _P. spinosa_. In the flowers of the Plum and Cherry the stamens and stigma are developed simultaneously and self pollination seems general; the stigma, however, overtops the inner stamens and thus promotes cross-pollination.--DISTRIBUTION. 114 species in the N. Temp, zone; few in the warmer regions; the majority from W. Asia. _C. vulgaris_, from the regions of the Caspian; _Prunus spinosa_, _insititia_ (Bullace), _domestica_ (Plum, from the Caucasus, Persia).--USES, principally as fruit-trees: Cherry, Plum, Apricot, etc.; “Almonds” are the seeds of _Amygdalus communis_ (W. Mediterranean), “bitter,” “sweet,” and “shell” almonds are from different varieties, the latter being remarkable for the thin, brittle stone. In the majority of species and in almost all parts of the plant (especially the bark, seed and leaves) is found the glycoside, _amygdalin_, which forms prussic acid. Many form _gum_, and the seeds have _fatty oils_ (“Almond oil”). OFFICINAL: the seeds and oil of _Amygdalus communis_, and the fruit of the Cherry; in other countries also the leaves of _C. laurocerasus_.--The stems of _Cerasus mahaleb_ are used for pipes. Ornamental Shrubs: _Amygdalus nana_, _Cerasus laurocerasus_. Order 3. _Chrysobalanaceæ._ Tropical Amygdalaceæ with zygomorphic flower and gynobasic style. 200 species; especially Am. and Asia. _Chrysobalanus icaco_ (Cocoa-plum) is cultivated on account of its fruit (Am.) Order 4. =Pomaceæ.= Trees and shrubs, most frequently with simple leaves and caducous stipules. The flowers (Fig. 505) have 5 sepals, 5 petals and generally 20 stamens (10 + 5 + 5, or 10 + 10 + 5). There are from 1–5 _carpels_, which unite entirely or to some extent with each other, and with the hollow, fleshy receptacle (the _flower_ becoming _epigynous_), (Figs. 505, 506, 507). The carpels are nearly always free on the ventral sutures, rarely free at the sides also. The whole outer portion of the fruit becomes fleshy, but the portions of the pericarp surrounding the loculi (endocarp) are most frequently formed of sclerenchymatous cells, and are more or less firm (the “core”). The nature of the fruit varies, according to the thickness and hardness of the endocarp, being either a “berry” or a “drupe” (see _A_ and _B_). When the endocarp is thin and parchment-like, the fruit has the characteristics of a berry, each of the 5 loculi generally present containing several seeds; but when this is hard the fruit resembles a drupe, only one seed is developed in each loculus, and the number of the loculi is reduced to one or two. There are nearly always 2 ovules in the loculi of the ovary, but in _Cydonia_ there are a large number in 2 rows. In the genera which have stones, only one seed is developed in each stone. The genera are distinguished mainly in accordance with the kind of fruit and the number of ovules and seeds. [Illustration: FIG. 504.--Longitudinal and transverse section through the flowers of _A_, _B_ _Cotoneaster_; _C_ _Cydonia_; _D_ _Malus communis_; _E_ _Raphiolepis_; _F_ _Cydonia_; _G_ _Mespilus_.] [Illustration: FIG. 505.--Floral diagram of _Mespilus germanica_.] =A.= SORBEÆ. THE ENDOCARP IS PARCHMENT-LIKE OR PAPERY (drupe, with thin stone or berry). 1. _Pyrus_ and _Cydonia_; carpels completely embedded in the cup-like receptacle, styles always free.--_Pyrus_: the fruit is glabrous, and has only a small calyx, withering or deciduous, and a 5-locular ovary with at most 2 ascending ovules in each loculus (Fig. 504 _D_). The large flowers are situated in few-flowered umbels or corymbs. ~_P. communis_ (Pear; free styles, Fig. 507; it has the well-known pear-shaped fruit; the core is reduced to several groups of sclerenchymatous cells embedded in the pulp, the leaf-stalk is as long as the blade).~--_Cydonia_ (Quince) has a hairy fruit with _many seeds in 2 rows_ in each loculus of the endocarp (Figs. 504 _C_, _F_; 506); the testa of these seeds is mucilaginous. _C. vulgaris_, large, terminal flowers on lateral branches, and large leaf-like, persistent sepals. [Illustration: FIG. 506.--_Cydonia vulgaris._ Longitudinal section of fruit.] [Illustration: FIG. 507.--Longitudinal section of Pear flower.] 2. _Malus_ and _Amelanchier_ (_Aronia_); carpels free on the ventral edge; styles united. _Malus communis_ (Apple) the fruit is “umbilicate” at the base; no sclerenchymatous cells in the pulp; styles united at the base (Fig. 504 _D_); leaf-stalk shorter than the blade. _Sorbus_ (Mountain-ash) differs only in having a 2–3-locular fruit with extremely thin endocarp. Cymose inflorescences in umbellate cymes. ~_S. aucuparia_ has pinnate leaves, _S. aria_ (White-beam) and other species have simple leaves.--_Amelanchier_ (the Service-tree) has a false divisional wall springing from the dorsal suture, and more or less projecting into each of the loculi of the ovary; _Raphiolepis_ (Fig. 504 _E_) has racemes and a juicy berry; _Eriobotrya japonica_ (Loquat).~ =B.= CRATÆGEÆ. THE ENDOCARP IS HARD AND BONY (“drupes,” generally with several, sometimes, however, with only 1–2 stones, rarely one multilocular stone; only 1 seed in each of the loculi).--_Cratægus_ (Hawthorn, May). There are 1–5 stones in the spherical or ovoid fruit. The disc, found on the apex of the fruit, inside the small, withered calyx, is small (much less than the transverse section of the fruit). Shrubs with thorns (branches) and moderately large flowers borne in corymbs.--_Mespilus_ (Medlar) differs from the last-named only in having a _large disc_ at the apex of the fruit, inside the large, _leaf-like sepals_, _i.e._ almost equal to the greatest diameter of the fruit. The flowers are solitary and terminal.--_Cotoneaster_ is chiefly distinguished from the others by its syncarps, the 2–5 carpels (and stones) being free from one another, and only united to the receptacle by a larger or smaller portion of their dorsal surface (Figs. 504 _A_, _B_). Small shrubs with leathery leaves, generally covered with white, felted hairs on the lower surface, and with small flowers; the fruit is red or black. Pear, Apple, Mountain Ash and Hawthorn have protogynous flowers which secrete honey, and are conspicuous to ensure insect pollination.--180 species; in the northern temperate regions.--Pear and Apple are especially cultivated as fruit trees in a number of varieties; the Paradise Apple (_Pyrus baccata_); especially in southern countries also the Quince (from N. Persia and the Caucasian districts), Medlar and _Amelanchier vulgaris_. _Malus pumila_ (Caucasus, Altai) and _M. dasyphylla_ (Orient, S. Eur.) are regarded as primitive forms of the Apple-tree; _M. sylvestris_, which grows wild in European forests, appears to have been less used. The early Lake-dwellers in Switzerland had the apple-tree both wild and cultivated.--The original form of the Pear is supposed to be _Pyrus achras_ (Central Asia).--Many of the species of _Cratægus_, some with double flowers, and _Pyrus (Chænomeles) japonica_, with brilliant red flowers, are cultivated as ornamental shrubs. OFFICINAL: Quince pips, on account of the mucilaginous testa.--The fruits contain free organic acids and sugar; prussic acid may be obtained from the seeds. The wood of the Pear-tree is used in manufactures. Family 21. =Leguminosæ.= The most characteristic feature is, that the _gynœceum is 1-locular_ and formed of _1 carpel, the ventral suture of which is turned posteriorly_. The fruit, in most instances, is a _pod_ (legume), which opens generally along both sutures, the two valves twisting more or less in opposite directions. ~In other instances it opens along one suture only, or as a pyxidium (Red Clover), or it is indehiscent, in which case it is more or less berry-like (_e.g._ the Tamarind, Carob-bean), or it is a drupe (_e.g._ the Tonquin-bean), or a 1–few-seeded nut (_e.g._ _Melilotus_), or a lomentum, which divides transversely into as many joints as there are seeds (_Ornithopus_, see Fig. 513).~ The inflorescences belong to the _centripetal_ type (_i.e._ indefinite); cymes do not occur. The flowers are _zygomorphic_, with vertical plane of symmetry, seldom regular; _5-merous_ with but a few exceptions, ☿, and slightly _perigynous_. The following diagram is the most general (Fig. 511): 5 sepals, with the _unpaired sepal median and anterior_, 5 petals, 5 + 5 stamens, all in alternating whorls, 1 carpel. The calyx is most frequently gamosepalous, the gynœceum is narrowed down at the base to a short stalk and, in the majority, is more or less bent. The seed is most frequently kidney-shaped, with a smooth, hard and shining testa, the hilum being very distinct. _Endosperm is wanting_, or is reduced to a thin layer, which is of service when the seed swells during germination. The vegetative parts have these features in common, namely, the _leaves are scattered, stipulate_, and almost always _compound_. Peculiar _sleep-movements_ and _sensitiveness_ are found in some, chiefly in the Mimosas. Many, probably all, Leguminosæ have _small tubercles on their roots_ which are produced by a kind of bacterium, and assist in the assimilation of free nitrogen. Spontaneous movements are exhibited by _Desmodium gyrans_ (Telegraph-plant). This family is closely allied to the Rosifloræ, with which it agrees in the scattered leaves, the presence of stipules, the generally 5-merous and most frequently perigynous flowers with eucyclic stamens, and the absence of endosperm. _Amygdalaceæ_ and _Chrysobalanaceæ_, with solitary carpels, approach on one side to the Leguminosæ, among which genera with drupes are also found; _Mimosaceæ_, with their many stamens, form a connecting link on the other side. In this respect the Mimosa-genus _Affonsea_, and certain Cæsalpineæ and Swartzieæ, are of special interest in having more than one carpel (syncarp), a condition which is sometimes met with abnormally in other Leguminosæ, as well as in Amygdalaceæ. About 7,000 species of the Leguminosæ are known. Order 1. =Cæsalpiniaceæ.= These are _leguminous plants with straight embryo and a flower which is not papilionaceous and has not the same æstivation_ (Figs. 508–510); but in reality there is not a single characteristic which absolutely distinguishes them from the Papilionaceæ.--The majority are arborescent; the leaves as a rule are pinnate or bipinnate. The flower is 5-merous, most frequently perigynous and slightly zygomorphic; the calyx is free or gamosepalous, the corolla polypetalous with _ascending imbricate æstivation_ (_i.e._ the two lowest petals envelop the lateral ones, and these again the posterior; Fig. 508); 10 _free stamens_; fruit various. [Illustration: FIGS. 508–510.--_Cassia floribunda._ FIG. 508.--Floral diagram. FIG. 509.--Flower. FIG. 510.--The same in long. sect.] _Cassia_ (Figs. 508–510) is the largest genus (about 200 species); it has an almost hypogynous, zygomorphic flower with 5 free sepals and petals; of the 10 stamens the 3 posterior are generally barren, the others are of very unequal length and open at the apex by _pores_ (Fig. 509). In some (the _Senna_ group) the fruit is a flat, short, thin, dehiscing pod; in others (_Cathartocarpus_) it is round, long, woody or fleshy, indehiscent, and divided internally by more or less fleshy transverse walls into as many cells as there are seeds.--The following also have DEHISCENT FRUITS: _Bauhinia_ (often lianes, tropical climbers with tendrils [stem-structures] and anomalous stems), _Copaifera_, _Hæmatoxylon_ (whose pod does not dehisce along the suture, but laterally), _Cercis_ (simple leaves; the corolla resembles that of the Papilionaceæ, but the posterior petal is the smallest, and is enveloped by the 2 lateral ones, which are enveloped in their turn by the 2 anterior).--FRUIT INDEHISCENT: _Tamarindus indica_; the pod is almost round, often a little abstricted between the seeds; the wall is formed by a thin, brittle external layer, enclosing an acid pulp; well-developed septa are present, between the seeds; the most internal layer is parchment-like. Calyx 4-merous by the coalescence of 2 sepals. Only 3 fertile stamens.--_Ceratonia siliqua_ (Carob-bean, Locusts); the pod is long, compressed, with thick sutures, and has a wall, the central part of which is more or less leathery, fleshy and sweet; there are transverse septa between the seeds, as in the Tamarind. Embryo greenish in endosperm. The flower is without a corolla, 5 stamens.--_Pterogyne_ (winged fruit), etc.--KRAMERIEÆ with _Krameria_ is an anomalous group. DISTRIBUTION. 80 genera, with 740 species; almost exclusively in the Tropics. The Carob-tree and _Cercis_ grow in the Mediterranean basin. The largest and most widely distributed genus is _Cassia_, which is found as trees, shrubs, and weeds in all tropical countries. The order has many important uses to mankind. MEDICINAL: the leaves and pods of _Cassia acutifolia_ and _angustifolia_ (officinal, Senna-leaves), the fruit-pulp of the _Cassia_-sub-genus, _Cathartocarpus_. Rhatany root from _Krameria triandra_ (Peru, officinal). _Balsam_ is extracted from a number of _Copaifera_-species (Balsam of Copaiba) from S. Am. (officinal), and from _Hymenæa_ (Copal balsam), _Trachylobium_ and others. _Edible fruits_ are obtained especially from the Carob-tree (from the East) and the Tamarind (officinal). The heart-wood of several species of _Cæsalpinia_, such as _C. brasiliensis_ (the Pernambuco-tree), _echinata_ (Red-tree), and _sappan_, yield _dyes_; _Hæmatoxylon_ (_H. campechianum_, Logwood), _Copaifera bracteata_ (Amarant-tree).--_Timber_ is obtained from many (_Melanoxylon_ and others). In Europe they are of little importance as ornamental plants, these being confined principally to the species of _Gleditschia_ (_G. triacantha_, from N. Am.) and _Cercis_ (the Judas-tree, _C. siliquastrum_, S. Eur.), which are cultivated in gardens; but in tropical gardens beautiful flowering species, _e.g._ of _Cassia_, _Poinciana_, _Brownea_, are found, and the most beautiful of all ornamental plants, the Indian _Amherstia nobilis_. [Illustration: FIG. 511.--Diagram of _Faba vulgaris_: _f_ the standard; _v_ the wings; _k_ the keel.] Order 2. =Papilionaceæ.= The flower (Figs. 511, 512) is _strongly zygomorphic_ and somewhat perigynous (Fig. 512 _B_; most frequently more on one side than the other). The calyx is _gamosepalous_ and persistent. The polypetalous corolla has _descending_ imbricate æstivation, the posterior, large leaf, the _standard_ (Figs. 511 _f_; 512 _B’_, _e_), _covering in the bud_ the two lateral ones, the _wings_ (Figs. 511 _v_; 512 _B’_, _a_), which again cover the two anterior; these are united in the form of a boat, the _keel_ (_k_ and _c_); the wings and the two petals of the keel are very unsymmetrical. That the keel is formed of two petals is seen by its position (in front of one sepal) and by the two often more or less free claws. The 10 (5 + 5) _stamens_ (monadelphous) _are either all united into one bundle, or into two bundles_ (diadelphous), the posterior one being free (Fig. 512 _C_). The ovules are _curved_ and _also the embryo_ (Fig. 512 _G_), especially the hypocotyl, so that the radicle assumes a position close to the edge of the thick, fleshy cotyledons. Endosperm wanting; the cotyledons are very rich in proteid reserve material. The forms of the fruit and exceptions are described under the genera. [Illustration: FIG. 512.--_Pisum sativum_: _A_ entire flower; _B_ in longitudinal section; _C_ gynœceum and stamens; _D_ gynœceum; _B’_ corolla dissected, _e_ standard, _a_, _a_ wings, _c_ keel; _D_ seed opened to show the cotyledons (_c_), the radicle (_r_), the plumule (_g_); _E_ fruit (legume); _F_ seed.] _Geocarpic_ fruits, _i.e._ those which penetrate the soil during their development and ripen underground, are found in _e.g._ _Arachis hypogæa_ (see page 472), _Trifolium subterraneum_, _Vicia amphicarpæa_. _Germination_ takes place in various ways. In the majority the cotyledons are raised above the ground as green, leaf-like bodies; in the Vicieæ they remain thick and white, and are always enclosed in the testa, and are therefore never able to take part in the work of assimilation; in species of _Phaseolus_, on the other hand, they are raised well above the ground and become green, but remain however thick and fleshy. =1, 2.= The two groups PODALYRIEÆ (the majority of the genera are Australian) and SOPHOREÆ (_Sophora_, _Edwardsia_, etc.), represent the oldest type, as they have 10 _free stamens_ and so form the transition to the Cæsalpiniaceæ. Nearly all are trees and shrubs. =3.= ASTRAGALEÆ. Herbs or shrubs, less frequently trees, with _imparipinnate_ leaves (without tendrils). The flowers are generally borne in racemes or spikes. Stamens monadelphous or diadelphous.--_Astragalus_ (Milk-Vetch) has the legume incompletely divided longitudinally into 2 loculi by a septum formed by the incurved dorsal suture. Diadelphous.--_Glycyrrhiza_ (Liquorice); _Colutea_ (Bladder-Senna) from S. Europe; _Robinia_ (the false Acacia) with thorny stipules; _Indigofera_ (the Indigo plant); _Amorpha_ (which has only one petal, namely the standard, and the fruit a nut), _Caragana_, _Wistaria_ (a climbing shrub), _Galega_. _Carmichælia australis_, when old, produces flat branches with scale-like leaves. =4.= VICIEÆ. _Climbing herbs_ with _paripinnate_ leaves, the midrib ending in a point or frequently in a _tendril_, which generally is branched, representing lateral veins without mesophyll; stamens diadelphous; the cotyledons remain underground on germination.--_Vicia_ (Vetch) has a filamentous style, hairy towards the tip, and a pod with many seeds; climbing by means of tendrils; the leaves have many leaflets.--_Faba_ (_F. vulgaris_, Horse-bean) is erect, without tendrils; its pod is thick with spongy septa between the seeds.--_Ervum_ (Lentil) has a pod with only 1–2 seeds, and sweeping hairs (stylar-brush) on the inner side of the style.--_Pisum_ (Pea; Fig. 512) has very large stipules, the bent style has a hollow groove on the anterior side. _P. sativum_ (Common Pea), _P. arvense_ (Grey Pea).--_Lathyrus_ (Sweet Pea) generally has an angular, winged stem and most frequently only a few pairs of leaflets. The style is flattened, with sweeping hairs on the back. ~In _L. aphaca_ the stipules alone are developed into foliage-leaves, while the remainder of the leaf is modified into a tendril.~--_Cicer_ has a nearly straight embryo and imparipinnate leaves with dentate or incised leaflets. _C. arietinus_ (Chick-pea).--~_Abrus_ (_precatorius_, etc.); the seeds (“Crab’s eyes,” “Paternoster peas,” “Jequirity”) are scarlet with a black spot round the hilum.~ =5.= PHASEOLEÆ. Herbs, twining or erect, but not climbing by tendrils; the leaves are imparipinnate, generally _ternate_, and bear small, linear bodies resembling stipules at the base of the stalks of the leaflets. The inflorescences are most frequently compound, groups of few flowers being situated on short, nodose, lateral axes borne on a longer stem. On germination the cotyledons are raised a considerable distance above the ground, and become greenish, but do not become leaf-like; in _P. multiflorus_ they remain underground. Stamens as in the Vetches.--_Phaseolus_ (Kidney-bean): the keel with the stamen and style is spirally _twisted_ (to the right). Herbs, twining to the left.--~The “Calabar-bean” (_Physostigma venenosum_), _Erythrina_, _Clitoria_, _Glycine_, _Soja_, _Mucuna_, _Apios_, _Canavalia_, _Vigna_, _Dolichos_, _Cajanus_, _Rhynchosia_, etc.~ =6.= TRIFOLIEÆ (CLOVERS). Herbs with _ternate_ leaves, the leaflets are often dentate with the veins prolonged into the teeth; stamens diadelphous; fruit 1-locular, 1–few-seeded, pyxidium-like, irregularly dehiscent, or more frequently a _nut_. The flowers are generally borne in capitula, racemes, or spikes.--_Trifolium_ (Clover). The corolla is gamopetalous. The calyx persists, together with the corolla, round the ripe fruit. The inflorescence is a spike, capitulum or capitate umbel; the leaves are ternate, and have adnate stipules.--_Medicago_ (Medick). The corolla falls off after flowering; fruit curved like a sickle or spirally twisted; it is a nut, and opens with difficulty. Leaves ternate.--_Melilotus_ (Melilot) has a small, spherical or lanceolate, thick and wrinkled fruit, which as a rule is indehiscent. The inflorescence is a raceme, often long, or a spike, sometimes a capitulum. Leaves ternate.--_Ononis_ (Rest-harrow) differs in having monadelphous stamens and in being more shrub-like and bushy, and in having a normal, 2-valved pod, by which characteristic it approaches the Genisteæ. The flowers are generally rose-coloured, solitary, or in few-flowered racemes in the leaf-axils. Thorns (branches) are often present; the leaves are compound with only one small leaflet (the terminal one), or ternate with adnate stipules. =7.= LOTEÆ. Herbs with ternate or imparipinnate leaves, with entire leaflets. In the latter case, when the lowest pair of leaflets is placed quite close to the sheath, the stalk is wanting, and apparently a trifoliate leaf with large stipules is developed. Flowers in an umbel or capitulum. Stamens monadelphous or diadelphous, the filaments (either all of them, or only the 5 sepal-stamens) are widened at the top.--_Lotus_ (Bird’s-foot-trefoil) has a long, round pod.--_Tetragonolobus._--_Anthyllis_ (Lady’s-finger); the fruit is a nut, which is distributed by the wind by means of the membranous, bladder-like calyx, which completely encloses and falls off with it. =8.= GENISTEÆ. The majority are shrubs or trees with apparently simple leaves, _i.e._ compound leaves with only one leaflet (the terminal leaflet), or ternate leaves; the stipules in most instances are very small or are entirely wanting; stamens monadelphous.--_Genista_ (Dyer’s-weed) has apparently simple leaves; the branches often terminate in a thorn. ~The strongly-winged stems in _G. sagittalis_ are its most important organs of assimilation. _Bossiæa rufa_ has flat branches, its leaves being reduced to small, pointed stipules.~--_Sarothamnus_ (Broom) has switch-like, angular branches and often both the apparently simple and ternate leaves on the same shoot; style spirally rolled.--_Cytisus_ (Laburnum). _Ulex_ (Furze; ~in _U. europæus_, the seedlings bear a few foliage leaves, but the leaves succeeding these are modified into thorns~); _Spartium_; _Crotalaria_, etc.--_Lupinus_ (Lupin) is allied to this group; it has a thick, often somewhat fleshy pod, and digitate leaves with adnate stipules.--_Retama._ =9.= HEDYSAREÆ are especially recognised by having the ovary divided by transverse septa into as many cells as there are seeds, the fruit thus becomes a _lomentum_, dehiscing transversely into nut-like joints (Fig. 513).--_Ornithopus_ (Bird’s-foot); _Coronilla_; _Hippocrepis_; _Onobrychis_ (Sainfoin) has a fruit with only 1 joint (_i.e._ a 1-seeded nut); _Desmodium_; _Alhagi_; _Hedysarum_, etc.--_Arachis hypogæa_ (Earth-nut) has a pod which is abstricted between the seeds, and is indehiscent, but is not multilocular nor a true lomentum; it is reticulately wrinkled externally, and ripens underground; the basal part of the ovary is prolonged after flowering, attaining a length of several inches, and buries the young fruit in the soil. The embryo is straight.--~_Desmodium gyrans_ is well-known for its motile leaflets.~ [Illustration: FIG. 513.--_Hedysarum coronarium._] =10.= DALBERGIEÆ. 25 genera; especially in Tropical America; the majority are trees, a few shrubs or lianes; the leaves are simple or imparipinnate. The fruit is _indehiscent_ in all; in some it is a winged, in others a wingless _nut_ (_Machærium_, _Dalbergia_, _Centrolobium_, etc.), in others, again, a drupe, _e.g._ in _Dipteryx_ (Tonquin-bean) and _Andira_. In some genera the embryo is straight. POLLINATION. Especially effected by Bees. The nectar is secreted by a ring or disc-like portion round the base of the gynœceum or the inner surface of the receptacle. The flower is constructed with a peculiar mechanism to ensure cross-pollination by insects. The pollen is shed just before the flower opens, and is retained in a pouch formed by the keel. An insect visiting the flower uses the wings and keel for a landing-stage, and in attempting to reach the honey presses down the wings and the keel which are locked together near the standard; the stylar-brush by this means is forced through the apical opening of the keel and a little pollen is thus swept out and deposited upon the abdomen of the visiting insect as it presses against the apex of the keel; the insect thus carries away pollen and may effect cross-pollination. In the different flowers this arrangement is modified in various ways to promote pollination. 5000 species (319 genera); especially in the Tropics, where many are important forest trees.--The following plants are used FOR FOOD: _Pisum sativum_ (W. Asia?) and _arvense_ (Italy); _Phaseolus vulgaris_ (Kidney-bean, American; _Dolichos sinensis_ was known to the Greeks and Romans under the name “φασηλος,” “phaseolus”), _P. compressus_ (French-bean), etc.; _Faba_ _vulgaris_ (Field-bean, Horse-bean; from the Old World); _Ervum lens_ (Lentil, Eastern Mediterranean); in tropical countries the oil-containing seeds of _Arachis hypogæa_.--The following are FODDER plants: _Vicia sativa_, _Faba vulgaris_, _Onobrychis sativa_ (Sainfoin), _Medicago sativa_ (Lucerne), and _lupulina_ (Medick), species of _Trifolium_, _Hedysarum coronarium_. OFFICINAL: “Liquorice root,” from _Glycyrrhiza glabra_ (S. Europe); “Red Sandalwood,” from _Pterocarpus santalinus_ (Tropical E. Asia); Gum Tragacanth, from _Astragalus_-species (E. Mediterranean); Balsam of Peru, from _Toluifera pereiræ_, and Balsam of Tolu, from _Toluifera balsamum_. Calabar-beans, from _Physostigma venenosum_; Kino, from _Pterocarpus marsupium_; the pith of _Andira araroba_ is used under the name of “Chrysarobin.”--Of use TECHNICALLY: _Genista tinctoria_ (yellow dye) and _Indigofera-species_ (Indigo), the bast of _Crotalaria juncea_ (Sunn Hemp); the seeds of _Dipteryx_, which contain Coumarin, and are highly scented, and Balsam of _Myroxylon_. POISONOUS: the seeds of _Laburnum_ (_Cytisus laburnum_), various species of _Lathyrus_, and _Abrus precatorius_; the latter contain two poisonous proteids, paraglobulin and albumose, which resemble snake-poison in their effects. The following are ORNAMENTAL plants: _Phaseolus multiflorus_ (Scarlet runner, from America), _Robinia pseudacacia_, _Amorpha_, _Colutea_, _Coronilla_, _Indigofera dosua_, _Wistaria polystachya_, _Cytisus laburnum_ (Laburnum, S. Europe, Orient.) and other species. Order 3. =Mimosaceæ.= The flowers are most frequently hypogynous and _regular_, the æstivation of the corolla is _valvate_ and, in the majority of instances, that of the calyx also. The flower is 4-merous, less frequently 5- or 3-merous.--The flowers are generally small, but are always borne in compact, round _capitula_ or spikes (Fig. 514); they are hypogynous or perigynous. The calyx is generally _gamosepalous_ and the corolla _gamopetalous_, the latter being frequently wanting. The stamens are equal or double the number of the petals (_Mimosa_, etc., in _M. pudica_, _e.g._ S4, P4, A4, G1) or (in _Acacia_, _Inga_, etc.) in a large, indefinite number, free or monadelphous, often united to the corolla (Fig. 514 _b_). The colour of the flower in most cases is due to the long and numerous stamens. The _fruit_ is various. The embryo is _straight_ as in the Cæsalpiniaceæ. _Entada_ and many species of _Mimosa_ have a flat, straight, or somewhat sickle-like pod, which resembles the siliqua of the Cruciferæ in that the sutures (in this instance, however, dorsal and ventral suture) persist as a frame, but the intermediate portion divides, as in the transversely divided siliqua, into as many nut-like portions as there are seeds. Some species have a pod of enormous dimensions. The seeds of _Entada gigalobium_ are often carried from the West Indies to the N. W. coasts of Europe by the Gulf Stream.--The fruit of _Acacia_ in some species is an ordinary pod, in others it is transversely divided, or remains an undivided fruit, a nut.--This order includes both trees and herbaceous plants, which are often thorny; the leaves are usually bipinnate (Fig. 514) and are sensitive, and also possess sleep-movements.--Many Australian Acacias have compound leaves only when young, but when old have _phyllodia_, _i.e._ leaf-like petioles without blades, placed vertically. A large number have thorny stipules, which in some (_Acacia sphærocephala_) attain an enormous size, and serve as a home for ants, which in return protect their host-plant against the attacks of other, leaf-cutting ants. [Illustration: FIG. 514.--_Acacia farnesiana_: _a_ inflorescence; _b_ flower.] Other genera besides those mentioned are: _Adenanthera_, _Desmanthus_, _Parkia_, _Inga_ (with rather fleshy, indehiscent fruit), _Calliandra_, etc. 1350 species (30 genera); none natives of Europe, their home being the Tropics and sub-tropical regions, especially Australia and Africa.--Fossils in Tertiary.--Gums are found in many species of _Acacia_, especially the African (Gum arabic) and Australian, of which some are _officinal_. The bark, and also the fruits, contain a large amount of _tannic acid_ and are used as astringents and in tanning (“Bablah” is the fruits of several species of _Acacia_). Catechu is a valuable tanning material extracted from the wood of _Acacia catechu_ (E. Ind). The flowers of _Acacia farnesiana_ (Fig. 514) are used in the manufacture of perfumes. With us they are cultivated as ornamental plants, _e.g._ _A. lophantha_ and many others, in conservatories. Family 22. =Passiflorinæ.= The flowers are most frequently regular, 5-merous in the three most external whorls, eucyclic and perigynous or epigynous, less frequently hypogynous. A characteristic feature is that the ovary is _tricarpellary_, _unilocular_, and with 3 _parietal_ placentæ which sometimes meet in the central line (_Cucurbitaceæ_). The styles are generally free and _bifid_. To all these characteristics, however, there are exceptions. ~The Cucurbitaceæ are sometimes placed among the Sympetalæ, close to the Campanulinæ, but they are not allied to the Sympetalæ, from which they differ especially, for instance, in the structure of the ovule. The position of the Begoniaceæ in this family is also open to doubt.~ [Illustration: FIG. 515.--_Passiflora cœrulea_ (reduced).] Order 1. =Passifloraceæ= (=Passion-flowers=). The majority are herbs which climb by means of tendrils (modified branches) and have scattered, stipulate leaves, often palminerved and lobed (Fig. 515). The flowers, which are often large and beautiful, are regular, ☿, with S5, P5, A5, G3; the calyx and corolla are _perigynous_, and immediately inside the corolla is the “corona,” consisting of numerous, tapering, filamentous bodies, or sometimes united in rings, most frequently petaloid and coloured; the stamens are raised on a long, round internode above the _cup-like receptacle_; immediately above these is the gynœceum with its 3 free styles and capitate stigmas; the ovary is unilocular with 3 parietal placentæ. Fruit most frequently a _berry_. The seeds have an aril. 210 species; especially in Tropical America. Several _Passiflora_-species are ornamental plants, and the fruits of some species are edible. Order 2. =Papayaceæ.= The best known representative is the Papaw (_Carica papaya_), a Tropical American tree whose stem is usually unbranched, and bears at its summit several large, palmilobed leaves on long stalks. The stem and leaves have latex. The large, Melon-like berries are edible, and for this reason it is cultivated in the Tropics. Flowers unisexual, with slightly different structure in the ♂-and ♀-flowers, besides intermediate forms. The ♂-flower has a gamopetalous, the ♀-flower a polypetalous corolla.--The milky juice contains a substance with similar action to pepsine. 10 stamens. 5 carpels. Order 3. =Turneraceæ.= 85 species; especially in America. Order 4. =Samydaceæ.= 160 species; tropical. Order 5. =Loasaceæ.= Herbaceous plants seldom shrubs, sometimes climbing, and nearly always studded with _stiff hairs_, in some instances stinging or hooked. The leaves are most frequently palmilobed and without stipules. The flowers are regular, ☿, polypetalous, entirely _epigynous_, with 4–5 sepals, petals and stamens, or more frequently (by splitting) many stamens, those which are placed before the sepals being generally barren and more or less petaloid; carpels most frequently 3, united into an inferior, unilocular ovary with 3 parietal placentæ, above which the receptacle is generally more or less prolonged. Fruit a capsule; in _Gronovia_ an ovary with 1 ovule and fruit a nut. 115 species; principally from S. Am. A number of annuals are often grown in our gardens: _Bartonia aurea_ (California); _Mentzelia_; _Cajophora_; _Gronovia_. Order 6. =Datiscaceæ.= 4 species, especially in the Tropics.--_Datisca cannabina_ (Asia Minor) resembles the Hemp in external appearance. The flowers are diœcious, insignificant; ♂-flowers: a low, gamosepalous calyx, no corolla, and an indefinite number of stamens; ♀-flowers; _epigynous_; ovary unilocular with free, mostly bifid, styles, and generally 3 parietal placentæ. In most cases the ovary is not entirely closed at the top (as in _Reseda_). [Illustration: FIG. 516.--_Begonia rex_ (reduced).] Order 7. =Begoniaceæ.= This order principally comprises herbs or under-shrubs with succulent stems (having scattered vascular bundles in the pith); the leaves are arranged in two rows (a divergence of 1/2) and _are asymmetrical_, as a rule more or less obliquely cordate, or ovate with cordate base (Fig. 516); large, caducous stipules are present. Inflorescences dichasial, or unipared scorpioid cymes; the flowers are unisexual; the first ones (the oldest) are ♂-flowers, while ♀-flowers are found especially on the younger axes. The ♂-flowers have most frequently 2 + 2 coloured perianth-leaves, and many stamens collected into a head in the centre of the flower; the ♀-flowers are _epigynous_ with 5 coloured perianth-leaves (placed spirally with a divergence of 2/5) and a trilocular ovary, bearing 3 bifid styles and 3 wings (the wings usually of unequal size); in the inner angle of each loculus there is one large projecting placenta, or two plate-like placentæ (the bent back edges of the carpels) studded with ovules. Fruit a capsule, with many extremely small seeds.--_Begonia._ 420 species; almost all from the Tropics (Am., Asia).--Many species, with varieties and hybrids, are ornamental plants in houses and conservatories, chiefly on account of the form, colour and markings of their leaves; but also for their very beautiful flowers. They reproduce easily by adventitious buds from leaves and portions of leaves placed on damp soil; some have bulbils. Like the Oxalideæ they contain an acid sap. [Illustration: FIG. 517.--_Ecballium agreste._ Diagram of a ♂-and a ♀-flower.] Order 8. =Cucurbitaceæ.= The flower is _epigynous_, and, as a rule, is also provided with a leaf-like, cup- or bell-shaped receptacle above the ovary, to which the perianth and stamens are attached; the flowers are regular, _unisexual_, with rudiments of the other sex, and 5-merous: sepals 5, narrow and pointed, with the median sepal posterior (Fig. 517), petals 5, stamens 5, and carpels 3 (rarely 4–5); the corolla is _gamopetalous_ in the majority, polypetalous in some; generally plicate-valvate in the bud. _The anthers in the ♂-flowers are extrorse, and monothecious, i.e. only one half of each of the anthers of the 5 stamens is developed_, the _pollen-sac_ having frequently a peculiar [tilde]-shaped curve (Fig. 518 _A_, _B_); the stamens are _either all united_ into a column (_e.g._ in _Cucurbita_), or they are _united in pairs_, so that only one remains free (Figs. 517 _A_; 518 _A_); in the latter case there appears to be one small stamen with a [tilde]-shaped, curved pollen-sac and two larger ones, each with two curved pollen-sacs placed as in Fig. 517 _A_. The original form appears to be _Fevillea_ with free petals and 5 free stamens. Sometimes the rudiment of a gynœceum is present. The carpels are united into an _ovary_ with 3 (4–5) placentæ formed by their united edges. These are thick, fleshy, and _bifid_, bearing a number of ovules on each side (Figs. 517 _B_; 518 _C_, _D_); in general the placentæ are so large that they not only meet in the centre, but also fill up the ovary as far as the wall of the pericarp. The whole interior of the fruit thus becomes a juicy mass in which three lines may be seen, meeting in the centre (the boundaries of the individual placentæ), and near the circumference 6 groups of seeds (Fig. 518 _D_). When the carpels are equal in number to the petals they alternate with them. The _style_ is short and thick, and generally divided into 3 (4–5) branches, with a horse-shoe shaped stigma on each branch (Fig. 518 _C_). The _fruit_ is most frequently a many-seeded _berry_; in some it attains a considerable size and has a firm external layer (_Cucurbita_, _Lagenaria_, etc.). _The embryo is straight_, has _no endosperm_, but contains a large quantity of _oil_. The exceptions to the above characters will be found under the genera. [Illustration: FIG. 518.--_Citrullus colocynthis_: _A_ ♂-flower, cut open and spread out; _B_ stamen; _C_ ♀-flower in long section; _h_ receptacle; _ca_ calyx; _D_ transverse section of ovary.] Exclusively herbs, generally with stiff hairs and yellow flowers. Many species are annuals, others are perennial, having tuberous roots or hypocotyls. The leaves are scattered, long-stalked, in most cases more or less heart-shaped, palminerved, palmilobed, and exstipulate; in their axils are found both flowers (singly, or in an inflorescence) and a vegetative bud, and outside the axil, _on the anodic[37] side of the leaf, a simple or branched tendril_, by which the plant _climbs_ (exceptions: _e.g._ _Ecballium_). The position of the flowers, branches and tendrils situated in and near the leaf-axils is as follows. In the leaf-axils, a flower is borne (as a branch of the first order), ♂ or ♀, according to the conditions of the various genera. This branch is not situated in the centre of the axil, but is removed slightly towards the anodic side of the leaf. Of its two bracteoles as a rule only the one lying on the anodic side is developed, namely as a tendril, which is displaced to a position outside the axil. The branch of the first order bears on its catodic side an inflorescence (in the axil of the suppressed bracteole), on the anodic side a vegetative bud which grows out into a branch like the main axis. The subtending leaf of this branch is thus the tendril; but when it has several arms the condition is complicated by the appearance of an accessory bud which unites with its subtending leaf, the tendril, its leaves also becoming tendrils (situated on an undeveloped internode); the many-branched tendril is thus a branch, and the tendril-arms are its leaves, except the main arm which is its subtending leaf. Other explanations of these difficult relations have been given.--The _germination_ is somewhat peculiar, owing to the fact that a heel-like prolongation is formed at the base of the hypocotyl to assist in separating the two halves of the testa from each other, and to facilitate the unfolding of the cotyledons. _Cucurbita_ (Pumpkin, Marrow) has branched tendrils; the flowers are monœcious, and are borne singly; the corolla is bell-shaped, and divided almost as far as the middle. The stamens are all united into a tube; the compressed seeds have a thick, blunt edge.--_Cucumis_ has (generally) unbranched tendrils; the ♀-flowers are borne singly, whilst the ♂-flowers are borne in groups: the corolla is divided nearly as far as the base, and the stamens are united 2-2-1. The connective is elongated above the anthers. The seeds have a sharp edge.--_Citrullus_ (Fig. 518) has a corolla similar to _Cucumis_, but ☿-and ♂-flowers are borne singly; the stigma is only 3-lobed, the fruit most frequently spherical.--_Ecballium_ (Squirting Cucumber, only 1 species, E. _elaterium_) has no tendrils, and is therefore not a climber. The oblong fruit is pendulous from the apex of its stalk, and when ripe is distended with an acrid, watery fluid; on being touched the fruit is detached, and the seeds, together with the watery fluid, are violently ejected through the aperture formed at the base of the fruit. The ♂-flowers are borne in racemes near the solitary ♀-flowers (Fig. 517).--_Bryonia_ (White Bryony) has chiefly unbranched tendrils and small, greenish-yellow, usually diœcious flowers with rotate corolla, in many-flowered inflorescences; the small, spherical berry has no specially firm outer layer, and generally only few seeds. The tap-root and a few of the other roots are tuberous. _B. alba_ (berry black; monœcious) and _dioica_ (berry red; diœcious). ~Among other genera may be mentioned: _Lagenaria_ (Gourd); the fruit has a woody external layer which, after the removal of the pulpy integument, may be used as a gourd. _Luffa_ has a polypetalous corolla; the fruit is dry, and consists internally of a network of vascular bundles; it opens by an aperture at the summit. _Benincasa_; the fruit has a close, bluish coating of wax. _Trichosanthes_ (Snake Cucumber) has a thin, round, long and curved fruit. _Momordica_; the fleshy fruit opens and ejects the seeds. _Cyclanthera_ takes its name from the staminal column which is found in the centre of the ♂-flower, bearing a bilocular, ring-like anther which opens by a horizontal cleft. The fruit is unilocular by suppression, has 1 placenta, and when touched opens and ejects the seeds. _Sicyos_ and _Sechium_ have only unilocular ovaries with one pendulous ovule. _Sechium_ has, moreover, 5 free stamens, of which only one is halved, the other 4 having both halves of the anther. _Fevillea_ and _Thladiantha_ also have 5 free stamens. _Dimorphochlamys_ has dimorphic flowers.~ POLLINATION is effected by insects, chiefly bees or wasps, the nectar being secreted by the inner, yellow portion of the receptacle; in the ♂-flower access is gained to the nectar through the slits between the stamens, which arch over the nectary.--85 genera; about 637 species; especially in the Tropics. Only two are found in the whole of N. Europe, _Bryonia alba_ and _dioica_; in S. Europe, _Ecballium_ also. Most of the cultivated species have been obtained from Asia, such as the Cucumber, Melon, Colocynth, several _Luffa_-species (the “Gourds” mentioned in Scripture are _Cucumis chate_); from Africa, the Water-melon, _Cucurbita maxima_, and others; from S. Am., no doubt, the Pumpkin (_C. pepo_ and _melopepo_). USES. Many species are used in medicine or for domestic purposes. _Bitter_, _poisonous properties_ are found; the fruits of the two _officinal_ ones are purgative: _Citrullus colocynthis_ (Mediterranean, E. India, Ceylon) and _Ecballium elaterium_, as well as various tropical species, the roots of Bryonia, etc.--The following are cultivated AS ARTICLES OF FOOD: Pumpkin (_Cucurbita pepo_, etc.), Cucumber (_Cucumis sativus_), Melon (_Cucumis melo_), the Water-melon (_Citrullus vulgaris_), _Sechium edule_ (Chocho), certain species of _Luffa_ (the young fruit). The Bottle Gourd is cultivated in tropical countries for the sake of its hard pericarp, which is useful for bowls, bottles, etc. The fruits of _Luffa_ have a number of reticulately felted, tolerably firm vascular bundles, which render them serviceable in various ways (as a kind of “sponge”). The Cucurbits are of no use in the manufactures. Only a few are cultivated as ornamental plants, chiefly as curiosities. Family 23. =Myrtifloræ.= The leaves are most frequently _opposite_, _simple_, _entire_ (rarely dentate), and _exstipulate_. The flowers are _regular_ and _epigynous_ (perigynous in _Lythraceæ_ and a few others), ☿, polypetalous; the number of members in a whorl is generally 4 or 5 (S, P, A, or most frequently A 2, G), but sometimes it becomes (_e.g._ Myrtles and _Lythraceæ_) very large in the andrœcium by splitting, and in the gynœceum also is often different. (When suppression takes place it is principally in the corolla and petal-stamens.) In nearly all instances the calyx is _valvate_. Gyncœceum multicarpellary, multilocular, with only one _style_ (except _Haloragidaceæ_). In the majority the ovules are situated on an axile placenta in the multilocular ovary. _Endosperm is wanting_ in the majority.--~Less important exceptions: _Rhizophoraceæ_ and _Gunnera_ have stipules. _Haloragidaceæ_ have several styles and endosperm. _Rhizophora_ also has endosperm.~ Order 1. =Lythraceæ.= _Hermaphrodite_, _perigynous_ flowers which are _most frequently =6=-merous_, viz. S 6 (often with a _commissural_ “_epicalyx_,” Fig. 519 _c_), one segment posterior, P 6, A 6 + 6 or 6 + 0 and G =2–6=, forming a 2–6-locular ovary with many ovules in the loculi, style single, and capitate stigma. The _gynœceum is free_ at the base of the tubular, or bell-shaped, _thin_, strongly veined receptacle, which bears the other leaf-whorls on its edge and inner side. Fruit a capsule. No endosperm.--To this order belong both herbs, shrubs and trees. The branches are frequently square, the leaves always _undivided_, _entire_, and without stipules, or with several very small stipules, and often opposite. The calyx is valvate. The flower is regular (except _Cuphea_) and frequently large and beautiful. The stamens are generally incurved in the bud, and the petals irregularly folded. [Illustration: FIG. 519.--_Lythrum salicaria._ _c_ the “epicalyx.”] _Lythrum_ (Loose-strife). The flower is diplostemonous and 6-merous, with a long, tubular receptacle with epicalyx-teeth (Fig. 519 _c_). The 12 stamens are arranged in two tiers on the inner side of the receptacle. The gynœceum is bicarpellary. ~The flowers are borne in small dichasia in the leaf-axils, and their number is increased by accessory inflorescences beneath the main inflorescence.--The native species, _L. salicaria_, is trimorphic (long-styled, mid-and short-styled forms, Fig. 520). Cross-pollination is chiefly effected by humble-bees and bees, which seek the nectar formed at the bottom of the receptacle. Other species are only dimorphic, or even monomorphic.~--Closely allied are, _Nesæa_, _Diplusodon_, _Lagerstrœmia_, and _Cuphea_, whose flower resembles that of _Lythrum_, but is zygomorphic. In _Cuphea_ the receptacle is oblique and at the back prolonged into a _spur_, in which the nectar, secreted by a gland situated behind the ovary, is collected; the calyx and corolla gradually become reduced in size toward the anterior side of the flower; the reverse, however, is the case with the 11 stamens (the posterior one is absent); the posterior loculus in the bilocular ovary is sometimes barren; the fruit, when ripe, dehisces along the posterior side, the ovary as well as the wall of the receptacle being ruptured by the placenta, which expands and projects freely. ~The flowers stand singly in the centre of the stem, between the pairs of leaves. This may be explained as follows: of the two foliage-leaves in each pair, one supports a foliage-shoot, the other a flower; the foliage-shoot remains in the axil, but the flower is displaced through the length of an entire internode to the next pair of leaves, and then assumes a position between these two leaves. All foliage-shoots stand in two rows, the flowers in two other rows.~ [Illustration: FIG. 520.--_Lythrum salicaria._ One side of the perianth is removed from all three flowers. _A_ is long-styled, _B_ mid-styled, and _C_ short-styled. The direction of the arrows and dotted lines indicates the best (legitimate) methods of crossing.] _Peplis_ (Water-purslane), a small, annual plant, with thin, bell-shaped receptacle without projecting nerves. The small flowers have no petal-stamens, and often also no corolla; fruit indehiscent.--_Ammannia_ is closely allied to it. 365 species; 30 genera; mostly in the Tropics, and more especially S. Am.--Some yield _dyes_, _e.g._ _Lawsonia inermis_ (cultivated in Africa and Asia) and _Lagerstrœmeria indica_; some contain tannin; others are ornamental plants, especially in gardens in warm countries. Order 2. =Blattiaceæ.= 12 species. Tropical Asia and Africa. Trees. Formerly included with _Punica_, but best placed as an independent order. Order 3. =Melastomaceæ.= A very natural and very large order (150 genera; 2,500 species), its home being chiefly in tropical S. America, especially the Brazils (termed by Schouw “The kingdom of Palms and Melastomaceæ”). There are both herbaceous and arborescent species, which are easily recognized by the opposite or verticillate, simple leaves which have (with the exception of a few heather-like species) 3–5–7–9 curved veins proceeding from the base of the leaf, and connected very regularly by closely parallel, transverse veins. The flower is perigynous or epigynous; its type is that of the Onagraceæ (4–5-merous; 1 whorl of sepals, petals and carpels, 2 of stamens); the calyx is valvate, the corolla is twisted (to the left) in æstivation; the stamens are very characteristic; in the bud they are geniculate; the anther opens in the often long, beak-like, prolonged point, with 1, less frequently with 2 pores, and has generally ear-like appendages at its base. The fruit is a berry or capsule. These large and beautiful flowering-plants play a very important part in South American landscapes; otherwise they are of slight importance (a few are cultivated in conservatories, _e.g._ _Centradenia_, _Medinilla_, _Lasiandra_, _Tibouchina_, _Miconia_, etc.). Order 4. =Œnotheraceæ= (or =Onagraceæ=). The flowers are arranged in racemes or spikes, ☿, epigynous, regular, polypetalous, _=4=-merous in all 5 whorls_ (1 whorl of sepals, petals and carpels, 2 of stamens); 2–3–5–6-merous flowers are less frequent; _the calyx is valvate_, the _corolla twisted_ in æstivation (the left edge being covered). Gynœceum simple with multilocular ovary; the _style is undivided_, filiform, and bears a capitate or 4-partite stigma; endosperm wanting; embryo straight.--The majority are herbs, especially water- and marsh-plants; several are shrubs. No essential oils. The leaves are alternate or opposite, always single, and without (or with very small) stipules. ~The odourless flowers sometimes have a coloured calyx. In some instances (_e.g._ _Œnothera_, _Fuchsia_) the receptacle is prolonged more or less beyond the inferior ovary, and finally falls off. The stamens are obdiplostemonous (carpels epipetalous); the petal-stamens are sometimes suppressed. The anthers in some genera are divided into storeys. The well-pronounced, triangular pollen-grains are connected together by viscous threads. Small stipules are sometimes found, _e.g._ _Fuchsia_, _Lopezia_.~ [Illustration: FIG. 521.--Flower of _Lopezia_.] =A.= =Fruit a capsule.= _Œnothera_ (Evening Primrose) is 4-merous, has 8 stamens, a tubular receptacle, and an oblong capsule with loculicidal dehiscence leaving a centrally placed column, bearing the seeds.--_Epilobium_ (Willow-herb) deviates from _Œnothera_ especially in the seeds being hairy (at the chalazal end of the seed).--_Chamænerium_ is a Willow-herb with zygomorphic flowers.--~The following may be included here: _Clarkia_, _Eucharidium_ (an _Œnothera_ with 4 stamens and 3-lobed petals), _Godetia_ and _Boisduvalia_, _Jussiæa_ (dehiscence septicidal), _Isnardia_ (petal-stamens absent, sometimes the petals also).--_Lopezia_ has a peculiar, zygomorphic flower (Fig. 521); one of the four sepals is bent forwards and the other 3 backwards; the posterior petals are narrower than the 2 anterior ones which are turned obliquely backwards and bent like a knee, with a greenish nectary at the bend; 2 stamens, one only fertile (the posterior), while the anterior is barren, petaloid, and spoon-shaped; both are sensitive, which is essential for pollination. In Fig. 521, _a_ represents an early stage, in which the stamen and style lie concealed in the staminode; _b_ is the ♂ stage, the stamen projects from the centre of the flower; _c_, the ♀ stage, the style occupies the place of the stamen.~ =B.= =Fruit a berry.= _Fuchsia_ generally has a coloured calyx and tubular receptacle; the corolla may be wanting. =C.= =Fruit a nut.= _Circæa_ (Enchanter’s Nightshade) has a 2-merous flower (S2, P2, A2 + 0 [petal-stamens are wanting], G2). The flowers are borne in racemes without bracts.--_Gaura._ =D.= =Fruit a drupe.= _Trapa_ (Horn-nut); a peculiar aquatic plant; the submerged stem has long internodes and lanceolate leaves, falling off at an early period, but at each node are found 4 long roots with thin, lateral roots (sometimes erroneously regarded as leaves) borne pinnately; the stem reaching the surface of the water, bears a rosette of rhombic foliage-leaves, with large, inflated stalks containing air, and forming the floating apparatus of the plants. In the axils of the leaves (as in _Gunnera_) 8 small, stipular structures are present. The flowers are solitary in the axils of the foliage-leaves (S4, P4, A4 + 0, G2), _semi_-epigynous. There is an 8-lobed, crenate disc on the free portion of the ovary; one ovule in each loculus. The fruit is a _drupe_ with 4 (or 2) prominent horns (the persistent sepals), which after the pulp has decayed away bear a series of hooks turned downwards on each side, _i.e._ sclerenchymatous bundles which formerly lay concealed in the pulp of the sepals. ~The germination is peculiar: one of the cotyledons is large, and its thick extremity remains in the fruit, the other however is small and is pushed out at the apex of the fruit together with the radicle and plumule; the development of the root soon ceases, and the plumule usually grows into a stem entirely without branches, similar to the one described above, only that 1–2 precisely similar shoots arise in the axil of each cotyledon, so that each embryo produces 3–5 shoots.--_Trapa_, by its mode of life, its 1-seeded fruit, etc., forms a transition to _Haloragidaceæ_.~ The large-flowered forms are adapted for insect-pollination and are often protandrous, the small-flowered ones are homogamous and may pollinate themselves. _Œnothera_ is adapted for hawk-moths and bees.--330 species; especially in temperate climates, chiefly in the Northern Hemisphere. _Epilobium_, _Circæa_ are natives of this country; _Trapa_ is extinct in this country, it has been found in a semi-fossilized condition near Cromer and in bogs in Denmark, and existed in Sweden until a few years ago; _Œnothera_ has been introduced from N. Am.--A number of N. Am. species are grown as ornamental plants in our gardens. The seeds of _Trapa natans_ are edible, and used as food in China. Order 5. =Haloragidaceæ.= This is a reduced form of the Œnotheraceæ, and principally differs from these in the presence of _endosperm_ and _free styles_. _Only 1 ovule in each loculus._--84 species distributed over the entire globe; the majority are aquatic plants. The most advanced type is _Myriophyllum_ (Water-Milfoil), with a regular, epigynous flower (S4, P4, A4 + 4, G4), most frequently _diclinous_ (monœcious); the fruit is a _2–4-partite schizocarp_. Aquatic plants, most frequently with pectinate, pinnate leaves.--_Haloragis._--~_Gunnera_ (a dozen species from the Southern Hemisphere) forms the next step in the reduction. Large, scattered, rough-haired, and softly-spined leaves, with small flowers in crowded inflorescences. The flower, when most complete, has S2, P2, A2 (petal-stamens) and G2, forming an inferior, unilocular ovary with 1 ovule. It is remarkable for the great number of stipules placed in transverse rows in the leaf-axils, for the peculiar glandular organs, and for the colonies of _Nostoc_, which are found embedded in the cortex as a kind of parasite.~--The simplest form is _Hippuris_ (Mare’s-tail) with an extremely small, crenate or entire calyx, without corolla, and with only one stamen and one carpel, forming an inferior, unilocular ovary with only one ovule. Fruit a drupe with thin pulp. ~It is an aquatic plant with creeping, sympodial rhizome, and erect unbranched shoots, bearing numerous small, verticillate leaves. The small flowers are situated singly in the leaf-axils.~ Order 6. =Rhizophoraceæ.= Tropical trees or shrubs (50 species, the best known being _Rhizophora mangle_, Mangrove) which grow gregariously, especially along the banks of rivers and by sea-coasts, where the water is quiet and brackish, and where they form the so-called Mangrove-swamps. Aerial roots are formed on the stems and branches (Fig. 522 _A_). The seeds germinate in the fruit, which by arrest contains only one seed (Fig. 522 _B_), before it is detached from the tree. The radicle projects considerably from the seed, and hangs down freely in the air; when the embryo is finally detached from the mother-plant, the separation is effected by the hood-like cotyledon, which entirely envelops the plumule, becoming detached from the rest of the embryo, which falls down, while the hood-like cotyledon remains enclosed in the fruit. The embryo, after it has fallen, strikes root, and continues growing in the undisturbed mud under the trees, or perhaps it may first be drifted about by the water, being well adapted for this by its peculiar, tough nature, and large, intercellular spaces.--It may also further be remarked that the anther is divided into a number of small loculi. The leaves are stipulate. The endosperm projects from the micropyle, growing out from the base of the seed, and thus serves as an organ of suction to convey nutriment to the embryo from the mother-plant. Order 7. =Combretaceæ.= Trees and shrubs, partly lianes. An inferior, unilocular ovary with few pendulous ovules. _Conocarpus_ and _Laguncularia_ form, in conjunction with the species of Rhizophoraceæ, the tropical Mangrove-swamps. _Terminalia._--280 species; Tropics. [Illustration: FIG. 522.--_Rhizophora mangle_ with the germinating fruit (much reduced).] Order 8. =Myrtaceæ (Myrtles).= The plants belonging to this order are shrubs or trees, the majority being easily recognised by the vegetative characters. The leaves, for instance, are most frequently opposite, without stipules, undivided and entire, parchment-like or leathery, evergreen, _aromatic_, finely dotted by _pellucid glands containing essential oils_; the venation is penninerved with a nerve just inside and running parallel to the edge of the leaf. The flowers are regular, epigynous (Figs. 523, 524, 525) and ☿, most frequently =4-= or 5-merous in the calyx and corolla, with _many_ stamens (by splitting, so that they are often in several distinct bundles) and an ovary with one style, formed of 2–5–many carpels; the receptacle is most frequently united for its entire length with the ovary. The fruit varies, but is _most frequently a berry_. The embryo is thick, often curved, with united cotyledons; no endosperm. =1.= MYRTEÆ, MYRTLE GROUP. Chiefly American, though some are found also in Africa and Asia. The fruit is a _berry_ with generally 2–5 loculi in the ovary, and many ovules in each.--_Myrtus_; _Eugenia_ (the petals fall off together as a hood in the Clove, _E. caryophyllata_, Figs. 523, 524); _Myrcia_; _Jambosa_; _Amomis_; _Psidium_, etc. =2.= PUNICEÆ, POMEGRANATE GROUP. Only 2 species (_Punica granatum_; from Persia, Afghanistan), differing in several respects from the typical form of the Myrtaceæ. The leaves are generally _opposite_, without glands and marginal veins. The receptacle, calyx and corolla are red; the latter 5–8–(generally 6-) merous. Calyx valvate and corolla folded as in Lythraceæ, stamens also and epicalyx as in this order. The most characteristic feature is the inferior, spherical berry, with dry pericarp, formed from two whorls of carpels in two tiers (Fig. 525); the interior whorl, which is also the lower, has 3 carpels, and the placentæ are situated in the inner angles of the 3 loculi; the external whorl is 5-merous, and the placentæ have originally the same position in the inner angles of the loculi, but their position is changed to the outer side of the loculi owing to the growth of the wall of the ovary, which takes place early, causing the carpels to become, as it were, turned inside out, so that the part which was turned downwards is turned upwards, and the part which was turned inwards becomes turned outwards (as in _Mesembrianthemum_). The edible part of the fruit is the _fleshy testa_, as in _Ribes_. The cotyledons are rolled together spirally. [Illustration: FIGS. 523, 524.--_Eugenia caryophyllata._ FIG. 523.--Flowers (nat. size). FIG. 524.--A bud (“clove”), long. sec. (mag.).] [Illustration: FIG. 525.--_Punica granatum._ Flower, long. sec. (nat. size).] =3.= LECYTHIDEÆ. The majority are South American. The leaves are scattered, without pellucid glands, and frequently dentate. The flowers are zygomorphic. The woody fruits are either indehiscent, or open by a lid. To this belong: _Bertholletia_ (_B. excelsa_), the seeds well known as “Brazil-nuts,” _Lecythis_ (Sapucaia-nuts from _L. ollaria_), _Barringtonia_. =4.= LEPTOSPERMEÆ. Almost entirely from Australia and the East Asian and Pacific Islands. The fruit is a _capsule_. The leaves are scattered, and in some placed edgewise by the twisting of the leaf-stalks.--_Eucalyptus_, the Australian Gum-tree; the calyx falls off like a lid (Figs. 526, 527). Some of the species attain gigantic heights, _E. amygdalina_ 140–150 m. with a diameter of 8 m. The leaves in _E. globulus_ are opposite and dorsiventral on the young plant; on the older scattered, placed edgewise by the twisting of the leaf-stalk, and isolateral; _Metrosideros_, _Calothamnus_ (stamens distinctly polyadelphous), _Melaleuca_, _Leptospermum_, _Callistemon_ (the flowers are borne in spikes whose axis continues to grow after flowering, thus several zones of fruits may be seen on the same branch). [Illustration: FIGS. 526, 527.--_Eucalyptus globulus._ FIG. 526.--Long. sect. of flower. FIG. 527.--Flower opening.] =5.= CHAMÆLAUCIEÆ. Australian shrubs with heath-like appearance; they differ from the other Myrtaceæ in having a unilocular ovary with few, basal ovules, and a 1-seeded _nut_. The sepals are often pappus-like, and divided into many bristles.--_Chamælaucium_, _Darwinia_, etc. This large order (2,100 species) is confined almost entirely to the Tropics, being found principally in America and Australia. In Europe, only _Myrtus communis_.--Several are useful on account of the large quantity of _volatile oils_ (contained in internal glands): the flower-buds (“Cloves”) of _Eugenia caryophyllata_ (the Moluccas, cultivated in the Tropics, Figs. 523, 524); the unripe, dry berries (“Pimento”) of _Myrtus pimenta_ (_Pimenta officinalis_, W. Indies); Cajeput oil is extracted from _Melaleuca minor_ and _leucadendron_ (East Asian Islands). _Eucalyptus globulus_ (Australia) has of late years become well known on account of its rapid growth, its hard wood, and its antipyretic qualities; it is cultivated on swampy soils, which it helps to drain.--OFFICINAL: “Cloves,” and the cork of both stem and root of _Punica granatum_. Several have EDIBLE FRUITS, such as _Psidium guyava_ (Guava, var. _pomiferum_ and _pyriferum_, Am.), _Eugenia cauliflora_ and others, _E. jambosa_, _Punica granatum_ (the Pomegranate), etc. EDIBLE SEEDS (with abundance of _fatty oil_): “Brazil nuts” from _Bertholletia excelsa_ (Trop. S. Am.). “Bay-rum” is extracted from the leaves and fruits of the Bayberry-tree (_Pimenta acris_, W. Ind.); Guava-rum from the berries of _Eugenia floribunda_. _Tannin_ is found in large quantities _e.g._ in _Punica_. _Gum_ is formed by many Australian Eucalypti (“Gum-trees”). ORNAMENTAL PLANTS cultivated in this country are: _Myrtus communis_ (Mediterranean), several in conservatories, especially the Australian Leptospermeæ, Eucalyptæ and others. Family 24. =Umbellifloræ.= The flower is regular, ☿, and _completely epigynous_, 5- or 4-merous, with =1= whorl of stamens and 5–2 carpels. _Sepals very small, tooth-like._ The _corolla is polypetalous, most frequently valvate in æstivation_ (least pronounced in the Umbelliferous plants). Round the base of the styles, which are generally free, there is an _epigynous_ (undivided, or divided) _nectar-disc_ (“stylar-foot”: Figs. 528 _B_, _C_, _D_; 539); the number of loculi in the ovary equals that of the carpels; _only =1= pendulous (anatropous) ovule_ (Fig. 528 _C_) _in each loculus_. Endosperm copious (Fig. 528 _D_). To this must be added that the inflorescence in the majority of cases is an _umbel_ or a capitulum, especially in the _Umbelliferæ_ and _Araliaceæ_. Stipules are absent, but most frequently the base of the petiole forms a large sheath. The Umbellifloræ are on one side so closely allied to the Frangulinæ, especially Rhamnaceæ, that they may perhaps be regarded as the epigynous continuation of this family. On the other hand, the similarities to the Rubiales, especially those between Cornaceæ and Sambuceæ, are so great that there is scarcely any character to distinguish them except the polypetalous corolla of the former and the gamopetalous corolla of the latter. Whether this is more than a merely analogous resemblance, and if not, whether the Cornaceæ at least should not be included in the Rubiales, must be left in abeyance.--The sepals are very small, as is generally the case in epigynous flowers. Order 1. =Cornaceæ.= The majority of the species are shrubs with solid internodes, _opposite_ (rarely scattered) leaves, which are _simple_, _entire_ (rarely incised), penninerved, _without_ stipules or large sheaths; flowers _=4=-merous_ (most frequently S4, P4, A4, G2), borne in dichasia which are either collected into corymbs (_e.g._ _Cornus sanguinea_), or in closely crowded umbels or capitula (_Cornus mas_, _C. suecica_), in which latter case there is often a _large_, leafy, or coloured, most frequently 4-leaved _involucre_ round the base of the inflorescence; the _style is undivided_, with lobed stigma; the raphe of the ovule is turned _outwards_. The fruit is a _berry_ or a _drupe_, with a 1–4-locular stone or 2 free stones. _Cornus_ (Dogwood, Cornel) has S4, P4, A4, G2. Leaves opposite. _Drupe_ with a bilocular, 2-seeded stone.--_Aucuba_, diœcious; unilocular ovary; 1 ovule; 1-seeded berry.--_Garrya._--_Helwingia._ 80 species; N. Temp. The fruits of _Cornus mas_ are edible; the wood is very hard; gum is found in some. Several species of _Cornus_ and _Aucuba japonica_ (Japan) are cultivated as ornamental shrubs. Order 2. =Araliaceæ (Ivies).= Principally _trees_ or _shrubs_ with _solid stems_. The leaves are _scattered_, simple or compound, with a sheath more or less developed. The flowers are most frequently situated in umbels or capitula which are either borne singly or in racemes, or in paniculate inflorescences. The small, most frequently yellowish-green flowers are =5=-_merous_, in the calyx, corolla, and andrœcium; the gynœceum may be 5-merous or may have some other number (=2=-∞). The styles are most frequently several, free; the _raphe_ of the ovules is turned _inwards_ as in the Umbelliferous plants. The fruit is a _drupe_ or _berry_.--~Stellate hairs often occur. The petals generally have a broad base, and a thick apex which is slightly incurved, and a distinctly valvate æstivation.~ _Hedera helix_ (Ivy) climbs by adventitious roots. The leaves are palminerved and lobed on the sterile branches, but often ovate and not lobed on the flowering branches. ~The flowers are yellowish-green and open in the autumn; they are slightly protandrous, and are visited by flies and wasps. Berries black. Endosperm ruminate.--_Panax._ _Aralia_ (with _Dimorphanthus_).~ 375 species, 51 genera; especially in the Tropics (E. Asia).--The Ivy, several species of _Aralia_, _e.g._ _A. japonica_ (_Fatsia_), _Gastonia palmata_, are cultivated as ornamental plants. Paper is manufactured from the pith of _Aralia papyrifera_ (China). Order 3. =Umbelliferæ.= _The stem is herbaceous_ with _hollow internodes_; the leaves are _scattered_, and have a broad, amplexicaul base, a _large, most frequently inflated sheath_, and generally a pinnate (often very much dissected) blade. ~Entire leaves are found in _Hydrocotyle vulgaris_; _Bupleurum_.~ The flowers are ☿, regular, small, but collected in _compound umbels_, that is, in “simple umbels,” which again are borne in umbels (for exceptions see _Hydrocotyleæ_); the external flowers in the simple umbel have often subtending bracts, which surround the base as an _involucre_, and may be termed the _small involucre_; the internal ones have no bracts; when involucral leaves are present at the base of the compound umbel, they may be termed the _large involucre_. [Illustration: FIG. 528.--_Daucus carota_ with flower and fruit.] The _flower_ has =5= sepals (the median, as usual, posterior), =5= petals, =5= stamens and =2= carpels (in the median line) (Fig. 528). The calyx is often scarcely indicated. The petals have a short claw are most frequently obcordate, or have an incurved apex (Fig. 528 _B_, _C_), being incurved in the bud; they are white, rarely yellow (Fennel and Parsnips), blue or red. The flowers are sometimes zygomorphic, especially those on the circumference of the umbel, and in that case it is the petal which is directed outside (anterior) which is the largest, and the two posterior are the smallest (_e.g. Heracleum_). The stamens are _incurved_ in the bud. The 2 _free styles_ unite at the base into the “stylar-foot” (_stylopod_), a swollen nectary (Fig. 528 _B_, _C_); the ovary is bilocular, the raphe of the ovules being directed inwards. _The fruit is a schizocarp_, _dividing into two mericarps_; the plane in which these separate coincides with that of the union of the carpels, and the two _nut-like mericarps_ are in most genera kept together for awhile at the top of a thin, bifid, or undivided stalk (_carpophore_) which is in direct continuation with the flower-stalk (Fig. 537). Each mericarp has most frequently 5 more or less strongly projecting ridges, the _primary ridges_ (Figs. 530, 532, 534, 535, etc.), of which 3 lie on the back of the mericarp, the _dorsal ridges_, and 2 on its edge near the plane of division, the _marginal ridges_; five of these (10 ridges in all in the entire fruit) are placed opposite the calyx-teeth and the others between them. In some genera there are in addition 4 _secondary ridges_ to each mericarp between the primary ones (Fig. 528 _E_: the secondary ridges bear the long bristles). Inside these secondary ridges, or inside the grooves between the primary ridges, when the secondary ridges are absent, _oil ducts_ (vittæ, schizogenous ducts) are found in the pericarp, most frequently one in each groove; two are also often found on the ventral side of each mericarp (Figs. 528 _E_, 530 _ol_, etc.). The seed is most frequently united with the pericarp. The _embryo_ is _small_ and lies high up in the large, most frequently horny endosperm (Fig. 528 _D_).--The endosperm _does not contain starch, but oil_, and presents three different forms, of important systematic value: (=a=) those which are quite flat on the ventral side (_i.e._ the side turned towards the plane of splitting) (Figs. 528 _E_, 530, 531, 534, etc.): the majority of the genera, ORTHOSPERMEÆ (_e.g._ _Carum_, _Pastinaca_); (=b=) those in which the endosperm on the ventral side is provided with a longitudinal groove, often deep: CAMPYLOSPERMEÆ (_e.g._ _Anthriscus_); the transverse section is nearly a crescent (Fig. 532); (=c=) those in which the endosperm is concave on the ventral side (hollow in both longitudinal and transverse sections): CŒLOSPERMEÆ (_e.g._ _Coriandrum_) (Fig. 538). The genera are distinguished first of all by the endosperm and forms of fruit, the ridges and oil-ducts; then by the form of the umbel, the calyx and corolla, by the absence or presence of an involucre, etc. [Illustration: FIG. 529.--_Hydrocotyle vulgaris._ Transverse section of fruit.] 1. HYDROCOTYLEÆ, PENNY-WORT GROUP. _Capitula_ or _simple umbels_ (all the other groups have compound umbels). No oil-ducts. Orthospermous.--_Hydrocotyle_ (Penny-wort). The fruit is _considerably compressed_ laterally (Fig. 529). The calyx-teeth are small. The leaves are peltate.--_Didiscus._--_Sanicula_ (Sannicle). The umbels are small, capitate, generally collected in a raceme; calyx-teeth distinct. ♂-and ♀-flowers in the same umbel. The fruits are round, studded with hooked bristles. No carpophore.--_Astrantia_ has an umbel surrounded by a large, often coloured involucre, with this exception it is the same as the preceding, but the fruit is slightly compressed, with 5 equal ridges. _Hacquetia_ (_Dondia_).--_Eryngium_ (Sea Holly): leaves often thorny. The flowers _are all sessile_, the inflorescence is thus a capitulum; each flower is often subtended by a bract, which is thorny like the involucre, resembling the burrs of the Teasel. The sepals are large.--~_Lagœcia_: one of the loculi of the ovary is suppressed.~ [Illustration: FIG. 530.--Fruit of _Carum petroselinum_: _fr_ endosperm; _ol_ oil-ducts.] [Illustration: FIG. 531.--_Pimpinella._ Transverse section of fruit.] =2.= AMMIEÆ, CARAWAY GROUP (Figs. 530–532). The fruit has only the 10 primary ridges; it is usually short, almost spherical or broadly ovate and distinctly _compressed_ laterally. Oil-canals are most frequently present. Orthospermous (except _Conium_).--_Cicuta_ (Cow-bane). Pointed calyx-teeth. Glabrous herbs with pinnate or bipinnate leaves. ~_C. virosa_ has a thick, vertical rhizome, divided by transverse septa into many compartments; the leaflets are narrow, lanceolate, and dentate; the large involucre is wanting.~--_Apium_ (Celery). No calyx-teeth. _A. graveolens_, a maritime plant, has neither large nor small involucre; the umbels are short-stalked or sessile.--_Carum_ (Caraway). Calyx-teeth small; the large involucre is wanting or is only few-leaved. _C. carvi_ (Caraway). _C. petroselinum_, (Parsley) (Fig. 530). _Falcaria_; _Ammi_; _Helosciadium_; _Bupleurum_ (Hare’s-ear) with simple leaves and yellow corolla; _Pimpinella_ (Fig. 531); _Sium_; _Ægopodium_ (_A. podagraria_, Gout-weed) has bi- or tri-ternate leaves, with ovate, dentate leaflets; the large involucre is wanting.--_Conium_ is campylospermous (Fig. 532); the short, broadly ovate fruit has distinctly projecting, often wavy crenulate ridges. _C. maculatum_ (Hemlock) has a round, smooth stem with purplish spots. [Illustration: FIG. 532.--_Conium maculatum._ Fruit entire and in transverse section.] =3.= SCANDICEÆ. This group has a distinctly oblong or linear fruit which is _slightly compressed laterally_, and generally prolonged upwards into a “beak”; wings absent. _Campylospermous._ Otherwise as in the Ammieæ.--_Anthriscus_ (Beaked Parsley) has a lanceolate fruit, round on the dorsal side, without ridges, but with a ten-ridged beak.--_Scandix_ (Shepherd’s-needle).--_Chærophyllum_ (Chervil): fruit lanceolate or linear with low, blunt ridges; beak absent or very short. _C. temulum_ has a red-spotted, hairy stem.--_Myrrhis_ (Cicely) has a short beak and sharp, almost winged ridges. _M. odorata_ (Sweet Cicely) has very long fruits. [Illustration: FIG. 533.--_Œnanthe phellandrium._ Fruit entire and in transverse section. _emb_ The embryo; _ol_ the oil-ducts; _fr_ endosperm.] [Illustration: FIG. 534.--_Fœniculum vulgare._ Fruit in transverse section.] =4.= SESELINEÆ, FENNEL GROUP (Figs. 533, 534). The fruit is slightly elliptical or oblong, in transverse section circular or nearly so, without grooves in the dividing plane; only primary ridges are present. Orthospermous.--_Fœniculum_ (Fennel) has yellow petals; both involucres are wanting; the fruit is oblong. The ridges are thick, all equally developed, or the lateral ridges are slightly larger (Fig. 534).--_Æthusa_ (_A. cynapium_, Fool’s Parsley); the large involucre is wanting or is reduced to one leaf, the small involucre is composed of three linear leaves which hang downwards on the outer side of the umbels. The fruit is spherical-ovate, with thick, sharp, keeled ridges, the lateral ones of which are the broadest.--_Œnanthe_ (Dropwort); the fruit (Fig. 533) has usually an ovate, lanceolate form, with distinct, pointed sepals and long, erect styles; the ridges are very blunt, the marginal ones a trifle broader than the others.--_Seseli_, _Libanotis_, _Cnidium_, _Silex_, _Silaus_, _Meum_, etc. =5.= PEUCEDANEÆ, PARSNIP GROUP (Figs. 535–537). The fruit is most frequently very strongly _compressed_ dorsally, with broad, mostly _winged_, lateral ridges. Only primary ridges. The dorsal ridges may project considerably, but are not winged. Orthospermous. [Illustration: FIG. 535.--_Archangelica officinalis._ Transverse section of fruit.] [Illustration: FIG. 536.--_Scorodosma fœtidum._ Transverse section of fruit.] [Illustration: FIG. 537.--_Heracleum sphondylium._ Fruit.] =a.= The winged lateral ridges stand _out from each other_, so that the fruit appears to be 4-winged (Fig. 535).--_Angelica_; _Archangelica_ (Fig. 535); _Levisticum_ (Lovage). =b.= The winged lateral ridges lie _close together_, and form one wing on each side of the fruit (Fig. 536).--_Pastinaca_ (Parsnip). Corolla yellow. The dorsal ridges are very weak; the oil-ducts do not reach quite as far as the base of the fruit. Both large and small involucres are wanting; leaflets ovate. _Anethum_ (Dill) is a Parsnip with more distinct dorsal ridges and filamentous leaflets. _Peucedanum_ (Hog’s-fennel); _Ferula_ (with _Scorodosma_, Fig. 536, and _Narthex_); _Dorema_.--_Heracleum_ (Cow-parsnip); the flowers in the margin of the umbels are often very large, zygomorphic, and project like rays, _e.g._ in _H. sibiricum_. The fruit is very flat, with very small dorsal ridges; the oil-ducts are more or less club-like and _do not reach as far as_ the base of the fruit (Fig. 537). _Imperatoria_; _Tordylium_. =6.= DAUCEÆ, CARROT GROUP (Fig. 528). The fruit has 18 ridges, _i.e._ each fruitlet has 5 primary and 4 secondary ridges, the latter being often more prominent and projecting further than the primary ones. The oil-ducts are situated under the secondary ridges (Fig. 528). =a.= ORTHOSPERMOUS: _Daucus_ (Carrot). The secondary ridges project much further than the primary, and bear on their crests a series of hooked spines (Fig. 528 _D_, _E_); these are much longer than the small bristles on the primary ridges. ~The involucral leaves of _D. carota_ (Carrot) are numerous and deeply pinnate; the inflorescence contracts during the ripening of the fruit, and since the external umbels have longer stalks than the central ones, they arch over them, and the inflorescence becomes hollow. For the terminal flower, see below.~--_Cuminum_; _Laserpitium_; _Melanoselinum_. =b.= CAMPYLOSPERMOUS: _Torilis_ (Hedge Parsley). The primary ridges are covered with bristles; the secondary ridges are not. very distinct on account of the spines, which entirely fill up the grooves. _Caucalis_ (Bur Parsley). [Illustration: FIG. 538.--_Coriandrum sativum_: _b_ secondary ridges; _d_ primary ridges; _f_ endosperm; _l_ embryo.] =c.= CŒLOSPERMOUS: _Coriandrum_ (Coriander) has a smooth, spherical fruit (Fig. 538) with a distinct, 5-dentate calyx, the two anterior (_i.e._ turned outward) teeth being generally longer than the others; the two fruitlets scarcely separate from each other naturally; all the ridges project only very slightly, the curved primary ones least, the secondary ridges most. POLLINATION. The flowers are adapted for insect-pollination; they secrete nectar at the base of the styles; individually they are rather small and insignificant, but yet are rendered conspicuous by being always crowded in many-flowered inflorescences. _Protandry_ is common, sometimes to such an extent that the stamens have already fallen off before the styles begin to develop (Fig 539, 2). Insect visits are more frequent and numerous as the inflorescences are more conspicuous. The flowers as a rule are ☿, but ♂-flowers are often found interspersed among the others (Fig. 539), and the number of these becomes greater on the umbels developed at the latest period. A terminal flower, which differs from the others in form, and in _Daucus carota_ often in colour also (purple), is sometimes found in the umbel. The nectar lies so exposed and flat that the flowers are principally visited by insects with short probosces, especially Diptera; bees are less frequent visitors, and butterflies rare.--1400 species (175 genera); especially from temperate climates in Europe, Asia, N. Am. About 68 species in this country. [Illustration: FIG. 539.--_Anthriscus silvester_: 1 ♂-flower; 2 ☿-flower.] USES. A few are cultivated as ornamental plants. They are, however, useful in medicine,[38] and for culinary purposes on account of the _essential oils_ and _gum-resins_ which in many are formed in root, stem, and fruit. The FRUITS of the following are used: _Carum carvi_ [+] (Caraway), _Carum petroselinum_ (Parsley; also the leaves and root; its home is the Eastern Mediterranean); _Fœniculum capillaceum_ [+] (Fennel; S. Europe); _Pimpinella anisum_ [+] (Anise; E. Mediterranean); _Coriandrum sativum_ [+] (Coriander; S. Eur.); _Œnanthe phellandrium_ (Water Dropwort); _Cuminum cyminum_ (Point Caraway; Africa; cultivated in S. Europe); _Anethum graveolens_ (Dill). The LEAVES of the following are used as pot-herbs: _Anthriscus cerefolium_ (Chervil); _Myrrhis odorata_ (Sweet Cicely; Orient.); _Conium maculatum_ [+] (the green portions; Hemlock). Besides Parsley, the ROOTS of the following are used: Carrot, Parsnip, _Sium sisarum_ (Sugar-root; E. Asia); _Chærophyllum bulbosum_ (Chervil-root); _Levisticum officinale_ (foliage-shoots; S. Europe); _Imperatoria ostruthium_; _Apium graveolens_ (Celery, the root in conjunction with the internodes); _Pimpinella saxifraga_ and _magna_ (Pimpinell); _Archangelica_ (Angelica, the root of _A. norvegica_ was formerly an article of food in Norway). _Poisonous alkaloids_ are found in a few, such as Fool’s Parsley (_Æthusa cynapium_), Hemlock (_Conium maculatum_), Cow-bane (_Cicuta virosa_) and species of _Œnanthe_.--_Gum-resin_ is extracted from various species: “Galbanum” from _Ferula galbaniflua_ [+] and _rubricalis_ [+] (Persia); Asafœtida from _Ferula scorodosma_ [+] and _F. narthex_ [+]; Ammoniac-gum from _Dorema ammoniacum_ [+], all from Central and S. W. Asia. “_Silphium_” was an Umbelliferous plant which grew in ancient times in Cyrene, and from which the Romans extracted a valued condiment. Family 25. =Hysterophyta.= This family (with the exception of Aristolochiaceæ) includes only parasitic plants. Partly on this ground, and partly because they all have _epigynous_ flowers, they are considered to belong to the youngest type (which is expressed in the name ὕστερος, the one that comes after). It is not certain to which of the preceding families they are most nearly allied. ~Again, it is a matter of doubt whether the Aristolochiaceæ are related to the others; they are by Engler united with Rafflesiaceæ into one family, _Aristolochiales_.~ [Illustration: FIG. 540.--Flower of _Aristolochia clematitis_ (long. sect.). _A_ Before pollination, and _B_ after: _n_ stigma; _a_ anthers; _t_ an insect; _kf_ ovary.] Order 1. _Aristolochiaceæ._ The majority are perennial herbs or twining shrubs, whose stalked, simple, and generally more or less cordate or reniform leaves are borne in 2 rows and are exstipulate. The flowers are _hermaphrodite_, _epigynous_, regular or zygomorphic; perianth-leaves united, _simple_ but most frequently _petaloid_ and 3-merous; 6 or 12 (in _Thottea_ as many as 36) stamens with _extrorse_ anthers. The ovary is more or less completely 4–6-locular with ovules attached in the inner angles of the loculi (Fig. 540 _kf_). The style is short, and has a large, radiating stigma (Fig. 540 _n_). Fruit a capsule. Seeds rich in endosperm. _Asarum europæum._ Each shoot has 2 reniform foliage-leaves, between which the terminal flower is borne (the rhizome becomes a sympodium by development of the bud in the axil of the upper foliage-leaf). The flower is _regular_ and has a bell-shaped perianth with 3 outer valvate, and 3 inner small segments (which may be wanting). =12= (2 × 6) free, extrorse stamens, 6 carpels.--_Aristolochia clematitis_ (Birth-wort) has an erect, unbranched stem, bearing many flowers in the leaf-axils, in a zig-zag row (accessory buds in a unipared scorpioid cyme). The flowers are zygomorphic (Fig. 540), formed by 3 alternating, 6-merous whorls. The perianth has a lower, much-distended part (_k_), succeeded by a narrow, bent tube (_r_), which passes over into an oblique, almost tongue-like projection (6 vascular bundles indicate that the number 6 is prevalent here, as in _Asarum_); =6= stamens (Fig. 540 _a_), with the dorsal portion turned upwards, are united with the short style to form a _stylar column_; they are placed quite beneath the 6 commissural stigmatic rays, which arch over them as short, thick lobes. ~Protogynous; POLLINATION is effected in _Arist. clematitis_ by small flies; these enter the erect unfertilised flower through the tube (Fig. 540 _A_, _l_) without being prevented by the stiff, downwardly-turned hairs which line the tube and prevent their escape; they find the stigma (_n_) fully developed, and may pollinate it with the pollen they have brought with them. The stigmas then straighten and wither (_B_, _n_), the anthers open, and the flies may again be covered with pollen; but the hairs which blocked up the tube do not wither until the anthers have shed their pollen, and only then allow the imprisoned flies to escape and effect cross-pollination. Prior to pollination, the flowers stand erect, but after this has taken place they become pendulous, and the perianth soon withers.--_A. sipho_ (Pipe-flower), another species, is a climber, and often grown in gardens; it has only one row of accessory buds in the leaf-axils.--200 species; chiefly in S. Am. OFFICINAL: the rhizome of _Aristolochia serpentaria_ (N. Am.).~ [Illustration: FIG. 541.--A fruit of _Myzodendron brachystachyum_ (slightly mag.) germinating on a branch.] Order 2. =Santalaceæ.= Parasites containing chlorophyll, which, by the help of peculiar organs of suction (haustoria) on their roots, live principally on the roots of other plants. Some are herbs, others under-shrubs. The regular, most frequently ☿-flowers have a simple perianth, which is gamophyllous, 3- or 5 partite with the segments valvate in the bud, and a corresponding number of stamens opposite the perianth-leaves. In the inferior ovary there is a _free, centrally placed_, often long and curved _placenta_ with three ovules (one opposite each carpel); these are naked, or in any case have an extremely insignificant integument. Fruit a nut or drupe. Seed without testa. Endosperm fleshy. 225 species; chiefly in the Tropics.--_Thesium_, a native, is a herb with scattered, linear leaves and small 5-merous flowers (P5, A5, G3) in erect racemes; the subtending bracts are displaced on the flower-stalks. Fruit a nut.--_Osyris_ (diœcious shrub; 3-merous flowers) is another European genus.--_Santalum album_, which grows in E. Ind., yields the valuable, scented Sandalwood, the oil of which is used medicinally.--_Quinchamalium._ _Myzodendron_ is a reduced form of the Santalaceæ; the ♂-flowers are without perianth; the perianth of the ♀-flower is 3-merous. About 7 species; S. Am.; parasitic on a Beech (_Nothofagus_). The fruit has 3 feathery brushes, alternating with the lobes of the stigma, which serve as flying organs and to attach the fruits to a branch (Fig. 541), the brushes twining round as soon as they come in contact with it. There is only 1 seed in the fruit, which germinates by a long, negatively heliotropic hypocotyl, and is attached by a radicle modified into an haustorium. Order 3. =Loranthaceæ= (=Mistletoes=). Plants containing chlorophyll which are parasites on trees, and most frequently have opposite, simple, entire leaves and regular, epigynous, often unisexual, 2- or 3-merous flowers, with single or double perianth. Stamens equal in number and opposite to the perianth-leaves, free, or in varying degrees united to one another. The inferior ovary is constructed as in the Santalaceæ, the ovules being situated on a low, free, centrally-placed placenta, but the placenta and ovules unite with the wall of the ovary into _one connected, parenchymatous mass_, in which _the embryo-sacs are imbedded_. Only 1 (less frequently 2–3) of the 1–6 embryo-sacs is fertile. The number of the carpels however varies. The fruit is a _1-seeded berry_, whose inner layer is changed into a _tough slimy mass_ (bird-lime), which serves to attach the fruits to other plants. The two groups, _Loranthoideæ_ and _Viscoideæ_, are distinguished by the fact that the former has a distinct “calyculus,” _i.e._ an entire or lobed, or dentate swelling on the receptacle below the perianth. The majority of the Loranthoideæ have a petaloid perianth; in all the Viscoideæ, on the other hand, it is sepaloid. [Illustration: FIG. 542.--_Viscum album_: _A_ branch with leaves and berries: _a_ scale-leaves; _b_ foliage-leaves; _n_ _m_ _n_ flowers; _B_ seedling, the bark of the branch being removed; _C_ an older embryo which still retains the cotyledons.] [Illustration: FIG. 543.--To the left the Rafflesiaceous _Cytinus hypocistus_, parasitic on the roots of _Cistus_. To the right the Balanophoraceous _Cynomorium coccineum_, parasitic on the roots of _Salicornia_.] The Mistletoe (_Viscum album_, Fig. 542) is a native, evergreen plant which may be found growing on almost any of our trees (sometimes on the Oak), and, like other Loranthaceæ, it produces swellings of the affected branches. ~Its spherical white berries (Fig. 542 _A_) enclose (1–) 2–3 green embryos; they are eaten by birds (especially Thrushes), and are partly sown with their excrement, partly struck or brushed off the branches of the trees, the seed being enclosed, at maturity, by viscin, _i.e._ “bird-lime.” The seeds may also germinate on the branches, without having first passed through the alimentary canal of the birds. On germination, the hypocotyl-axis first appears, as in Fig. 541, and bends towards the branch; the apex of the root then broadens, and forms at the end a disc-like haustorium, from the centre of which a root-like body grows through the bark into the wood, and ramifies between the bark and wood. Suckers are developed on the root like strands which are formed in this manner, without, however, having a rootcap; they are green, and penetrate the wood by the medullary rays (Fig. 542 _C_). Adventitious buds may also be developed from the root-like strands which break through the bark and emerge as young plants. The young stem quickly ceases its longitudinal growth, and lateral shoots are developed from the axils of its foliage-leaves. These and all following shoots have a similar structure; each of them bears a pair of scale-leaves (Fig. 542 _A_, _a_) and a pair of foliage-leaves (Fig. 542 _A_, _b_), and then terminates its growth, if it does not produce an inflorescence; new lateral shoots proceed from the axils of the foliage-leaves, and the branching, in consequence, is extremely regular and falsely dichotomous. Only one internode (shoot-generation) is formed each year, so that each fork indicates one year. The foliage-leaves fall off in the second year. The inflorescence is a 3(-5)-flowered dichasium (Fig. 542 _A_, _m_ is the central flower, _n_ the lateral). The plants are _diœcious_; the ♂-flower as a rule is 2-merous: perianth 2 + 2, each leaf of which bears on its inner side 6–20 pollen-sacs, each of which opens by a pore; this relationship may be considered to have arisen from the union of the perianth-leaves with the multilocular stamens (2 + 2) placed opposite them. The ♀-flowers always have Pr 2 + 2, G2.--_Loranthus_ is also found in Europe (it has a 3-merous flower), especially in the central and south-eastern districts, on _Quercus cerris_ and _Q. pubescens_; but the great majority of the 520 species grow in the Tropics on trees which they ornament with their often brightly-coloured flowers, and ultimately kill when present in too great numbers. The pollination in the numerous Loranthaceæ with unisexual flowers, is effected by the wind. In _Viscum album_ this takes place in autumn, the actual fertilisation in the following spring, and the maturity in November or December; in the succeeding month of May the berry is ready to germinate, and falls off.~ USES. Birdlime from _Viscum album_. Order 4. =Rafflesiaceæ= and Order 5. =Balanophoraceæ=. These orders comprise _root-parasites_, almost entirely devoid of chlorophyll; they are reddish or yellow, without foliage-leaves (Fig. 543). As far as our knowledge of these rare tropical plants extends, they have thalloid organs of vegetation resembling the root-like strands of _Viscum_, or they are filamentous and branched like Fungus-hyphæ; they live in and on the tissues of the host-plant, from which their flowering-shoots, often of mushroom-like form, are subsequently developed (Fig. 543). In order to unfold they must often break through the tissues of the host-plant. Of the RAFFLESIACEÆ, _Cytinus hypocistus_ is found in S. Europe living on roots of _Cistus_-plants and to some extent resembling _Monotropa_ (Fig. 543). _Rafflesia_ is the best known; it lives on roots of _Cissus_-species (belonging to the Ampelidaceæ) in Java; its yellowish-red, stinking flowers attain a gigantic size (one metre or more in diameter), and are borne almost directly on the roots of the host-plant. Besides these there are other genera: _Brugmansia_, _Pilostyles_, _Hydnora_.--To BALANOPHORACEÆ (Fig. 543) belong: _Balanophora_, _Langsdorffia_, _Scybalium_, _Sarcophyte_, _Helosis_, etc., and in S. Europe, _Cynomorium coccineum_. Sub-Class 2. =Sympetalæ.= The characters which separate this from the first Sub-class, the Choripetalæ, have been described on page 336. They consist in the following: the flower is always verticillate, generally with =5= sepals, =5= petals, =5= stamens, and =2= carpels (in the median plane), the calyx is generally persistent and gamosepalous, the corolla is gamopetalous and united to the stamens, which are therefore adnate to it, the ovules have only _one_ thick integument and a small nucellus. (The exceptions are noted later.) This Sub-class is no doubt more recent than the Choripetalæ; it is also peculiar in including fewer trees and shrubby forms than the latter. The Sympetalæ may be separated into 2 sections:-- =A.= PENTACYCLICÆ (FIVE-WHORLED). The flowers in this section have 5 _whorls equal in number_, namely, 2 staminal whorls in addition to the calyx, corolla, and carpels; in some instances, one of the staminal whorls is rudimentary or entirely suppressed, but in this case it is frequently the sepal-stamens which are suppressed, and the whorl which is present stands opposite the petals. The flowers are regular. The _number of carpels equals that of the sepals_, but in one of the orders (_Bicornes_) they are opposite the petals (the flower being obdiplostemonous); in the other two orders (_Primulinæ_ and _Diospyrinæ_) they are placed opposite the sepals (the flower being diplostemonous). This section is the most closely allied to the Choripetalæ, since the petals may sometimes be found entirely free, and the stamens inserted directly on the receptacle (Ericaceæ); ovules with two integuments are also found. ~It is very doubtful, whether the orders included under this head have any relationship with the other Sympetalæ. They appear in any case to represent older types.~ =B.= TETRACYCLICÆ (FOUR-WHORLED). The flowers have only 4 whorls, namely, beside sepals, petals, and carpels, only one whorl of stamens, which alternates with the petals; there is no trace of the second staminal whorl, and when the number of carpels is the same as that of the preceding whorls (“isomerous”) they alternate with the stamens; but in most cases there are 2 _carpels placed in the median plane_ (see the diagrams, _e.g._ Figs. 559, 567, 583, 590, etc.). This section is the largest, and the one which shows the characteristics of the Sympetalæ best. Very irregular flowers are met with. The following families belong to the =Pentacyclicæ=: 26, _Bicornes_; 27, _Diospyrinæ_; 28, _Primulinæ_. The remaining families belonging to the =Tetracyclicæ= are:-- =a.= HYPOGYNOUS flowers (with a few exceptions): 29, _Tubifloræ_; 30, _Personatæ_; 31, _Nuculiferæ_; 32, _Contortæ_. =b.= EPIGYNOUS flowers: 33, _Rubiales_; 34, _Dipsacales_; 35, _Campanulinæ_; 36, _Aggregatæ_. The ovaries and ovules in the last family are always reduced to one; and at the same time the fruits become nuts, and the flowers are united into crowded inflorescences. A. Pentacyclicæ. Family 26. =Bicornes.= This family is chiefly composed of shrubs, less frequently of small trees, or perennial herbs; their leaves are undivided, most frequently evergreen, stiff and leathery, and always without stipules. The flowers are ☿ and _regular_, rarely slightly zygomorphic, most frequently obdiplostemonous, and 4- or 5-merous through all the 5 whorls. _The stamens are attached to the receptacle_, and as a rule are quite free from the petals, an attachment which is very rare among the Gamopetalæ. They have a simple gynœceum with _one_ undivided style, a commissural stigma, and a _multilocular_ ovary, whose axile placentæ project considerably into the loculi, and bear a large number of ovules. ~The placentæ are sometimes not united, and in consequence, the ovary is 1-locular with incomplete partition-walls, _e.g._ _Pyrola_, _Monotropa_.~ Embryo straight, with endosperm. _The carpels are placed opposite the petals._ The _diagram_ is generally Sn, Pn, An + n, Gn, in which n is 4 or 5. To this may be added, that the _corolla is in most cases gamopetalous_, but in some (especially _Pyrolaceæ_) perfectly polypetalous; and that the _anthers usually open by pores_, and often have _two horn-like_ appendages (hence the name “Bicornes”) (Figs. 545, 546); frequently the two halves of the anther are also widely separated from each other at the upper end, so that the pores are placed each one at the end of its own tube (Fig. 546); the pollen-grains in the majority are united into _tetrads_ (Fig. 542 _D_).--The flowers, as a rule, are pendulous and borne in racemes, coloured (red or white), but odourless. When the fruit is a capsule, the placenta with the seeds attached persists as a central column. A _mycorhiza_ occurs on many. The majority of plants belonging to this family inhabit cold and temperate countries, or high mountains in tropical regions; they prefer cold and dry or damp places (bogs, heaths, etc.). Plentiful in N. America. Order 1. =Pyrolaceæ.= Perennial _herbs_; _petals most frequently quite free from each other_, and falling off singly after flowering; _the anthers are without appendages_, and open by pores (Fig. 544), or by a transverse slit. The placentæ are thick. The seeds in the _capsule-like_ fruit (loculicidal dehiscence) are exceedingly small and light, they have a sac-like testa which loosely envelops them, an oily endosperm, and an _extremely simple embryo_, which consists only of an ellipsoidal, cellular mass, without cotyledons or differentiation into plumule and radicle. _Pyrola_ (Winter-green) is green, and has also large evergreen foliage-leaves. The flowers, 5-merous, are most frequently borne in racemes without a terminal flower; the anthers are extrorse in the bud with the pores in the lower portion (Fig. 544 _A_), but they become inverted at a later period, so that the pores open at the top (Fig. 544 _C_). ~_P. uniflora_ has a single, terminal flower; it winters by its roots, producing from these in the spring aerial, quite unbranched shoots. _Chimaphila umbellata._~ [Illustration: FIG. 544.--_Pyrola minor_: _A_ portions of a young flower; _B_ the stigma; _C_ portions of an older flower (longitudinal section).] _Monotropa_ (Yellow Bird’s-nest) is very pale yellow, without chlorophyll, succulent, and has only scale-like leaves closely pressed upon the stem; it is a saprophyte. The raceme has a terminal flower, and is pendulous before flowering. The anthers open by a semicircular, transverse cleft. ~_M. hypopitys_ reproduces chiefly by root-shoots.~ About 30 species, especially N. Europe, N. America, and N. Asia. Order 2. =Ericaceæ.= The flower (Fig. 545) is _hypogynous_, the median sepal posterior; corolla, _gamopetalous_; the stamens are generally _2-horned_, and the fruit is a _capsule_, less frequently a berry or drupe. At the base of the ovary is a nectar-secreting disc (Fig. 545 _B_). This order comprises shrubs or undershrubs (rarely small trees), which are evergreen, and as a rule have densely crowded leaves. =1.= ERICEÆ, HEATH GROUP. Flowers most frequently _4-merous_ (S4, P4, A4 + 4, G4, united in a 4-locular gynœceum), rarely 5-merous. The withered corolla _persists_ after flowering. The leaves are most frequently acicular, opposite or verticillate; the buds are without scales. The fruit is a capsule.--_Calluna_ (_C. vulgaris_, Ling) has a deeply 4-cleft corolla, which is less than the coloured calyx; capsule with septicidal dehiscence.--_Erica_ (about 420 species; _E. tetralix_, Cross-leaved Heath) has a tubular or bell-shaped, 4-dentate corolla, which is much longer than the calyx. Capsule with loculicidal dehiscence.--_Pentapera._ =2.= ANDROMEDEÆ. The flowers are 5-merous (S5, P5, A5 + 5, G5), with _deciduous_ corolla. Capsule with loculicidal dehiscence. The leaves are scattered, and incline more to the ordinary broad-leaved forms.--_Andromeda_; _Gaultheria_; _Cassandra (Lyonia)_; _Cassiope_. [Illustration: FIG. 545.--_Arctostaphylos uva-ursi._] =3.= ARBUTEÆ. The flowers as in the preceding group (Fig. 545), but the fruit is a berry or drupe. _Arctostaphylos_ (_A. uva-ursi_, Bear-berry) has a drupe with 5 stones in a dry, farinaceous pulp; in other species there is 1 stone with several loculi. _Arbutus_ (_A. unedo_, Strawberry-tree) has a spherical berry. _Pollination_ is effected by means of insects, especially by bees. The pollen is light and dry, and is shaken out through the pores of the anthers when the insects agitate the horn-like appendages during their visits. Self-pollination takes place, no doubt, in many cases.--800 species; the very large genus, _Erica_, especially in S. Africa (the Cape).--OFFICINAL: the leaves of _Arctostaphylos uva ursi_. _Arbutus unedo_ (S. Europe) has an edible, peculiarly warted (strawberry-like) fruit. Many _Erica_-species are cultivated as ornamental plants. Order 3. =Rhodoraceæ= (=Rhododendrons=). This differs from the preceding order in the _median sepal being anterior_, and hence the position of the other floral whorls is also reversed. The flower is _hypogynous_, in most cases 5-merous; the corolla is most frequently deeply cleft or polypetalous, and falls off after flowering; the anthers open by pores, and have _no horn-like appendages_. _Capsule_ with _septicidal_ dehiscence.--The shrubs or small trees belonging to this order have, like the Vaccineæ, ordinary foliage-leaves, and the buds are generally provided with _large bud-scales_. _Rhododendron_ has 10 stamens, and a slightly zygomorphic flower with deeply 5-cleft corolla (the section _Azalea_ has frequently only 5 stamens, the petal-stamens being absent). They are Alpine plants (200 species) in the mountains of Asia, especially the Himalayas; some in S. Europe.--_Menziesia._--_Ledum_; small, rusty-brown, hairy shrubs with polypetalous, expanded, star-like corolla.--_Kalmia_ (N. Am.) has a cupular corolla, with 10 small, pocket-like depressions in which the anthers are concealed until the arched, elastic filaments are freed from this position by means of the insects, when they quickly straighten themselves in the centre of the flower.--_Phyllodoce_; _Loiseleuria_ (5 stamens); (_Clethra_ (?); also placed among the Ternstrœmiaceæ). About 270 species. Several species are ornamental plants. Several plants of the order are more or less _narcotic_. _Ledum palustre_ has been used as a substitute for hops. Order 4. =Diapensiaceæ.= Hypogynous flower. 3 floral-leaves beneath the flower (S5, P5, A5 + 0, G3). Stamens on the throat of the corolla. Pollen-grains single. Disc absent. Capsule loculicidal.--9 species from the Arctic regions. It is doubtful whether this order should be included in the Bicornes; perhaps it would be more correctly assigned to the _Polemoniaceæ_. Order 5. =Epacridaceæ.= This order comprises those species of the family which are confined to Australia and the South Sea Islands. They are shrub-like plants, resembling the Ericaceæ in habit, in the inflorescence, and in the structure, form, and colour of the flower. They differ especially in having only 1 _whorl of stamens_ (placed opposite the sepals) and in the anthers having only 2 loculi, and opening by a longitudinal slit. Fruit most frequently a drupe (or loculicidal capsule). _Epacris_-and _Styphelia_-species are ornamental plants. About 325 species. Order 6. =Vacciniaceæ= (=Bilberries=). _The flower_ (Fig. 546) _is epigynous, the corolla gamopetalous_, and _the fruit a berry_. The latter is most frequently spherical, and bears on its apex the calyx, which is generally very low, almost entire, and with a _disc-like expansion_ inside. The flower is 4- or 5-merous (Fig. 546 _B_, _D_). The anthers have 2 pores, and are most frequently 2-horned (Fig. 546 _F_, _G_). Small shrubs; the leaves are scattered, not needle-like. _Vaccinium_ (Bilberry, Whortleberry) has an urceolate, gamopetalous, only slightly dentate corolla, and horn-like appendages to the anthers (Fig. 546). ~_V. vitis idæa_ (Cowberry) is evergreen, with flowers in racemes, and bright red berries; _V. myrtillus_ (Bilberry) and _V. uliginosum_ (Bog Whortleberry) both have black berries with a blue bloom, leaves deciduous.~--_Oxycoccus_ has a _polypetalous_ corolla with the petals projecting backwards. Anthers without appendages. ~_O. palustris_ (Cranberry) has a slender, creeping stem, and is evergreen. Dark red berry.~ Pollination essentially the same as the preceding order.--320 species; especially in N. Am. Some are useful on account of their edible fruits, especially _Vaccinium myrtillus_ and _V. vitis-idæa_, and in a less degree _Oxycoccus_, etc. The fruits of _V. myrtillus_ are _officinal_. [Illustration: FIG. 546.--_Vaccinium uliginosum_ (var. _microphyllum_). The parts of the flower _A-E_ are enlarged 5–6 times; _C_ and _E_ are longitudinal sections; _B_ and _D_ the flower seen from above; _F_ and _G_ a stamen seen from the back and front; _H_ the style and stigma.] Family 27. =Diospyrinæ.= The flowers are _regular_, gamopetalous, typically diplostemonous, with the same number throughout all 5 whorls, thus: Sn, Pn, An + n, Gn, where n most frequently =5 (4–6), rarely 3, 7 or 8. Of the two whorls of stamens the one opposite the sepals is often present only as rudiments or is entirely suppressed, and the completely developed _stamens are thus placed opposite the petals_. The carpels are generally placed opposite the sepals. The _ovary is multilocular_ with the ovules attached in the inner angles. The fruit is most frequently a _berry_. The seeds are large, generally solitary, or a few in each loculus.--All plants belonging to this family are _trees_ or shrubs with _scattered_, _single_, _most frequently entire_, _penninerved_ and _leathery_ leaves without stipules; the majority are tropical (America, Asia), some are found in N. Am. and the Mediterranean. Order 1. =Sapotaceæ.= Plants with latex; anthers extrorse, 1 _erect_ ovule in each loculus; fruit a berry; the seeds with bony, shiny brown testa have a large, lateral hilum. The leaves are frequently covered with silky hairs.--A useful order in several respects (400 tropical species). The wood of some genera, such as _Sideroxylon_ (Iron wood) and _Bumelia_, is as hard as iron. The latex of _Palaquium_ (_P. oblongifolium_, _P. gutta_, and other species), _Mimusops_ and _Payena_ (Sumatra, E. Ind.), is the raw material of _gutta percha_. The following have very delicious fruits: _Lucuma mammosa_, _Achras sapota_, _Chrysophyllum cainito_ (Star-apple), etc. The seeds of _Bassia_ (E. Ind.) contain a large quantity of a fatty oil. _Isonandra_, _Mimusops schimperi_ are often found in the Egyptian royal tombs. Order 2. =Ebenaceæ.= Plants without latex, often diœcious; flowers with a more or less leathery perianth. The number of stamens is sometimes increased (by splitting?); ovules 1–2, _pendulous_ in each loculus. Fruit a berry.--250 species; chiefly tropical. Some are well known on account of their hard and black-coloured heart-wood, _e.g._ _Maba ebenus_ (the Moluccas) and _Diospyros ebenum_ (Ebony-wood, from Tropical Asia) and others.--The fruits are edible _e.g._ of _Diospyros lotus_ (Date-plum, Asia), which is also cultivated as an ornamental shrub, together with several other species. Order 3. =Styracaceæ.= The flower is more or less _epigynous_, and the corolla is almost _polypetalous_. The stamens (by splitting?) are more than double the number of the petals, and often united at the base. Stellate hairs are frequent.--235 species; Tropical Asia and America, a few for example in the East.--OFFICINAL: Gum-benzoin from _Styrax benzoin_ and perhaps other species (Sumatra and Siam). _Halesia tetraptera_ (N. Am.) is an ornamental shrub with 4-winged fruits. [Illustration: FIG. 547.--Diagram of _Primula_.] Family 28. =Primulinæ.= The flowers are _regular_, ☿, _hypogynous_, and gamopetalous. The _stamens_ are _equal in number_ to the petals (Fig. 547) and _are placed opposite to them_. The ovary is _unilocular_, with _a free, central_ placenta with 1–many ovules.--The flower is a further development of the Diospyrinæ; the suppression of the calyx-stamens, which commenced in this family, is carried further in the Primulinæ, so that in the majority of cases no trace of them is present, but in certain species and genera (_Samolus_, _Lysimachia thyrsiflora_, _Soldanella_, certain Myrsineæ) some small bodies (scales, teeth, etc.) are found in the position of the suppressed stamens. Again, the lateral portions of the carpels are suppressed, so that the _ventral placentæ_ with the ovules are separated from the dorsal portions, and _are united into a free central placenta_; this theory is supported by the branching of the vascular bundles, the development, and various comparative considerations.--Sn, Pn, A0 + n, Gn; where n = 4–8, generally 5. The carpels are placed opposite the sepals (Fig. 547). Order 1. =Primulaceæ= (=Primroses=). This order has _many ovules_ attached to a _thick, free, central placenta_ (Fig. 547); _style undivided_ with a _capitate_ stigma; ovules semi-anatropous; fruit a _capsule_ with many seeds. All the plants belonging to this order are _herbs_; stipules wanting; the flower is most frequently 5-merous (S5, P5, A0 + 5, G5; except _Centunculus_ and _Trientalis_). The corolla and capsule have various forms, but the capsule generally opens by teeth at the apex. The ovules are semi-anatropous (in _Hottonia_ they are anatropous), and the seeds are therefore _peltate_, with the hilum situated in the centre of one side. The endosperm is fleshy or horny. The flowers are borne either in racemes or in umbels; as _bracteoles are typically_ absent (Fig. 547), cymose branching does not occur. [Illustration: FIG. 548.--_Primula_: dimorphic flowers. _A_ short-styled; _B_ long-styled.] [Illustration: FIG. 549.--_Cyclamen persicum._] _Primula_ (Primrose) has most frequently a vertical rhizome, bearing a rosette of leaves at its summit, and long-stalked umbels; corolla _rotate_ or slightly funnel-shaped; the capsule opens at the apex by 5 _teeth_. The flowers in some species are heterostyled (long-styled or short-styled; Fig. 548). Closely allied are _Androsace_ (with ovate, cup-shaped corolla-tube and ligular scales, alternating with the corolla-lobes) and _Soldanella_ (funnel-shaped corolla with laciniate lobes and most frequently ligular scales).--_Hottonia_ (Water-Violet) is an aquatic plant with pectinate leaves and heterostyled flowers.--_Cortusa._ _Dodecatheon._ _Cyclamen_ (Fig. 549) has solitary, long-stalked flowers, and a rotate corolla with the lobes reflexed; the stalk of the capsule rolls up spirally; the tuberous rhizome is formed by the hypocotyledonary internode. Only 1 cotyledon.--_Lysimachia_ (Money-wort); stem-internodes well developed, leaves opposite or verticillate, calyx almost polysepalous, corolla deeply 5-partite (Fig. 550). The flowers are solitary or in racemes.--_Anagallis_ (Pimpernel), leaves opposite, flowers solitary; the fruit a pyxidium (Fig. 551); similarly in _Centunculus_, which is 4-merous.--_Trientalis_, the flowers are most frequently 7-merous.--_Glaux_ (Sea Milk-wort) is a creeping maritime plant with opposite leaves; flowers solitary in the leaf-axils, _corolla absent_, but with coloured calyx. ~The petals are usually developed later than the stamens in the Primulaceæ; but in this instance they are entirely suppressed.~--_Samolus_ (Brookweed) differs from all the others in having an _epigynous_ flower; barren sepal-stamens are also present. The bracts in the racemose inflorescences are displaced along the flower-stalks. [Illustration: FIG. 550.--_Lysimachia thyrsiflora._] [Illustration: FIG. 551.--_Anagallis arvensis._ Fruit dehiscing.] POLLINATION. Insect-pollination in the majority; cross-pollination is promoted in some by heterostyly (Fig. 548).--300 species; especially in northern temperate zones; the majority on mountains (_Soldanella_, _Androsace_, etc.); almost absent in the Tropics. A large number are ORNAMENTAL PLANTS, _e.g._ _Primula auricula_ (from the Alps), _P. sinensis_ (China), _P. elatior_ (Oxslip, a native) and _grandiflora_, etc. _Cyclamen europæum_ (Alpine Violet); the tubers are poisonous. Order 2. =Myrsinaceæ.= Trees or shrubs; evergreen, tropical Primulaceæ with fleshy fruits and few seeds, embedded in the placenta. The leaves are nearly always dotted with yellow glands (schizogenous resin-receptacles).--550 species; especially Am.--ORNAMENTAL PLANTS: _Ardisia crenulata_ (W. Ind.); other genera: _Clavija_, _Maesa_, _Theophrasta_ (barren sepal-stamens), _Myrsine_, _Jacquinia_ (barren sepal-stamens), etc.--_Ægiceras_, allied to this order, comprises arborescent plants, often growing with _Rhizophora_ in tropical forests, along the shore. The embryo germinates while still in the fruit. Order 3. =Plumbaginaceæ.= This order has a position of the stamens similar to that in Primulaceæ (S5, P5, A0 + 5, G5), but it differs from these in the flower, which has generally a _membranous_, dry, thin, coloured, folded, almost entire calyx and an _almost entirely polypetalous corolla_, which, as a rule, has twisted æstivation and is _only united_ with the stamens _at its base_; but more especially it differs in the ovary, which bears 5 _free_ or almost free _styles_ and only 1 _basal_ ovule with a _long_, twisted funicle (the placenta of the Primulaceæ is here so much reduced that it bears only 1 ovule). The fruit is a _nut_ or _capsule_. The radicle is turned outwards. Endosperm mealy.--To this order belong herbs or under-shrubs, which are especially natives of the sea-coast and of salt-steppes; they also resemble the Primulaceæ in the scattered, undivided, entire leaves (without stipules), often in rosettes, and the inflorescence borne on a long stalk. In opposition to the Primulaceæ, the _bracteoles are typically present, and hence the branching is generally cymose_ (scorpioid). _Armeria_ (Thrift) has a round _capitulum_, composed of closely-packed dichasia, surrounded at its base by an involucre with peculiar prolongations, directed downwards, and united into a sheath protecting the intercalary zone of growth. The pericarp is finally ruptured at the base, and drops off like a hood.--In _Statice_ (Sea-lavender), the unipared scorpioid cymes are prolonged and collected into panicle-like inflorescences.--~_Plumbago_ is the genus which approaches nearest to the Primulaceæ, and differs most from the characters given above. It has capitate or spike-like inflorescences, a salver-shaped corolla, and the stamens are not attached to the corolla. The style is only divided at the extremity; the calyx is not membranous, but is covered with sticky, glandular hairs.~ 250 species; chiefly in the Mediterranean and about the Caspian Sea, on salt-steppes and beaches. Some are Tropical; a few are ornamental plants. B. Tetracyclicæ. a. Tetracyclicæ with hypogynous flowers. Family 29. =Tubifloræ.= The flower is regular, ☿, and _hypogynous_. The gamopetalous type is present in this family with great uniformity, without suppression or splitting; S5, P5, A5, G2 (3–5). The stamens are all fertile, alternating with the lobes of the corolla. Gynœceum with 2, more seldom 3–5 syncarpous carpels. Style nearly always simple; 2 dorsal stigmas. In each carpel 2–∞ ovules. At the base of the ovary is found a yellowish ring-like nectary (Fig. 552 C), sometimes 5-sinuate or 5-partite.--The leaves are nearly always scattered; stipules are absent.--~The Solanaceæ, which formerly were classed here, are so closely allied to the Personatæ, that it would be unnatural not to place them first in this family; and the Boraginaceæ (which were also placed in the Tubifloræ) appear to be best united, with the Labiatæ and others, into one family Nuculiferæ.~ Order 1. =Polemoniaceæ.= The flowers are regular; S5, P5, A5, G3. The calyx and corolla have united leaves, the petals _twisted_ to the right in _æstivation_ (all the left edges being covered). The ovary is 3-locular with 2–∞ ovules in each loculus; the style is trifid at the apex; the fruit is a 3-valved capsule. Embryo straight; endosperm fleshy. The inflorescences are dichasia passing over into unipared helicoid cymes (the shoot of the _lower_ bracteole being the more strongly developed).--Herbs without latex. 150 species; especially Western N. Am.--_Phlox_ (salver-shaped corolla; entire, opposite leaves), _Polemonium_ (campanulate or almost rotate corolla; scattered, pinnate leaves), _Leptosiphon_, _Gilia_, _Collomia_, _Cobæa_ (climbing, like the Vetches, by tendrils at the ends of the leaves), etc. They are frequently ornamental plants. Order 2. =Hydrophyllaceæ.= This order approaches very closely to the Boraginaceæ. Herbs with pinnate or palmate leaves; S5, P5, A5, G2. The lobes of the corolla are imbricate in æstivation. Generally 2 median carpels. The ovary is _most frequently unilocular_, and the seeds are situated on 2 _parietal placentæ_; capsule 2-valved; embryo straight; endosperm fleshy. In the corolla-tube, opposite the corolla-lobes, there are frequently appendages of various forms, which resemble those of _Cuscuta_. The inflorescences correspond exactly with those of the Boraginaceæ, being _unipared scorpioid cymes_, which, prior to opening, _are tightly rolled up_.--130 species, especially in N. Am. (California, etc.). Many annual species of _Phacelia_, _Nemophila_, _Whitlavia_, _Eutoca_, _Cosmanthus_, etc., are cultivated in gardens as ornamental plants. _Hydrolea_ (has a bilocular ovary, and two free styles). Order 3. =Convolvulaceæ= (=Bindweeds=). The flower is regular, hypogynous, with 5 almost free sepals (quincuncial æstivation), P5, A5, G2 (rarely 3–5). The _corolla_ is very characteristic; it is (with various forms) almost entire, or slightly 5-lobed, and _folded_ longitudinally _in the bud_ in such a way that 5 projecting, flat portions, tapering towards the top and frequently differing in colour and hairiness from the rest, are visible externally and applied close together, while the remainder of the corolla is folded inwards (Fig. 552 A); and hence the whole corolla is _strongly twisted to the right_ in the bud. The gynœceum most frequently has a bilocular ovary; _in each loculus_ there are _only_ 2 (erect) _anatropous ovules_ on the placenta, which is not especially thickened (Fig. 552 _D_, _E_); each loculus is sometimes divided into two by a false septum (a relationship with the _Boraginaceæ_, etc.); style simple with most frequently a bilobed stigma, or a bipartite style. The fruit is nearly spherical, most frequently a _capsule_. The seeds are erect, and have a large hilum at the base. The embryo is _curved_, with leaf-like, thin, bilobed, most frequently folded cotyledons; _endosperm absent or mucilaginous_. =1.= CONVOLVULEÆ, BINDWEED GROUP. The majority are _twining_ (to the left) _herbs_, with _latex_. The leaves are scattered, without stipules, often long stalked, and nearly always with cordate base; some are palmately lobed. The flowers are most frequently solitary in the leaf-axils, large, quickly withering.--_Convolvulus_ (Fig. 552), _Calystegia_ (unilocular ovary, 2 large bracteoles), _Ipomœa_, _Batatas_, _Evolvulus_ (with a doubly bifid style), _Calonyction_, _Pharbitis_, etc. [Illustration: FIG. 552.--_Convolvulus scammonia._] =2.= DICHONDREÆ. This group is a more primitive form, not twining, and without latex. It has 2 _free_ carpels with basal style (as in Boraginaceæ) and valvate corolla. =3.= CUSCUTEÆ, DODDER GROUP (Fig. 553). Parasites, with round, filamentous stems, bearing only scale-like leaves and almost destitute of chlorophyll (they are reddish or yellowish); they are parasitic upon other plants, around which they twine, first with narrow, compact coils from which haustoria (Fig. 553 _A_) are developed which enter the host-plant, and then with wider coils by which they raise themselves to other portions of their host or try to reach other plants. On germination a very temporary primary root is developed, which bears root-hairs as far as the tip (rootcap is wanting); it only serves as a kind of reservoir for water, and perishes very soon after the seedling has fastened on to a host. The embryo is filamentous and rolled up _spirally_ (Fig. 553 _C_), and is sometimes destitute of cotyledons. The flowers are crowded into capitulate inflorescences, complicated by accessory shoots (Fig. 553 _A_); they have S5, P5 (_imbricate_ æstivation), A5 (and beneath the stamens 5 scales on the corolla-tube), G2. Fruit a capsule opening by a lid.--_Cuscuta europœa_, _C. epilinum_ (Flax-Dodder), _C. epithymum_ (Lesser-Dodder), _C. trifolii_ (Clover-Dodder), etc., are parasitic on different hosts, or parasitic each on its own particular host. [Illustration: FIG. 553.--_Cuscuta trifolii_, parasitic on Red Clover. _A_ A portion of the stem with an inflorescence and haustoria (mag.); _B_ seed (nat. size); _C_ seed (mag.); _D_ embryo (nat. size).] 840 species; the majority in the Tropics, especially Am. Many are ornamental plants. OFFICINAL: some on account of their purgative properties: the tuberous roots of _Ipomæa purga_ (Jalap, from Mexico) and the dried latex (“Scammony”) of _Convolvulus scammonia_ (from the East). The tuberous roots of _Batatas edulis_ (Trop. S. Am.) are used as a common vegetable (Sweet Potato) in the Tropics. Family 30. =Personatæ.= The type of the flower is: S5, P5, A5 (of which one, or in some cases several, are suppressed), and G2. The flowers are _hypogynous_, ☿, perfect with gamopetalous corolla, but most frequently irregular (medianly zygomorphic, except _Solanaceæ_), the _corolla_ being _bilabiate_ (divided into a posterior part of two lobes and an anterior part of three lobes), and the _stamens_ 4, _didynamous_ (the posterior being suppressed). The ovary has 2 loculi (only 1 in _Utriculariaceæ_, _Gesneriaceæ_, _Orobanche_); the placenta in the first-named orders (1–7) is most frequently very thick, and bears a _great many ovules_ (Figs. 554, 555, 557, 562); the number of ovules in the last orders (8–9) is considerably reduced (Fig. 570). Special mention may be made of the apparently 4-merous flower which is found, _e.g._ in _Veronica_ and _Plantago_ (Figs. 567, 562 _C_, 570, 571), and which arises from the typical 5-merous flower by the suppression of the posterior sepal and the posterior stamen, and by the union of the two posterior petals into one.--Terminal flowers very seldom occur on the main axis, and would not harmonise well with the very irregular form of the flower. When they do occur, they are, as a rule, “peloric,” _i.e._ regular (in _Linaria vulgaris_ two kinds of peloric flowers occur,--one with 5 spurs, and one without spurs). The halves of the anthers are often divided as far as the base, and laterally so widely separated from each other as to assume an almost straight line (Figs. 563, 564). There is generally a nectary (“disc”) round the base of the ovary, often 5-lobed (or divided into free glands).--A common vegetative characteristic is the _absence of stipules_. The 9 orders of the Personatæ are: 1, Solanaceæ; 2, Nolanaceæ; 3, Scrophulariaceæ; 4, Utriculariaceæ; 5, Gesneriaceæ; 6, Bignoniaceæ; 7, Pedaliaceæ; 8, Acanthaceæ; 9, Plantaginaceæ. [Illustration: FIG. 554.--Diagram of _Petunia_.] Order 1. =Solanaceæ.= The flower (Figs. 554, 555, 559) is hypogynous, regular (zygomorphic in _Hyoscyamus_), ☿, and gamopetalous, with S5, P5 (most frequently _imbricate_ or _valvate_), A5, G2, the 2 carpels being placed obliquely (Fig. 554); the bilocular ovary has a very _thick axile placenta_ (Figs. 554, 555 _H_, 557), which extends almost as far as the wall of the ovary. The fruit is a capsule or berry; the seeds are more or less reniform, and the embryo is _curved_ (rarely straight), in a fleshy endosperm (Figs. 555 _F_, _G_; 561).--Both arborescent and herbaceous forms are found in the order; leaves scattered without stipules, but with variously formed laminæ (always penninerved). _A peculiar leaf-arrangement_ is found in many species, viz. the leaves are borne _in pairs, a large and a smaller one together_; these pairs stand in 2 rows, and the flowers are then situated _between_ the individual leaves in each pair, apparently _not_ in a leaf axil. The inflorescences are frequently unipared scorpioid cymes without floral-leaves. [Illustration: FIG. 555.--_Atropa belladonna_: _A_ is reduced.] Zygomorphic flowers occur, and thus form a transition to the closely allied Scrophulariaceæ; the zygomorphy sometimes shows itself only in the relative length of the stamens, sometimes also in the corolla (_Hyoscyamus_).--_Nicandra_ is 5-merous throughout all the whorls.--The peculiar relative _leaf-arrangement_ in this order occurs from sympodial branching and displacement. The most simple is, _e.g._ _Datura_ (Fig. 556 _A_); each shoot-generation in the floral parts of the plant has only 2 foliage-leaves (_f^1_ and _f^2_), and then terminates in a flower; the axillary buds of both the foliage-leaves are developed and form a dichasium, but since the leaves are displaced on their axillary-shoots as far, or almost as far, as the first leaf of these axillary-shoots, the flowers are borne singly on the dichasial branches, and all the branches appear to be without subtending leaves (Shoot I is white, II shaded, III white, etc., diagram _A_). _Scopolia_ and others (Fig. 556 _B_) differ in that the lowest and smallest (_f^1_) of the two leaves on each shoot is barren, and is therefore not displaced; but the upper one (the second bracteole, _f^2_) is displaced as in the first instance, and consequently it assumes a position near the first leaf (the shaded leaf _f^2_ of shoot I being placed near the white leaf _f^1_ of shoot II, etc.,) of the next youngest shoot-generation, and hence the leaves are borne in pairs; the flower placed between the two leaves of a pair is therefore the terminal flower of the shoot to which the smaller of the two leaves belongs, and the larger leaf is the subtending leaf for the floral shoot itself. [Illustration: FIG. 556.--Diagrammatic representation of the branching in Solanaceæ. The various shoot-generations are white or shaded.] [Illustration: FIG. 557.--Fruit of _Hyoscyamus niger_ after removal of calyx.] [Illustration: FIG. 558.--Fruit of _Datura stramonium_.] =A.= FRUIT A CAPSULE. _Nicotiana_ (Tobacco) has a 2-valved capsule with septifragal dehiscence; the valves separate at the apex; the corolla is funnel-shaped, tubular, salver-shaped or campanulate. The flowers in panicles.--_Datura_ (_D. stramonium_, Thorn-apple) has a (frequently spiny) capsule (Fig. 558), which is _falsely 4-locular_ (at the top, bilocular) and opens septifragally with 4 valves. The lower part of the calyx persists as a thick collar (see Fig. 558). The corolla is funnel-shaped. The flowers are solitary, large.--_Hyoscyamus_ (_H. niger_, Henbane) has a pyxidium (Fig. 557) enclosed in the campanulate, completely persistent, thick-walled calyx. The flowers are slightly _zygomorphic_, and borne in unipared scorpioid cymes. ~_Scopolia_ (pyxidium); _Fabiana_ (Heather-like shrub); _Petunia_ (slightly zygomorphic flower; funnel-shaped corolla); _Nierembergia_; _Brunfelsia_ (almost a drupe); _Franciscea_; _Browallia_.~--Among those with capsular fruits are found the most anomalous forms, which by their zygomorphic flowers and often didynamous stamens present the transition to the Scrophulariaceæ: _Salpiglossis_; _Schizanthus_ (lobed petals; 2 perfect, and 3 rudimentary stamens). [Illustration: FIGS. 559–561.--_Solanum tuberosum._ FIG. 559.--Flower (1/1). FIG. 560.--Stamen, ejecting pollen. FIG. 561.--Longitudinal section of seed.] =B.= FRUIT A BERRY. _Solanum_ (Nightshade); rotate corolla (Fig. 559). The stamens have short filaments, the anthers stand erect, close together round the style, like a cone in the centre of the flower, and open by pores at the apex (Fig. 560). ~_S. tuberosum_ (the Potato-plant); the Potato-tuber is a swollen, underground stem; the “eyes” are buds, situated in the axils of its scale-like, quickly-perishing leaves.~--_Lycopersicum_ resembles _Solanum_ in the flower, but the united anthers open by longitudinal clefts and have an apical appendage. The cultivated species, _L. esculentum_ (Tomato), has often a higher number than 5 in the flower, and in the fruit several loculi of unequal size.--_Physalis_ (Winter Cherry); the calyx ultimately swells out in the form of a bladder, becomes coloured, and loosely envelopes the spherical berry.--_Capsicum_ (Guinea Pepper-plant); some species have very large, irregular, rather dry (red, yellow, black) berries, which are unilocular in the upper part.--_Lycium_ (false Tea-plant); the corolla is salver- or funnel-shaped; shrubs; often thorny.--_Atropa_ (_A. belladonna_, Deadly Nightshade, Fig. 555); corolla campanulate; the calyx projects beneath the spherical, black berry. The flowers are borne singly.--_Mandragora_; (Mandrake); _Nicandra_ (ovary often 5-locular).--~A small tropical group: CESTREÆ (_Cestrum_, _Habrothamnus_, etc.) has an almost _straight_ embryo, which may also be found _e.g_. in species of _Nicotiana_. Related to the Scrophulariaceæ.~ About 1,500 species; the majority within the Tropics, outside these limits especially in America. _Solanum nigrum_ is a common weed.--_The Potato-plant_ (_Solanum tuberosum_), from Peru and Chili, was introduced into Europe in 1584 by Sir Walter Raleigh. (Potatoes = Batatos). The fruits of several serve as _condiments_: Chilies or Pod-pepper (_Capsicum annuum_ and _longum_), and the Cayenne-pepper (_C. baccatum_ and others), whose fruits also are officinal, were brought to Europe from S. America by Columbus, and are commonly cultivated in Tropical America; _Lycopersicum esculentum_ (Tomato) and others from Peru; _Solanum ovigerum_ (Egg-plant); _Solanum melongena_, etc. _Poisonous_, _acrid_, _narcotic_ properties (alkaloids, etc., solanine, nicotine, atropine, hyoscyamine) are found in many: _Atropa belladonna_ (from S. Europe; the roots and leaves are officinal); _Solanum dulcamara_ (Bitter-sweet; formerly officinal), _S. toxicarium_ (Guiana); _Datura stramonium_ from Asia (leaves and seeds officinal), _D. sanguinea_, _metel_, _tatula_, and others; _Hyoscyamus_ (officinal: the leaves and seeds of _H. niger_); _Nicotiana tabacum_ (Virginian tobacco, officinal: the leaves), _N. rustica_ and others from Trop. America (_Tobacco_ was introduced into Europe in 1560); _Cestrum_-species. _Duboisia myoporoides_ (Australia); the leaves contain _hyoscyamine_ and are used in medicine. A number of species of these genera are ornamental plants. Order 2. =Nolanaceæ.= These most resemble the Convolvulaceæ in the corolla, but the Solanaceæ in their branching, and leaf-arrangement (in pairs, etc.). The diagram is the same as in _Nicandra_ with 5 carpels, but the fruits of this order most frequently form, by invaginations in various directions, an ovary (with 1 style) consisting of numerous and irregularly grouped, 1-ovuled cells; the fruit is a schizocarp with many 1-seeded fruitlets.--_Nolana_ (Western S. America): a few are ornamental plants. Order 3. =Scrophulariaceæ.= The flower is hypogynous, ☿, _zygomorphic_, with the usual type: S5, P5, A5, and G2, the latter placed _in the median plane_; some genera have all 5 stamens developed (Fig. 562 _A_), but most frequently the posterior one is suppressed and the flower becomes _didynamous_ (Fig. 562 _B_). The fruit, as in the capsular-fruited Solanaceæ, is a bilocular, 2-valved _capsule_, with a _thick, axile placenta_, and most often septicidal dehiscence (Fig. 563 _C_). The _numerous seeds_ are not reniform as in many Solanaceæ, and have a _straight, or only slightly curved embryo_, with abundant endosperm (Fig. 563 _D_).--The majority are herbs; some are arborescent; the leaves are opposite or scattered, but stipules are wanting as in the whole family. The Scrophulariaceæ are closely allied to the Solanaceæ, and there is, properly speaking, no characteristic feature which absolutely separates them. The somewhat irregular corolla, with five stamens of unequal length in _Verbascum_, is also found in _Hyoscyamus_; curved and straight embryos are found in both orders. The activation of the corolla in the Scrophulariaceæ is _simple imbricate_, in the Solanaceæ most frequently _folded imbricate_ (in _Atropa_ and those allied to it, imbricate without folding). The genera (about 164) are distinguished according to the form of the corolla, number of stamens, inflorescence, arrangement of the leaves, etc. _Verbascum_ belongs to the most primitive 5-stamened forms, and from it proceed a long series down to _Veronica_, with only two stamens and most frequently the posterior sepal suppressed. [Illustration: FIG. 562.--Diagrams. _A_ _Verbascum_; _B_ _Linaria_; _C_ _Veronica_.] =1.= ANTIRRHINEÆ, SNAPDRAGON GROUP. This has most frequently a descending æstivation of the petals (the posterior petals are outside the lateral ones, which again enclose the anterior; Fig. 562 _A_, _B_). The plants belonging to this group are not parasites. =a.= =5-stamened.=--_Verbascum_ (Mullein, Fig. 563 _A_) has a slightly irregular, rotate corolla; five stamens (frequently covered with woolly hairs), of which the two anterior ones are the longer and differ often also in other respects. ~The inflorescences are racemose, often with several series of accessory dichasia in the axil of each primary floral-leaf. The leaves are scattered and, together with the stems, are often covered with a grey felt of branched hairs.~ [Illustration: FIG. 563.--_Verbascum thapsiforme._] [Illustration: FIG. 564.--_Antirrhinum majus._ A flower, and the upper lip of a flower with the stamens.] [Illustration: FIG. 565.--_Scrophularia nodosa._ Protogynous flower in various stages: _A_ ♀ stage; _g_ the stigma projecting from the throat of the corolla; _B_ the same in longitudinal section; _C_ ♂ stage, the stigma is bent down and its former position occupied by the stamens; _s_ staminode; _g_ stigma; _d_ nectary.] [Illustration: FIG. 566.--_Digitalis purpurea._] =b.= =4-stamened, didynamous= (Fig. 564).--_Scrophularia_ (Fig-wort, Fig. 565) has cymose inflorescences in a panicle; the corolla (Fig. 565) is urceolate, short two-lipped; the posterior stamens are present as a scale below the upper lip of the corolla (Fig 565 _s_). ~_S. nodosa_ has a tuberous rhizome.--_Pentstemon_; the posterior stamen is barren and very long.~--_Antirrhinum_ (Snapdragon). The corolla (Fig. 564) is personate, _i.e._ bilabiate, but with the under lip arched to such an extent that it meets the upper lip, closes the corolla throat, and entirely conceals the stamens and style; the corolla-tube is produced into a short pouch at the base on the anterior side. The capsule is oblique and opens by 2–3 pores, formed by small, dentate valves. In _Linaria_ (Toad-flax) the pouch is produced into a spur. Sometimes there are traces of the posterior stamens. The capsule opens by large pores (one for each loculus), produced by large, many-partite valves. _L. vulgaris_ reproduces by suckers.--_Digitalis_ (Foxglove, Fig. 566) has long racemes with drooping flowers; the posterior sepal is small (a step towards complete suppression, as in _Veronica_); the corolla is obliquely campanulate, and generally nearly 4-lobed, the two posterior petals coalescing.--_Alonsoa_; _Nemesia_; _Chelone_; _Herpestis_; _Mimulus_; _Torenia_; _Vandellia_; _Limosella_ (_L. aquatica_, Mud-wort, native); _Scoparia_; _Capraria_; _Erinus_ (found on the Roman Camp at Chesters, Northumberland, and supposed to have been introduced from Spain by the Roman soldiers); _Celsia_ (near _Verbascum_); _Maurandia_; _Lophospermum_; _Rhodochiton_; _Collinsia_; _Nycterinia_, etc. [Illustration: FIG. 567.-Flower of _Veronica_.] =c.= =2-stamened.=--_Gratiola_ (Water-hyssop). 5-partite calyx. The upper lip of the corolla is undivided or slightly bifid; the two anterior stamens are either entirely absent or are reduced to staminodes (a transition to _Veronica_).--_Veronica_ (Speedwell), most frequently 4-partite calyx; 4-lobed, rotate, zygomorphic corolla with 2 perfect stamens and no trace of the others (Figs. 567, 562 _c_); capsule with loculicidal dehiscence. _Calceolaria_; the corolla has two slipper-like lips. =2.= RHINANTHEÆ, YELLOW-RATTLE GROUP. Herbs, all of which (with the exception of _Lathræa_) are annual _parasites_ with green foliage-leaves. They attach themselves by haustoria to the roots of other plants and draw nourishment from them. The majority turn black when dried. Racemose inflorescences. In many the calyx is 4-partite, the posterior sepal being absent, or very small. The corolla is distinctly bilabiate (Fig. 568), with _most frequently ascending æstiration_; in the majority it does not become detached at the base, but by means of a ring-like cut some distance up the tube; 4 didynamous stamens; pollen-grains dry, easily falling out; the anthers are often furnished at the base with bristles or hairs (Fig. 568) which play a part in the pollination, the probosces of the insects, being forcibly pushed against them, agitate the anthers and shake out the pollen-grains. Capsule with loculicidal dehiscence.--_Euphrasia_ (Eye-bright), _Melampyrum_ (Cow-wheat), _Rhinanthus_ (Yellow-rattle), _Odontites_ (Bartsia), _Pedicularis_ (Louse-wort), and _Lathrœa_ (Tooth-wort) all have native species. The last named is pale yellow, or reddish (without chlorophyll); ~it is a parasite on the roots of the Hazel, Beech and other shrubs, having an aerial stem, and an underground, perennial rhizome, covered with opposite, scale-like, more or less fleshy leaves with a number of internal glandular, labyrinthine cavities. The inflorescence is a unilateral raceme. It approaches _Gesneriaceæ_ in having a _unilocular_ ovary with two parietal placentæ.~ [Illustration: FIG. 568.--_Euphrasia officinalis._ Flower of the large and the small-flowered forms; showing the anthers and stigmas.] The mechanical contrivances for POLLINATION are so numerous that no general principle can be laid down. Personate flowers, like those of _Antirrhinum_ are only accessible to strong insects, such as humble-bees, which can force themselves between the two lips, and so become dusted with pollen on the back. In _Euphrasia_ and other _Rhinantheæ_ the insects become covered with smooth, powdery pollen when they shake the anther-apparatus in touching the hairs and bristles mentioned above. _Scrophularia nodosa_ is protogynous (Fig. 565). _Digitalis purpurea_, however, is protandrous. _Mimulus luteus_ and some others have sensitive stigmatic lobes, which shut up on being touched. The _Veronica_-species constitute a series, from large-flowered down to small-flowered forms, and parallel with them are found various gradations from insect-to self-pollination. In some (as _Euphrasia officinalis_, _Rhinanthus crista galli_) there are two kinds of flowers: large, which are pollinated by insects, and small, which are self-pollinated (Fig. 568). _Lathræa squamaria_ (Tooth-wort) is a protogynous spring-flowering plant, largely visited by humble-bees. Others have cleistogamic flowers. _Nycterinia capensis_ opens its flowers at night. 2,000 species; chiefly from the Temp. OFFICINAL: _Digitalis purpurea_ (the leaves; Europe), a poisonous plant. _Verbascum thapsus_ and _thapsiforme_, _Veronica officinalis_ (“Herba V.”), _Gratiola officinalis_ (“Herba”) have medicinal uses. The whole of the Scrophulariaceæ are more or less suspicious, if not actually poisonous, and none serve as food. Many are ORNAMENTAL PLANTS: _Mimulus luteus_ (N. America), _Paulownia imperialis_ (the only species; in Japan; a tree), _Antirrhinum vulgare_ (S. Eur.), _Linaria_, _Pentstemon_, _Veronica_, _Calceolaria_ (Peru, Chili, etc.). [Illustration: FIG. 569.--Leaf of _Utricularia vulgaris_, with bladder. Median longitudinal section through a bladder containing a _Cyclops_. At a a hair of the upper-lip, at _i_ 2 bristles of the under-lip of the entrance (_a_, _b_); in the latter are placed 4 bristles _h_; _k_ stalk of the bladder, in which is seen a vascular bundle. (After Cohn.)] Order 4. =Utriculariaceæ.= To this order belong only perennial, _insectivorous_, _aquatic_, and _marsh-plants_ (200 species) with a more or less characteristic appearance. They differ from the Scrophulariaceæ, especially in having =2= stamens (the anterior) and a _unilocular ovary_, with _free, central placenta_ (like that of the Primulaceæ). For the rest the flower is distinctly bilabiate, both in the calyx and corolla. Two-valved capsule; no endosperm. _Pinguicula_ (Butter-wort) has a rosette of leaves close to the ground; these are sticky, covered with glandular hairs, and roll round any small insects which may be caught upon them; flowers solitary, terminal on a long scape; calyx, 5-partite; corolla with spur. The embryo germinates with 1 cotyledon.--_Utricularia_ (Bladder-wort). Our native species are floating, _without roots_, with hair-like, divided leaves, studded with peculiar bladders (in the Tropics there are terrestrial species, with ordinary foliage). The bladders (Fig. 569) have an aperture, closed by a valve opening inwards, so that small aquatic animals are allowed to enter, but are not able to escape; they are thus entrapped in the bladders, and are probably used as food. Calyx bipartite; corolla personate with spur. The _embryo_ of _Utricularia_ is very imperfect, scarcely more than a spherical, cellular mass, with a few slight leaf-rudiments. On the germination of _U. vulgaris_, several bristle-like leaves develop into a compact rosette; the stem then develops, and also the finely-divided, bladder-bearing leaves. A primary root is not developed. The stems branch copiously and in a very peculiar manner. The growing-point of the stem is rolled spirally.--The stigmatic lobes are sensitive and close on being touched; self-pollination often takes place, however, in _Pinguicula_. Order 5. =Gesneriaceæ.= The flower in this order may be both _epigynous_ (_Gesnerieæ_) and _hypogynous_ (_Cyrtandreæ_), but otherwise is nearly the same as in Scrophulariaceæ, only that _the ovary is unilocular_, with 2 _parietal_, often bifid, _placentæ_. Of the 5 stamens the posterior is rudimentary, or (more rarely) entirely wanting, and the others are didynamous (Cyrtandreæ have often only 2 stamens); their anthers are generally glued into a quadrangular mass. The majority are herbs with juicy stems, opposite, verticillate or scattered leaves without stipules, often, like the stems, thick and juicy, soft-haired or glabrous. The corollas are often highly-coloured (scarlet, red-yellow, etc., and spotted internally), large and magnificent, so that many species are ornamental plants. GESNERIEÆ (often epigynous) have endosperm; S. Am.--CYRTANDREÆ, hypogynous, without endosperm; Asia, S. Africa.--_Streptocarpus_, neither the primary root nor primary shoot attains development; one of the cotyledons dies, while the other grows and becomes a very large foliage-leaf, from which spring adventitious roots and adventitious inflorescences. 500 species. _Gloxinia_, _Achimenes_, _Gesneria_, _Alloplectus_, _Tydæa_, _Columnea_, _Nægelia_, _Æschynanthus_, and others, especially in the forests of tropical America. Some are epiphytes on trees, others prefer the leaf-mould of the forest and crevices of cliffs. Several genera have peculiar, catkin-like, underground shoots, with scale-like compact leaves; others have tubers. _Orobanche_ (Broom-rape) is allied to this order as a _parasitic_ form. It is a parasite on the roots of other plants, not like _Lathræa_ by means of thin rootbranches with haustoria, but growing with the base of its stem in close contact with its host, and probably even often protruding a kind of thallus into it, in a manner similar to the Loranthaceæ. Its aerial shoots are not entirely destitute of chlorophyll, but are not green; they only bear scale-leaves and terminate in a raceme or spike-like inflorescence.--Some _Orobanche_-species are detrimental to various cultivated plants (Hemp, Lucerne, Tobacco, etc.). The flowers are strongly zygomorphic; the posterior sepal is often wanting, and the anterior are united to the two lateral ones. Ovary unilocular, as in Gesneraceæ, with 2 or 4 parietal placentæ.--The exceedingly small seeds have a very rudimentary embryo, formed of an ellipsoidal, cellular mass, without indication of cotyledons or other organs.--About 100 species; especially in the Mediterranean region. Order 6. =Bignoniaceæ.= 500 species; nearly all trees and shrubs, and to a great extent lianes, climbing by tendrils (modified leaves), which are sometimes terminated by a special clasping apparatus. These lianes have, as a rule, an _anomalous stem structure_, the wood being either divided into four wedges at right angles to each other, separated by four grooves filled with secondary wood-parenchyma, or a greater number of wedges occur, by the cambium ceasing to form wood in several places. The leaves are most frequently opposite and compound; the flowers in the main are similar to the didynamous Scrophulariaceæ, and especially resemble those of _Digitalis purpurea_; they are bilabiate, large, and beautiful, campanulate or trumpet-shaped, many of the prettiest ornamental plants in the Tropics belonging to this order. The fruit is most frequently a large, woody, 2-valved, siliqua-like, septifragal capsule, whose valves separate from the flat and broad partition-wall, which bears the large, generally winged seeds: _Tecoma_; _Bignonia_.--In gardens: _Catalpa syringæfolia_ (Trumpet-wood); _Tecoma radicans_ (from S. Am.).--“Palisander”-wood is from _Jacaranda_ (S. Am.).--_Eccremocarpus_ (N. Am.) forms, by its unilocular capsule, a transition to the Gesneriaceæ (_E. scaber_; herbaceous). _Crescentia_ is allied to this order; _C. cujete_ (Calabash) is its best known species. The fruit (unilocular with 2 parietal placentæ) is a very large, spherical or ellipsoidal berry, with a firm, finally woody outer layer. After the removal of the juicy interior, these are commonly used as drinking vessels in Tropical America. Order 7. =Pedaliaceæ.= _Sesamum_ (_orientale_ and _indicum_); very important oil-plants, which from olden times have been cultivated in tropical Asia and Africa for food and as medicinal plants, and are now cultivated in America also. The seeds are used as a raw material in the manufacture of soap in Europe.--To this order also belong _Martynia_ and _Craniolaria_, which have a long horned capsule and sensitive stigmas.--46 species. Order 8. =Acanthaceæ.= 1,500 species; mostly erect, slender, branched herbs or shrubs, rarely arborescent, especially in S. Am. and Ind. The branches frequently have swollen nodes; the leaves are _opposite_, penninerved, undivided, more or less lanceolate or elliptical, and generally leave a distinct scar when they fall off. Stipules are wanting. The flowers are solitary or in dichasia, which are arranged in 4-rowed spikes or racemes, each flower with its subtending bract, which may be brightly coloured, and most frequently also with two bracteoles. With regard to the corolla (which is often labiate, in any case irregular, and frequently prettily coloured), the 2 or 4 didynamous stamens (of whose anthers one half is inserted lower than the other, or suppressed) and the gynœceum, the Acanthaceæ are true Personatæ, approaching most nearly to the Scrophulariaceæ: they differ from the other orders especially in the _fruit_, which is a bilocular, 2-valved, often elastically dehiscing capsule, which never has more than 2 rows, and in some only 2 seeds in each loculus, the seeds being often compressed and borne on _strong_, _curved_ or _hook-like funicles_ (_retinacula_) which persist after dehiscence. _Embryo curved without endosperm_; radicle pointed downwards.--Cleistogamic flowers are found in several species. Cystoliths are common. The following grow wild in Europe: _Acanthus_ (_spinosus_ and _mollis_, whose pinnatifid leaves served as models for the capitals of the Corinthian columns). The posterior sepal is the largest of all the leaves of the flower, and covers the other parts like a helmet; the 2 anterior sepals are united, and the two lateral ones are small and greenish; the corolla has no upper-lip, but only a 3-lobed under-lip. The anthers are bilocular; the filaments ultimately become very firm.--_Justicia_, _Eranthemum_, _Goldfussia_, _Thunbergia_ (a twiner), _Ruellia_, _Dicliptera_, etc.--Ornamental plants in conservatories. Order 9. =Plantaginaceæ= (=Plantains=). The flowers (Figs. 570, 571) are regular, ☿, hypogynous, with a =4=-partite, persistent calyx, a gamopetalous, _scarious_ corolla with =4= projecting lobes, =4= stamens, incurved in the bud, later on projecting considerably, about equal in length, and a bilocular ovary with _one_ long, filamentous, _undivided_, _feathery_, papillose style (see Fig. 571). The ovary is most frequently bilocular with 1–few ovules in each loculus. An hypogynous disc is wanting. The fruit is a _pyxidium_ with 1–few peltate seeds attached in each loculus (_Littorella_ is in several respects an exception). All species are herbs, the majority with leaf-rosettes near the ground, and the flowers in spikes or capitula. The labiate-like flowers are in this case entirely concealed under a regular, apparently 4-merous exterior. The structure of the flower, however, is the same as in the _Scrophulariaceæ_, only the reduction, which is found in _Veronica_ (compare Figs. 562 _C_, 567 with 570, 571), is also present in this instance and the lobes are also more equally developed; the posterior petal corresponds to the bilobed upper-lip; the posterior stamen and the posterior sepal also are entirely wanting. In the development of the flower there is no trace of posterior sepal or stamen, and the posterior petal arises from one primordium, but the two anterior sepals arise before the lateral ones. The position of sepals and petals does not agree with that of a true 4-merous flower, which is represented in Fig. 361 _E._ The bracteoles are always suppressed in _Plantago_. _Plantago_ (Plantain, Rib-grass). The foliage-leaves are most frequently scattered, entire, with curved veins, arranged in a rosette close to the ground on an unlimited rhizome; the spike-like inflorescence is borne on a long scape; in some (_P. psyllium_) the leaves are opposite on a stem with well-developed internodes, and the inflorescences are borne in their axils. The order also presents a transition from insect-pollinated to wind-pollinated flowers. ~The flowers are protogynous, wind-pollinated in _P. major_ and _P. lanceolata_, partly also in the other species, but insect pollination also occurs, and _P. media_ has three kinds of flowers, some of which are adapted for wind-pollination (Fig. 571), others, with short filaments, for insects.~ _Littorella lacustris_ (Shore-weed) is the most reduced of the Plantaginaceæ: an aquatic plant with rosettes of round, awl-like leaves and diclinous (monœcious) flowers. ~In the axils of the foliage-leaves is a very short 3-flowered spike, formed by 2 sessile ♀-flowers, and above them a long-stalked ♂-flower; all the flowers are lateral, the terminal one being absent, as in _Plantago_. The ♂-flower is essentially the same as in _Plantago_, but the ♀-flower has a scarious corolla, with a narrow, 3–4-dentate mouth, which closes tightly round the nut-like fruit.~ [Illustration: FIGS. 570, 571.--_Plantago media._ FIG. 570.--Diagram of _Plantago media_. FIG. 571.--Two different forms of the flower (magnified): 1, chiefly adapted for pollination by wind; 2, for insect-pollination. _a_ The stigma; _b_ the calyx; _k_ the corolla.] The genus _Plantago_ constitutes nearly the entire order (200 species). Some are widely distributed weeds (_e.g._ _P. major_, “The white man’s footstep”). In _P. psyllium_ (S. Eur.) the integument of the seeds is mucilaginous, and swells considerably in water. Family 31. =Nuculiferæ.= The flowers are _hypogynous_ and _zygomorphic_ (in _Boraginaceæ_ and _Cordiaceæ_, however, they are regular, except _Echium_ and _Anchusa arvensis_). The calyx is gamosepalous, the corolla _bilabiate_ (except in the two orders mentioned), mostly after 2/3, _i.e._ divided into a 2-leaved posterior portion, and a 3-leaved anterior portion. The æstivation of the corolla is nearly always descending.--In _Boraginaceæ_ and _Cordiaceæ_ there are 5 stamens of equal length; in the other orders 4 didynamous ones, or only 2 fertile; the posterior stamen is sometimes developed as a staminode, sometimes fertile (in _Stilbaceæ_). The ovary is formed of 2 median carpels (except some _Verbenaceæ_), with (1-) =2= ovules on each carpel; in the majority of the orders it is, however, divided by a false partition-wall between the dorsal and ventral sutures, into =4= _loculi_, each of which is often raised independently, causing the style to be situated in the depression between the four lobes (“gynobasic” style, Figs. 572, 573, 575, 579). The fruit in these orders most frequently becomes a _4-partite schizocarp_ with _nut-like fruitlets_. The other orders have a 1(-2)-locular ovary.--The leaves are _simple, without stipules_. The family is related to (and proceeds from) the _Tubifloræ_, especially _Convolvulaceæ_, which has an almost similar construction of the ovary. It is doubtful whether the _Cordiaceæ_ and _Boraginaceæ_ should be classed with the others. The orders are: 1, Cordiaceæ; 2. Boraginaceæ; 3, Verbenaceæ; 4, Labiatæ; 5, Selaginaceæ; 6. Globulariaceæ; 7, Stilbaceæ. Order 1. =Cordiaceæ= unites Convolvulaceæ and Boraginaceæ. Tree-like plants with 5-(4–10) merous flowers, doubly bifid style, and drupe with 4 or less loculi. No endosperm; cotyledons folded.--185 species; tropical. Order 2. =Boraginaceæ.= The vegetative parts are very characteristic: _herbs_ with _cylindrical_ stems and _scattered_, undivided, nearly always sessile, entire leaves, without stipules, and generally, together with the other green portions of the plant, covered with stiff hairs, consequently rough and often even stinging (hence the other name for the order _Asperifoliæ_). The inflorescences are _unipared scorpioid cymes_ with the branches coiled spirally (“helicoid,” Fig. 573) before the flowers open. The flower is perfect, _regular_ (obliquely zygomorphic in _Echium_ and _Anchusa arvensis_), hypogynous, gamopetalous: S5, P5 (often with ligular outgrowths), A5, G2, but each of the two loculi of the ovary becomes divided by a false partition-wall into two, each of which contains one _pendulous_ anatropous ovule with the micropyle turned upwards; the four loculi arch upwards, so that the ovary becomes 4-lobed, and the style is then, as in the _Borageæ_, placed _at the base_ (“gynobasic”) between the four projections (Figs. 572, 573). The fruit is a _4-partite schizocarp_ with four nut-like fruitlets (Fig. 572).--_Endosperm is wanting_ (except in _Heliotropium_); the radicle is turned _upwards_. The INFLORESCENCES are often double unipared scorpioid cymes; the bud of the second bracteole is developed, that of the first suppressed; in some cases both the bracteoles are suppressed (_Myosotis_, _Omphalodes_, etc.), but in other instances all the first bracteoles (_a_) only are suppressed, and the others are then situated in two rows towards the under side of the coiled axis, while the flowers are situated on the upper side. Displacement of the branches or of the floral-leaves sometimes takes place. The flowers are often red at first, and later on become blue or violet; they hardly ever have any smell. The fruit entirely resembles that of the Labiatæ, but the radicle of the latter is turned downwards. The fruitlets present small differences which have systematic importance; they are hollow or flat at the base, attached to a flat or columnar receptacle, etc. =1.= HELIOTROPIEÆ. This group deviates from the characteristics mentioned above in the undivided ovary and terminal (“apical”) style. In this, as well as in the fact that in some genera (_Tournefortia_, _Ehretia_, etc.) the fruit is a drupe, it connects this order with the Cordiaceæ. _Heliotropium_, _Tiaridium_, and others have schizocarps. =2.= BORAGEÆ, BORAGE GROUP. Style gynobasic; fruit a schizocarp. =A.= The throat of the corolla is without ligules, or with very small ones.--_Pulmonaria_ (Lung-wort); funnel-shaped corolla; a whorl of hairs in the corolla-throat.--_Echium_ (Viper’s-bugloss) has zygomorphic flowers, the plane of symmetry almost coinciding with that of the very well-developed inflorescence (through the fourth sepal); the corolla is obliquely funnel-shaped, the style is more deeply cleft at the apex than in the others; stamens 2 longer, 2 shorter, and 1 still shorter.--_Cerinthe_ has a tubular corolla with five small teeth and two bilocular fruitlets. The bracts are large and leafy, and, like all the rest of the plant, are _almost glabrous_.--A few _Lithospermum_-species have a naked corolla-throat; others have small hairy ligules, which do not close the corolla-throat. The fruitlets are as hard as stone, owing to the presence of carbonate of lime and silica.--_Mertensia_ (_Steenhammera_); _Arnebia_; _Nonnea_ (small ligules). =B.= The corolla-throat is closed by, or in any case provided with _ligules_, _i.e._ scale-like bodies or small protuberances, situated in the throat of the corolla _opposite_ the petals, and which are invaginations or _internal_ spurs of the petals (Fig. 572 _D_).--The nuts in _Cynoglossum_ (Hound’s-tongue) bear _hooked bristles_ over the entire surface, or, in _Echinospermum_, only on the edge. The following have smooth nuts:--_Symphytum_ (Comfrey) has a cylindrical, campanulate corolla, and prolonged-triangular, pointed ligules.--_Borago_ (Borage) has a rotate corolla with projecting, emarginate ligules; the stamens have a horn-like appendage, projecting upwards from the back of the filament. The fruitlets are hollow below.--_Anchusa_ (Alkanet, Fig. 572). The corolla is salver-shaped; the ligules small, hairy protuberances. _A. (Lycopsis) arvensis_ has an S-curved corolla-tube.--_Myosotis_ (Forget-me-not, Fig. 573); rotate corolla with small (yellow) protuberances in the throat; scorpioid cyme without floral-leaves; fruitlets flat.--_Omphalodes_; fruitlets hollow at the back, with a scarious, turned-in, toothed edge.--_Asperugo_ (Mad-wort); the calyx grows after flowering, becoming large, compressed, and deeply bifid. [Illustration: FIG. 572.--_Anchusa officinalis_: _A_ diagram; the brocteole _a_ is suppressed (dotted); β supports a flower. _B_, _C_ _Myosotis_, the fruit, entire and with the calyx in longitudinal section. _D_, _F_ _Alkanna tinctoria_: D the corolla opened (4/1); _e_ the ligule; _f_, _g_ the anthers; _E_ gyncœceum (3/1); _F_ fruit, with three fruitlets; _i_ an aborted loculus; _h_ disc.] CROSS-POLLINATION is most commonly effected by insects (especially bees). There are a great many contrivances for pollination; some flowers are protandrous (_Echium vulgare_, _Borago officin._), others are heterostylous (long-and short-styled: _Pulmonaria officin._); the corona (ligules) is a protection against rain, and excludes certain insects. Some are barren when self-pollinated (_Pulmonaria officinalis_, _Echium vulgare_); others which have but little honey, may, failing insect-pollination, fertilise themselves, and in _Myosotis versicolor_ this regularly occurs by the growth of the corolla during flowering, so that the anthers are brought into contact with the stigma. Honey is secreted on the hypogynous disc.--About 1,150 species, growing especially in the northern temperate zone, _Mucilage_ is found (_e.g._ in the _officinal_ root of _Cynoglossum officinale_, in the root of _Symphytum_): red _dyes_ are found in some roots (_e.g._ Alkanet-root, the root of _Alkanna tinctoria_, which is also medicinal; S. E. Europe, Asia Minor); some are _poisonous_: _Cynoglossum_, _Echium_, _Anchusa_, etc. Several species are ornamental plants. _Heliotropium_ (Peru) is cultivated chiefly on account of its pleasant scent; essential oils are otherwise very rare. [Illustration: FIG. 573.-_Myosotis._ Inflorescence and gynœceum.] Order 3. =Verbenaceæ.= The majority are shrubs; a few are herbs or trees (Teak-tree); some are lianes. The branches are often square. The leaves are opposite or verticillate, without stipules; in some compound. The inflorescences are racemes, spikes, capitula, or dichasia. Five sepals; five petals in a gamopetalous, zygomorphic corolla, which is often bilabiate, but rarely to such an extent as in the Labiatæ, and the upper lip in some is larger than the under, in others smaller; stamens four didynamous, or two; the ovary is entire (not grooved or divided), 1- or 2-locular, or, as in the Labiatæ, divided into four loculi with an _erect_ ovule in each, but in some the anterior carpel is suppressed. One _terminal_ style. The fruit is, _e.g._ in _Verbena_, a 4 partite schizocarp with nut-like fruitlets; in _Vitex_ (digitate leaves) a drupe with a 4-locular stone; in _Clerodendron_ a similar fruit, with four free stones; in _Lantana_ a bilocular stone, or two unilocular stones. The radicle is _turned downwards_. Endosperm small or absent.--_Lippia_, _Stachytarpheta_, _Bouchea_, _Priva_, _Citharexylon_, _Callicarpa_, etc.--The Verbenaceæ are closely allied to the Labiatæ; they differ especially in the ovary not being 4-lobed with gynobasic style, but undivided, almost spherical or ovoid with a terminal style. Again, the leaves are not so constantly opposite, and the inflorescences are various. 730 species; especially in the Tropics; there are several in America, especially _Lantana-species_; shrubby weeds.--Many of those mentioned are ORNAMENTAL PLANTS, especially _Verbena_; _Vitex agnus castus_ is a S. European shrub. _Lippia citriodora_ (S. Am.) etc., have strongly-scented leaves; the Teak tree (_Tectona grandis_) is one of the largest trees in East India, and has a very hard wood. _Avicennia_ is allied to this order; it inhabits the Mangrove swamps on tropical coasts. The endosperm emerges from the ovule, carrying the embryo with it; the embryo ultimately bursts the endosperm and lies free in the loculus of the fruit; this is then filled by the embryo with its large, green cotyledons, which are borne on an already hairy or rooted stem. The seedling thus developed falls from the tree, together with the fruit, and strikes root in the mud. One special cell of the endosperm at an earlier period becomes a highly-developed organ of suction, growing into a much-branched sac, very rich in protoplasm. Order 4. =Labiatæ.= The special characteristics are: the _square_ stem, the _opposite leaves_ (without stipules), the inflorescences which are formed by _two double unipared scorpioid cymes_, the _labiate_ corolla, the 4 _didynamous_ stamens (the posterior being entirely suppressed) (Fig. 574), and the _4-partite schizocarp_ with _nut-like fruitlets_. The floral formula is S5, P5, A5 (the posterior stamen is generally absent), G2. [Illustration: FIG. 574.--Diagram of _Lamium album_: _sv_ dichasia.] They are chiefly aromatic plants (herbs, shrubs, _e.g._ Lavender, or trees), volatile oil being formed in internal cells or in the glandular hairs, which cover all green parts. The stem is always more or less markedly square; the leaves are borne upon the flat sides, and are simple and penninerved, but vary in the other characters. The inflorescences are double unipared scorpioid cymes, which may be situated at some distance from one another in the axils of the foliage-leaves (Fig. 575 _A_), but frequently when the subtending leaves are bract-like, they are crowded into spike-like inflorescences (_Lavandula_, _Mentha_, _Salvia_, etc.), each of the so-called “whorls” (verticillaster, glomerulus) being a double unipared scorpioid cyme (Fig. 574). (Solitary flowers are found in _e.g._ _Scutellaria_, and _Origanum_). The calyx is strongly gamosepalous, 5-toothed, often bilabiate (Fig. 575 _B_). The corolla is strongly bilabiate (Figs. 575, 576, etc.), with 2 lobes in the upper lip and 3 lobes in the under lip (an approach to regularity occurs only when the upper lip is small, and thus resembles one lobe, as in _Mentha_ (Fig. 578) and _Lycopus_, so that the corolla approaches the 4-merous corolla of _Veronica_ and _Plantago_). The posterior stamen in the diagram (Fig. 574*) is entirely suppressed; in most of the genera the posterior lateral stamens are the smaller (Fig. 575 _D_), and are entirely suppressed in some (see below); in others, _e.g._ _Nepeta_, they are the longer. 2 stamens are found in _Salvia_, _Rosmarinus_, _Lycopus_, etc. The two halves of the anthers are often separated from one another, and are placed at an angle with each other. The gynœceum has 1 style with a bifid extremity (Fig. 575 _C_) bearing the stigma; the true bilocular ovary is divided by a false partition-wall into 4 loculi, each with 1 erect ovule (Fig. 575 _H_). These 4 loculi project so strongly that the ovary becomes deeply 4-lobed with the style situated in the centre of the lobes and at their base, “gynobasic” (Figs. 575, 579). A ring-like, often crenate, nectary surrounds the base of the ovary (Fig. 575 _G_, _H_). The embryo in this order, as in the _Verbenaceæ_, is directed downwards (Fig. 575 _J_) (it is directed upwards in the _Boraginaceæ_, which have an entirely similar fruit). _Endosperm absent._ [Illustration: FIG. 575.--_Thymus vulgaris._] The 142 genera are mainly distinguished according to the form of the calyx and corolla, the number, direction, and length of the stamens, the forms of the nuts, etc. =1.= AJUGEÆ, BUGLE GROUP. Calyx 10-nerved; the upper lip is small; 4 stamens. The ovary is not so strongly lobed as in the following group, so that it is most nearly allied to the _Verbenaceæ_. The nuts are reticulately wrinkled. _Ajuga_ (Bugle) has a very small upper lip. The upper lip of _Teucrium_ (Germander) is deeply cleft, and the two lobes are bent on their respective sides towards the under lip, which in consequence appears to be 5-lobed, and the upper lip to be wanting. [Illustration: FIG. 576.--_Lamium album_: _A_ lateral view of flower; _B_ longitudinal section; _C_ ovary with nectaries (_a_); _D_ the apex of the style; _e_, upper lip of corolla; _c_, _b_, _c_ the three petals of the lower lip; _f_ anthers; _g_ stigma.] =2.= STACHYDEÆ, BETONY GROUP. The calyx is 5- or 10-nerved. The upper lip of the corolla is most frequently _strongly arched_ or helmet-shaped; 4 stamens, the _anterior pair the longer_ (Fig. 576). =a.= A somewhat regular and 5–10-dentate calyx with _projecting_ stamens.--_Stachys_ (Betony, Woundwort); the lobes of the under lip are rounded off. The anterior filaments, after pollination, _bend outwards_. _Betonica_--_Ballota_ (Horehound); the calyx is funnel-shaped, and has triangular, long, pointed, awn-like teeth.--_Galeopsis_ (Hemp-nettle) has two conical protuberances on the under lip between the lateral and the central lobes. The anthers open by 2 _unequal_ valves. _Lamium_ (Dead-nettle, Fig. 576) has dentate, lateral lobes on the under lip. _L. album_ (White Dead-nettle), _L. rubrum_, etc. _Galeobdolon._--_Leonurus_; _Phlomis_. =b.= Tubular, regular, often 10-toothed calyx and _concealed_ stamens.--_Marrubium vulgare_ (Fig. 577); 10 calyx-teeth, hooked at the apex; many almost spherical whorls of flowers in the axils of the foliage-leaves, at some distance from one another.--_Sideritis._ [Illustration: FIG. 577.--_Marrubium vulgare._] =c.= Strongly bilabiate calyx, the lips _closing together_ after flowering.--_Scutellaria_ (Skull-cap); the two lips of the calyx are entire, the upper lip has a large spur, and drops off on the ripening of the fruit. The flowers are generally solitary and turned to one side.--_Prunella_ (Heal-all); the calyx is compressed, its two lips are strongly dentate, the upper lips closing slightly round the under. The stamens have a tooth-like projection beneath the anthers. =3.= NEPETEÆ, CATMINT GROUP. 13–15 nerves in the calyx; this deviates from the other groups in the _posterior stamens being the longer_. The upper lip is slightly arched. _Nepeta_ (Catmint), also _Glechoma_ (Ground Ivy), with regular, and _Dracocephalum_ with irregular calyx. [Illustration: FIG. 578.--_Mentha aquatica_, var. _crispa_.] =4.= SATUREIEÆ, MINT GROUP. The upper lip is _flat_, most frequently ovate, or almost spherical, and emarginate (Fig. 578). The calyx is most frequently 5–10-nerved. 4 stamens, _the anterior being the longer_; rarely, 2 stamens only.--_Mentha_ (Mint, Fig. 578) has a regular, 5-dentate calyx, a small, almost regular, 4-partite corolla, and 4 erect stamens of nearly equal size. The verticillasters are many-flowered, and are often collected into cylindrical inflorescences. Herbs.--_Lycopus_ (Gipsy-wort); corolla almost regular. 2 stamens, the posterior lateral ones are wanting. _Preslia_: 4-dentate calyx, 4-partite, regular corolla; 4 stamens of equal size.--_Thymus_ (Thyme, Fig. 575) has a strongly bilabiate calyx, the throat being closed by a whorl of hairs (Fig. 575 B). The corolla is distinctly labiate. Under-shrubs, with small entire leaves; verticillasters few-flowered and separate.--_Origanum_ (Marjoram); spike or capitate inflorescences with the flowers solitary in the axils of the rather large and distinctly 4-rowed (often slightly coloured) floral-leaves. _Melissa._ _Calamintha._ _Clinopodium_ (Wild Basil). _Satureia._ _Hyssopus_ (Hyssop); small, entire leaves; the verticillasters are situated unilaterally in a slender, spike-like inflorescence. _Lavandula_ (Lavender); shrubs with verticillasters collected in cylindrical, long-stalked inflorescences; the calyx is tubular, has 13–15 nerves, the posterior tooth is much larger than the others. Stamens and style do _not_ project. ~_Coleus_ differs, among other characters, in having united filaments; the stamens and style are bent down and concealed in the boat-shaped under lip.~ [Illustration: FIG. 579.--_Salvia officinalis._] =5.= MONARDEÆ, SALVIA GROUP. _Only the 2 anterior stamens are developed._--_Salvia_ (Fig. 579); calyx deeply bilabiate; the upper lip of the corolla is generally strongly compressed. Rudiments of the two lateral stamens are present. The connective in the two fertile stamens is long and filamentous, and bears at the upper end a normal half-anther, but at the lower one a barren, often broader portion, against which the insect is obliged to push its proboscis during its visits to the flowers, causing the pollen-bearing half-anther to be pressed down against its back. Floral-leaves often coloured.--_Rosmarinus_ (Rosemary); a shrub with leathery linear leaves, with rolled back edge. A small tooth on the filament represents the barren half of the anther. _Monarda._ The POLLINATION is generally effected by insects, especially bees; the under-lip is the landing-stage and the pollen is deposited on their backs. Cross-fertilisation is promoted by dichogamy; honey is secreted by an hypogynous disc and collected in the corolla-tube. Some genera are homogamous (_Lamium_, _Galeopsis_, etc.); others are dichogamous (protandrous); a few are _gynodiœcious_: ♀-and ☿-flowers in various relative sizes (_Glechoma hederaceum_, _Thymus_, _Salvia pratensis_, and others). The entrance of uninvited guests to the honey is often rendered difficult by whorls of hairs, etc. In numerous instances the upper lip protects the pollen from rain. _Cleistogamy_ is found _e.g._ in _Lamium amplexicaule_. 2,700 species; distributed over the entire globe, but the greater number in Mediterranean countries (especially in the Eastern regions), where many are shrub-like.--Poisonous and acrid properties are absent. On account of their _volatile oils_ they are principally used as _condiments_, for _perfumery_ and in _medicine_ (the officinal parts are therefore nearly always “folia” and “herba,” in _Lavandula_ the flowers, and the volatile oils extracted from them). Such are:[39]_Mentha piperita_ [+] (Peppermint)--menthol is obtained from this species and from _M. arvensis_--_M. viridis_ [+] (Spearmint), _M. crispa_ (Curly-mint), _Thymus vulgaris_ (Garden Thyme), _Melissa officinalis_ (S. Eur.), _Hyssopus officinalis_ (Hyssop, S. Eur.), _Origanum majorana_ (Marjoram, from the Mediterranean), _O. vulgare_ (Wild Marjoram), _creticum_, _smyrnæum_, etc., _Salvia officinalis_ (S. Eur.), _Rosmarinus officinalis_ (oil of Rosemary, S. Eur.), _Lavandula vera_ [+] (oil of Lavender, S. Eur.). Also: _Satureia hortensis_ (S. Eur.), _Ocimum basilicum_ (E. India), _Pogostemon patchouli_ (E. India), etc.--As _ornamental_ plants, _e.g._ _Monarda_, _Plectranthus_, and _Coleus_ (foliage-plants, often with red stems and leaves), _Stachys lanata_ (white, woolly), _Phlomis_, _Salvia_-species, _Perilla_, etc. Order 5. =Selaginaceæ.= 130 species; small, most frequently heath-like shrubs or herbs, mainly from S. Africa. They differ from the other Nuculiferæ especially in the bilocular, transversely-placed anthers of the 4 stamens (2 stamens divided as far as the base (?)). The ovary has 2, or by suppression only 1 loculus, each with 1 ovule, and the fruit is a schizocarp dividing into two, or is a 1-seeded nut. Radicle turned upwards.--A few are ornamental plants (_Selago_, _Hebenstreitia_). Order 6. =Globulariaceæ.= 12 species; especially in the Mediterranean. They form an analogy to the Compositæ, and in the main resemble _Jasione montana_ in appearance, the flowers being crowded into a spherical head (hence their name) and supported by bracts, but _without_ involucre; the ovary is _unilocular_ with 1 pendulous ovule. The _1-seeded nut_ is enveloped by the persistent calyx. The corolla is more or less labiate, the upper-lip is often absent as in the ligulate corollas of the Astereæ; stamens 4, didynamous, with transversely placed anthers opening by one transverse cleft. The leaves are scattered, simple, entire, and generally form a rosette. _Globularia._ Order 7. =Stilbaceæ.= Heath-like shrubs. The ovary is bilocular; 1 erect seed in each loculus, or the posterior cell is empty. _Stilbe._ 7 species. S. Africa. Family 32. =Contortæ.= _Hypogynous_, regular, ☿, gamopetalous flowers (Figs. 581, 582), which are generally 5- or 4-merous, with 5 or 4 stamens (with the exception of _Oleaceæ_ and _Jasminaceæ_ which have _only_ 2 stamens, alternating with the carpels). The gynœceum is formed of 2 (nearly always median) carpels. The corolla _very frequently has twisted æstivation_ (the upper edges of the petals being free; Fig. 581 _A_), and hence the individual lobes of the corolla are oblique, but the flower as a whole is regularly actinomorphic. A nectary, in the form of a honey-secreting ring or glands, is often found round the base of the ovary.--The leaves, with a few exceptions, are _opposite_ and _without stipules_. Endosperm large (Fig. 581 _C_), except in _Jasminaceæ_ and _Asclepiadaceæ_. The Apocynaceæ and the Asclepiadaceæ, on account of the free ovaries, without doubt represent a more primitive form, but the Asclepiadaceæ on the other hand form an offshoot on account of their peculiar pollen-masses. The Loganiaceæ form a transition to the Rubiaceæ. The orders are:-- A. STAMENS 5. 1, Gentianaceæ; 2, Apocynaceæ; 3, Asclepiadaceæ; 4, Loganiaceæ. B. STAMENS 2. 5, Oleaceæ; 6, Jasminaceæ; 7, Salvadoraceæ. Order 1. =Gentianaceæ= (=Gentians=). _Glabrous_ herbs, without latex; the opposite, undivided and _entire_ leaves are often slightly united at the base; many have rosette-like radical leaves. _Stipules absent_. The flowers are generally borne in regular, dichotomously-branched _dichasia_ (Figs. 580, 581 _A_), which finally become transformed into unipared scorpioid cymes; the parts of the flower are 4–5-merous as far as the gynœceum, which is 2-merous; the calyx frequently is almost polysepalous; the corolla has distinctly twisted æstivation (the upper edges being free) (Fig. 581 _A_), except _Menyantheæ_. The carpels are _entirely_ united, and most frequently form a _1-locular_ ovary with 2 _parietal placentæ_ bearing many ovules (often in several rows, Fig. 581 _D_, _F_). _Capsule_, 2-valved, with septicidal dehiscence, the incurved edges bearing the seeds (Fig. 581 _D_, _F_). [Illustration: FIG. 580.--_Erythræa._ Inflorescence. 1, 2, 3, etc., the successive shoot-generations.] =1.= GENTIANEÆ.--_Gentiana_ (Gentian) has most frequently a tubular, campanulate or funnel-shaped corolla, sometimes with teeth between the corolla-lobes and fringed in the throat of the corolla; _G. lutea_ has a rotate, yellow corolla.--~_Swertia_: rotate corolla; each lobe has at its base 1–2 nectaries, with fringed edges.~ _Erythræa_ (Centaury, Fig. 581); corolla most frequently salver-shaped. The anthers ultimately become spirally twisted (_E_). The style prolonged, deciduous. The flower has the _Lobelia_-arrangement, _i.e._ the median sepal is anterior; the corolla is rose-coloured (in the native species). The capsule is semi-bilocular (Fig. 581 _F_, _G_).--~_Cicendia_ has a low creeping stem, fine as a thread, and small, yellow flowers, 4-merous (without twisted anther).--_Chlora_ (Yellow-wort) 6–8-merous.~ [Illustration: FIG. 581.--_Erythræa centaurium._ Inflorescence, flower and fruit: _br^1_, _br^2_ floral-leaves of the 1st and 2nd order; _G_ a valve of the capsule separated from its fellow.] =2.= MENYANTHEÆ. _Menyanthes_ (Buck-bean) deviates in several respects from the type of the order. The leaves are _scattered_ and, in _M. trifoliata_, trifoliate; the corolla has _valvate_ æstivation; the testa is also very hard (thin in the true Gentians). They are aquatic plants with creeping rhizome; the flowers borne in racemes, with terminal flower, heterostylous. The corolla is funnel-shaped with a very hairy throat.--~_Limnanthemum_ with floating leaves, like the Water-lilies.~ 575 species; distributed over the entire globe, but most numerous in _Alpine_ districts. Neither poisonous nor nutritive plants are found, but several are used in medicine on account of the _bitter_ properties so prevalent amongst them. OFFICINAL: the roots of _Gentiana lutea_. The roots of other species, _e.g._ _G. purpurea_, _punctata_ and _pannonica_ (Europe) and the leaves of _Menyanthes trifoliata_ are medicinal. Some are grown as ornamental plants on account of the pure (often deep blue) colour of the flowers. Order 2. =Apocynaceæ= (=Periwinkles=). Trees and shrubs (also lianes), less frequently herbs, generally _with latex_. The leaves are opposite, simple, entire, _without stipules_; the flowers are regular; corolla-lobes oblique, æstivation twisted. The stamens are individually free, and the _pollen-grains are free_ or at most united in fours (see Asclepiadaceæ). The two carpels have 2–∞ ovules, in all cases there is only 1 style and a capitate stigma, which towards the base is widened out into a disc-like table (stigma-disc) abstricted in the centre; but the carpels in most of the genera (_e.g._ those mentioned below) are entirely separate, and the fruit consists of two _follicles_, the seeds of which often have a tuft of _woolly hairs_ projecting from the micropyle, less frequently of two drupes. In some other genera there is a 1-locular (provided with 2 parietal placentæ) or a 2-locular ovary becoming a 2-valved capsule or a berry. Endosperm abundant. _Vinca_ (Periwinkle) has a salver-shaped corolla, which is twisted to the left in æstivation (_i.e._ the left edge of the petals is free); nectaries 2, alternating with the carpels; the summit of the style is hairy. Follicles; seeds without hairs. ~Mostly creeping, perennial, evergreen plants, whose large flowers are apparently axillary; in reality they are terminal, but by the development of the bud in the axil of one of the two uppermost leaves, they are thus displaced over the other leaf of the pair (a helicoid sympodium being formed).--_Plumeria_, _Tabernæmontana_, _Cerbera_ (drupe). _Aspidosperma._~ _Nerium_ (Oleander). The leaves are in whorls of 3. Corolla funnel-shaped, in æstivation twisted to the right, and with a corona resembling that of _Lychnis_. The anthers are prolonged at the base and each also bears at the apex a long, linear, hairy appendage; these finally become spirally twisted. Follicles; seeds hairy. _Apocynum_, _Echites_, etc. _Epigynum_ is epigynous. 124 genera, 1,000 species; principally in the Tropics. Only 2 species of _Vinca_ are natives of this country; the following are cultivated as ornamental plants:--_Vinca minor_, _V. major_, _V. (Lochnera) rosea_, _Amsonia salicifolia_, _Nerium oleander_ (Eastern Mediterranean). The _latex_ of some is _poisonous_ (_Tanghinia venenifera_, _Cerbera_). Caoutchouc is obtained from others (_Hankornia_, _Landolphia_, _Vahea_, etc.). Tough bast is frequently developed. The bark of _Aspidosperma quebracho_ and the seeds of _Strophanthus hispidus_ are used in medicine (also for African arrow-poison), the latter is officinal. Order 3. =Asclepiadaceæ.= A natural and easily recognised order, closely allied to the Apocynaceæ, having, like it, frequently a poisonous latex, opposite, single, entire leaves and fundamentally the same floral diagram and floral structure (S5, P5, A5, G2); but in some the æstivation of the corolla is valvate. The carpels here also have _free ovaries_, but are united for some distance above into a _large, shield-like, 5-angular head_, having on its underside the true stigmas, and the fruit always consists of 2 _follicles_; seeds most frequently numerous and _hairy_ at the micropyle (“vegetable silk”); endosperm scanty.--The order is distinguished from the Apocynaceæ and from all other plants also, except the Orchids, by having all the pollen-grains in each of the =2= loculi of the anthers (true 2-locular anthers) united into _one waxy, club-shaped pollen-mass_ (“pollinium”), for the purpose of pollination by insects. These heavy masses, in order to secure pollination (as in the case of the Orchids), must be attached to sticky discs (corpuscula); there are 5 corpuscula, one at each of the corners of the 5-angular stylar-head (alternating with the anthers), and to each of these are attached 2 pollinia, one from each of the anthers situated on either side (thus each anther gives its right pollinium to one corpusculum and its left to another). The stamens are frequently united at the base, and each bears on the back a variously formed, petaloid appendage, termed a “cucullus.” [Illustration: FIG. 582.--_Asclepias cornuti._ _A_ An open flower with the calyx (_k_) and corolla (_c_) turned down; the stamens are bent together and surround the gynœceum. _B_ The andrœcium after removal of the sterile part (cucullus) of the anther, which functions as a nectary: _e_ the lateral expansions of the fertile portion of the anthers; _f_ the slit between the expansions of two contiguous anthers, through which the insect’s foot, and later a pollinium which is caught by it, is dragged, and behind which the only receptive part (stigma) is hidden; above the slit _f_ is the gland (_r_), which secretes the horny corpusculum, which is split at its base and joined on either side with a pollinium (this is more distinctly seen in _D_ and _E_). When the foot of the insect is caught in the slit (_f_) and is drawn upwards, it becomes entrapped in the slit of the corpusculum, which is then pulled out together with the pollinia firmly attached to it. In walking over the flowers the insect will draw its foot through other slits (_f_) and so leave the pollinia on the stigmas. _C_, _D_ The gynœceum with the pollinia hanging freely. _E_ A corpusculum and two pollinia.] A peculiar relative position (and therefore a good, distinctive characteristic) is often found in the _inflorescence_, which is cymose; it is placed _between_ the two leaves of a whorl, nearer to one than to the other. ~The leaf-pairs are placed obliquely in the floral region, at acute and obtuse angles, and not at right angles (as in the purely vegetative parts); the inflorescences are placed in two rows only which are nearly 90° from each other, and the two contiguous to one another are antidromous; they are in reality terminal, each on its own axis, and the entire floral portion of the shoot is a unipared scorpioid cymose sympodium; in addition, complications also arise through individual parts becoming united.--Herbs and shrubs, some twining or climbing.~ In _Asclepias_ the corolla is bent back and there is a cup-like cucullus, from the base of which protrudes a horn-shaped body, bent inwards.--_Vincetoxicum_ has a rotate corolla and a ring-like, 5-lobed cucullus, without internal prominences.--~_Stapelia_ (especially from S. Africa) is remarkable on account of its Cactus-like, leafless stems and large, brownish flowers, often with carrion-like smell. _Periploca_ has more powdery pollinia (S. Eur., etc.); _Hoya carnosa_ (Wax-flower; Trop. Asia) is a climber, and has small, annual, flower-bearing dwarf-branches. _Ceropegia._~ 201 genera with 1700 species, distributed over all tropical countries; few outside these limits: no native species. Several are used in medicine on account of the pungent properties of the latex. Condurango-bark of _Gonolobus condurango_ is medicinal. Caoutchouc is obtained from the latex of some (_e.g._ from _Cynanchum_). The seed-hairs, which are most frequently shining, silk-like, and white, are not sufficiently pliant to be of much value. Ornamental plants in our gardens: _Asclepias_-species, etc. Order 4. =Loganiaceæ.= Ovary single, with two loculi, in structure resembling the Rubiaceæ, but superior. 360 species are included in this order; the majority are tree-like, some lianes which climb by tendril-like branches. The _interpetiolar stipules_ of some species are very characteristic (as in Rubiaceæ, to which they maybe considered to be closely related). The fruit is a capsule or berry. The most familiar genus is _Strychnos_, which has spherical berries with an often firm external layer, and compressed seeds with shield-like attachments; endosperm abundant. The leaves have 3–5 strong, curved nerves proceeding from the base.--_Spigelia._--They have _no latex_, as in the two preceding orders, but many are _very poisonous_ (containing the alkaloid “strychnine,” etc.); the South American arrow-poison, urare or curare, is made from various species of _Strychnos_, also an arrow-poison in the East Indian Islands (Java, etc.). OFFICINAL, the seeds of _Strychnos nux vomica_ (“Vomic nut,” Ind.). The seeds of _Strychnos ignatii_ (Ignatius-beans, medicinal), and others are poisonous. Order 5. =Oleaceæ.= The leaves are always opposite. The inflorescences are racemes or panicles. The calyx and corolla are _4-merous_, more or less united, free in some species; the corolla has most frequently _valvate_ æstivation. All four forms of fruit occur (see the genera). _Ovules pendulous_, 2 in each loculus (Fig. 583 _C_). Endosperm oily.--_Syringa_ (Lilac) and _Forsythia_ (anthers somewhat extrose) have _capsules_ with loculicidal dehiscence and winged seeds.--_Fraxinus_ (Ash) has _winged nuts_ (samara) (Fig. 583 _D_); trees with most frequently imparipinnate leaves; the flowers are _naked_ and sometimes unisexual (polygamous), the Manna Ash (_F. ornus_) has however a double perianth with 4 free petals (Fig. 583 _a_); in the native species, _F. excelsior_, the flowers open before the foliage appears.--_Ligustrum_ (Privet) has _berries_.--_Olea_ (_O. europæa_; Olive) has _drupes_; the pulp and seeds of the ellipsoidal fruits are rich in oil. The lanceolate leaves are grey on the under surface, being covered with stellate hairs. In the wild state it is thorny (modified branches).--_Phillyrea_; _Chionanthus_.--Few species of _Linociera_ have 4 stamens. [Illustration: FIG. 583.--_Fraxinus ornus_: _A_ flower; _ca_ calyx; co corolla; _B_ gynœceum and calyx; _C_ longitudinal median section of gynœceum; _D_ fruit.] 180 species; chiefly in the northern temperate zone. The _Olive-tree_ (_Olea europæa_) has been an important cultivated plant from ancient times (Olive oil, Provence oil, “Sweet oil”). The best oil is extracted from the fruit-pulp. The fruits are edible. Home: Western Asia, Eastern Mediterranean. TIMBER: the Ash (_Fr. excelsior_). OFFICINAL: the Manna Ash (_Fr. ornus_), cultivated in the Mediterranean countries for the sake of its saccharine juice, which flows out and coagulates into “Manna.”--The following are ornamental plants: species of _Ligustrum_ and _Syringa_ (introduced in the 16th century, from S.E. Europe and Asia), _Forsythia_ (China, Japan; the large, yellow flowers are borne on dwarf-branches with scale-like leaves, before the opening of the foliage-leaves), _Chionanthus_. Order 6. =Jasminaceæ.= The æstivation of the corolla is _imbricate_; the _ovules are erect_; seeds almost without endosperm; radicle directed downwards. The number of lobes in the calyx and corolla is not 4, but _e.g._ 5, 8, 10, and variations are sometimes found in the same individual. The fruit is a berry or capsule. Many species are twiners, and their scattered or opposite leaves are most frequently imparipinnate.--120 species; especially in Trop. Asia (E. India). Some _Jasminum_-species are cultivated as ornamental shrubs in the warmer districts on account of their elegant foliage, and beautiful, sweet-scented flowers, the essential oil of which is also used in perfumery; the best known are: _J. sambac_ and _grandiflorum_. _Nyctanthes arbor-tristis_ opens its sweet-scented flowers only at night (E. India). Order 7 (?). _Salvadoraceæ._ 8–9 species; Asia, Africa.--_Salvadora._ b. Tetracyclicæ with epigynous flowers. Family 33. =Rubiales.= _The leaves are always opposite or verticillate. The flower is epigynous_, ☿, 5-(or 4-) merous, with the usual sympetalous diagram; 2–5 carpels. The inflorescences are frequently dichasial. The sepals are small, reduced to teeth, and become almost entirely suppressed in the higher forms.--The flower is regular in _Rubiaceæ_ and some _Caprifoliaceæ_, but in other genera of this latter order (especially of _Lonicereæ_) it is unsymmetrical. In several genera of the order first mentioned the loculi of the ovary contain many ovules, but in the last the number of loculi and ovules becomes reduced. This is to some extent connected with the nature of the fruit which is many-seeded in most instances, namely a capsule or berry, but in others nut-like. Endosperm is present. The family on one side is allied to the Contortæ (not only through the _Loganiaceæ_ but also through the _Apocynaceæ_), and may be regarded as an epigynous continuation of this family; on the other side it is allied to the Valerianaceæ and Dipsacaceæ. Many points of agreement with the _Cornaceæ_ and _Araliaceæ_ are also found, and in fact several Caprifoliaceæ are distinguished from these by hardly any other feature than the gamopetalous corolla. [Illustration: FIG. 584.--_Cinchona calisaya._ Flowering branch.] Order 1. =Rubiaceæ.= Leaves opposite (or verticillate), undivided and entire, with _interpetiolar stipules_ (Fig. 586). Flowers epigynous and hermaphrodite, _regular_, 4- or 5-merous with the usual arrangement (Figs. 585, 588–590); corolla gamopetalous, in æstivation often valvate; ovary _frequently 2-locular_. [Illustration: FIG. 585.--_Cinchona calisaya._ _A_ entire flower; _B_ after removal of the corolla; _C_ longitudinal section of ovary; _D_ fruit; _E_ seed.] There are no external characters which at once distinguish this exceedingly large order, as in many other natural orders (Compositæ, Umbelliferæ, etc.), but the _opposite_ leaves with _interpetiolar stipules_ form an excellent mark of recognition. It is divided into many sub-orders and groups, especially characterised by the nature of the ovary (1 or several ovules in each loculus), and of the fruit (schizocarp, berry, drupe, capsule).--The corolla is bilabiate in 4 genera; its æstivation in some is twisted; in _Capirona_, etc., the filaments are of unequal size. The ovary is semi-epigynous in _Henriquezia_, etc. In _Morinda_ all the fleshy fruits coalesce into one multiple fruit. =1.= CINCHONEÆ. The fruit is a 2-valved _capsule_, with many winged seeds (Fig. 585). _Cinchona_ (Quinine, Fig. 584). Trees and shrubs with the foliage and inflorescence somewhat resembling _Syringa_; the corolla also being of a lilac colour, more or less salver- or funnel-shaped, and frequently edged with a fringe of hairs (Fig. 585), is somewhat similar to that of _Menyanthes_. Their home is the Andes from Bolivia to Venezuela, varying in altitude from 1–3000 metres. There are now large plantations in Java and E. India. ~(The name “quinine” is of Indian origin; that of the genus “_Cinchona_,” is from the Spanish Duchess Cinchon, who in 1638 first introduced the bark into Europe.) The following are closely allied: _Cascarilla_, _Remijia_, _Ladenbergia_, _Manettia_, _Bouvardia_, etc.~ =2.= GARDENIEÆ. Trees and shrubs, frequently having a many-locular berry. _Randia_, _Gardenia_, _Genipa_, _Hamelia_, etc. =3.= COFFEEÆ. Only 1 seed in each of the two loculi of the ovary; _the fruit is a drupe with 2 stones_. _Coffea_ has an ellipsoidal fruit about the size and colour of a cherry; the two thin-shelled, parchment-like stones are enclosed by a thin layer of pulp; the two seeds are flat on the side turned to one another, which has also a deep, longitudinal groove curving to the sides. The endosperm is hard, horny and greyish (without starch); the small embryo lies in the lower end near the circumference. The Coffee-plant (_C. arabica_) is a small tree, or more frequently, and especially in plantations, a shrub with large dark-green leaves and scented, white flowers. Its home is in Tropical Africa; it is now cultivated in many tropical countries. _C. liberica_, W. Africa.--_Cephaëlis_ (_C. ipecacuanha_, Fig. 586; the roots are officinal).--~_Psychotria_, _Chiococca_, _Ixora_, _Hydnophytum_, _Myrmecodia_, etc.~ [Illustration: FIG. 586.--_Cephaëlis ipecacuanha._ Portion of a branch: _st_ stipules.] =4.= SPERMACOCEÆ. Chiefly small shrubs and herbs, many of which are weeds in tropical countries. The stipular sheaths bear numerous bristles at the edge. _Spermacoce_, _Borreria_, _Diodia_, _Richardsonia_, etc. =5.= STELLATÆ. _Herbaceous plants with_ verticillate leaves (Figs. 587, 588–590); _the stipules are large, leaf-like_, and resemble the lamina of the leaves, so that _the leaves appear to be placed several in a whorl_, while in reality there are only two opposite leaves, the stipules of which project _freely_, and are not erect (Fig. 587). [Illustration: FIG. 587.--_Rubia tinctorum._] In some cases there are apparently 4 leaves in the whorl, and then 2 of these are leaves, and the other two are their interpetiolar stipules. When there are apparently 6 leaves, then the two of these which are opposite each other are leaves, and the other four are stipules; if there are several members in the whorl, then a division of the stipules has taken place. The proof of this theory is founded upon the fact that not more than 2 of the leaves of the whorl ever support buds (which, in addition, are seldom of equal vigour), and also that the whorls do not alternate with each other, which, according to the rules of the position of the leaves, they should do if all the members of a whorl had equal value. If there are, for instance, 4 members in two successive whorls, they stand right above one another, and do not alternate. The development and anatomical relations (the branching of the vascular bundles) also point to the same conclusion.~--All the other groups of the order have only 2 small scale-like interpetiolar stipules, or they form at the base of the leaf-stalks an interpetiolar sheath, having often a toothed edge (Fig. 586).--Another characteristic feature in this group is that the calyx is rudimentary, the corolla _valvate_ (Fig. 588), and that each of the two loculi of the ovary has only 1 ovule. The fruit is a _schizocarp dividing into 2 fruitlets_ (Fig. 590). ~The forms of the fruit, as well as many other characters, as, for example, the epigynous flower, the rudimentary calyx, the two free or almost free styles, present interesting analogous resemblances to the polypetalous order of the Umbelliferæ.~ This group has its home chiefly in the temperate regions of the northern hemisphere, especially about the Mediterranean; it is the only group which occurs in this country, represented by 4 genera. [Illustration: FIGS. 588–590.--_Rubia tinctorum._ FIG. 588.--Diagram. FIG. 589.--Longitudinal section of flower. FIG. 590.--Longitudinal section of fruit (3/1).] _Galium_ (Cleavers) is almost destitute of a calyx; it has a small _4-partite, rotate corolla_, 4 stamens, and 2 free styles. The fruitlets are _nut-like_. The inflorescence is a paniculate dichasium passing into helicoid cymes.--_Asperula_ (Woodruff) is distinguished from the above by its salver- or funnel-shaped corolla. 1 style.--_Rubia_ (Madder, Figs. 587–590) has almost the same form of corolla as _Galium_, but (most frequently) a _5-merous flower_, and the fruitlets are “_drupes_.” ~_Sherardia_ (Field Madder); the flowers are clustered in closely arranged cymes surrounded by _an involucre_; _the calyx has 6 distinct teeth_, while the number of petals and stamens is 4. The corolla is funnel-shaped.--_Vaillantia._ _Crucianella._~ The DISTRIBUTION OF SEEDS, in some instances, is promoted by hooked appendages on the fruitlets (_e.g._ _Galium aparine_). The small flowers of the Stellatæ are frequently collected in compact inflorescences, and are therefore rendered more conspicuous; slight protandry is found in some, self-pollination in the species which are less conspicuous. Many species are heterostylous. _Myrmecodia_, _Hydnophytum_, and other genera have large tubers (hypocotyledonous stems), whose labyrinthine cavities and passages are inhabited by ants. About 4,500 species; tropical or sub-tropical except the Stellatæ; especially American. The tropical ones are mostly trees.--Several are ~OFFICINAL~ on account of the large amount of _alkaloids_ and _glycosides_ which they contain. The most important are the Cinchonas (_Cinchona calisaya_, _C. succirubra_, _C. officinalis_, _C. micrantha_, etc.), whose bark contains the well-known febrifuge and tonic, Quinine, Cinchonin, etc.; Quinine is also found in _Exostemma_, _Ladenbergia_, and _Remijia_. The root “Ipecacuanha” (an emetic) from _Cephaëlis ipecacuanha_ (Brazils). Caffeine is officinal. The use of the seeds of the coffee plant (“the beans”) was first known in Europe in 1583.--There are only a few which contain _aromatic_ properties, principally among the Stellatæ (coumarin in _Asperula odorata_, the Woodruff), in which group _colouring materials_ are also found. The root and root-stalks of _Rubia tinctorum_, the Madder (S. Eur., Orient., Fig. 587), were formerly largely used for dyeing, but are now superseded by the analine colours. Red dyes are also obtained from the roots of species of _Asperula_ and _Galium_. Gambier is a splendid colouring material, obtained from _Uncaria gambir_ (S.E. Asia), which is used in dyeing and tanning.--The order does not furnish many ornamental flowers. Order 2. =Caprifoliaceæ.= This order agrees with the Rubiaceæ in having opposite leaves and an epigynous flower, most frequently 5-merous with the ordinary tetracyclic diagram, but in some species it is zygomorphic; the corolla has imbricate æstivation, _carpels 3–5, most frequently 3_ (not 2, which is the most usual number in the Rubiaceæ). The fruit is generally a _berry_ or a _drupe_, but the most important, and in any case most easily recognisable feature, is the _absence of stipules_; in exceptional cases, where they are present, they are not interpetiolar, and are most frequently small.--~The majority of plants belonging to this order are shrubs or trees. Compound leaves sometimes occur. Stipules only appear in a few species of _Lonicera_, _Sambucus_ and _Viburnum_; in the common Elder (_Sambucus nigra_) they are in some instances glandular and small, but in other cases larger and more leaf-like (upon long, well-developed shoots); in the Dwarf Elder (_S. ebulus_) they have the normal leaf-like form; in _Viburnum opulus_ they are present as narrow lobes at the base of the petiole; in others they are completely absent. The leaves are frequently penninerved, rarely palminerved. The calyx, as in the Stellatæ and Aggregatæ, is often very insignificant.~ =1.= LONICEREÆ, HONEYSUCKLE GROUP. This has _campanulate or tubular corollas_ which are often zygomorphic; in connection with the length of the corolla the _style is long, filamentous_, and most frequently has a large, capitate stigma. There are _several ovules_ in the loculi of the ovary, and the fruit is most frequently a _berry_. [Illustration: FIG. 591.--_Lonicera._] _Lonicera_ (Honeysuckle). Shrubs, sometimes twiners. The corolla in some species is considerably bilabiate (Fig. 591), with 4 lobes in the upper lip, and 1 in the under lip, but in others more regular, tubular, or campanulate. The flowers are either borne in capitate inflorescences, which are compound and formed of closely compressed 3-flowered dichasia (sect. _Caprifolium_), or in dichasia with 2 flowers (the terminal flower is wanting). The ovaries and fruits coalesce in some (sect. _Xylosteum_). ~The opposite leaves in some species unite with each other and form a broad collar encircling the stem (Fig. 591). Above the primary bud 1–2 accessory buds are often found in the leaf-axils.--_Diervilla_ (_Weigelia_); with a 2-locular, 2-valved capsule.--_Symphoricarpus_ (Snowberry) has an almost regular, funnel-shaped corolla; a peculiar feature is found in the ovary which has 4 loculi, the 2 median having many ovules in 2 rows, all of which are aborted; the 2 lateral ones, on the other hand, each have only 1 ovule which is developed. Different forms of leaves are frequently found on the same branch; they are entire or lobed.~ =2.= SAMBUCEÆ, ELDER GROUP (Fig. 592). This has a _rotate_, _regular corolla_, extrorse anthers, a very short and thick (or almost absent) _style_, with tripartite stigmas, and only 1 pendulous ovule in each of the 3 (-5) loculi of the ovary. The fruit is a “_drupe_” with 1–3 (-5) stones. The inflorescence is made up of _cymes grouped in an umbel-like arrangement_. _Sambucus_ (Elder, Fig. 592) has _imparipinnate_ leaves and a “drupe” with 3 (-5) _stones_. Between the calyx and the style a disc remains on the apex of the fruit. _S. nigra_ with black fruit; _S. racemosa_ with red fruit; _S. ebulus_ is a perennial herb; the others are woody.--_Viburnum_ (Guelder-rose) has _simple_ leaves (penninerved or palminerved, entire, dentate or lobed), and a “drupe” with only 1 _stone_, which is compressed, cartilaginous, and parchment-like; 2 of the loculi of the ovary are aborted. ~(In _V. opulus_ the marginal flowers of the inflorescence are barren, and in that case their corollas are generally specially large; the cultivated _Viburnum_ has only barren flowers, with large corollas.)~ [Illustration: FIG. 592.--_Sambucus nigra_: _cor_ corolla; _s_ calyx.] =3.= LINNÆEÆ. _Linnæa borealis_ (the only species) is an extreme form of the order; it has a 2-flowered dichasium, funnel-shaped, slightly bilabiate corollas (2/3); 4 didynamous stamens. Two of the 3 loculi of the ovary have several ovules which are not developed, while the third has only 1 ovule, which developes into a seed. The fruit is a nut, which is enveloped by the two large bracteoles, which are covered by sticky, glandular hairs, and serve as a means of distribution. It is a small undershrub. [_Adoxa_, which was formerly classed in this order, appears, according to recent investigations, to be more properly placed among the Saxifraginæ.] In cases where the flowers are small, as in _Sambucus_ and _Viburnum opulus_, they are rendered conspicuous by being arranged in closely-packed inflorescences; they are massed together and form large surfaces, and in the last named are still more conspicuous on account of the barren, but large ray-flowers, which are of service in this respect. Honey is secreted in the nectaries at the base of the styles. In the genera with rotate flowers, as _Viburnum_ and other Sambuceæ, the honey lies so exposed and in such a thin layer, that only flies and insects with short probosces can procure it; bees, however, visit these flowers for the sake of the pollen. There is hardly any nectar in the Elder; self-pollination frequently takes place. The flowers of the Caprifoliaceæ, which, with their long corolla-tube are adapted for evening-and night-flying insects with long probosces, open in the evening, and at that time give off their strongest scent. DISTRIBUTION. 230 species; especially outside the Tropics in the Northern Hemisphere. In this country they are found especially in hedges and as under-shrubs.--OFFICINAL: the flowers and fresh fruits of the Elder (_S. nigra_), the fruits (“berries”) being also used in the household. ORNAMENTAL SHRUBS: species of _Lonicera_, _Symphoricarpus_, _Diervilla_, which are chiefly from N. Am., _Abelia_ and _Viburnum_. Family 34. =Dipsacales.= The leaves are _opposite and without stipules_. The flower (Figs. 593, 595, 598, 599, 600) is _epigynous_, _zygomorphic_ or _asymmetrical_, 5-merous with S5, P5, stamens typically 5, but by suppression _never more than 4_, sometimes less, carpels 3–2. The calyx is more or less insignificant, and almost suppressed in the extreme forms. The ovary has 3–1 loculi, but _only one loculus_ has an ovule, which is _pendulous_ with the micropyle _turned upwards_ (Fig. 594). Fruit a nut. Embryo straight, with the radicle _pointing upwards_ (Fig. 597), without or with endosperm. The inflorescences are distinct dichasia in Valerianaceæ, but in Dipsacaceæ and Calyceraceæ they are crowded together into capitula. This family is closely allied to the Rubiales through the Valerianaceæ, which have almost the same structure as many of the Caprifoliaceæ. It attains the highest development in the Dipsacaceæ, which are composite plants, but differs from Compositæ in the position of the ovule, etc. Order 1. =Valerianaceæ.= Herbaceous plants or under-shrubs with opposite leaves, often pinnate; stipules absent. The flowers are borne in _dichasia_ and in _scorpioid cymose inflorescences_ and are _entirely without any plane of symmetry_ (Fig. 593). The calyx and corolla are 5-merous, but the calyx is frequently very insignificant and ultimately a pappus, as in Compositæ; the corolla is frequently saccate or produced into a spur at the base. Most frequently, only 3 (4–1) of the 5 stamens are developed; these are free. Carpels =3=, which form an inferior _ovary_, often with 3 _loculi_, but only _1 of the loculi_ contains =1= _pendulous, anatropous ovule_ (Figs. 593, 594 _A_), the other loculi are empty and shrink up more or less completely. (Compare Fig. 593 _A_, _B_). Style 1, stigma tripartite. Endosperm absent; embryo straight, with the radicle directed _upwards_. The inflorescences are dichasia, or unipared scorpioid cymes with the branches developed in the axil of the second bracteole. Both the bracteoles are generally present and frequently form 4 very regular, longitudinal rows on the branches of the inflorescence.--5 stamens do not occur (except perhaps in _Patrinia_). The suppression of stamens and carpels takes place most readily on the anterior side of the flower and that turned towards the first bracteole (_a_) (Fig. 593), whose branch is suppressed in the dichasium; after this the posterior median stamen is next suppressed. By the vegetative characters as well as by the inflorescence and the flower, the order is allied to the Caprifoliaceæ and especially to the Sambuceæ. [Illustration: FIG. 593.--_A_ Diagram of _Valeriana officinalis_. _B_ Diagram of _Centranthus_.] In the least modified (oldest) forms, _Patrinia_ and _Nardostachys_, there is an almost regular flower, a 5-merous calyx, 4 stamens, and 3 loculi in the ovary, 2 of which however are barren. The stamens in _Valerianella_ are reduced to 3, in _Fedia_ to 2 (posterior), and the calyx is less distinctly 5-dentate; the 2 empty loculi in the ovary are still visible. _Fedia_ has a small spur at the base of the corolla. _Valeriana_ has a very reduced, hair-like calyx (pappus), an unsymmetrical, salver-shaped corolla with a _sac-like_, nectariferous spur at the base, 3 stamens and only 1 loculus in the ovary (Figs. 594, 593). _Centranthus_ (Fig. 593) is still further reduced. The corolla has a spur and only 1 stamen; ~unipared scorpioid cymes with 4 rows of bracteoles. In the last two genera there is a peculiar wall in the corolla-tube, which divides it longitudinally into two compartments (indicated by a dotted line in Fig. 593), one of which encloses the style. This wall is low in _Valeriana_, but in _Centranthus_ it reaches as far as the throat.--The rays of the _pappus_ are pinnately branched and rolled up before the ripening of the fruit. 12–20 in number (Fig. 594 _A_, _B_).~ _Val. officinalis_ and others are protandrous: in the first period the stamens project from the centre of the flower (Fig. 595 _a_), the stigmas in the second (_b_) when the stamens have become bent backwards. (_V. dioica_ is diœcious with large ♂-and small ♀-flowers).--275 species; especially from the temperate and colder parts of the northern hemisphere of the Old World, Western North America and the Andes.--_Bitter_ properties are characteristic, such for instance as the volatile acid and volatile oil of _Valeriana_; these occur especially in the rhizomes. OFFICINAL; the rhizomes of _V. officinalis_.--The true Indian “Nardus,” an important medicine and perfume in India, is extracted from _Nardostachys_ (Himalaya). A variety of _Valerianella olitoria_ is sometimes used as salad. [Illustration: FIG. 594.--_Valeriana_: _A_ ovary (longitudinal section); _B_ ripe fruit.] [Illustration: FIG. 595.--_Valeriana_: _a_ flower in the ♂ stage; _b_ in the ♀.] [Illustration: FIG. 596.--_Centranthus ruber._ Flower, its lowermost portion (the ovary and spur) in longitudinal section. (Mag.)] [Illustration: FIG. 597.--_Scabiosa atropurpurea._ Fruit in longitudinal section. Inside the “epicalyx” may be seen the fruit drawn out into a beak, with straight embryo and radicle directed upwards.] Order 2. =Dipsacaceæ= (=Teasels=). Herbs with _opposite_ leaves without stipules. The flowers are situated in compact capitula each with an involucre. A characteristic feature of the order is that _each flower_ of the capitulum has a _gamophyllous_ “_epicalyx_” (Figs. 597, 599, 600), which envelopes the inferior ovary. The flowers (Figs. 599, 600) are ☿, 5-merous (S5, P5, stamens typically 5, G=2=), but the calyx often expands at the edge into a membrane with 5, or an indefinite number of bristles or teeth (pappus, Figs. 597, 600), and the _zygomorphic, funnel-shaped corolla_ is sometimes 5-lobed and bilabiate (2/3), but most frequently 4-partite (Fig. 599), the two lobes of the upper lip coalescing into one lobe, as in certain Labiatæ, _Veronica_ and _Plantago_; the æstivation is _imbricate_. [Illustration: FIGS. 598–600.--_Dipsacus fullonum._ FIG. 598.--Inflorescence (the flowers in a zone below the apex commence to flower first). FIG. 599.--Flower (4/1). FIG. 600.--The same in longitudinal section.] _The stamens are never more than 4_, the posterior one _remaining undeveloped_; they _usually have free anthers_ which generally project considerably (Fig. 599). The ovary is unilocular with 1 _pendulous_ ovule and bears 1 _undivided style_; fruit a nut with 1 _seed, containing endosperm_ and with the radicle turned _upwards_ (Fig. 597). The flowers do not always open in centripetal order, a fact which may be observed especially in the Dipsacaceæ, in which a zone of flowers round the centre of the capitulum opens first, and the flowering then proceeds both upwards and downwards (Fig. 598). This has probably some connection with the fact that the capitulum has arisen from the coalescence of several dichasial inflorescences. In species of _Scabiosa_ the flowers open simultaneously at the circumference, or in a zone at the centre.--The morphological explanation of the “_epicalyx_” is not quite certain; in all probability it is formed from two united bracteoles, for an “epicalyx” is distinctly formed in this way in one of the Valerianaceæ, _Phyllactis_.--The _ray-flowers_ are larger and more irregular, labiate or ligulate, than the disc-flowers, yet not in so high a degree as in the Compositæ. =A.= A scarious bract to each flower. _Scabiosa_ has a 5-lobed corolla; the “epicalyx” has a dry, scarious, often finally large collar, and the true calyx is formed of long bristles (generally 5) (Fig. 597). _Succisa pratensis_ (Devil’s-bit) has a 4-lobed corolla, the collar of the “epicalyx” is herbaceous; the calyx as in the preceding.--_Pterocephalus._--_Dipsacus_ (Teasel); large, spiny and stiff-haired herbs with capitula, or short, thick spikes on which both the involucral-leaves and bracts project considerably, and are stiff and spinose (Fig. 598). The “epicalyx” has short teeth, or is almost entire. ~The leaves of the stem unite together in pairs, so that shallow cups are formed round the stems in which rain-water may collect.--_Cephalaria._--_Morina_: the flowers are falsely verticillate as in the Labiatæ; the calyx has 2 laterally-placed, entire, or emarginate lobes; 2 stamens, or 2 large and 2 small ones.~ =B.= Bristles, but _no_ true bract to each flower. _Knautia_; the corolla is 4-partite, the calyx cup-like, with many bristles or teeth on the edge. POLLINATION is in many species effected by insects. The honey is secreted by a ring round the base of the style. The flowers in our native species are considerably protandrous. Gynodiœcious flowers also occur.--150 species; especially in the Mediterranean and the Orient; the order is not represented in the South Sea Islands, Australia and America.--The heads of the true Teasel (_Dips. fullonum_) are used for carding wool, on account of the elastic bracts, which are hooked at the point. The order has bitter properties; tanin, etc.; but no species are used in medicine or the household.--_Scabiosa atropurpurea_, etc., are used as ornamental plants. Order 3. =Calyceraceæ.= This order resembles the Compositæ in the valvate æstivation of the corolla and the more or less united stamens, and the Dipsacaceæ in the undivided style, pendulous ovule and endosperm. The calyx is frequently composed of 5 distinct scales. An “epicalyx” is wanting.--20 species; America. Family 35. =Campanulinæ.= The flower is _epigynous_, perfect, with 5 sepals, 5 petals, and 5 stamens in regular alternation, and =3= (2–5) carpels. The sepals in all cases are _distinct_, but narrow and pointed, so that the æstivation is open. The corolla is gamopetalous with (as in the Compositæ) _valvate_, or slightly infolded-valvate æstivation. The stamens are nearly always _situated on the torus_ without being united to the corolla (Figs. 601, 604). The anthers adhere or unite and form a tube with introrse anthers from which the pollen is swept out by the projecting, brush-like hairs on the style (as in the Compositæ). The ovary is =3=-(2–5) locular, _many ovules_ in each loculus. The fruit is generally a _many-seeded_ capsule (or berry). Embryo in the centre of a fleshy _endosperm_.--The majority are herbs with scattered leaves, without stipules. The presence of _latex_ and _inulin_, together with the tubular formation of the anthers, the pollination, etc., indicate a relationship with the Compositæ. The _Cucurbitaceæ_ are by some authorities placed in this family as being most closely related to the Campanulaceæ. Although the corolla is most frequently gamopetalous, and other similarities to the Campanulaceæ are present, yet on account of the structure of the ovule, and for other reasons, the Cucurbitaceæ are here placed in the Choripetalæ. The Campanulinæ without doubt proceed upwards to the Compositæ, with which, in addition to the occurrence of inulin and laticiferous vessels (Cichorieæ), there are many corresponding features both in the structural and biological relations (epigyny, valvate æstivation of the corolla, tendency of the anthers to adhere or unite, protandry with a stylar-brush, etc.) The inflorescence of _Jasione_ is almost identical with that of the Compositæ. Order 1. =Campanulaceæ= (=Campanulas=). The flowers are _regular_ and in some only semi-epigynous, 5-merous, except in the gynœceum which is 3-merous (the unpaired, median carpel being generally posterior), more rarely 2–5-merous, and has a corresponding number of stigmas and loculi in the ovary; the placentation is axile with a large number of ovules. The median sepal is posterior. The stamens frequently have broad, free bases (Fig. 601 _H_) which cover the nectariferous upper surface of the ovary; the anthers only fit loosely together, and become separated as soon, as the pollen is shed (Fig. 601 _G_), 1 long style, which is studded by sweeping-hairs (stylar-brush), which ultimately become invaginated; the stigmas do not unfold until the stamens have shed the pollen (Fig. 601 _E_, _G_). Fruit a capsule.--Herbs, more rarely under-shrubs or shrubs, with latex and scattered, undivided leaves without stipules. The inflorescence is most frequently a raceme or spike _with_ terminal flower. =A.= Capsule opening at the side by pores and small valves: _Campanula_ (Canterbury-bell); the corolla is bell-shaped, rarely almost rotate; capsule obconical. ~The pores of the capsule are found near the top of the fruit when it is erect, and near the base when it is pendulous, so that the seeds are not liberated unless the capsule is forcibly shaken, and they are thus ejected to a considerable distance.~--_Phyteuma_ (Rampion) has free petals, which for a long time adhere at the apex and form a tube round the stamens (Fig. 601); inflorescence compact, spike-like or capitate, in the latter case resembling that of the Compositæ, and frequently with an involucre similar to the one possessed by this order. ~_Specularia_ (rotate corolla, prismatic capsule), _Michauxia_ (flower 8-merous).--_Symphyandra_ has syngenesious anthers.~ =B.= Capsule with valves at the apex, loculicidal dehiscence: _Jasione_; the petals are almost free. The anthers are united at the base (syngenesious). The flowers are situated in capitate umbels with involucres.--_Wahlenbergia_; _Platycodon_. [Illustration: FIG. 601.--_Phyteuma spicatum._ Flowers and parts of flowers in various stages of development.] =C.= Berry: _Canarina_; flower, 6-merous; leaves opposite. Protandry is general (Fig. 601). 510 species; principally in temperate countries. Several genera furnish ornamental plants, but are of little use for other purposes. The roots of some _Campanula_-and _Phyteuma_-species are large and may serve as pot-herbs (_C. rapunculus_, _P. spicatum_). Order 2. =Cyphiaceæ.= In this order the corolla is zygomorphic and the stamens free, hence it is intermediate between orders 1 and 3.--About 24 species; Africa. Order 3. =Lobeliaceæ= (=Lobelias=). This order may briefly be described as Campanulaceæ with _zygomorphic_ flowers and anthers _united into a tube_, in most cases slightly bent; generally 2 carpels and an _inverted_ position of the flower, _i.e._ the median sepal is turned anteriorly (Fig. 602) (a position which is found to occur within the Campanulaceæ). A twisting of the peduncle takes place even before flowering (as in the Orchids) so that the ordinary position of the 5-merous Dicotyledons appears to be restored. The zygomorphy of the flower is especially present in the corolla, which has a _bipartite_ under-lip and a _tripartite_ upper-lip, and is, in _Lobelia_, anteriorly (apparently posteriorly) deeply cleft (Fig. 602). There is 1 style, but the stigma is capitate and bilobed and surrounded at its base by a _whorl of hairs_, which assists in pollination (as a stylar-brush) in the same manner as the sweeping-hairs in the Campanulaceæ and Compositæ. There is _no terminal flower_ in the spicate, or racemose inflorescences.--_Lobelia_ has a capsule, several others have berries. ~_Isotoma_ (regular flower); _Heterotoma_ has a spur; _Siphocampylos_; _Lysipoma_ (pyxidium); _Clintonia_ (1–locular fruit). _Metzleria_ (all the petals are free).~ [Illustration: FIG. 602.--Diagram of _Lobelia fulgens_.] [Illustration: FIGS. 603, 604.--_Lobelia syphilitica._ FIG. 603. Flower (2/1). FIG. 604.--Longitudinal section of the same.] Entomophilous and protandrous. About 500 species, especially in the Tropics; in this country, _L. dortmanna_ (margin of lakes).--Several are cultivated in gardens and conservatories as ornamental plants (_Lobelia bicolor_, _erinus_, _fulgens_, etc., _Siphocampylos_, _Centropogon_). The latex of several species of _Tupa_ is poisonous; caoutchouc is also obtained from them. OFFICINAL: “herba _Lobeliæ_” (the alkaloid lobeline) from the poisonous _L. inflata_ (N. Am.). Order 4. =Goodeniaceæ.= Chiefly Australian (200 species), closely related to Orders 3 and 5, but without latex. The style is provided with a “collecting-cup” which receives the pollen before the flower opens; it has a small, hairy aperture through which the pollen is forced out by the stigmas, and through which they emerge when the pollen is shed; it is sensitive and exhibits movements when touched.--Herbs, under-shrubs, less frequently shrubs. _Goodenia_, _Leschenaultia_, _Scævola_. Order 5. =Stylidiaceæ= (or =Candolleaceæ=); 100 species, the majority Australian; zygomorpbic flowers, but with the ordinary position. The anterior petal is very small. The chief characteristic feature is the presence of only 2 stamens (with extrorse anthers) which are united with the style and form a _stylar-column_; this is bent like a knee and sensitive at the bend to such a degree that when touched it jerks violently across the flower to the opposite side and then loses its sensitiveness.--Herbs, less frequently under-shrubs. _Stylidium_ (_Candollea_). Family 36. =Aggregatæ.= The flowers, which are borne in “capitula” (Figs. 605, 610), are _epigynous_ (Fig. 605 _C_, _D_), _5-merous_ in the calyx, corolla and andrœcium, the corolla is _valvate_ in æstivation, with =2= carpels (S5, P5, A5, G2). The anthers are united into a tube (syngenesious) (except _Ambrosieæ_) which surrounds the bifid style. There is never more than =1= _loculus_ in the ovary, with =1= _erect_, anatropous ovule. The fruit is a 1–seeded nut (cypsela), with thin pericarp, the calyx generally persists as a tuft of hairs (_pappus_) (Fig. 606) on the summit of the fruit. Embryo _without endosperm_; the radicle _directed downwards_. Only 1 Order: Compositæ. With respect to the inflorescence and the development of the individual flowers, there is a very close resemblance to the Dipsacaceæ, which stand on the same plane of progression as the Compositæ. But while the latter are allied to Campanulinæ as the last stage in the process of evolution, the Dipsacaceæ form the final stage of the Rubiales-Dipsacales. Order =Compositæ=. (For the principal characteristics compare those of the family.) The Compositæ are chiefly herbs, but trees and shrubs also occur in tropical countries. The leaves may be scattered or opposite, but have no stipules. The outer leaves of the _involucre_ as a rule are barren, especially when numerous and imbricate, while the innermost ones support the ray-flowers of the capitulum; in a few instances all are fertile (_e.g._ _Tragopogon_, _Tagetes_). The CAPITULA are many-flowered, with the exception, _e.g._ of _Echinops_, which has 1-flowered capitula (see page 570). The capitula are again arranged in inflorescences, most frequently corymbose with centrifugal order of development. The _form of the receptacle_ is an important character for the division of the genera (flat, convex, conical), and also the _presence of scales_; these may be one scale (bract) for each flower (Fig. 610 _br_), or a large number of bristles, which do not each correspond to a leaf, or the receptacle may be entirely without covering (_naked_). The flowers open in acropetal order in each capitulum. All the flowers in a capitulum may be of the same _sex_, and their form and colour are in that case the same, or the sexes may be different, in which case the form and colour are also most frequently different: the ray-flowers have projecting labiate or ligulate corollas, while the disc-flowers have tubular corollas. As a rule in the latter case the ♀ flowers are at the circumference, and the ☿ in the centre, less frequently ♀-flowers at the edge and ♂-flowers in the centre. The ray-flowers in some genera are neuter (_e.g._ _Centaurea_). Some are diœcious. [Illustration: FIG. 605.--_Calendula arvensis_: _A_ capitulum; _B_ capitulum in longitudinal section; _C_ ♀-flower; _D_ ☿-flower; _E_ the stamens; _F_ capitulum with ripe fruits; _G_ ripe fruit.] There is no trace of an epicalyx (in contrast to the Dipsacaceæ, which they generally so resemble). The formation of the CALYX is very varied. The calyx always consists of a very small cushion-like structure, most frequently developed later than the corolla; the 5 corners, which correspond to the 5 sepals, in a few instances are raised as 5 large, flat, membranous bodies, _e.g._ in species of _Xeranthemum_, _Catananche_, _Sphenogyne_, etc.; in other instances each of these bears a shorter or longer bristle on its apex, followed by others in rather uncertain numbers and with but slight indications of order, on the edge and on the outer side of the calyx between the 5 points; in other instances, again, the calyx is covered with bristles and hairs without any indication of order or definite number (Fig. 606 _a_, _b_); finally instances occur in which the edge is raised as a membranous collar, irregularly toothed and notched, or divided into small scales. There are naturally differences in the means of distribution corresponding to the differences in structure of the calyx. The fruits _a_ and _b_ represented in Fig. 606 are distributed by the wind, those like _c_, on the other hand, by attaching themselves to animals and human beings. The rays of the pappus are termed _rough_ when special cells project a little beyond the surface, but if these grow out, and are hair-like, the pappus is said to be _feathery_. In some genera the pappus is raised on a long stalk, which is developed from the upper part of the fruit, and termed a _beak_ (Fig. 606 _a_). The pappus does not attain its full development till the ripening of the fruit, _i.e._ until it is about to be of use. [Illustration: FIG. 606.--_a_ Fruit of _Taraxacum_; _b_ of _Senecio_; _c_ of _Bidens_.] The COROLLA has various forms: (_a_) _tubular_ (Fig. 605 _D_), with a shorter or longer tube, not always of the same bore throughout and especially slightly widened at the top to form a bell-shaped opening, with 5 _regular_ teeth: (_b_) _labiate_ after 2/3, _i.e._ with 2 petals in the upper and 3 in the under lip: (_c_) _ligulate_, _i.e._ the corolla is split for a considerable distance on the posterior side (as in the Labiate genus _Teucrium_) and prolonged into a long, strap-like portion (Fig. 609 _A_), which projects upwards. A distinction must, however, be drawn between the true and false ligulate corolla. In the first case the corolla has 5 teeth at the apex (Fig. 609 _A_) and is made up of all the petals of the corolla united together; this is the usual condition in the _Ligulate-flowered_. In the latter case (Fig. 605 _C_) the tongue has only 3 teeth (or is more irregularly 2–3-dentate), and is only formed of 3 petals; the corolla is then truly bilabiate, the tongue is the large under lip, and the upper lip is very slightly developed, or even at an early stage quite suppressed. This false “ligulate” corolla is found among the _ray-flowers_; sometimes the upper lip is seen quite plainly, _e.g._ in _Tagetes_, especially in the double capitula. ~The VENATION of the corolla is peculiar; there are always commisural veins which branch dichotomously at the angles between the teeth of the corolla, and send a branch into the edge of the two nearest teeth. The midrib is frequently absent, but may be present, and then it has sometimes no connection with the other veins of the corolla.~ [Illustration: FIG. 607.--_Centaurea cyanus_: _A_ the anther-tube (_st_) with the crescentic curved filament before irritation; _g_ the style; _k_ the base of the corolla; _B_ the same after irritation, the anthers are drawn further down.] The STAMENS are attached to the corolla, and have free filaments (_Silybum_ has united filaments), but the anthers, which at first are free, adhere together and form a tube (Fig. 605 _E_: only _Ambrosieæ_ have free anthers). The _connective_ is generally prolonged, and protrudes above the anthers as a thin, brown membrane of various forms (Fig. 605 _E_); appendages of various forms may also be found at the base of the anthers. The anthers open introrsely, and the pollen must be carried out at the top of the tube by upward growth of the style, and by means of the “stylar-brush” (Figs. 607, 608, 609); the filaments are sometimes sensitive (_e.g._ in the Corn-flower, Fig. 607), and shorten on being touched, so that the anther-tube is pulled downwards, and the pollen swept out at the top (Figs. 607, 608 _A_, _B_). [Illustration: FIG. 608.--_Cirsium arvense_: _A_ the upper portion of a flower, the pollen (_e_) is being ejected; _B_ part of the upper portion of the style with stylar-brush (_b_, _c_) and the stigmatic papillæ (_d_).] [Illustration: FIG. 609.--_Leontodon autumnale_: _A_ ligulate flower; _B_ extremity of the style with stylar-brush (_a_), stigma (_b_) and pollen-grains (_c_). _C_ _Centaurea cyanus_.] [Illustration: FIG. 610.--_Achillea millefolium._] The STYLE divides at the apex into two branches (Figs. 609, 610), both of which generally bear on the inner surface two lines of stigmatic papillæ (Fig. 610 _B_, _C_) and being in shape, etc., very varied, are therefore employed as systematic characters.--~The most important types are: =A.= The style is uniformly cylindrical; its branches are semi-cylindrical, long, and with long hairs, and finally bend backwards; the stylar branches bear slightly projecting stigmatic papillæ on the inner side. This form is characteristic of the _Cichorieæ_ (Fig. 609 _A_ _B_). =B.= The style is uniformly cylindrical; the branches are long, cylindrical or club-like, short, not rolled back, with fine hairs externally; the stigmatic lines do not reach beyond the centre, and do not meet together. Characteristic of _Eupatorium_, _Petasites_, _Tussilago_. =C.= The style is thickened beneath the stigmatic branches in the form of a knob, or very hairy (Fig. 609 _C_); the stigmatic lines reach as far as the apex of the branches and then converge; sometimes the stigmatic branches are united as far as the apex. Characteristic of the _Cynareæ_. =D.= The stylar branches are lanceolate, or linear, pointed; externally flat and thickly covered with hairs in the upper portion; the stigmatic lines cease where the hairs commence externally. Characteristic of _Aster_, _Bellis_, _Inula_, _Dahlia_, etc. =E.= The stylar branches are linear, with long, brush-like hairs at the apex, where they are either abruptly cut off or prolonged into a very hairy, conical appendage; the stigmatic lines are broad, _reach as far_ as the brush-like hairs, and do not meet together (Fig. 610). Characteristic of _Senecio_, _Helianthus_, _Xanthium_, _Gnaphalium_, _Artemisia_, _Anthemis_, and others related to these.~ A _ring-like nectary_ is found round the base of the style. The thin-walled _cypsela_ (Fig. 606), with seeds fitting closely to the pericarp, has many different forms (smooth, ribbed, spined, etc.); its point of attachment generally lies at the lowest end but sometimes it is drawn obliquely up the side (_Centaurea_, etc.). The calyx, persistent on the apex of the fruit, has been described above. Some genera have two or three different forms of fruits in each capitulum.--The embryo is straight, with the radicle _turned downwards_, and _without endosperm_, but is rich in oil. The variously flowered capitula, whose normal tubular disc-flowers have been changed to ligulate flowers, may be termed “double flowers.” The relationship of the Compositæ to the Campanulinæ has been described above (page 561). The alliance with the Dipsacaceæ is more apparent than real. Similar capitate inflorescences also occur as the final stage in other lines of descent, as in _Eryngium_ among the _Umbelliferæ_. =1. Cynareæ, Thistle Group.= Flowers all ☿, regular, with _tubular_ corollas. The receptacle is covered with numerous _bristles_, which surround the flowers without any definite order, or the edges of the grooves in which these are placed have a well-marked fringe. The involucral leaves are numerous, imbricate, and are either prolonged into a _thorn_ or terminate with a _membranous edge_. The style has been described on page 568 (Fig. 609 _C_). Nearly all have a hairy or feathery pappus. The filaments are sensitive. _Carduus_ (Thistle); capitula ovoid; involucral leaves compact, imbricate, with thorny points; the pappus-rays are _hair-like_ and united at the base by a ring (_i.e._ the calyx), and fall off together.--_Cirsium_ (Fig. 608) has a _feathery_ pappus, in other respects it is like _Carduus_. ~_C. arvense_ reproduces and passes the winter by means of suckers.~--_Cynara_ (Artichoke) has a feathery pappus and large, _solitary_ capitulum, with broad involucral leaves; these have a fleshy base like the receptacle (edible).--~_Silylum_ has united filaments. _S. marianum_ (Milk-thistle), has leaves with numerous _white spots_. _Onopordon_ (Cotton-thistle). _Cnicus_ (_C. benedictus_) has a large, many-spined thorn on the involucral leaves; pappus trimorphic.~--_Lappa_ (Burdock) is easily recognized by the _hooked involucral leaves_, which assist in the distribution of the fruit; in this respect it differs from the other inflorescences, and also in the fact that the pappus is short, and quickly falls off, without serving as a means of distribution.--~_Carlina_; the external involucral leaves are _leafy_, _thorny_, with branched or unbranched spines standing straight out or bent backwards; the _internal ones are dry_, and prolonged as _dry_, _coloured_, radiating _scales_. The well-developed bristles on the receptacle and edge of the calyx are _deeply cleft and lobed_.~--_Centaurea_ (Knap-weed, Fig. 607). The ray-flowers are neuter, and generally larger than the disc-flowers; the involucral leaves are regularly imbricate, but are frequently provided at the apex with a dry, chaffy, often lobed, fringed appendage. The attachment of the fruit is lateral. _Serratula_ (Saw-wort).--~_Carthamus_, the outer and inner involucral leaves differ very much.~--_Echinops_ (Globe-thistle) is characterised by having “compound capitula,” _i.e._ there is only one flower in each capitulum, but many such capitula are collected into a spherical head, which at the base may also have a few involucral leaves. The individual capitula have narrow, linear involucral leaves. ~(There are altogether about 150 species of Compositæ with 1-flowered capitula, all from warm countries.)~--_Xeranthemum_, _Staehelina_, _Jurinea_, _Saussurea_, etc. =2. Mutisieæ, Labiate-flowered Group.= Tropical (S. American) forms whose zygomorphic flowers have a bilabiate corolla (2/3). The involucre is nearly the same as in the Thistles. =3. Cichorieæ, Chicory Group= (or LIGULIFLORÆ). The flowers are all ☿ and have a _ligulate, 5-dentate_ corolla. The stylar branches are thin and prolonged (Fig. 609 _B_). _Laticiferous vessels_ occur in the majority (in this feature they resemble the Lobeliaceæ and Campanulaceæ). =A.= The pappus is _wanting_, or it is _scale-like_, but not long and hairy.--_Cichorium_ (Chicory); capitula with _blue flowers_, borne singly or a few together in the leaf-axil; there are two whorls of involucral leaves, an outer one of short and radiating, an inner of more numerous, longer and erect leaves; pappus, scale-like.--_Lapsana_ (Nipplewort). The few involucral leaves are nearly of the same size, and persist forming a sort of capsule round the fruits, which are entirely without a pappus. There are only a few flowers in the small capitula.--_Arnoseris_ (Swine’s-succory), _Catananche_, etc. =B.= The pappus is long and _hairy_ (not branched), generally fine and snowy-white. There are _no scales_ on the receptacle. The two genera first considered have _beaked_ fruits.--_Taraxacum_ (Dandelion) (Fig. 606 _a_); the capitula are many-flowered, and borne singly on the top of a leafless, hollow stalk.--_Lactuca_ (Lettuce) has many small, few-flowered capitula borne in panicles.--_Crepis_ (Hawksbeard).--_Hieracium_ (Hawk-weed) has many imbricate involucral leaves, and a stiff, brittle, brownish pappus.--_Sonchus_ (Sow-thistle); the capitula, when a little old, have a broad base, and are abstricted above in the form of a jug; involucral leaves imbricate; the fruit is compressed, without a beak, ridged. The soft, white pappus falls off collectively. =C.= The pappus is _feathery_ and branched; no scales on the receptacle.--_Tragopogon_ (Goat’s-beard) generally has 8 involucral leaves in one whorl. The fruit has a long beak; the rays of the pappus are interwoven in the form of an umbrella.--_Scorzonera_ has fruits like the preceding, but almost without any beak; involucral leaves many, imbricate.--_Leontodon_ (Hawkbit) has a slightly feathery pappus, rays not interwoven; beak absent.--_Picris._ =D.= Long, chaff-like, deciduous scales on the receptacle; pappus _feathery_.--_Hypochœris_ (Cat’s-ear). =4. Eupatorieæ, Hemp-agrimony Group.= All the flowers are most frequently ☿; corollas tubular and regular; the involucral leaves are not stiff and spiny; the receptacle is not covered with stiff bristles. The stylar branches are long, club-like, or gradually tapering. There is no swelling below the stigma. _Eupatorium_ (Hemp-agrimony); all the flowers are ☿.--_Petasites_ (Butterbur); ray-flowers ♀, disc-flowers ☿ or ♂; sometimes diœcious. Capitula in racemes or panicles. The leaves develop after the flowering.--_Tussilago_ (_T. farfara_, Colt’s-foot) has a solitary capitulum borne on a scaly, scape-like stem; the ray-flowers are ♀ with _ligulate_ corollas, disc-flowers ♂. The leaves unfold after the flowering. _Ageratum_, _Mikania_, _Vernonia_. =5. Astereæ, Aster Group= (or RADIATÆ, Ray-flowered). The flowers are of two forms and different sexes; the ray-flowers are ♀ (sometimes neuter), most frequently with irregular, _falsely ligulate_, radiating corollas; the disc-flowers are ☿, regular, with tubular corollas (Fig. 610). Sometimes only tubular flowers are present, as _e.g._ in _Senecio vulgaris_ (Groundsel), and the exterior of the capitulum is then as in the Eupatorieæ. The stylar branches are straight, more or less flat and short (Fig. 610). =A.= ANTHEMIDEÆ. Involucral leaves imbricate, generally membranous at the edge; _pappus wanting_, or at most a _membranous margin_ to the calyx, but without hairs. [+]. _Chaff-like bracts_ on the receptacle are found in _Anthemis_ (Chamomile), _Anacyclus_ (_A. officinarum_), _Achillea_ (Milfoil, Fig. 610), _Santolina_, etc. [++]. A _naked_ receptacle is found in the following: _Bellis_ (Daisy) has solitary capitula on leafless stalks with white ray-flowers.--_Matricaria_ (Wild Chamomile) has a conical receptacle. ~(_M. chamomilla_ has a very high, hollow receptacle; _M. inodora_ has large, odourless capitula, and the receptacle is not hollow.)~--_Chrysanthemum_ (Ox-eye) most frequently large, solitary capitula; flat receptacle.--_Pyrethrum_; pappus scanty.--With these are classed _Tanacetum_ (Tansy) and _Artemisia_ (Wormwood) with tubular corollas only. =B.= HELIANTHEÆ. Most frequently a bract to each flower is found on the receptacle. The pappus is never exactly hairy, but consists of scales, spines, etc., and the fruits are most frequently compressed (Fig. 606 _c_).--_Helianthus_ (Sun-flower); _H. tuberosus_ (Jerusalem Artichoke) has tuberous underground stems. _Dahlia_ has tuberous roots (Am.). _Bidens_ (Bur-marigold, Fig. 606 _c_); the fruits are compressed with 2 (or more) spines provided with reflexed barbs.--_Calliopsis_; _Rudbeckia_; _Zinnia_; _Tagetes_ has united involucral leaves, and yellow, transparent oil-glands. _Spilanthes_, _Galinsoga_, _Melampodium_, _Silphium_ (Compass-plant), _Helenium_, _Gaillardia_. =C.= CALENDULEÆ have 1–2 rows of involucral leaves, a naked receptacle, and large, crescent-shaped, irregularly warted fruits, of different forms in the same capitulum; pappus absent (Fig. 605).--_Calendula_ (Marigold); ray-flowers ♀, disc-flowers ♂. =D.= SENECIONEÆ, have a fine, _hairy_, white pappus; no bracts, otherwise as in Anthemideæ. The involucral leaves are most frequently in 1–2 rows.--_Senecio_ (Groundsel) has two whorls of involucral leaves, which most frequently have black tips, the external being much shorter than the internal ones (_S. vulgaris_ has all flowers ☿ and alike).--_Cacalia_, _Doronicum_, _Cineraria_, _Ligularia_, _Arnica_ (_A. montana_; large, long-stalked capitula; leaves opposite, forming a kind of rosette). =E.= ASTEREÆ have a bristle-like, unbranched pappus, often of a dingy brown; receptacle naked; involucral leaves numerous, imbricate.--_Solidago_ (Golden-rod); capitula small, yellow-flowered, borne in panicles. _Aster_; disc-flowers most frequently yellow, ray-flowers violet; _Callistephus_; _Erigeron_ (Flea-bane)--_Inula_.--All the corollas are tubular in: _Gnaphalium_ (Cud-weed); involucral leaves dry, rattling, often coloured; the foliage-leaves and stem often white with woolly hairs; ray-flowers ♀, with narrow, tubular corolla; disc-flowers ☿ (few). _Antennaria_ (Cat’s-foot; diœcious), _Filago_, _Helichrysum_, _Ammobium_, _Rhodanthe_ and others. _Leontopodium_ (_L. alpinum_, “Edelweiss”). =F.= AMBROSIEÆ, a very reduced type of Compositæ, differing from the others in having _free anthers_; the capitula are generally unisexual, monœcious, the ♂ borne in a terminal inflorescence, the ♀ in the leaf-axils. In other respects they are most closely related to _Heliantheæ_.--_Xanthium._ In the ♂-capitula there are many flowers without calyx, but with tubular corolla and free involucral leaves. In the ♀-capitula there are only 2 flowers, which are entirely destitute of both calyx and corolla; involucral leaves 2-spined, united to form an ovoid, bilocular envelope, each compartment containing one flower. The envelope of involucral leaves unites with the fruits, enclosing them at maturity with a hard covering from which numerous hook-like spines project, assisting very greatly in the distribution of the fruit. The whole structure thus finally becomes a 1- or 2-seeded _false_ nut.--_Ambrosia_, the ♀ capitulum 1-flowered. POLLINATION. The flowers are somewhat insignificant, but become very conspicuous owing to a number being crowded together in one inflorescence. The corollas of the ray-flowers, being often very large (_Astereæ_; _Centaurea_), frequently render the capitula still more conspicuous. The capitula display many biological phenomena similar to those often shown by the individual flowers in other orders, e.g. by periodically opening and closing, in which the involucral leaves resemble the calyx in their action. (The name “Compositæ” originates from the term “flos compositus,” composite flower). An abundance of honey is formed, which to some extent fills up the corolla-tube, and since insects may visit a number of flowers in the course of a short period they are very frequently visited, especially by butterflies and bees. The pollination has been described on page 567. Protandry is universal. In the bud the tips of the styles, covered by the sweeping-hairs, lie closely enveloped by the anther-tube; in the next stage the style grows through the tube and sweeps out the pollen as it proceeds; ultimately the stylar branches expand and the stigma is then prepared to receive the pollen. In many, the sensitiveness of the filaments assists in sweeping out the pollen at the exact moment of the insect visit. Regular self-pollination is found _e.g._ in _Senecio vulgaris_; wind-pollination _e.g._ in _Artemisia_ and the plants related to it. This extremely natural and well-defined order is the largest (and no doubt one of the youngest?); it embraces 10–12,000 known species (in 770 genera), or about one-tenth of all Flowering-plants. They are distributed over the whole globe, but are most numerous in temperate countries; the majority prefer open spaces; a smaller number are forest-forms. They abound especially in open districts in America. Among the substances frequently found may be mentioned: INULIN (especially in the subterranean parts), BITTER materials, Tannin, volatile oils, fatty oils in the fruits. MEDICINAL:[40] “Herba” of _Artemisia absinthium_ (Wormwood) and _maritima_[+] (Sea-wormwood), _Achillea millefolium_; the _leaves_ of _Cnicus benedictus_ and _Tussilago farfara_; the unopened _capitula_ of _Artemisia maritima_, var. _stechmanniana_; the _capitula_ of _Tanacetum_, _Matricaria chamomilla_[+] (wild Chamomile), _Anthemis nobilis_[+] (common Chamomile); the separate flowers of _Arnica_; the _roots_ of _Arnica montana_[+], _Taraxacum officinale_[+], _Anacyclus officinarum_[+], _Lappa major_, _minor_, _nemorosa_ and _tomentosa_, _Inula helenium_ and _Artemisia vulgaris_; the latex of _Lactuca virosa_[+]. The following are cultivated for food:--_Lactuca sativa_ (Lettuce), _Cichorium endivia_ (from E. Asia, for salads), _Cynara scolymus_ (Artichoke, Mediterranean), _Scorzonera hispanica_ (S. Eur.), _Helianthus tuberosus_ (Jerusalem Artichoke, from N. Am., introduced into Europe 1616), _Cichorium intybus_ (roots as “chicory,”) _Tragopogon porrifolium_ (Salsafy), _Artemisia dracunculus_. OIL is extracted from the following (the seeds): _Helianthus annuus_ (Peru), _Madia sativa_ (Chili), _Guizotia oleifera_ (Abyssinia). DYES from: _Carthamus tinctorius_ (Safflower, used in the preparation of rouge; Egypt), _Serratula tinctoria_. INSECT-POWDER from: _Pyrethrum cinerariifolium_ (Dalmatia) and _roseum_ (Persia, Caucasus). The following are cultivated in houses and gardens for the sake of their scented leaves:--_Tanacetum balsamita_ (Balsam), _Artemisia abrotanum_ (Southernwood) and _A. argentea_. A great many of the genera enumerated are cultivated in dwelling-houses for the sake of the flowers; _e.g._ _Pericallis cruenta_ (generally termed “Cineraria”). _Asteriscus pygmæus_ is supposed to be the genuine “Rose of Jericho”; the involucral leaves envelop the fruits after their ripening and keep them enclosed for 8–10 months until rain occurs. APPENDIX ON THE CLASSIFICATION OF PLANTS. BY M. C. POTTER. The earliest systems of classification were derived from the properties and uses of plants; and it was not until some two centuries ago that any scientific grouping of plants was attempted. Aristotle and Theophrastus had adopted the groups of Trees, Shrubs and Herbs as the chief divisions of the Vegetable Kingdom, a system which persisted and was employed by Tournefort and Ray as late as the end of the 17th century. The arrangement by which these three divisions were separated into smaller divisions was often founded upon a single character, such as the formation of the corolla, the form of fruit, that of the calyx and corolla, etc. All these systems of classification which brought into close proximity plants distinguished by some one character alone, could only be considered as _artificial_, since plants related to one another would not necessarily be included in the same group. As the knowledge of the morphology, physiology, and reproduction of plants increased, such systems were recognised as unscientific, and it became the aim of botanists to establish a _natural_ system, founded upon mutual relationships, which would associate together _only_ those plants which are truly allied. The following are some of the chief systems of classification which will show the gradual development of the natural system, and may be of service to students making use of this text-book.[41] System of JOHN RAY (1703). I. Herbæ. A. IMPERFECTÆ (Flowerless). B. PERFECTÆ (Flowering). _Dicotyledones_. _Monocotyledones._ II. Arbores. A. _Monocotyledones._ B. _Dicotyledones._ Ray was the first botanist who recognised the importance of the one or two seed-leaves of the embryo, and initiated the division of the Flowering-plants into Monocotyledons and Dicotyledons. System of LINNÆUS (1733). In his well known artificial system Linnæus divided the Vegetable Kingdom into twenty-four classes, based upon the number, relative position and union of the stamens with regard to each other, and also to the gynœceum. Class I. MONANDRIA. Flowers with 1 stamen. „ II. DIANDRIA. „ „ 2 stamens. „ III. TRIANDRIA. „ „ 3 „ „ IV. TETRANDRIA. „ „ 4 „ „ V. PENTANDRIA. „ „ 5 „ „ VI. HEXANDRIA. „ „ 6 „ „ VII. HEPTANDRIA. „ „ 7 „ „ VIII. OCTANDRIA. „ „ 8 „ „ IX. ENNEANDRIA. „ „ 9 „ „ X. DECANDRIA. „ „ 10 „ „ XI. DODECANDRIA. „ „ 11 to 19 stamens. „ XII. ICOSANDRIA. „ „ 20 or more stamens inserted on the calyx. „ XIII. POLYANDRIA. „ „ 20 or more stamens inserted on the receptacle. „ XIV. DIDYNAMIA. Stamens didynamous. „ XV. TETRADYNAMIA. „ tetradynamous. „ XVI. MONADELPHIA. Filaments united into 1 bundle. „ XVII. DIADELPHIA. „ „ „ 2 bundles. „ XVIII. POLYADELPHIA. „ „ „ several bundles. „ XIX. SYNGENESIA. Anthers united together. „ XX. GYNANDRIA. Stamens and pistil united. „ XXI. MONŒCIA. Flowers diclinous, ♂ and ♀ on the same plant. „ XXII. DIŒCIA. „ „ ♂ and ♀ on different plants. „ XXIII. POLYGAMIA. ♂-, ♀-, and ☿-flowers on the same plant. „ XXIV. CRYPTOGAMIA. Flowerless plants (Ferns, Mosses, Algæ, Fungi). These classes were further divided into orders, according to the number of styles, as Monogynia, flowers with 1 style; Digynia, with 2 styles, etc. Thus a Dock (_Rumex_), having 6 stamens and 3 styles, would be placed in Class VI., HEXANDRIA, and Order III., Trigynia. Class XIV. was divided into two orders. Order I., Gymnospermia, with seeds apparently naked, comprising the Labiatæ; and Order II., Angiospermia, with the seeds enclosed in a capsule (_Bartsia_, _Rhinanthus_). Class XV. was divided into two orders: Order I., Siliculosa, fruit a silicula (_Capsella_); and Order II., Siliquosa, fruit a siliqua (_Brassica_). Class XIX. was divided into Order I., Æqualis, all the flowers perfect (_Sonchus_); Order II., Superflua, flowers in the centre perfect, those at the circumference with pistils only (seemingly superfluous), _e.g._ _Aster_; Order III., Frustranea, flowers in the centre perfect, those at the circumference neuter, _e.g._ _Centaurea_. “Fragments” of a natural system have also come down to us from Linnæus, who himself always recognised the imperfection of his artificial system. System of ANTOINE LAURENT DE JUSSIEU (1789). Class =Acotyledones.= Plants without cotyledons: Fungi, Ferns, Mosses, Algæ, Naiades I. =Monoctyledones.= Plants with _one_ cotyledon:-- 1. Stamens hypogynous II. 2. „ perigynous III. 3. „ epigynous IV. =Dicotyledones.= Plants with _two_ cotyledons:-- { Stamens epigynous V. 1. APETALÆ { „ perigynous VI. { „ hypogynous VII. { Corolla hypogynous VIII. 2. MONOPETALAE { „ perigynous IX. { „ epigynous, {anthers connate X. { „ free XI. { Stamens epigynous XII. 3. POLYPETALÆ { „ hypogynous XIII. { „ perigynous XIV. 4. DICLINES IRREGULARES, male and female flowers on different plants, corolla generally absent. System of A. P. DE CANDOLLE (1819). I. =Vasculares.= Plants with vascular bundles. 1. EXOGENÆ. Vascular bundles arranged in a ring. A. _Diplochlamydeæ._ Calyx and corolla present. _a._ Thalamifloræ. Corolla polypetalous and hypogynous. _b._ Calycifloræ. Corolla perigynous or epigynous; stamens inserted on the calyx. _c._ Corollifloræ. Corolla gamopetalous; stamens inserted on the corolla. B. _Monochlamydeæ._ Perianth simple. 2. ENDOGENÆ. Vascular bundles scattered, the youngest in the centre. A. _Phanerogamæ._ Flowers present. B. _Cryptogamæ._ Flowers absent. II. =Cellulares.= Vascular bundles absent. 1. FOLIACEÆ. Leaves present. 2. APHYLLÆ. Leafless. ROBERT BROWN published in 1827 his discovery of the gymnospermy of the ovules of the Coniferæ and Cycadeæ, and showed that the Gymnosperms, which had previously been classed with the Dicotyledons, must be regarded as an independent group. System of STEPHEN ENDLICHER (1836–40). I. =Thallophyta.= No differentiation into stem and root. 1. PROTOPHYTA. Class I., Algæ; Class II., Lichenes. 2. HYSTEROPHYTA. Class III., Fungi. II. =Cormophyta.= Differentiated into stem and root. 1. ACROBRYA. Stem growing at the point. _Anophyta_ (Hepaticæ, Musci). _Protophyta_ (Filices, etc.). _Hysterophyta_ (Balanophoreæ, etc.). 2. AMPHIBRYA. Stem growing at the circumference (Monocotyledons). 3. ACRAMPHIBRYA. Stem growing both at the point and circumference. _Gymnosperma_ (Coniferae). _Apetala._ Perianth single or absent. _Gamopetala._ Petals gamopetalous. _Dialypetala._ Petals polypetalous. System of A. BRONGNIART (1843). I. =Cryptogamæ.= Plants without flowers. 1. AMPHIGENÆ. Not differentiated into stem or leaf (Algæ, Fungi, Lichenes). 2. ACROGENÆ. Plants with stem and leaf (Muscineæ, Filicinæ). II. =Phanerogamæ.= Plants with flowers. 3. MONOCOTYLEDONES. _a._ Albuminosæ. Seeds with endosperm. _b._ Exalbuminosæ. Seeds without endosperm. 4. DICOTYLEDONES. _a._ Angiosepermæ. α. Gamopetalæ. β. Dialypetalæ. _b._ Gymnospermæ. System of JOHN LINDLEY (_Vegetable Kingdom_, 1845). Asexual, or Flowerless Plants. Stem and leaves undistinguishable I. =Thallogens.= Stem and leaves distinguishable II. =Acrogens.= Sexual, or Flowering Plants. Fructification springing from a thallus III. =Rhizogens.= Fructification springing from a stem. Wood of stem youngest in the centre; cotyledon single. Leaves parallel-veined, permanent; wood of stem always confused IV. =Endogens.= Leaves net-veined, deciduous; wood of the stem, when perennial, arranged in a circle with a central pith V. =Dictyogens.= Wood of stem youngest at the circumference, always concentric; cotyledons, 2 or more. Seeds quite naked VI. =Gymnogens.= Seeds inclosed in seed-vessels VII. =Exogens.= System of ALEXANDER BRAUN (1864). I. =Bryophyta.= 1. THALLODEA (Algæ, Fungi, Lichenes). 2. THALLOPHYLLODEA (Charas, Mosses). II. =Cormophyta.= 1. PHYLLOPTERIDES (Ferns, Equisetums). 2. MASCHALOPTERIDES (Lycopods). 3. HYDROPTERIDES (Water-ferns). III. =Anthophyta.= GYMNOSPERMÆ. 1. _Frondosæ_ (Cycadeæ). 2. _Acerosæ_ (Coniferæ). ANGIOSPERMÆ. 1. _Monocotyledones._ 2. _Dicotyledones._ Apetalæ. Sympetalæ. Eleutheropetalæ. W. HOFMEISTER published from 1849 to 1851 his researches upon the embryology of the Phanerogams, and upon the embryology and life-history of the Vascular Cryptogams, and established the phylogenetic connection existing between the Mosses, Vascular Cryptogams and Phanerogams. System of HOOKER and BENTHAM (_Genera plantarum_, 1862–1883). Dicotyledones. I. Polypetalæ. Series I. =Thalamifloræ.= Calyx most often free from the ovary. Petals uniseriate or often 2–∞-seriate. Stamens ∞ or definite, inserted on the receptacle, often small, or raised, or stipitate. Ovary most frequently free. Cohort I. RANALES. Stamens ∞, or if definite the perianth is 3–∞-seriate. Carpels apocarpous, or immersed in the receptacle. Endosperm usually abundant, fleshy. Order 1. Ranunculaceæ. „ 2. Dilleniaceæ. „ 3. Calycanthaceæ. „ 4. Magnoliaceæ. „ 5. Anonaceæ. „ 6. Menispermaceæ. „ 7. Berberideæ. „ 8. Nymphæaceæ. Cohort II. PARIETALES. Stamens ∞ or definite. Ovary unilocular, or divided into loculi by spurious dissepiments, with parietal placentation. Endosperm absent or fleshy. Order 9. Sarraceniaceæ. „ 10. Papaveraceæ. „ 11. Cruciferæ. „ 12. Capparideæ. „ 13. Resedaceæ. „ 14. Cistineæ. „ 15. Violarieæ. „ 16. Canellaceæ. „ 17. Bixineæ. Cohort III. POLYGALINÆ. Stamens definite. Ovary usually perfectly or imperfectly bilocular. Micropyle often superior. Fruit very often compressed laterally. Endosperm very often abundant and fleshy. Order 18. Pittosporeæ. „ 19. Tremandreæ. „ 20. Polygaleæ. „ 20_a._ Vochysiaceæ. Cohort IV. CARYOPHYLLINEÆ. Stamens definite, or rarely ∞. Ovary unilocular, or imperfectly septate. Placenta central, more rarely parietal. Micropyle inferior. Embryo curved, rarely straight. Endosperm farinaceous. Order 21. Frankeniaceæ. „ 22. Caryophylleæ. „ 23. Portulaceæ. „ 24. Tamariscineæ. Cohort V. GUTTIFERALES. Sepals inbricate. Stamens usually ∞. Ovary septate, placentæ on the inner angles of the loculi. Endosperm absent or fleshy. Order 25. Elatineæ. „ 26. Hypericineæ. „ 27. Guttiferæ. „ 28. Ternstrœmiaceæ. „ 29. Dipterocarpeæ. „ 30. Chlænaceæ. Cohort VI. MALVALES. Sepals valvate. Stamens usually ∞ or monadelphous. Ovary septate, placentæ on the inner angles of the loculi. Endosperm absent or fleshy. Order 31. Malvaceæ. „ 32. Sterculiaceae. „ 33. Tiliaceæ. Series II. =Discifloræ.= Calyx usually free from the ovary. Petals uniseriate. Stamens usually definite, inserted within, or upon, or around the receptacle, which is more often expanded as a disc. Ovary usually free, or embedded in the disc. Cohort VII. GERANIALES. Disc usually as a ring between the stamens, or adnate to the staminal tube, or reduced to glands alternating with the petals, more rarely absent. Gynœceum entire, or more often lobed, or sub-apocarpous. Ovules most often 1–2 in each loculus, _pendulous_, _raphe ventral_. Leaves various. Order 34. Lineæ. „ 35. Humiriaceæ. „ 36. Malpighiaceæ. „ 37. Zygophylleæ. „ 38. Geraniaceæ. „ 39. Rutaceæ. „ 40. Simarubeæ. „ 41. Ochnaceæ. „ 42. Burseraceæ. „ 43. Meliaceæ. „ 44. Chailletiaceæ. Cohort VIII. OLACALES. Disc cupular or annular, free, or bearing the stamens and petals on its edge. Gynœceum entire. Ovules 1–3 in the unilocular ovaries, or 1–2 in each loculus, _pendulous_, _raphe dorsal_. Leaves simple. Order 45. Olacineæ. „ 46. Ilicineæ. Cohort IX. CELASTRALES. Disc tumid, adnate to the calyx, or covering its base. Stamens inserted round the disc or affixed to its margin. Gynœceum usually entire. Ovules most often two in each loculus, _erect_, _raphe ventral_. Leaves simple, or rarely compound. Order 47. Celastrineæ. „ 48. Stackhousieæ. „ 49. Rhamneæ. „ 50. Ampelideæ. Cohort X. SAPINDALES. Disc various. Stamens variously inserted on the disc. Gynœceum entire, or more often lobed, or sub-apocarpous. Ovules more often 1–2 in each loculus, _ascending_ with _ventral_ raphe, or reversed, or _solitary_ and _pendulous from an ascending funicle_, or rarely ∞ horizontal. Leaves pinnate, or more rarely simple or digitate. Order 51. Sapindaceæ. „ 52. Sabiaceæ. „ 53. Anacardiaceæ. Anomalous orders, or rather genera,-- Order 54. Coriarieæ. „ 55. Moringeæ. Series III. =Calycifloræ.= Calyx-tube usually surrounding the ovary, or adnate to it. Petals uniseriate, inserted on the calyx-tube. Stamens ∞ or definite, inserted on the calyx-tube, or most often on the disc lining the calyx-tube. Ovary often enclosed by the calyx-tube, or inferior. Cohort XI. ROSALES. Carpels solitary, or free, or united at the base, more rarely at the apex; styles distinct, or very rarely united into a column, and easily separated. Order 56. Connaraceæ. „ 57. Leguminosæ. „ 58. Rosaceæ. „ 59. Saxifrageæ. „ 60. Crassulaceæ. „ 61. Droseraceæ. „ 62. Hamamelideæ. „ 63. Bruniaceæ. „ 64. Halorageæ. Cohort XII. MYRTALES. Ovary syncarpous, inferior, or enclosed in the calyx-tube, usually divided into loculi; style undivided. Ovules 2–∞ in the loculi. Order 65. Rhizophoreæ. „ 66. Combretaceæ. „ 67. Myrtaceæ. „ 68. Melastomaceæ. „ 69. Lythrarieæ. „ 70. Onagrarieæ. Cohort XIII. PASSIFLORALES. Ovary syncarpous, inferior or superior, enclosed in the calyx-tube or exserted, unilocular with parietal placentation, or divided into loculi; styles distinct, one style divided, or undivided. Order 71. Samydaceæ. „ 72. Loaseæ. „ 73. Turneraceæ. „ 74. Passifloreæ. „ 75. Cucurbitaceæ. „ 76. Begoniaceæ. „ 77. Datisceæ. Cohort XIV. FICOIDALES. Ovary syncarpous, inferior or superior, divided into loculi with sub-basilar placentæ, or more rarely unilocular with parietal placentæ. Styles distinct, or divided at the apex. Embryo curved or excentric. Order 78. Cacteæ. „ 79. Ficoideæ. Cohort XV. UMBRELLALES. Ovary syncarpous, inferior, crowned by the disc, divided into loculi, or unicarpellate. Styles distinct or divided at the apex. Ovules solitary and pendulous in the loculi. Order 80. Umbelliferæ. „ 81. Araliaceæ. „ 82. Cornaceæ. II. GAMOPETALÆ. Series I. =Inferæ.= Ovary inferior. Stamens equal to the lobes of the corolla, rarely fewer. Cohort I. RUBIALES. Stamens adnate to the corolla. Ovary 2–∞-locular, loculi 1–∞-ovuled. Order 83. Caprifoliaceæ. „ 84. Rubiaceæ. Cohort II. ASTERALES. Stamens adnate to the corolla. Ovary formed of 2 carpels, unilocular and 1-ovuled. Order 85. Valerianeæ. „ 86. Dipsaceæ. „ 87. Calycereæ. „ 88. Compositæ. Cohort III. CAMPANALES. Stamens generally free from the corolla. Ovary 2–6-locular, loculi most often ∞-ovuled. Order 89. Stylidieæ. „ 90. Goodenovieæ. „ 91. Campanulaceæ. Series II. =Heteromeræ.= Ovary most often superior. Stamens free from the corolla, opposite to, or double the lobes of the corolla, or ∞, or if epipetalous, equal and alternating with them. Carpels more than 2. Cohort IV. ERICALES. Stamens double the lobes of the corolla, or alternating with them. Ovary 2–∞-locular. Seeds small, frequently minute. Order 92. Vacciniaceæ. „ 93. Ericaceæ. „ 94. Monotropeæ. „ 95. Epacrideæ. „ 96. Diapensiaceæ. „ 97. Lennoaceæ. Cohort V. PRIMULALES. Stamens equal to and opposite the lobes of the corolla. Ovary unilocular, with a free central placenta, 1–∞ ovules. Order 98. Plumbagineæ „ 99. Primulaceæ. „ 100. Myrsineæ. Cohort VI. EBENALES. Stamens equal to and opposite the lobes of the corolla, or double, or ∞. Ovary 2–∞-locular. Seeds few and large. Trees or shrubs. Order 101. Sapotaceæ. „ 102. Ebenaceæ. „ 103. Styraceæ. Series III. =Bicarpellatæ.= Ovary most often superior. Stamens equal, or fewer than the lobes of the corolla, and alternating with them. Carpels 2, rarely 1 or 3. Cohort VII. GENTIANALES. Corolla regular. Stamens equal to the lobes of the corolla, or if fewer, usually alternating with the carpels. Leaves generally opposite. Order 104. Oleaceæ. „ 105. Salvadoraceæ. „ 106. Apocynaceæ. „ 107. Asclepiadeæ. „ 108. Loganiaceæ. „ 109. Gentianeæ. Cohort VIII. POLEMONIALES. Corolla regular. Stamens equal to the lobes of the corolla. Leaves generally alternate. Order 110. Polemoniaceæ. „ 111. Hydrophyllaceæ. „ 112. Boragineæ. „ 113. Convolvulaceæ. „ 114. Solanaceæ. Cohort IX. PERSONALES. Corolla most often irregular or oblique. Posterior stamen less than the others, more often reduced to a staminode, or altogether absent. Ovary ∞-ovuled, or 2-ovuled. Order 115. Scrophularineæ. „ 116. Orobanchaceæ. „ 117. Lentibularieæ. „ 118. Columelliaceæ. „ 119. Gesneraceæ. „ 120. Bignoniaceæ. „ 121. Pedalineæ. „ 122. Acanthaceæ. Cohort X. LAMIALES. Corolla most often irregular or oblique. Posterior stamen less than the others, most frequently reduced to a staminode or absent. Carpels 1-ovuled or with 2 collateral ovules. Fruit enclosed in the persistent calyx, indehiscent, and with one seed, or dehiscing into 2 or 4, rarely ∞, 1-seeded nuts. Order 123. Myoporineæ. „ 124. Selagineæ. „ 125. Verbenaceæ. „ 126. Labiateæ. Anomalous Order 127. Plantagineæ. III. MONOCHLAMYDEÆ. Perianth simple, lobes or segments 1–2-seriate and often sepaloid, or small, or wanting. Series I. =Curvembryeæ.= Endosperm frequently farinaceous. Embryo curved, excentric, lateral or peripheral, rarely straight. Ovules most frequently 1 in the ovary, or 1 in each loculus. Flowers ☿, in some genera unisexual or polygamous. Petals very rare. Stamens equal to the segments of the perianth, rarely fewer or more. Order 128. Nyctagineæ. „ 129. Illecebraceæ. „ 130. Amarantaceæ. „ 131. Chenopodiaceæ. „ 132. Phytolaccaceæ. „ 133. Batideæ. „ 134. Polygonaceæ. Series II. =Multiovulatæ Aquaticæ.= Aquatic herbs, submerged. Ovary syncarpous; ovules numerous in each loculus or on each placenta. Order 135. Podostemaceæ. Series III. =Multiovulatæ Terrestres.= Terrestrial trees or shrubs. Ovary syncarpous; ovules numerous in each loculus or on each placenta. Order 136. Nepenthaceæ. „ 137. Cytinaceæ. „ 138. Aristolochiaceæ. Series IV. =Micrembryeæ.= Ovary syncarpous, monocarpous, or apocarpous. Ovules generally solitary in each carpel, rarely 2 or few. Endosperm copious, fleshy, or rarely farinaceous. Embryo very minute. Order 139. Piperaceæ. „ 140. Chloranthaceæ. „ 141. Myristiceæ. „ 142. Monimiaceæ. Series V. =Daphnales.= Ovary monocarpous, very rarely syncarpous, with 2–4 loculi; ovules in the ovary or in each loculus, solitary, or in pairs. Trees or shrubs, very rarely herbs; flowers generally ☿. Perianth perfect, sepaloid, 1–2 seriate. Stamens perigynous, equal to the lobes of the perianth, or double unless fewer. Order 143. Laurineæ. „ 144. Proteaceæ. „ 145. Thymelæaceæ. „ 146. Penæaceæ. „ 147. Elæagnaceæ. Series VI. =Achlamydosporeæ.= Ovary unilocular, 1–3 ovules. Ovules most frequently poorly developed before flowering. Seeds endospermous, but without testa, either free in the pericarp or attached to its walls. Perianth generally perfect, sepaloid or petaloid. Order 148. Loranthaceæ. „ 149. Santalaceæ. „ 150. Balanophoreæ. Series VII. =Unisexuales.= Flowers unisexual. Ovary syncarpous or monocarpous, ovules in the ovary or in each loculus, solitary, or in pairs. Endosperm copious, fleshy, or scanty, or absent. Trees or shrubs, rarely herbs. Stipules generally present. Perianth sepaloid, or minute, or absent. Styles equal in number to the carpels, not rarely bifid. Order 151. Euphorbiaceæ. „ 152. Balanopseæ. „ 153. Urticaceæ. „ 154. Platanaceæ. „ 155. Leitnerieæ. „ 156. Juglandeæ. „ 157. Myricaceæ. „ 158. Casuarineæ. „ 159. Cupuliferæ. Series VIII. =Ordines Anomali.= Anomalous Orders. Order 160. Salicineæ. „ 161. Lacistemaceæ. „ 162. Empetraceæ. „ 163. Ceratophylleæ. GYMNOSPERMEÆ Order 164. Gnetaceæ. „ 165. Coniferæ. „ 166. Cycadaceæ. MONOCOTYLEDONES. Series I. =Microspermæ.= At least the inner series of the perianth petaloid. Ovary inferior, unilocular, with 3 parietal placentæ, or rarely 3-locular, with axile placentation. Seeds minute, numerous, without endosperm. Order 167. Hydrocharideæ. „ 168. Burmanniaceæ. „ 169. Orchideæ. Series II. =Epigynæ.= At least the inner series of the perianth petaloid. Ovary most often inferior. Endosperm copious. Order 170. Scitamineæ. „ 171. Bromeliaceæ. „ 172. Hæmodoraceæ. „ 173. Irideæ. „ 174. Amaryllideæ. „ 175. Taccaceæ. „ 176. Dioscoreaceæ. Series III. =Coronarieæ.= At least the inner series of perianth petaloid. Ovary free, very rarely slightly adnate at the base. Endosperm copious. Order 177. Roxburghiaceæ. „ 178. Liliaceæ. „ 179. Pontederiaceæ. „ 180. Philydraceæ. „ 181. Xyrideæ. „ 182. Mayaceæ. „ 183. Commelinaceæ. „ 184. Rapateaceæ. Series IV. =Calycinæ.= Perianth sepaloid, small, rigid, or herbaceous (inner series subpetaloid or small). Ovary free. Endosperm copious. Order 185. Flagellarieæ. „ 186. Juncaceæ. „ 187. Palmæ. Series V. =Nudifloræ.= Perianth absent, or reduced to hairs or scales. Ovary superior, carpel solitary, or if many, syncarpous, 1–∞-ovuled. Endosperm most frequently present. Order 188. Pandaneæ. „ 189. Cyclanthaceæ. „ 190. Typhaceæ. „ 191. Aroideæ. „ 192. Lemnaceæ. Series VI. =Apocarpæ.= Perianth 1–2-seriate, or absent. Carpels superior, solitary, or if more, apocarpous. Endosperm absent. Order 193. Triurideæ. „ 194. Alismaceæ. „ 195. Naiadaceæ. Series VII. =Glumaceæ.= Flowers solitary, sessile in the axils of bracts and arranged in capitula or spikelets with bracts. Segments of perianth small, scale-like, glumaceous or absent. Ovary 1-ovuled, or divided into 1-ovuled loculi. Endosperm present. Order 196. Eriocauleæ. „ 197. Centrolepideæ. „ 198. Restiaceæ. „ 199. Cyperaceæ. „ 200. Gramineæ. Classification of the Thallophytes proposed by SACHS (_Text-Book of Botany_, English Edition, 1882). THALLOPHYTES. _Containing chlorophyll._ | _Not containing chlorophyll._ Class I. =Protophyta.= Cyanophyceæ. | Schizomycetes. Palmellaceæ (in part). | Saccharomycetes. Class II. =Zygosporeæ.= Conjugating cells motile. Pandorineæ. | Myxomycetes. (Hydrodictyeæ). | Conjugating cells stationary. Conjugatæ (including | Zygomycetes. Diatomaceæ). | Class III. =Oosporeæ.= Sphæroplea. | Vaucheria (_Cœloblastæ_). | { Saprolegnieæ. | { Peronosporeæ. Volvocineæ. | Œdogonieæ. | Fucoideæ. | Class IV. Carposporeæ. Coleochæteæ. | Ascomycetes (including Lichens). Florideæ. | Æcidiomycetes (Uredineæ). Characeæ. | Basidiomycetes. System of A. W. EICHLER (1883). A. =Cryptogamæ.= I. =Thallophyta.= 1. Class. ALGÆ. 1 Group. Cyanophyceæ. 2 „ Diatomeæ. 3 „ Chlorophyceæ. 1 Series. Conjugatæ. 2 „ Zoosporeæ. 3 „ Characeæ. 4 Group. Phæophyceæ. 5 „ Rhodophyceæ. 2. Class. FUNGI. 1 Group. Schizomycetes. 2 „ Eumycetes. 1 Series. Phycomycetes. 2 „ Ustilagineæ. 3 „ Æcidiomycetes. 4 „ Ascomycetes. 5 „ Basidiomycetes. 3 Group. Lichenes. II. =Bryophyta.= 1 Group. Hepaticæ. 2 „ Musci. III. =Pteridophyta.= 1 Class. EQUISETINÆ. 2 „ LYCOPODINÆ. 3 „ FILICINÆ. B. =Phanerogamæ.= 1. Gymnospermæ. 2. Angiospermæ. The subdivisions of the Phanerogamæ have with little variation been adopted in this book. Classification of the THALLOPHYTES, adopted in the 3rd Danish Edition (1891). [Algæ by Wille; Fungi by Rostrup (_after Zopf_).] =I. DIVISION. THALLOPHYTA.= I. Sub-division. =Algæ.= 1 Class. CHLOROPHYCEÆ (GREEN ALGÆ). 1 Family. Conjugatæ. 2 „ Protococcoideæ. 3 „ Confervoideæ. 4 „ Siphoneæ. 5 „ Gyrophyceæ. 2 Class. PHÆOPHYCEÆ (BROWN ALGÆ). 1 Family. Syngeneticæ. 2 „ Dinoflagellata. 3 „ Pyritophyceæ (Diatomeæ). 4 „ Phæosporeæ. 5 „ Cyclosporeæ. 6 „ Dictyoteæ. 3 Class. ACILIATÆ. A. Sub-class. _Schizophyceæ._ 1 Family. Myxophyceæ (Blue-Green Algæ). 2 „ Bacteria. B. Sub-class. _Rhodophyceæ._ 1 Family. Bangioideæ. 2 „ Florideæ. II. Sub-division. =Myxomycetes.= III. „ =Fungi.= A. =Phycomycetes.= 1 Class. OOMYCETES. 2 „ ZYGOMYCETES. B. =Mycomycetes.= 3 Class. BASIDIOMYCETES. A. Sub-class. _Protobasidiomycetes._ B. „ _Autobasidiomycetes._ 1 Family. Hymenomycetes. 2 „ Gasteromycetes. 3 „ Basidiolichenes. 4 Class. ASCOMYCETES. 1 Family. Gymnoasci. 2 „ Perisporieæ. 3 „ Pyrenomycetes. 4 „ Discomycetes. 5 „ Ascolichenes. System of A. ENGLER (_Syllabus der Vorlesungen_, etc., 1892). =I. DIVISION. MYXOTHALLOPHYTA.= Sub-division. =Myxomycetes.= 1 Class. ACRASIEÆ. 2 „ PLASMODIOPHORALES. 3 „ MYXOGASTERES. 1 Series. Ectosporeæ. 2 „ Endosporeæ. =II. DIVISION. EUTHALLOPHYTA.= I. Sub-division. =Schizophyta.= 1 Class. SCHIZOPHYCEÆ. 2 „ SCHIZOMYCETES. II. Sub-division. =Dinoflagellata.= Class. DINOFLAGELLATA. 1 Series. Adinida. 2 „ Dinifera. III. Sub-division. =Bacillariales.= Class. BACILLARIALES. IV. Sub-division. =Gamophyceæ.= 1 Class. CONJUGATÆ. 2 „ CHLOROPHYCEÆ. 1 Sub-class. _Protococcales._ 2 „ _Confervales._ 3 „ _Siphoneæ._ 3 Class. CHARALES. 4 „ PHÆOPHYCEÆ. 1 Sub-class. _Phæosporeæ._ 2 „ _Cyclosporeæ._ 5 Class. DICTYOTALES. 6 „ RHODOPHYCEÆ. 1 Sub-class. _Bangiales._ 2 „ _Florideæ._ 1 Series. Nemalionales. 2 „ Gigartinales. 3 „ Rhodymeniales. 4 „ Cryptonemiales. V. Sub-division. =Fungi.= 1 Class. PHYCOMYCETES. 1 Series. Zygomycetes. 2 „ Oomycetes. 1 Sub-series. Chytridiales. 2 „ Mycosiphonales. 2 Class. MESOMYCETES. 1 Sub-class. _Hemiasci._ 2 „ _Hemibasidii._ 3 Class. MYCOMYCETES. 1 Sub-class. _Ascomycetes._ 1 Series. Exoasci. 2 „ Carpoasci. 1 Sub-series. Gymnoascales. 2 „ Perisporiales. 3 „ Pyrenomycetes. Appended. Pyrenolichenes. 4 Sub-series. Hysteriales. 5 „ Discomycetes. Appended. Discolichenes. 2 Sub-class. _Basidiomycetes._ 1 Series. Protobasidiomycetes. 1 Sub-series. Uredinales. 2 „ Auriculariales. 3 „ Tremellinales. 4 „ Pilacrales. 2 Series. Autobasidiomycetes. 1 Sub-series. Dacryomycetes. 2 „ Hymenomycetes. Appended. Hymenolichenes. 3 Sub-series. Phalloideæ. 4 „ Gasteromycetes. Appended. Gasterolichenes. Fungi imperfecti. =III. DIVISION. EMBRYOPHYTA ZOIDIOGAMA= (Archegoniatæ). I. Sub-division. =Bryophyta (Muscinei).= 1 Class. HEPATICÆ. 1 Series. Marchantiales. 2 „ Anthocerotales. 3 „ Jungermanniales. 1 Sub-series. Anacrogynæ. 2 „ Acrogynæ. 2 Class. MUSCI. 1 Sub-class. _Sphagnales._ 2 „ _Andreæales._ 3 „ _Archidiales._ 4 „ _Bryales._ 1 Series. Cleistocarpæ. 2 „ Stegocarpæ. 1 Sub-series. Acrocarpæ. 2 „ Pleurocarpæ. II. Sub division. =Pteridophyta.= 1 Class. FILICALES. 1 Sub-class. _Filices._ 1 Series. Planithallosæ. 2 „ Tuberithallosæ. 2 Sub-class. _Hydropterides._ 2 Class. EQUISETALES. 1 Sub-class. _Isosporæ._ 2 „ _Heterosporæ._ 3 Class. SPHENOPHYLLALES. 4 „ LYCOPODICELES. 1 Sub-class. _Isosporæ._ 2 „ _Heterosporæ._ IV. DIVISION. EMBRYOPHYTA SIPHONOGAMA. (Siphonogamæ, Phanerogamæ). I. Sub-division. =Gymnospermæ.= 1 Class. CYCADALES. 2 „ CORDAITALES. 3 „ BENNETTITALES. 4 „ CONIFERÆ. 5 „ GNETALES. II. Sub-division. =Angiospermæ.= 1 Class. CHALAZOGAMÆ. Series. Verticillatæ. 2 Class. ACROGAMÆ. 1 Sub-class. _Monocotyledoneæ._ 1 Series. Pandanales. 2 „ Helobiæ. 3 „ Glumifloræ. 4 „ Principes. 5 „ Synanthæ. 6 „ Spathifloræ. 7 „ Farinosæ. 8 „ Liliifloræ. 9 „ Scitamineæ. 10 „ Microspermæ. 2 Sub-class. _Dicotyledoneæ._ 1 Group of Series. Archichlamydeæ. 1 Series. Piperales. 2 „ Juglandales. 3 „ Salicales. 4 „ Fagales. 5 „ Urticales. 6 „ Proteales. 7 „ Santalales. 8 „ Aristolochiales. 9 „ Polygonales. 10 „ Centrospermæ. 11 „ Ranales. 12 „ Rhœadales. 13 „ Sarraceniales. 14 „ Rosales. 15 „ Geraniales. 16 „ Sapindales. 17 „ Rhamnales. 18 „ Malvales. 19 „ Parietales. 20 „ Opuntiales. 21 „ Thymelæales. 22 „ Myrtifloræ. 23 „ Umbellifloræ. 2 Group of Series. Sympetalæ. 1 Series. Ericales. 2 „ Primulales. 3 „ Ebenales. 4 „ Contortæ. 5 „ Tubifloræ. 6 „ Plantaginales. 7 „ Rubiales. 8 „ Aggregatæ. 9 „ Campanulatæ. TABLE OF ABBREVIATIONS. S = Sepals. P = Petals. Pr = Perianth. A = Andrœcium. G = Gynœceum. ♂ = Male. ♀ = Female. ☿ = Hermaphrodite. ∞ = Indefinite. Names of continents and countries have sometimes been abbreviated, for example:--Am. = America; As.=Asia; Af. = Africa; Ind. = India, etc. N., S., E., W., = North, South, East, West; Temp. = Temperate Regions; Trop. = Tropics. INDEX. Abelia, 556. Abies, 124, 129, 130, 132, 133, 148, 155, 165, 246, 264, 265, 266. Abietaceæ, 255, 263, 272. Abrus, 470, 473. Abutilon, 427. Acacia, 473, 474, 475. False, 470. Acalypha, 434. Acanthaceæ, 518, 529, 530. Acanthus, 530. Acer, 122, 441, 442. Aceraceæ, 441. Aceranthus, 390. Acetabularia, 12, 63. Achillea, 568, 572, 574. Achimenes, 528. Achlya, 107, 108. Achnantheæ, 21. Achras, 511. Acinetæ, 68, 72. Aconitum, 379, 383. Acorin, 306. Acorus, 303, 304, 306. Acrasieæ, 6. Acrocarpi, 196. Acrocomia, 301. Acrogynæ, 192. Acrospermaceæ, 132. Acrostichum, 213. Acrotonous, 331. Acrotylaceæ, 83. Acrotylus, 83. Actæa, 379, 380, 382. Actinidia, 415. Adansonia, 427. Adder’s tongue, 211. Adenanthera, 475. Adiantum, 201, 206, 213. Adinida, 17. Adlumia, 395. Adonis, 379, 383. Adoxa, 453, 555. Aerobic, 31. Æchmea, 319, 320. Æcidiospores, 147. Æcidium, 147, 148, 150, 155. Ægiceras, 513. Ægilops, 296. Ægopodium, 494. Æschynanthus, 528. Æsculinæ, 439. Æsculus, 440. Æthalium, 8. Æthusa, 495, 498. Affonsea, 466. Agapanthus, 312, 314. Agar-Agar, 33, 84. Agaricaceæ, 166. Agaricinei, 171. Agathis, 263. Agave, 318. Agaveæ, 318. Ageratum, 571. Aggregatæ, 505, 564. Agraphis, 312. Agrimonia, 459, 460. Agrimonieæ, 459. Agrimony, 459. Agropyrum, 113, 295. Agrostemma, 365, 367. Agrostideæ, 294. Agrostis, 294. Ahnfeltia, 83. Ailanthus, 439. Aira, 294. Aizoaceæ, 374. Aizoideæ, 374. Aizoon, 375. Ajuga, 47, 537. Ajugeæ, 537. Akebia, 390. Akinetes, 10. Alaria, 71, 72. Albugo, 107. Albumen, 246. Albuminous, 249. Albumose, 473. Alchemilla, 460. Alchornea, 432. Alcoholic fermentation, 97. Alder, 8, 118, 341. Aldrovandia, 408, 409. Aleurites, 434. Algæ, 1, 4, 8. Algal-Fungi, 95, 96. Alhagi, 472. Alisma, 281, 282. Alismaceæ, 278, 281. Alismeæ, 281. Alkanet, 534. Alkanna, 534, 535. Alliariinæ, 404. Allieæ, 312. Allium, 312, 313, 314. Alloplectus, 528. Allosorus, 213. Almeidea, 437. Almond, 461, 462. Alnus, 8, 117, 118, 341, 342. Alocasia. 306. Aloë, 274, 312, 313, 314. Aloineæ, 312. Alonsoa, 525. Alopecurus, 290, 294, 296. Alpine Violet, 513. Alpinia, 326. Alsine, 364, 366. Alsineæ, 365. Alsodeia, 411. Alsophila, 214, 215. Alstrœmeria, 318. Alstrœmerieæ, 318. Alternanthera, 369. Althæa, 426, 428, 429, 430. Althenia, 279. Alyssinæ, 404. Alyssum, 400. Amanita, 167, 171. Amarantaceæ, 364, 368. Amarant-tree, 468. Amarantus, 368, 369. Amarylleæ, 317. Amaryllidaceæ, 310, 316. Amaryllis, 317, 318. Amber, 267. Ambrosia, 573. Ambrosieæ, 564, 567, 573. Ambrosinia, 305. Amelanchier, 464, 465. Amentaceæ, 337. Amherstia, 468. Ammannia, 483. Ammi, 494. Ammieæ, 494. Ammobium, 573. Ammoniac-gum, 498. Ammophila, 295. Amomis, 488. Amorpha, 470. Ampelidaceæ, 445. Ampelopsis, 445, 447. Amphidinium, 16. Amphigastria, 181, 188. Amphipleureæ, 21. Amphisphæriaceæ, 130. Amphithecium, 186. Amphitropideæ, 21. Amphoreæ, 21. Amsonia, 544. Amygdalaceæ, 461, 466. Amygdalin, 462. Amygdalus, 461, 462. Amyris, 438. Anabæna, 25, 219. Anacampseros, 373. Anacamptis, 332. Anacamptodon, 197. Anacardiaceæ, 439. Anacardium, 439. Anacrogynæ, 192. Anacyclus, 572, 574. Anadyomene, 62. Anaerobic, 31. Anagallis, 513. Anamirta, 390. Ananassa, 319, 320. Anastatica, 401. Anathyllis, 471. Anatropous, 242, 243. Anchusa, 150, 531, 532, 534, 535. Ancylistaceæ, 104. Ancylonema, 44. Andira, 472, 473. Andreæa, 185, 187, 188, 195. Andrœcium, 239. Androgenesis, 14. Andromeda, 161, 508. Andromedeæ, 508. Andropogon, 289, 293, 296. Andropogoneæ, 293, 296. Androsace, 512, 513. Androspore, 57. Aneimia, 215. Anelatereæ, 192. Anemone, 379, 384. Anemoneæ, 384. Anemonopsis, 379. Anethum, 496, 498. Aneura, 191, 192. Angelica, 496, 498. Angiopteris, 212. Angiospermæ, 3, 234, 239, 250, 273. Angiosperms, 237, 245, 248. Angiosporeæ, 82. Angosturæ, Cortex, 437. Anguliferæ, 21. Anise, 498. Anlage, 90. Annatto, 412. Annularia, 225. Annulariæ, 225. Annulus, 195, 209. inferus, 167. superus, 168. Anoda, 428, 429. Anodic, 480. Anomodon, 197. Anona, 388. Anonaceæ, 388. Antennaria, 124, 573. Anthemideæ, 572. Anthemis, 569, 572, 574. Anther, 237, 238. Fibrous layer of, 241. Structure of, 239. Anthericeæ, 312. Anthericum, 312, 313. Antheridium, 13, 100, 198. Antherozoid, 13. Anthocarp, 374. Anthoceros, 25, 186, 187, 188, 189, 191. Anthoceroteæ, 191. Antholyza, 321. Anthostema, 432, 433. Anthoxanthum, 295, 296. Anthrax bacillus, 31, 39, 40. Anthriscus, 493, 495, 498. Anthurium, 304. Anthyllis, 471. Antiaris, 356. Antipodal cells, 248. Antirrhineæ, 523. Antirrhinum, 524, 527. Antisepsis, 32. Apeiba, 424, 425. Apetalæ, 336, 337. Aphanizomenon, 25. Aphanocapsa, 24. Aphanochæte, 54. Aphthæ, 180. Aphyllanthes, 312. Apiocystis, 51. Apios, 471. Apiosporium, 124. Apium, 494, 498. Aplanogametangium, 12. Aplanogametes, 12. Aplanospores, 10. Apocynaceæ, 542, 543, 549. Apocynum, 514. Apogamy, 203. Aponogeton, 281. Aponogetonaceæ, 281. Apospory, 188. Apostasia, 329. Apostasieæ, 328, 329. Apothecium, 118, 132. Apple, 127, 130, 464, 465. Apricot, 121, 461, 462. Aquifoliaceæ, 444. Aquilegia, 378, 379, 381, 382. Arabis, 402. Araceæ, 276, 278, 303. Arachis, 469, 472, 473. Aralia, 491. Araliaceæ, 454, 491, 549. Araucaria, 237, 263. Araucariaceæ, 257, 263, 272. Arbor vitæ, 267. Arbuteæ, 508. Arbutus, 508. Archangelica, 496, 498. Archegoniata, 3, 185. Archegonium, 3, 184, 198. Development of, 201. Archesporium, 186, 202. Archicarp, 120. Archidium, 193, 195. Arctostaphylos, 161, 508. Arcyria, 7, 8. Ardisia, 513. Areca, 301, 302. Areca-palm, 302. Arecineæ, 301. Arenaria, 366. Arenga, 301. Argemone, 395. Aria, 152. Aril, 255, 258. Arineæ, 305. Arisarum, 305. Aristida, 295. Aristolochia, 499, 500. Aristolochiaceæ, 499. Aristolochiales, 499. Aristotelia, 425. Armeniaca, 461. Armeria, 514. Armillaria, 117, 169, 170. Arnebia, 533. Arnica, 572, 574. Arnoseris, 571. Aronia, 464. Arrack, 296, 301. Arrow-head, 282. Arrow-poison, 544, 546. Arrowroot, 327, 434. Artabotrys, 388. Artemisia, 569, 572, 573, 574. Arthonia, 134. Arthoniaceæ, 134. Arthrosporous, 29. Arthrotaxis, 267. Artichoke, 570, 574. Jerusalem, 572, 574. Artocarpeæ, 354. Artocarpus, 356. Arum, 303, 304, 305, 306. Arundo, 294, 296. Asafœtida, 498. Asarum, 499, 500. Asclepiadaceæ, 238, 542, 544. Asclepias, 545, 546. Ascobolaceæ, 135. Ascobolus, 136. Ascocarps, 88. Ascocorticium, 116, 117. Ascogone, 120. Ascoidea, 108. Ascoideaceæ, 108. Ascolichenes, 95, 116, 136. Ascomycetes, 95, 114, 116. Ascophyllum, 73, 75. Ascospore, 88. Ascus, 88. Aseroë, 173. Asexual reproductive cells, 10. Ash, 127, 546, 547. Asimina, 388. Asparageæ, 314. Asparagus, 314, 316. Aspen, 152, 338. Aspergillus, 122. Asperifoliæ, 532. Asperococcus, 70. Asperugo, 534. Asperula, 552, 553. Asphodelus, 312, 313, 314. Aspidistra, 314. Aspidium, 203, 204, 207, 213, 214. Aspidosperma, 344. Asplenium, 213, 214. Astelia, 316. Aster, 569, 571, 573. Astereæ, 571, 573. Asteriscus, 574. Asterocystis, 78. Asterophylliteæ, 225. Asterophyllites, 225. Astragaleæ, 470. Astragalus, 114, 470, 473. Astrantia, 493. Astrocarpus, 407. Atherurus, 305. Athyrium, 204, 207, 213. Atragene, 379, 385. Atraphaxis, 360. Atriplex, 371, 372. Atripliceæ, 371. Atropa, 519, 521, 522, 523. Atropine, 522. Attalea, 297, 301. Attar of Roses, 460. Aubrietia, 400. Aucuba, 491. Aulacomnium, 197. Aurantieæ, 437. Auricula, 156. Auricularia, 156. Auriculariaceæ, 145, 155. Austrian Pine, 267. Autobasidia, 144. Autobasidiomycetes, 96, 145, 157. Autœcious, 148. Autoxenous, 118. Auxiliary cells, 81. Auxospore, 19. Avena, 294, 296. Aveneæ, 294. Avens, 458. Averrhoa, 416. Avicennia, 535. Avignon grain, 448. Awlwort, 401. Awn, 288, 290. Azalea, 508. Azolla, 25, 219. “Bablah,” 475. Bacillus, 26, 28, 30, 31, 35, 36, 37. anthracis, 39. diphtheriæ, lepræ, mallei, tetani, tuberculosis, typhosus, 40. Bacteria, 4, 5, 8, 9, 10, 22, 26. Bacterium, 26, 28, 30, 35, 39. Bactris, 301. Bæomyces, 140, 142. Balanophora, 504. Balanophoraceæ, 504. Ballota, 538. Balsaminaceæ, 420. Balsamodendron, 438. Balsam of Copaiba, 468. of Peru, 473. Bamboo, 289, 291, 292, 293. Bambusa, 289, 291, 293. Bambuseæ, 293, 296. Banana, 324, 325. Baneberry, 382. Bangia, 77, 78. Bangioideæ, 77. Banksia, 450. Baobab, 427. Barbacenia, 318. Barbarea, 402. Barberries, 389. Barbula, 196. Bark-canker, 169. Barley, 113, 292, 296. Barosma, 436. Barringtonia, 489. Bartonia, 476. Bartramia, 197. Bartsia, 526. Basella, 371. Baselleæ, 371. Basidial-layer, 89. Basidiocarp, 89. Basidiolichenes, 96, 145, 176. Basidiomycetes, 96, 114, 144, 145. Basidiospore, 88. Basidium, 89, 144, 146. Basitonous, 331. Bassia, 511. Bast, 251, 425, 430. Bastardia, 428. Batatas, 516, 517. Batidaceæ, 372. Batis, 372. Batrachium, 383. Batrachospermum, 80, 83. Bauhinia, 467. Bayberry-tree, 490. “Bay-rum,” 489. Beaked parsley, 495. Beak-rush, 286. Bear-berry, 508. Beard lichen, 143. Beech, 127, 134, 164, 165, 526. Beef-steak fungus, 166. Beer-yeast, 177, 178. Beet, 369. Beet-root, 372. Beggiatoa, 26, 28, 37. Begonia, 477, 478. Begoniaceæ, 475, 477. Bellis, 569, 572. Benincasa, 481. Berberidaceæ, 238, 389. Berberis, 149, 389, 390. Bergamot, 438. Bergia, 413. Berteroa, 400. Bertholletia, 489. Beta, 369, 370, 372. Betel, 363. Betonica, 538. Betony, 538. Betula, 342. Betulaceæ, 341. Biarum, 305. Biatorella, 134. Bicornes, 336, 451, 505, 506. Biddulphieæ, 21. Bidens, 566, 572. Biebersteinia, 419. Bignonia, 529. Bignoniaceæ, 518, 529. Bilberry, 509. Billardiera, 455. Billbergia, 320. Bindweed, 515, 516. Biota, 268. Birch, 117, 135, 165, 342. Bird-cherry, 461, 462. Birdlime, 501, 504. Bird’s-foot, 472. Bird’s-foot-trefoil, 471. Biscutella, 401. Bitter-cress, 402. Bitter-sweet, 522. Bixa, 412. Bixaceæ, 412. Blackberry, 461. Black-boy, 312. Black-currant, 153, 455. Black-mustard, 401, 405. Black-pepper, 363. Blackthorn, 462. “Bladder” plums, 117. Bladder-senna, 470. Bladder-wort, 528. Blasia, 25, 191, 192. Blattiaceæ, 483. Blechnum, 209, 214, 254. Bletia, 332. Blight, 132. Blindia, 196. Blinks, 373. Blitum, 369. Blood-red Currant, 455. Blue-green Algæ, 5, 22. Bocconia, 395. Boehmeria, 353. Boerhaavia, 374. Bog-mosses, 193. Bog-myrtle, 351. Bog Wortleberry, 509. Boisduvalia, 485. Boletus, 166. Bomarea, 318. Bombaceæ, 427. Bombax, 427. Bonnemaisonia, 83. Bonnemaisoniaceæ, 83. Borage, 533. Borageæ, 532, 533. Boraginaceæ, 515, 531, 532, 537. Borago, 533, 534. Borassinæ, 301. Borassus, 301. Borderea, 323. Boronieæ, 436. Borreria, 550. Boschia, 190. Bossiæa, 472. Boswellia, 438. Bo-tree, 356. Botrychium, 202, 210, 211. Botrydiaceæ, 47, 59. Botrydium, 59. Botrytis, 128, 134, 135. Bottle-gourd, 481. Bouchea, 535. Bougainvillea, 374. Boussingaultia, 371. Bouvardia, 550. Bovista, 174. Bowenia, 253, 254. Bowiea, 312. Box, 434. Brachypodium, 294. Brachythecium, 197. Bracken-fern, 207, 213. Bract, 235. Bracteole, 235, 275, 334. Bradypus, 8, 54, 356. Brahea, 300. Bramble, 458. Branching of Palm, 298. Brand-fungi, 95, 108, 109. Brand-spores, 91. Brasenia, 386. Brassica, 399, 400, 401. Brassicinæ, 404. Brayera, 460. Brazil-nuts, 489. Bread-fruit, 356. Briza, 290, 294, 296. Brome, 296. Bromeliaceæ, 308, 309, 310, 318. Bromus, 287, 289, 290, 293, 296. Brookweed, 513. Broom, 472. Broom-rape, 528. Brosimum, 356. Broussonetia, 354. Browallia, 521. Brown Algæ, 1. Brownea, 468. Brownian movement, 28. Brugmansia, 504. Brunfelsia, 521. Bryaceæ, 197. Bryonia, 481. Bryophyllum, 451, 452. Bryophyta, 1, 234. Bryopsidaceæ, 47, 60. Bryopsis, 60, 62. Bryum, 197. Buchu, 436. Buck-bean, 543. Buckthorn, 448. Buckwheat, 361. Buettneria, 422. Buettneriaceæ, 422. Bugle, 537. Bulbine, 312. Bulbochæte, 55, 56. Bulbocodium, 310. Bulbophyllum, 332. Bulgaria, 134. Bulgariaceæ, 134. Bullace, 461, 462. Bulliarda, 452. Bull-rush, 303. Bumelia, 511. Bunchosia, 442. Bunias, 400, 403. Bupleurum, 491, 494. Burdock, 570. Burmanniaceæ, 328. Bur-marigold, 572. Bur Parsley, 497. Bur-reed, 302. Burseraceæ, 438. Butcher’s broom, 316. Butomeæ, 281. Butomus, 281, 282. Butterbur, 571. Butter-tree, 414. Butter-wort, 528. Butyric-acid-bacíllus, 38. Buxaceæ, 434. Buxbaumia, 197. Buxbaumiaceæ, 197. Buxus, 434. Cabbage, 401. Cabomba, 386. Cabombeæ, 386. Cacalia, 572. Cactaceæ, 375. Cacti, 375. Cactifloræ, 375. Cæoma, 147, 148, 152. Cæsalpinia, 468. Cæsalpiniaceæ, 466, 470. Caffeine, 441, 553. Cajanus, 471. Cajeput-oil, 489. Cajophora, 476. Cakile, 403. Calabar-bean, 471, 473. Calabash, 529. Caladium, 306. Calamagrostis, 289, 294. Calamintha, 540. Calamites, 224. Calamus, 298, 301, 303. Calamus-oil, 306. Calandrinia, 373. Calathea, 327. Calceolaria, 525, 527. Calcocytaceæ, 15. Calendula, 565, 572. Calenduleæ, 572. Caliciaceæ, 134. Calicium, 134. Calla, 305, 307. Calleæ, 305. Calliandra, 475. Callianthemum, 379. Callicarpa, 535. Calligonum, 361. Calliopsis, 572. Callistemon, 489. Callistephus, 573. Callithamnion, 78, 79, 84. Callitrichaceæ, 434. Callitriche, 434. Callitris, 269. Calloria, 134. Calluna, 507. Calocera, 158, 159. Calonyction, 516. Calophyllum, 414. Calothamnus, 489. Calothrix, 25. Caltha, 379, 380, 381, 382. Calycanthaceæ, 389. Calycanthus, 389. Calyceraceæ, 556, 560. Calypogeia, 192. Calypso, 332. Calyptospora, 152. Calyptra, 186. Calystegia, 516. Calyx-stamens, 335. Camelina, 400, 401. Camellia, 414, 415. Campanula, 153, 561, 562. Campanulaceæ, 561, 563. Campanulinæ, 505, 560, 564, 569. Camphor, 392. Campion, 367. Campylopus, 196. Campylospermeæ, 493, 497. Campylotropous, 242, 243. Canada-balsam, 266. Cananga, 388. Canarina, 562. Canary-grass, 295. Canavalia, 471. Candollea, 413, 564. Candolleaceæ, 564. Cane, 298, 301. “Canker,” 127. Canna, 326. Cannabaceæ, 356. Cannabis, 357, 358. Cannaceæ, 277, 326, 327. Canterbury-bell, 561. Cantharellei, 172. Cantharellus, 170, 172. Caoutchouc, 434, 544, 546, 563. Capers, 405. Capillitium, 7, 174. Capirona, 549. Capnodium, 124. Capparidaceæ, 405. Capparis, 405, 406. Capraria, 525. Caprification, 355. Caprificus, 355. Caprifoliaceæ, 454, 548, 549, 553, 556, 557. Caprifolium, 554. Capsella, 400, 401, 402. Capsellinæ, 404. Capsicum, 521, 522. Capsosira, 26. Capsule, 186. Caragana, 470. Caraway, 494, 498. Cardaminæ, 404. Cardamine, 400, 402, 404. Cardamom, 326. Cardiospermum, 441. Carduus, 569. Carex, 113, 151, 247, 286, 287. Carica, 476. Cariceæ, 286. Caries dentium, 38. Carlina, 570. Carludovica, 302. Carmichælia, 470. Carnation, 367. Carnaueba-wax, 301. Carob-bean, 466, 468. Carpels, 235, 238. Carpinus, 117, 344. Carpoasci, 95, 115, 116, 118. Carpogonium, 77, 81. Carpophore, 91, 492. Carpospore, 77, 82. Carragen, 33, 84. Carrot, 496, 497, 498. Carthamus, 570, 574. Carum, 493, 494, 498. Carya, 350. Caryophyllaceæ, 336, 364. Caryopsis, 288. Caryota, 301. Cascara, 448. Cascarilla, 434, 550. Cashew-nut, 439. Cassandra, 508. Cassava, 434. Cassia, 467, 468. Cassine, 444. Cassiope, 508. Cassytha, 392. Castanea, 346. Castilloa, 356. Castor-oil, 431, 434. Casuarinaceæ, 339. Casuarina, 273, 274. Casuarinifloræ, 339. Cataba, 414. Catabrosa, 294. Catalpa, 529. Catananche, 566, 571. Catasetum, 332, 333. Catch-fly, 367. Catechu, 475. Catha, 444. Catharinea, 197. Cathartocarpus, 467, 468. Catmint, 539. Catodic, 480. Cat’s-ear, 571. Cat’s-foot, 573. Cat’s-tail, 294. Cattle-beet, 372. Cattleya, 332. Caucalis, 497. Caudicle, 331, 332. Caulerpa, 10, 61, 62. Caulerpaceæ, 47, 61. Cauliflower, 405. Cayenne-pepper, 522. Ceanothus, 448. Cecropia, 356. Cedar, 266. Cedrat, 438. Cedrela, 436. Cedrus, 266. Celandine, 394. Celastraceæ, 444. Celastrus, 444. Celery, 494, 498. Celidium, 134. Cell, Vegetative, 228. Celosia, 368, 369. Celsia, 525. Celtideæ, 352. Cenangiaceæ, 134. Cenangium, 134. Cenchrus, 295. Centaurea, 565, 567, 568, 569, 570, 573. Centaury, 543. Centradenia, 484. “Central cell,” 185. Centranthus, 557, 558. Centrolepidaceæ, 308, 309. Centrolepis, 309. Centrolobium, 472. Centropogon, 563. Centunculus, 512, 513. Cephaëlis, 550, 553. Cephalanthera, 328, 331. Cephalaria, 560. Cephalotaceæ, 454. Cephalotaxeæ, 259. Cephalotus, 453. Ceramiaceæ, 84. Ceramium, 78, 80, 84. Cerastium, 364, 366. Cerasus, 462. Ceratiomyxa, 8. Ceratium, 16, 17. Ceratocapnos, 396. Ceratodon, 196. Ceratonia, 468. Ceratophyllaceæ, 388. Ceratophyllum, 388. Ceratostomaceæ, 130. Ceratozamia, 238, 253, 254. Cerbera, 544. Cercis, 467, 468. Cereus, 375, 377. Cerinthe, 533. Ceropegia, 546. Ceroxylon, 301. Cestreæ, 522. Cestrum, 522. Ceterach, 214. Cetraria, 138, 141, 142. Chænomeles, 465. Chærophyllum, 495, 498. Chætangiaceæ, 83. Chætoceros, 20. Chætocladiaceæ, 100. Chætocladium, 100. Chætomiaceæ, 129. Chætomium, 129. Chætomorpha, 58. Chætopeltis, 54. Chætophora, 54. Chætophoraceæ, 47, 54. Chætopteris, 70. Chalaza, 242. Chalazogames, 273. Chalazogams, 273. Chamæcyparis, 268, 269. Chamædorea, 298, 301. Chamædoris, 62. Chamælaucieæ, 489. Chamælaucium, 489. Chamænerium, 484. Chamaerops, 298, 300, 301, 302. Chamæsiphon, 22, 24, 25. Chamæsiphonaceæ, 24, 25. Chamomile, 572, 574. Chantransia, 83. Chara, 65, 66, 67. Characeæ, 1, 4, 10, 14, 64. Characium, 47, 51. Chareæ, 67. Charlock, 404. Cheilanthes, 213. Cheiranthus, 399, 400, 402. Cheirostemon, 427. Chelidonium, 394, 395. Chelone, 525. Chenopodiaceæ, 364, 369. Chenopodieæ, 369. Chenopodina, 371, 372. Chenopodium, 369, 372. Cherry, 117, 156, 461, 462. Cherry-laurel, 462. Chervil, 495, 498. Chervil-root, 498. Chick-pea, 470. Chickweed, 366. Chicory, 570, 574. Chilies, 522. Chimaphila, 505. Chimonanthus, 389. China-grass, 353. Chinese galls, 439. Chiococca, 550. Chionanthus, 547. Chionodoxa, 312. Chive, 312. Chlamydomonas, 48. Chlamydomoneæ, 14. Chlamydomucor, 97, 98. Chlamydospore, 90. Chlora, 47, 543. Chlorangium, 51. Chloranthaceæ, 363. Chloranthus, 363. Chlorideæ, 295. Chloris, 295. Chlorochytrium, 47, 51. Chlorococcum, 51. Chlorocystis, 51. Chlorophyceæ, 1, 14, 46. Chlorophytum, 312. Chlorosphæra, 51. Chlorosphæraceæ, 47, 51. Chlorosplenium, 135. Chlorotylium, 54. Choanephora, 100. Choanephoraceæ, 100. Chocho, 481. Choiromyces, 124. Choisya, 436. Chondrus, 79, 83, 84. Chorda, 72. Chordaria, 71. Chordariaceæ, 71. Choripetalæ, 336, 337, 505, 561. Chorisia, 427. Choristocarpaceæ, 70. Choristocarpus, 70. Chromaceæ, 15. Chromulina, 15. Chroococcaceæ, 24. Chroococcus, 24, 176. Chrysalis Fungus, 127. Chrysanthemum, 572. Chrysarobin, 473. Chrysobalanaceæ, 462, 466. Chrysobalanus, 462. Chrysomonadinaceæ, 15, 17. Chrysomyxa, 147, 148, 153, 155. Chrysophyllum, 511. Chrysopyxaceæ, 15. Chrysopyxis, 15. Chrysosplenium, 452, 454. Chylocladia, 83. Chysis, 333. Chytridiales, 95, 102. Chytridium, 103. Cibotium, 214, 215. Cicely, 495. Cicendia, 543. Cicer, 470. Cichorieæ, 561, 568, 570. Cichorium, 570, 574. Cicinnobolus, 120. Cicuta, 494, 498. Cilioflagellata, 17. Cimaruoli, 355. Cimicifuga, 383. Cinchona, 548, 549, 550, 553. Cinchoneæ, 550. Cinchonin, 553. Cinclidotus, 197. Cineraria, 572, 574. Cinnamon, 392. Cinnamomum, 391, 392. Cinquefoil, 458. Cipura, 321. Circaea, 485, 486. Circinate, 208. Cirsium, 151, 568, 569. Cissampelos, 390. Cissus, 445, 504. Cistaceæ, 412. Cistifloræ, 406, 451. Cistus, 412, 503. Citharexylon, 535. Citriobatus, 455. Citron, 438. Citronella oil, 296. Citrullus, 479, 480, 481. Citrus, 437, 438. Cladium, 286. Cladochytrium, 103. Cladonia, 139, 140, 141, 142, 143. Cladophora, 11, 58. Cladophoraceæ, 47, 58. Cladosporium, 124. Cladothrix, 27, 33, 34, 35. Clamp-connections, 86. Clarkia, 485. Clastidium, 25. Clatbrus, 173. Clavaria, 159, 161. Clavariaceæ, 161. Claviceps, 125, 126, 127. Clavija, 513. Claytonia, 373. Cleavers, 552. Cleistocarpeæ, 195. Clematideæ, 385. Clematis, 378, 379, 380, 385. Cleome, 406. Clerodendron, 535. Clethra, 509. Climacium, 197. Clinopodium, 540. Clintonia, 563. Clitocybe, 171. Clitoria, 471. Clivia, 317, 318. Closterium, 43, 44. Clostridium, 31. Cloudberry, 461. Clover, 135, 471. Cloves, 489. Club-mosses, 2, 205, 226. Club-rush, 285. Clusia, 414. Clusiaceæ, 414. Cluster-cups, 150. Clypeosphæriaceæ, 130. Cnicus, 570, 574. Cnidium, 495. Cobæa, 515. Coca, 442. Cocaine, 442. Cocci, 26. Coccochromaticæ, 21. Coccoloba, 360. Cocconeideæ, 21. Cocconeis, 21. Cocconema, 20. Cocculus, 390. Coccus, 356. Cochineal, 377. Cochineal-insect, 377. Cochlearia, 398, 400. Cochleariinæ, 404. Cock’s-comb, 369. Cock’s-foot, 294, 296. Cocoa-beans, 423. Cocoa-butter, 423. Cocoa-plum, 462. Cocoa-tree, 422. Cocoanut, 298, 300, 302. Cocoanut, Double, 301. Cocoanut-palm, 301. Cocoineæ, 300. Cocos, 298, 301, 302. Codiaceæ, 61. Codiolum, 59. Codium, 62. Cœlastrum, 52. Cœlebogyne, 432. Cœloglossum, 332. Cœlospermeæ, 493, 497. Cœlosphærium, 24. Cœnobia, 47, 51. Cœnogonium, 142. Coffea, 550. Coffeeæ, 550. Coffee, 555. Coffee-plant, 550, 553. Coix, 293. Cola, 422, 423. Colchicaceæ, 309, 310. Colchiceæ, 310. Colchicin, 311. Colchicum, 310, 311. Coleochætaceæ, 47, 57. Coleochæte, 57, 58. Coleonema, 436. Coleorhiza, 293. Coleosporium, 147, 148, 152, 154. Coleus, 540, 541. Collema, 138, 142. Colletia, 448. Collinsia, 525. Collomia, 515. Collybia, 171. Colocasia, 303, 305, 306. Colocynth, 481. Colts-foot, 571. Columba-root, 390. Columbine, 382. Columella, 187, 189, 193. Columnea, 528. Columniferæ, 421. Colus, 173. Colutea, 470, 473. Comarum, 457, 458. Combretaceæ, 487. Comfrey, 533. Comma-bacillus, 40. Commelina, 308. Commelinaceæ, 308. Commersonia, 422. Commiphora, 438. Compass-plant, 572. Compositæ, 556, 560, 561, 563, 564. Comptonia, 350. Condurango-bark, 546. Cone, 235. Cone-scales, 256. Conferva, 54. Confervoideæ, 47, 53. Conidia, 87, 90. Liberation and distribution of, 91. Conidial-layers, 88. Conidiocarp, 89, 147. Conidio-fructification, 87. Conidiophore, 87, 88. Coniferæ, 3, 237, 238, 252, 255. Female flower of, 255, 257. Pollination, 258. Coniocybe, 134. Conium, 494, 498. Conjugatæ, 1, 12, 14, 41, 88. Conjugation, 11. Connaraceæ, 435. Conocarpus, 487. Conomitrium, 196. Contortæ, 505, 541, 549. Convallaria, 314, 316. Convallariaceæ, 309, 314. Convallarieæ, 314. Convolvulaceæ, 5, 515, 522, 532. Convolvuleæ, 516. Convolvulus, 114, 516, 517. Co-operating cells, 248. Copaifera, 467, 468. Copal-balsam, 468. Copernicia, 300, 301. Copper-beech, 157. Coprinarius, 171. Coprinei, 172. Coprinus, 172. Coptis, 379, 382. Cora, 176. Corallina, 79, 84. Corallinaceæ, 84. Coralliorrhiza, 332. Corallorhiza, 5, 332. Coral-root, 332. Corchorus, 424, 425. Cordaitaceæ, 271. Cordiaceæ, 47–61, 531, 532. Cordyceps, 125, 127, 128. Cordyline, 316. “Core,” 463. Coriander, 497, 498. Coriandrum, 493, 497, 498. Cork-elm, 352. Cork-oak, 348. Cormophyta, 1. Cormophytes, 234. Cornaceæ, 490, 549. Cornel, 490. Corn-cockle, 367. Corn-flower, 567. Corn-poppy, 395. Cornus, 490, 491. Corona, 317, 476. Coronilla, 472, 473. Correa, 436. Corrigiola, 365, 367. Corsinia, 190. Corsiniaceæ, 190. Cortex angosturæ, 437. Corticium, 144, 161. Cortinarius, 171. Cortusa, 512. Corydalis, 334, 395, 396, 397. Corylaceæ, 341, 343. Corylus, 122, 343, 344, 348. Corypha, 298, 300. Coscinodisceæ, 21. Coscinodiscus, 20. Coscinodon, 197. Cosmanthus, 515. Cosmarium, 42, 43, 44. Costus, 326. Cotoneaster, 463, 465. “Cotton” 427, 429, 430. Cotton-grass, 286. Cotton-thistle, 570. Cotyledon, 451. Cotyledons, 247. Couch, 295. Coumarin, 296, 473, 553. Cover-scale, 255, 256. Cow-bane, 494, 498. Cowberry, 509. Cow-parsnip, 496. Cow-tree, 356. Cow-wheat, 526. “Crab’s-eyes,” 470. Crambe, 400, 403. Craniolaria, 529. Crassula, 452. Crassulaceæ, 451. Cratægeæ, 465. Cratægus, 152, 465. Craterellus, 162, 172. Craterocolla, 156. Crenothrix, 30, 37. Creosote, 438. Crepis, 571. Crescentia, 529. Crinum, 318. Crocus, 320, 321. Cronartium, 146, 147, 153, 155, 156. Crotalaria, 472, 473. Croton, 431, 434. Crowberry, 434. Crown-imperial, 314. Crozophora, 434. Crucianella, 552. Crucibulum, 176. Cruciferæ, 398. Crucifers, 398. Crucigenia, 51. Cruoria, 84. Cryptogams, 3, 234. Vascular, 2, 198. Cryptoglena, 15. Cryptogramme, 213. Cryptomeria, 267. Cryptonemia, 84. Cryptonemiales, 82, 84. Ctenanthe, 327. Ctenium, 295. Ctenomyces, 119. Cubeb, 363. Cucubalus, 367. Cucullus, 545. Cucumber, 481. Cucumis, 121, 480, 481. Cucurbita, 478, 479, 480, 481. Cucurbitaceæ, 475, 478, 561. Cucurbitariaceæ, 130. Cud-weed, 573. Cuminum, 497, 498. Cunninghamia, 263. Cunoniaceæ, 454. Cuphea, 482, 483. Cupressaceæ, 257, 262, 267, 272. Cupressus, 241, 245, 268, 269. Cupule, 343. Cupuliferæ, 341, 345. Curare, 546. Curculigo, 318. Curcuma, 326. Curly-mint, 541. Currants, 447, 454. Curvembryæ, 363. Cuscuta, 5, 515, 517. Cuscuteæ, 516. “Cushion,” 206. Cusparia, 437. Cusparieæ, 437. Cutleria, 68, 72. Cutleriaceæ, 11, 72. Cyanophyceæ, 22. Cyanophyll, 22. Cyanotis, 308. Cyathea, 214, 215. Cyatheaceæ, 210, 215. Cyathium, 432. Cyathus, 176. Cycadaceæ, 252. Cycadeæ, 3, 236, 252, 254. Cycas, 25, 231, 236, 238, 251, 252, 253, 254. Cyclamen, 334, 512, 513. Cyclanthaceæ, 302. Cyclanthera, 481. Cyclolobeæ, 371. Cyclosporeæ, 68, 73. Cydonia, 463, 464. Cylindrocapsa, 14, 55. Cylindrocapsaceæ, 47, 54. Cylindrocystis, 44. Cylindrospermum, 22, 25. Cymbella, 20, 21. Cymbelleæ, 20, 21. Cymodocea, 281. Cymopolia, 63. Cynanchum, 546. Cynara, 570, 574. Cynareæ, 569. Cynips, 355. Cynodon, 295. Cynodontium, 196. Cynoglossum, 533, 535. Cynomorium, 503, 504. Cynosurus, 294, 296. Cypella, 321. Cyperaceæ, 277, 283, 284, 291. Cyperus, 286, 287, 290. Cyphella, 162. Cyphiaceæ, 562. Cypress, 267, 268. Cypripedileæ, 329, 330. Cypripedilum, 330. Cypripedium, 330. Cypsela, 564. Cyrtandreæ, 528. Cystocarp, 14, 58, 82. Cystoclonium, 83. Cystopteris, 214. Cystopus, 107. Cytinus, 503, 504. Cytisus, 472, 473. Dacrydium, 255, 260, 261. Dacryomitra, 158, 159. Dacryomyces, 134, 158, 159. Dacryomycetaceæ, 159. Dacryomycetes, 96, 145, 159. Dactylis, 287, 294, 296. Dactylococcus, 51. Dædalea, 166, 171. Dahlia, 569, 572. Daisy, 572. Dalbergia, 472. Dalbergieæ, 472. Dalechampia, 434. Damasonium, 282. Dammara, 263. Danæa, 212. Dandelion, 571. Daphne, 449, 450. Darlingtonia, 409. Darwinia, 489. Dasycladaceæ, 63. Dasycladus, 63. Dasyscypha, 135. Date-palm, 298, 299, 301, 302. Date-plum, 511. Datisca, 477. Datiscaceæ, 477. Datura, 519, 520, 522. Dauceæ, 496. Daucus, 134, 492, 496. Davallia, 214. Davilla, 413. Deadly nightshade, 521. Dead-nettle, 538. Delesseria, 79, 80, 83. Delesseriaceæ, 83. Delphinieæ, 383. Delphinium, 379, 383. Dendrobium, 332. Derbesia, 10, 60. Derbesiaceæ, 47, 60. Dermatea, 116, 134. Dermateaceæ, 134. Dermateales, 134. Dermatophyton, 54. Dermocarpa, 25. Desmanthus, 475. Desmarestia, 71. Desmarestiaceæ, 71. Desmidiaceæ, 10, 18, 21, 42, 44, 48. Desmidium, 44. Desmodium, 466, 472. Deutzia, 455. Devil’s-bit, 560. Dianthus, 364, 367. Diapensiaceæ, 509. Diatoma, 19. Diatomaceæ, 10, 12, 14, 19, 20, 21. Diatomeæ, 1, 18. Diatomin, 18. Diatoms, 1. Diatrypaceæ, 130. Diatrype, 130. Dicentra, 395, 396, 397. Dichaenaceæ, 132. Dichelyma, 197. Dichondreæ, 516. Dichorisandra, 308. Dichospermum, 371. Dicksonia, 207, 215. Diclinous, 236. Dicliptera, 530. Dicotyledones, 3, 334. Dicranella, 196. Dicranum, 196. Dictamnus, 436. Dictyochaceæ, 15. Dictyonema, 176. Dictyosiphon, 71. Dictyosiphonaceæ, 71. Dictyosphærium, 51. Dictyostelium, 8. Dictyota, 76. Dictyotaceæ, 76. Dictyotales, 1, 14, 76. Dicypellium, 392. Didiscus, 493. Didymium, 8. Dieffenbachia, 306. Dielytra, 395. Diervilla, 554, 556. Digitalis, 524, 525, 527. Digraphis, 295, 296. Dill, 496. Dillenia, 413. Dilleniaceæ, 413. Dimorphanthus, 491. Dimorphochlamys, 481. Dinifera, 17. Dinobryinaceæ, 15. Dinobryon, 15. Dinoflagellata, 1, 14, 16, 17, 18, 21. Dinophysis, 17. Diodia, 550. Diœcious, 236. Dionæa, 408. Dioon, 254. Dioscorea, 322, 323. Dioscoreaceæ, 276, 309, 310, 322. Diosma, 436. Diosmeæ, 436. Diospyrinæ, 505, 510. Diospyros, 511. Diphtheria, 40. Diphyscium, 197. Diplarrhena, 321. Diplecolobeæ, 400. Diplococcus, 39. Diploderma, 78. Diplostemonous, 335, 336. Diplusodon, 483. Dipsacaceæ, 549, 556, 558, 559, 560, 569. Dipsacales, 505, 556, 564. Dipsacus, 559, 560. Dipterocarpaceæ, 415. Dipterocarpus, 415. Dipteryx, 472, 473. Discelium, 197. Discolichenes, 142. Discomycetes, 95, 116, 132. Discosporangium, 70. Disease, 32. Disinfection, 32. Dispora, 36. Distichium, 196. Doassansia, 110. Docidium, 44. Dock, 359. Dodder, 5, 516, 517. Dodecatheon, 513. Dog’s-tail, 294, 296. Dogwood, 499. Dolichos, 471. Dondia, 493. Dorema, 496, 498. Doronicum, 240, 572. Dorstenia, 131, 354. Dothideaceæ, 131. Double Cocoanut, 301. Doum-palm, 298, 301. Draba, 400. Dracæna, 274, 316. Dracæneæ, 316. Dracocephalum, 539. Dracunculus, 303, 305. Dragon’s blood, 301, 316. Dragon-tree, 316. Draparnaldia, 54. Drimys, 389. Drosera, 408. Droseraceæ, 407. Drosophyllum, 408. Dryas, 458. Dryobalanops, 415. Dry-rot, 165, 166. Dry yeast, 179. Duboisia, 522. Duckweed, 307. Dudresnaya, 84. Dumontia, 84. Dumontiaceæ, 84. Durio, 427. Durra, 296. Dwarf-elder, 553. Dwarf-male, 57. Dwarf-palm, 300. Dyer’s Weed, 407, 472. Earth-nut, 472. Earth-star, 174. Earth-tongue, 136. Eating-chestnut, 346. Ebenaceæ, 511. Ebony, 511. Ecballium, 478, 480, 481. Eccremocarpus, 529. Echeveria, 451. Echinocactus, 375, 376, 377. Echinodorus, 281. Echinops, 564, 570. Echinopsis, 376, 377. Echinospermum, 533. Echites, 544. Echium, 531, 532, 533, 534, 535. Ectocarpaceæ, 70. Ectocarpus, 69, 70. Edelweiss, 573. Edwardsia, 469. Egg-cell, 13. Egg-fertilisation, 13. Egg-plant, 522. Ehretia, 533. Eichhornia, 316. Elachista, 71. Elachistaceæ, 71. Elæagnaceæ, 449. Elæagnus, 450. Elæis, 301, 302. Elæocarpus, 425. Elaphomyces, 124. Elaphrium, 438. Elatereæ, 192. Elaters, 189. Elatinaceæ, 413. Elatine, 413. Elder, 156, 553, 555, 556. Elemi, 438. Elettaria, 326. Eleusine, 295. Elisma, 281, 282. Elm, 124, 165, 351. Elodea, 282. Elymus, 113, 296. Elyna, 286, 287. Embryo, 246, 247, 248. Embryo-sac, 241, 247. Emericella, 176. Emex, 360. Empetraceæ, 434. Empetrum, 434. Empleurum, 436. Empusa, 101, 102. Enantioblastæ, 277, 308. Encephalartos, 254. Enchanter’s Nightshade, 485. Encoeliaceæ, 70. Endocarpon, 142. Endomyces, 116, 117. Endophyllum, 147, 151. Endophytic parasites, 85. Endosperm, 233, 246, 248, 249. Endospermous, 249. Endosphæra, 47, 51. Endospore, 89, 187. Endosporous, 29. Endothecium, 186. Endozoic Fungi, 85. Enhalus, 283. Entada, 473, 474. Enteromorpha, 53. Entoderma, 54. Entomophthora, 102. Entomophthoraceæ, 102. Entomophthorales, 95, 102. Entyloma, 109, 111, 113. Enzyme, 32. Epacridaceæ, 509. Epacris, 509. Ephebe, 139, 142. Ephedra, 271. Ephemerum, 195. Epibasal, 186. Epichloë, 125, 127. Epiclemmydia, 54. Epidendreæ, 332. Epidendron, 332. Epigynum, 544. Epilobium, 484, 485. Epimedium, 390. Epipactis, 331, 333. Epipetalous, 336. Epiphyllum, 375, 377. Epiphytic parasites, 85. Epipogon, 331. Epipyxis, 15. Episepalous, 335. Epithemia, 20, 21. Epizoic Fungi, 85. Equisetaceæ, 202, 204, 221, 234, 235, 236, 240. Equisetinæ, 2, 204, 221, 225. Equisetum, 200, 206, 221, 222, 224. Eragrostis, 294. Eranthemum, 530. Eranthis, 379, 382. Ergot, 125, 127. Eria, 332. Erica, 507, 508. Ericaceæ, 238, 505, 507. Ericeæ, 507. Erigeron, 573. Erinus, 525. Eriobotrya, 465. Eriocaulaceæ, 308, 309. Eriocaulon, 309. Eriodendron, 427. Eriophorum, 285, 286. Erodium, 419. Eruca, 402. Ervum, 470, 473. Eryngium, 493, 569. Erysiminæ, 404. Erysimum, 402. Erysiphaceæ, 119. Erysiphe, 119, 120, 121. Erythræa, 542, 543. Erythrina, 471. Erythronium, 312. Erythrotrichia, 78. Erythroxylaceæ, 442. Erythroxylon, 442. Escalloniaceæ, 454. Escalloniæ, 451. Eschalot, 312. Eschsholzia, 393, 395. Esparto grass, 296. Euactæa, 379. Euaspergillus, 122. Euastrum, 44. Eucalyptus, 489. Eucalypta, 197. Eucharidium, 485. Eucharis, 317, 318. Euchlæna, 293. Eucomis, 312. Eudorina, 48, 50. Eugeissonia, 301. Eugenia, 488, 489. Euglena, 103. Eunotieæ, 21. Euonymus, 152, 444. Eupatorieæ, 571, 572. Eupatorium, 569, 571. Euphacidiaceæ, 133. Euphorbia, 148, 151, 430, 432, 433. Euphorbiaceæ, 430. Euphorbium, 434. Euphoria, 441. Euphrasia, 526. Eupodisceæ, 21. Eurhynchium, 197. Eurotium, 121, 122. Euryale, 386, 387, 388. Eusporangiatæ, 202, 210, 239. Euterpe, 301. Euthora, 83. Eutoca, 515. Evening Primrose, 484. Evernia, 143. Evodia, 436. Evolvulus, 516. Exalbuminous, 249. Exidia, 156. Exoasci, 95, 115, 116. Exobasidium, 160, 161. Exochorda, 457. Exospore, 87, 187. Exostemma, 553. Exuviella, 16, 17, 18, 21. Eye-bright, 526. “Eye-spot,” 10. Faba, 468, 470, 473. Fabiana, 521. Fabroniaceæ, 197. “Fæchel,” 284. Facultative parasites, 84. Fagonia, 438. Fagus, 122, 347, 348. “Fairy-rings,” 86, 136, 163, 168. Falcaria, 494. “Fan,” 284. Fan-palm, 298. Farinosæ, 308. Fatsia, 491. Feather-grass, 294. Feather palm, 298. Fedia, 557. Fegatella, 191. Fennel, 492, 495, 498. “Ferment of wine,” 178. Fermentation, 32. Alcoholic, 97. Ferns, 2. Stem of, 202, 204, 205. True, 204, 205. Water, 205. Various, 208. Ferraria, 321. Ferula, 496, 498. Fescue, 293, 296. Festuca, 293, 296. Festuceæ, 293. Fevillea, 478, 481. Ficaria, 334, 383. Ficus, 351, 354, 355, 356. Field-horsetail, 224. Field-madder, 552. Field-thistle, 151. Fig-wort, 524. Filago, 573. Filament, 238. Filbert, 345. Filices, 204, 205. Systematic division of, 210. Filicinæ, 2, 204, 205, 234, 236, 239. Fiori di fico, 355. Fiorin, 294. Fir, 124, 153, 155, 165, 170, 263, 264, 265. Fir-cones, 163. Firneedle-rust, 152. Fissidens, 196. Fissidentaceæ, 196. Fission-Algæ, 1, 14, 22, 29. Fission-Fungi, 26, 29. Fission-plants, 10. Fistulina, 166. Flag, 320. Flagellata, 48. Flagellatæ, 15. Flax, 417. Flea-bane, 573. “Fleur de vin,” 179. Floral-leaves, 235. Florideæ, 9, 10, 77, 78. Flower, 235. Monocotyledonous, 276. Flowering-plants, 3, 249. Flowering-rush, 281. Flowers-of-tan, 7. Fly-mould, 101. Fly-mushroom, 167, 171. Fly-trap, 408. Fœniculum, 495, 498. Foliage-leaves, 235. Fontinalaceæ, 197. Fontinalis, 197. Fool’s-parsley, 495, 498. Foot, 186. Fore-leaf, 275, 334. Forget-me-not, 334. Forskohlea, 353. Forsythia, 546, 547. Fossil Gymnosperms, 271. Fothergilla, 455. Fourcroya, 318. Fovea, 231. Foxglove, 525. Fox-tail, 294, 298, 369. Fragaria, 458, 461. Fragilarieæ, 21. Franciscea, 521. Francoaceæ, 454. Frangulinæ, 443, 449, 451, 490. Frankeniaceæ, 411. Frankincense, 438. Fraxinus, 122, 130, 546, 547. French-bean, 473. French Rose, 460. Freycinetia, 302. Fritillaria, 312, 313, 314. Frog-bit, 282. “Fruit,” 91. Fruit, 249. Fruit-bearers, 91. Fruit-bodies, 91. “Fruit-forms,” 91. Frullania, 191, 192. Frustule, 18. Frustulia, 20. Fucaceæ, 75. Fuchsia, 484, 485. Fucoideæ, 9. Fucus, 13, 73, 74, 75. Fuligo, 6, 8. Fumago, 124. Fumaria, 396, 397. Fumariaceæ, 395. Fumitory, 395. Funaria, 182, 188, 197. Funariaceæ, 197. Funckia, 312, 313, 314. Fundaments, 90. Fungi, 1, 4, 5, 8, 84. Fungi-galls, 85. Fungi Imperfecti, 96. Fungus chirurgorum, 164. laricis, 164. Funicle, 241. Furcellaria, 79, 84. Furze, 472. Fusicladium, 130. Gagea, 312. Gaillardia, 572. Galactodendron, 356. Galangal, 326. Galanthus, 317, 318. Galaxaura, 83. Galaxia, 321. Galbanum, 498. Galega, 470. Galeobdolon, 538. Galeopsis, 538, 540. Galinsoga, 572. Galipea, 437. Galium, 552, 553. Galphimia, 442. Gambier, 553. Gamboge, 414. Gambo-hemp, 430. Gametangium, 12. Gamete, 11. Gametophore, 183. Gametophyte, 181. Gamopetalæ, 336. Garcinia, 414. Garden-cress, 405. Gardenia, 550. Gardenieæ, 550. Garidella, 383. Garlic, 312. Garrya, 491. Gasteria, 312. Gasterolichenes, 176. Gasteromycetes, 96, 145, 173. Gastonia, 491. Gaultheria, 508. Gaura, 485. Geaster, 174. Gelidiaceæ, 83. Gelidium, 83, 84. Genipa, 550. Genista, 471, 473. Genisteæ, 471. Gentian, 542. Gentiana, 542, 543. Gentianaceæ, 542. Gentianeæ, 542. Geoglossum, 136. Geonoma, 301. Georgiaceæ, 197. Geraniaceæ, 418. Geranium, 419. Germ-pores, 93. Gesneria, 528. Gesneriaceæ, 518, 526, 528. Gesnerieæ, 528. Geum, 458, 460. Gigartina, 83, 84. Gigartinaceæ, 83. Gigartinales, 82, 83. Gilia, 515. Gillenia, 457. Gills, 166. Ginger, 326. Ginkgo, 255, 257, 259, 260, 272. Gipsy-wort, 539. Gladiolus, 321. Glandulæ, 329. Glasswort, 371. Glaucium, 394, 395. Glaucocystis, 22, 24. Glaux, 513. Gleba, 172. Glechoma, 539, 541. Gleditschia, 468. Gleichenia, 215. Gleicheniaceæ, 215, 236. Glenodinium, 17. Globba, 326. Globe-thistle, 570. Globularia, 541. Globulariaceæ, 532, 541. Glœocapsa, 24. Glœotrichia, 25. Gloiopeltis, 84. Gloiosiphoniaceæ, 84. Gloxinia, 528. Glume, 287. Glumifloræ, 277, 283. Glyceria, 113, 290, 294, 296. Glycine, 471. Glycyrrhiza, 470, 473. Glyptostrobus, 267. Gnaphalium, 569, 573. Gnetaceæ, 3, 251, 271, 272. Gneteæ, 252, 270. Gnetum, 271. Gnidia, 449. Gnomonia, 130. Gnomoniaceæ, 130. Goat’s-beard, 571. Godetia, 485. Godlewskia, 25. Golden-currant, 455. Golden-rod, 573. Golden Saxifrage, 452. Goldfussia, 530. Gold-of-pleasure, 401. Gomontia, 58. Gomontiaceæ, 47, 58. Gomphonema, 19. Gomphonemeæ, 20, 21. Gomphosphæria, 24. Gomphrena, 368, 369. Gonatozygon, 44. Gongrosira, 54. Gonidia, 138. Gonimoblast, 82. Goniotrichaceæ, 78. Goniotrichum, 78. Gonium, 48. Gonococcus, 39. Gonolobus, 546. Goodenia, 564. Goodeniaceæ, 563. Gooseberry, 455. Goosefoot, 369. Gossypieæ, 427. Gossypium, 427, 429, 430. Gouania, 448. “Gourds,” 481. Gout-weed, 494. Gracilaria, 83. “Grains of Paradise,” 390. Gramineæ, 277, 283, 287. Grape-disease, 121. Graphiola, 110. Graphis, 140, 142. Grasses, 287. Grass-flower, 290, 291. Grass-fruit, 292. Grass of Parnassus, 453. Grass-wrack, 279. Grateloupiaceæ, 84. Gratiola, 525, 527. Green Algæ, 1, 14. “Greenheart,” 393. Grevillea, 450. Griffithsia, 84. Grimmia, 197. Grimmiaceæ, 197. Gronovia, 476. Ground Ivy, 539. Groundsel, 153, 572. Gruinales, 416. Guaiacum, 438. Guano, 20. Guava, 489. Guava-rum, 490. Guazuma, 422. Guelder-rose, 455, 555. Guepinia, 159. Guinea-corn, 296. Guinea Pepper-plant, 521. Guizotia, 574. Gulf-weed, 75. Gum-arabic, 475. Gum-benzoin, 511. Gum-tragacanth, 473. Gum-trees, 490. Gunnera, 25, 482, 485, 486. Guttapercha, 511. Guttiferæ, 414. Gymnadenia, 332. Gymnoascaceæ, 119. Gymnoascales, 95, 116, 118. Gymnoascus, 119. Gymnodinium, 17. Gymnogramme, 214. Gymnospermæ, 2, 234, 239, 250, 251. Gymnosperms, 244, 246. Fossil, 271. Gymnosporangium, 146, 147, 151, 154. Gymnosporeæ, 82. Gymnostomum, 196. Gymnozyga, 42, 44. Gynandræ, 278, 328. Gynandropsis, 405, 406. Gynerium, 294, 296. Gynœceum, 237. Gynophore, 367. Gynostemium, 329. Gysophila, 368. Habenaria, 332. Hablitzia, 370. Habrothamnus, 522. Hacquetia, 493. Hæmanthus, 317, 318. Hæmatoxylon, 467, 468. Hæmodoraceæ, 320. Hæmodorum, 320. Hagenia, 460. Hair-grass, 294. Hakea, 450. Halesia, 511. Halianthus, 366. Halidrys, 73, 75. Halimeda, 62, 63. Halimus, 371. Halophila, 283. Haloragidaceæ, 482, 485, 486. Haloragis, 486. Halymenia, 84. Hamamelidaceæ, 455. Hamamelis, 455. Hamelia, 550. Hankornia, 544. Hapalosiphon, 26. Haplomitrium, 192. Haplospora, 72. Haptera, 4, 10. Hard-fern, 214. Hare’s-ear, 494. Hart’s-tongue, 214. “Harzsticken,” 169. Haschisch, 358. Hassalia, 26. Haustoria, 86. Hawkbit, 571. Hawksbeard, 571. Hawthorn, 465. Hay-bacillus, 37, 38, 39. Hazel, 526. Hazel-nut, 343. Heal-all, 539. Heath, 507. Hebenstretia, 541. Hechtia, 319. Hedera, 491. Hedge-mustard, 402. Hedge-parsley, 497. Hedwigia, 197. Hedycarya, 389. Hedychium, 326. Hedyosmum, 363. Hedysareæ, 472. Hedysarum, 472, 473. Helenium, 572. Heleocharis, 285. Heliantheæ, 572, 573. Helianthemum, 412. Helianthus, 569, 572, 574. Helichrysum, 573. Heliconia, 325. Heliconiæ, 325. Helicophyllum, 303. Helicteres, 422. Heliophilinæ, 404. Heliotropieæ, 533. Heliotropium, 533, 535. Hellebore, 382. Helleboreæ, 381. Helleborus, 379, 380, 382. Helminthocladiaceæ, 83. Helobieæ, 277, 278. Helosciadium, 494. Helosis, 504. Helotiaceæ, 135. Helotium, 135. Helvella, 136. Helvellaceæ, 136. Helvellales, 95, 116, 136. Helwingia, 491. Hemerocallideæ, 312. Hemerocallis, 312, 313, 314. Hemiasci, 95, 108. Hemibasidii, 95, 108, 109. Hemichlamydeous, 257. Hemileia, 155. Hemlock, 494, 498. Hemp, 356, 529. Hemp-agrimony, 571. Hemp-nettle, 538. Henbane, 521. Henriquezia, 549. Hepaticæ, 2, 188. Hepialus, 128. Heracleum, 492, 496. Herb-Paris, 314. Heritiera, 422. Hermannia, 422. Hermaphrodite, 236. Herminium, 332. Hermodactylus, 321. Hernandia, 392. Herniaria, 365, 367. Herpestis, 525. Herposteiron, 54. Herpotrichia, 129. Hesperideæ, 404. Hesperidinæ, 404. Hesperis, 400, 402. Heteranthera, 316. Heterobasidion, 145, 165. Heterocysteæ, 24. Heterocysts, 22. Heterœcious, 148. Heteromerous, 138. Heteropteris, 442. Heterosphæria, 116, 133. Heterosphæriaceæ, 133. Heterosporous Vascular Cryptogams, 200. Heterotoma, 563. Heuchera, 452. Hibiscus, 427, 430. Hickory, 350. Hieracium, 571. Hierochloa, 295, 296. Higher Fungi, 95, 114. Hilum, 243. Himanthalia, 75. Himantidium, 20. Hip, 459, 460. Hippocrateaceæ, 444. Hippocrepis, 472. Hippomane, 434. Hippophaë, 450. Hippuris, 486. “Hochblatt,” 235. Hog’s-fennel, 496. Holbœllia, 390. Holcus, 294, 296. Holly, 444. Hollyhock, 151, 430. Holochlamydeous, 256. Holosteum, 366. Homalia, 197. Homalothecium, 197. Homocysteæ, 24. Homoiomerous, 138. Honckenya, 366. Honesty, 400. Honey-dew, 126. Honey-leaves, 379. Honeysuckle, 553, 554. Hookeriaceæ, 197. Hop, 124, 356, 357. Hopea, 415. Hordeæ, 295. Hordeum, 291, 296. Horehound, 538. Hormidium, 54. Hormogonia, 10, 24. Hornbeam, 157, 343, 344. Horned Pond-weed, 279. Horn-nut, 485. Horn-poppy, 395. Horn-wort, 388. Horse-bean, 470, 473. Horse-chestnut, 440. Horse-radish, 400, 405. Horsetails, 2, 204, 221. Hosta, 312. Hoteia, 452. Hottonia, 512. Hound’s-tongue, 533. House-leek, 452. Houttuynia, 359, 362. Hoya, 546. Humiriaceæ, 421. Humulus, 121, 357, 358. Hura, 432. Hyacintheæ, 312. Hyacinthus, 312, 313, 314. Hyalotheca, 42, 44. Hydnaceæ, 162. Hydnophytum, 550, 553. Hydnora, 504. Hydnum, 162. Hydra, 9. Hydrangea, 455. Hydrangeaceæ, 455. Hydrastin, 385. Hydrastis, 381. Hydrilla, 283. Hydrocharis, 282. Hydrocharitaceæ, 278, 282. Hydrocleis, 281. Hydrocotyle, 491, 493. Hydrocotyleæ, 493. Hydrodictyaceæ, 47, 51. Hydrodictyon, 9, 52. Hydrolea, 515. Hydrophyllaceæ, 515. Hydropterideæ, 205, 215, 239. Hydruraceæ, 16. Hydrurus, 16. Hygrophorei, 172. Hygrophorus, 172. Hylocomium, 197. Hymenæa, 468. Hymenium, 88. Hymenogaster, 174, 175, 176. Hymenogastraceæ, 176. Hymenolichenes, 176. Hymenomycetes, 96, 145, 159. Hymenophore, 159. Hymenophyllaceæ, 206, 210, 215. Hymenophyllum, 215. Hyoscyamine, 522. Hyoscyamus, 518, 519, 520, 521, 522, 523. Hypecoum, 395, 396. Hypericaceæ, 413. Hypericum, 413, 414. Hypha, 85. Hyphæ-like threads, 9. Hyphæne, 298, 301. Hypholoma, 171. Hypnaceæ, 197. Hypnum, 47, 196, 197. Hypobasal, 186. Hypochæris, 571. Hypochnus, 161. Hypocreaceæ, 125. Hypocreales, 125. Hypoderma, 132. Hypodermaceæ, 132. Hypomyces, 125. Hyporhodius, 171. Hypothecium, 132. Hypoxideæ, 317. Hypoxis, 318. Hypoxylon, 131. Hypsophyllary leaves, 235. Hyssop, 540, 541. Hyssopus, 540, 541. Hysteriaceæ, 132. Hysteriales, 95, 116, 132. Hysterium, 132. Hysterophyta, 498. Iberis, 398, 400, 401. Icacinaceæ, 439. Iceland-lichen, 142. Iceland-moss, 143. Ice-plant, 375. Icica, 438. Ignatius-beans, 546. Ilex, 444. Illecebrum, 367. Illicieæ, 389. Illicium, 389. Impatiens, 421. Imperatoria, 496, 498. Incense, 438. Indian-corn, 293. Indian-cress, 420. Indigo, 470, 473. Indigofera, 470, 473. Indusium, 210. Inflorescence of Palm, 299. Infusoria, 9. Inga, 473, 475. Integuments, 242. Inula, 569, 573, 574. Inulin, 574. Involucre, 189. Involution-forms, 36. Ionidium, 410. Ipecacuanha, 553. Ipomæa, 515, 517. Iridaceæ, 277, 310, 320. Iris, 276, 291, 320, 321. Irish-moss, 84. Iron-bacteria, 33. Iron-wood, 339, 511. Irpex, 163. Isactis, 25. Isaria, 127, 128. Isatis, 403, 404. Isnardia, 485. Isoëtaceæ, 230. Isoëtes, 200, 202, 204, 228, 230, 245. Isogamous fertilisation, 11. Isolepis, 287. Isonandra, 511. Isopyrum, 382. Isosporous Vascular Cryptogams, 200. Isothecium, 197. Isotoma, 563. Ivy, 491. Ixia, 321. Ixora, 550. Jacaranda, 529. Jack, 356. Jacquinia, 513. Jalap, 517. Jambosa, 488. Japanese wax, 439. Jasione, 541, 561, 562. Jasminaceæ, 541, 542, 547. Jasmine, 547. Jasminum, 547. Jateorhiza, 390. Jatropha, 431. Jequirty, 470. Jerusalem-Artichoke, 572, 574. Jonquil, 318. Judas’-ear, 156. Judas-tree, 468. Juglandaceæ, 337, 349. Juglandifloræ, 349. Juglans, 349, 350. Juncaceæ, 277, 283, 284, 291. Juncaginaceæ, 278. Juncus, 283, 284. Jungermannia, 191, 192. Jungermannieæ, 191. Juniper, 259, 268, 269. Juniperus, 151, 152, 241, 268, 269. Jurinea, 570. Jussiæa, 485. Justicia, 530. Jute, 425. Kalanchoë, 451. Kale, 403, 405. Kalmia, 509. Kæmpferia, 325, 326. Kamala, 434. Kaulfussia, 212. Kefir-grains, 36. Kelp, 76. Kerria, 457, 460. Kidney-bean, 471, 473. Kielmeyera, 415. “King Charles and the Oak,” 207. Kingia, 312. Kino, 473. Kitaibelia, 429. Knap-weed, 570. Knapwell, 367. Knautia, 560. Knot-grass, 359. Knowltonia, 379. Kobresia, 287. Kochia, 371. Koeleria, 294. Koelreuteria, 441. Koenigia, 361. Kohlrabi, 405. Krameria, 468. Kramerieæ, 468. Koso-tree, 460. Labellum, 277, 323, 325. Labiatæ, 515, 532, 535, 536. Labiate-flowered, 567, 570. Laburnum, 472, 473. Labyrinth Fungus, 166. Lace-tree, 449. Lacmus, 142. Lactarius, 171. Lactoridaceæ, 362. Lactoris, 362. Lactuca, 571, 574. Ladanum, 412. Ladenbergia, 550, 553. Ladies-mantle, 460. Lady-fern, 213. Lady’s-finger, 471. Lælia, 332. Lagenandra, 306. Lagenaria, 479, 481. Lagenedium, 104. Lagerstrœmia, 483. Lagetta, 449. Lagœcia, 494. Laguncularia, 487. Lagurus, 296. Lamellæ, 166. Laminaria, 71. Laminariaceæ, 71. Lamium, 536, 538, 540, 541. Lamprothamnus, 67. Landolphia, 544. Langsdorffia, 504. Lantana, 535. Lappa, 570, 574. Lapsana, 570. Larch, 266, 267. Larch-canker, 135. Larch-fungus, 164. Lardizabalaceæ, 390. Larix, 266. Larkspur, 383. Larrea, 438. Laserpitium, 497. Lasiandra, 484. Latania, 301. Lathræa, 525, 526, 528. Lathyrus, 470, 473. Lattice-rust, 147. Laudatea, 176. Lauraceæ, 238, 391, 449. Laurus, 161, 391, 392, 393. Lavandula, 536, 540, 541. Lavatera, 428, 430. Lavender, 540. Oil of, 541. Lawsonia, 483. Leafy-mosses, 183. Leathesia, 71. Leaven, 179. Lecanora, 140, 142. Lechenaultia, 564. Lecidea, 142. Lecythideæ, 489. Lecythis, 489. Ledum, 153, 509. Leea, 445. Leek, 312. Leersia, 291, 293. Leguminosæ, 466. Legume, 466. Lejolisia, 81. Lemanea, 80, 82. Lemaneaceæ, 82. Lemna, 25, 47, 307. Lemnaceæ, 307. Lemon, 438. Lentil, 470, 473. Lentinus, 171. Leontice, 390. Leontodon, 568, 571. Leontopodium, 593. Leonurus, 538. Lepidiinæ, 404. Lepidium, 400, 401. Lepidocaryinæ, 301. Lepidodendraceæ, 233. Lepidozia, 192. Lepiota, 171. Leptobryum, 197. Leptogium, 140, 142. Leptomitus, 108. Leptopleura, 387. Leptopuccinia, 151. Leptosiphon, 515. Leptospermeæ, 489. Leptospermum, 489. Leptosporangiatæ, 202, 210, 212, 239. Leptothrix, 26, 33, 35, 38. Leptotrichum, 196. Lepturus, 295. Lescuræa, 197. Leskea, 197. Leskeaceæ, 197. Lessonia, 72. Lettuce, 571, 574. Leucobryaceæ, 196. Leucobryum, 192, 196. Leucodon, 197. Leucojum, 317, 318. Leuconostoc, 28, 29, 35. Levisticum, 496, 498. Liagora, 83. Libanotis, 495. Libocedrus, 269. Lichen, 4, 8. Lichen-forming Ascomycetes, 116, 136. Basidiomycetes, 176. Lichenin, 142. Lichina, 142. Licmophoreæ, 21. Lignum Vitæ, 438. Ligularia, 572. Ligulate-flowered, 567. Ligule, 283. Ligulifloræ, 570. Ligustrum, 547. Lilac, 547. Lilæa, 279. Liliaceæ, 274, 309, 311. Lilies, 311, 314. Liliifloræ, 278, 309. Lilium, 245, 312, 313, 314. Lily of the Valley, 314. Lime, 165. Limnanthaceæ, 421. Limnanthemum, 543. Limnanthes, 421. Limnocharis, 281. Limodorum, 331. Limonia, 437. Limosella, 525. Linaceæ, 417. Linaria, 523, 525, 527. Lindera, 393. Ling, 507. Linnæa, 555. Linnæeæ, 555. Linociera, 547. Linseed, 418. Linum, 417, 418. Liparis, 332. Lippia, 535. Liquidambar, 455. Liquorice, 470, 473. Liriodendron, 388. Listera, 331. Litchi, 441. Lithoderma, 71. Lithodermataceæ, 71. Lithophyllum, 84. Lithospermum, 533. Lithothamnion, 80, 84. Littorella, 530, 531. Liverworts, 2, 181, 188. Livistona, 298, 299, 300, 302. Lloydia, 312. Loasaceæ, 476. Lobelia, 562, 563. Lobeliaceæ, 335, 562. Lobeline, 563. Lochnera, 544. Locusts, 468. Lodicules, 288, 291. Lodoicea, 301. Loganiaceæ, 542, 546, 549. Logwood, 468. Loiseleuria, 509. Lolium, 295, 296. Lomandra, 312. Lomaria, 214. Lomentaceæ, 403. Lomentaria, 83. Lonicera, 553, 554, 556. Lonicereæ, 549, 553. Long-pepper, 363. Loose-strife, 482. Lopezia, 484, 485. Lophiostomaceæ, 130. Lophocolea, 192. Lophodermium, 132. Lophospermum, 525. Loquat, 465. Loranthaceæ, 501. Loranthoideæ, 501. Loranthus, 504. Loteæ, 471. Lotus, 471. Louse-wort, 526. Love-in-the-mist, 382. Lucerne, 473, 529. Lucuma, 511. Luehea, 424, 425. Luffa, 481. Lunaria, 400, 401. Lung-Lichen, 143. Lung-wort, 533. Lunularia, 191. Lupin, 472. Lupinus, 472. Luzula, 283, 284. Lychnis, 365, 367. Lychnothamnus, 67. Lycium, 521. Lycogala, 6, 8. Lycoperdaceæ, 174. Lycoperdon, 174. Lycopersicum, 521, 522. Lycopodiaceæ, 202, 226. Lycopodieæ, 205, 226. Lycopodinæ, 2, 205, 226, 228, 234, 235, 236, 240. Lycopodium, 200, 226, 227, 228, 233. Lycopsis, 534. Lycopus, 536, 539. Lygeum, 293. Lygodium, 215. Lyme-grass, 296. Lyngbya, 24. Lyngbyaceæ, 22, 24. Lyonia, 508. Lysimachia, 47, 151, 513. Lysipoma, 563. Lythraceæ, 482. Lythrum, 482, 483. Maba, 511. Machærium, 472. “Mace,” 393. Macleya, 395. Maclura, 354, 356. Macrosporangium, 241, 243. Macrospore, 200, 242, 243, 245, 246. Macrocystis, 72. Macrozamia, 254. Madder, 552, 553. Madia, 574. Madotheca, 192. Mad-wort, 534. Maesa, 513. Magnolia, 389. Magnoliaceæ, 388. Magnolieæ, 388. Mahernia, 422. Mahogany, 436. Mahonia, 149, 390. Maiden-hair, 206, 213. Maize, 289, 293, 296. Maize-blight, 113. Majanthemum, 309, 314. Malachium, 366. Malachra, 428. Malaxis, 332. Malcolmiinæ, 404. Male-Fern, 214. Mallow, 425. Malope, 429, 430. Malopeæ, 428. Malpighiaceæ, 442. Malpighia, 422. Malt, 296. Malus, 152, 463, 464, 465. Malva, 426, 428, 429, 430. Malvaceæ, 425. Malveæ, 428. Malvaviscus, 428. Mamme, 355. Mammea, 414. Mammillæ, 377. Mammillaria, 375, 377. Mammoni, 355. Mancinil-tree, 432. Mandragora, 522. Mandrake, 522. Manettia, 550. Mangifera, 439. Manglesia, 450. Mango, 439. Mangold, 369, 372. Mangosteen, 414. Mangrove, 486. Manihot, 431, 434. Manilla Hemp, 325. Maniok, 434. “Manna,” 547. Manna Ash, 546, 547. Manna-grass, 296. Manna-lichen, 142. Mannit, 72. Maple, 442. Maranta, 327. Marantaceæ, 277, 327. Marasmiei, 171. Marasmius, 168, 171. Marattia, 212. Marattiaceæ, 209, 210, 212, 236. Marcgraviaceæ, 415. Marchantia, 181, 183, 184, 190. Marchantiaceæ, 190. Marchantieæ, 190. Mare’s-tail, 486. Marigold, 572. Marjoram, 539, 541. Marrow, 480. Marrubium, 538. Marsilia, 216, 217, 219, 220, 245. Marsiliaceæ, 210, 218, 239. Marsh Cinquefoil, 458. Marsh-marigold, 382. Martynia, 529. Masdevallia, 332. Massariaceæ, 130. Massulæ, 331. “Mast,” 347. Mastic, 439. Mastigobryum, 192. Mastigocoleus, 24. Maté, 445. Matico, 363. Matricaria, 572, 574. Matthiola, 400, 402. Maurandia, 525. Mauritia, 301. Maxillaria, 332. May, 465. Mayacaceæ, 308. Maydeæ, 293. Meadow-grass, 151, 294, 296. Meadow Rue, 385. Meadow-sweet, 457. Mecca-balsam, 438. Meconopsis, 395. Medicago, 471, 473. Medick, 471, 473. Medinilla, 484. Medlar, 465. Meesea, 197. Megacarpæa, 400, 401. Melaleuca, 489. Melampodium, 572. Melampsora, 147, 152, 153. Melampsorella, 147. Melampyrum, 526. Melanconidaceæ, 130. Melandrium, 367. Melanogaster, 176. Melanommaceæ, 30. Melanoselinum, 497. Melanosinapis, 402. Melanospora, 125. Melanoxylon, 468. Melanthium, 310. Melastomaceæ, 483. Meliaceæ, 435. Melianthaceæ, 440. Melianthus, 440. Melica, 287, 290, 294. Melilotus, 466, 470, 471. Melinophyl, 18. Melissa, 540, 541. Melobesia, 80, 84. Melocactus, 375, 377. Melochia, 422. Melogrammataceæ, 130. Melon, 481. Melosira, 19. Melosireæ, 21. Menispermaceæ, 390. Menispermum, 390. Mentha, 47, 536, 539, 541. Menthol, 541. Mentzelia, 476. Menyantheæ, 542, 543. Menyanthes, 240, 543, 550. Menziesia, 509. Mercurialis, 431, 434. Mercury, 431. Merendera, 310. Mericarp, 492. Meridieæ, 21. Merismopedium, 10, 24. Merismopedium form, 27. Mertensia, 533. Merulius, 166. Mesembrianthemeæ, 375. Mesembrianthemum, 375. Mesocarpaceæ, 46. Mesomycetes, 1, 95, 108. Mesotænium, 43, 44. Mespilus, 463, 465. Metaxenous, 148. Metrosideros, 489. Metroxylon, 298, 301. Metzgeria, 191, 192. Metzleria, 563. Meum, 495. Michauxia, 562. Miconia, 484. Micrasterias, 44. Microcachrys, 255, 260, 261. Microchæte, 26. Microchloa, 295. Micrococcus, 26, 35, 38. Microcoleus, 22, 24. Microconidia, 89. Microcycas, 254. Microdictyon, 62. Microglena, 15. Micropyle, 242. Microsphæra, 121. Microspira-comma, 40. Microspora, 54. Microsporangia, 237, 240. Microspore, 200, 214. Microtea, 372. Mignonette, 406. Mikania, 571. Mildews, 119, 122. Milfoil, 572. Milium, 294. Milk-thistle, 570. Milk-vetch, 470. Milk-wort, 443. Millet, 296. Mimosa, 473. Mimosaceæ, 466, 473. Mimulus, 525, 526, 527. Mimusops, 511. Mint, 539. Mirabilis, 374. Mistletoe, 501. Mitella, 452. Mitromyces, 173. Mitrula, 136, 159. Mnium, 197. Mock Orange-blossom, 455. Modiola, 427. Moehringia, 366. Mohria, 215. Molinia, 151, 294. Mollinedia, 389. Mollisia, 135. Mollisiaceæ, 135. Mollugo, 375. Momordica, 481. Monacanthus, 333. Monangic, 243. Monarda, 540, 541. Monardeæ, 540. Money-wort, 513. Monimia, 389. Monimiaceæ, 389. Monkshood, 383. Monoblepharis, 102, 108. Monocotyledones, 3, 273, 274, 276. Monocotyledonous flower, 276. Monœcious, 236. Monostroma, 53. Monotropa, 334, 506, 507. Monstera, 303, 305, 307. Montia, 373. Moonwort, 211. Moraceæ, 351, 353. Moræa, 321. Morchella, 136. Moreæ, 354. Morell, 136. Moricandiinæ, 404. Morina, 560. Morinda, 549. Mortierellaceæ, 100. Mortierella, 100. Morus, 351, 354. Moschatel, 453. Moss, 182. “Moss-flower,” 183. Moss-fruit, 186. Moss-rose, 460. Mosses, 1, 2, 181, 188, 192, 234. Mougeotia, 46. Moulds, 31, 94, 122. Mountain-ash, 465. Mountain-meal, 20. Mountain-pine, 266. Mouse-tail, 383. Mucor, 97, 98, 99. Mucoraceæ, 96. “Mucor-yeast,” 97. Mucro, 257. Mucuna, 471. Mud-wort, 525. Muehlenbeckia, 360. Mulberry, 353, 356. Mullein, 523. Murracytaceæ, 15. Musa, 324, 325. Musaceæ, 277, 323. “Muscardine,” 128. Muscari, 312, 314. Musci, 2. frondosi, 188, 192. Muscineæ, 1, 181. Museæ, 325. Mushroom, 159, 166, 168. Musk-rose, 460. Mutisieæ, 570. Myanthus, 333. Mycelium, 85. Mycena, 171. Mycoidea, 8, 54. Mycoideaceæ, 47, 54. Mycomycetes, 1, 95, 114. Mycorhiza, 124, 175, 180, 506. Mycosiphonales, 95, 104. Myosotis, 533, 534, 535. Myosurus, 379, 380, 383, 384. Myrcia, 488. Myrica, 350. Myricaceæ, 337, 350. Myricaria, 411, 412. Myriophyllum, 486. Myriotrichia, 71. Myriotrichiaceæ, 71. Myristica, 392, 393. Myristicaceæ, 393. Myrmecodia, 550, 553. Myroxylon, 473. Myrrh, 438. Myrrha, 438. Myrrhis, 495, 498. Myrsinaceæ, 513. Myrsine, 513. Myrtaceæ, 487. Myrteæ, 488. Myrtifloræ, 451, 482. Myrtle, 487, 488. Myrtus, 488, 489. Myxamœba, 6. Myxogasteres, 5. Myxomycetes, 1, 4, 5. Myxophyceæ, 22. Myzodendron, 500, 501. Naccaria, 83. Nægelia, 528. Najadaceæ, 278, 281. Najas, 281. Nandina, 390. Narcissus, 316, 317, 318. Nardostachys, 557, 558. Nardus, 291, 295, 558. Narthecium, 310. Narthex, 496. Nasturtium, 400, 402, 420. Navicula, 19. Naviculeæ, 20, 21. Neck-canal-cells, 184. Neckera, 197. Neckeraceæ, 197. Nectandra, 392, 393. Nectria, 116, 125, 127. Neea, 374. Negundo, 441, 442. Nelumbo, 386. Nelumboneæ, 386. Nemalion, 81. Nemalionales, 82. Nemastomaceæ, 84. Nemesia, 525. Nemophila, 515. Neomeris, 63. Neottia, 5, 331. Neottieæ, 331. Neovossia, 111. Nepenthaceæ, 408, 409. Nepenthes, 409. Nepeta, 536, 539. Nepeteæ, 539. Nephelium, 441. Nephrolepis, 214. Nephroselmis, 15. Nerium, 544. Nesæa, 483. Neslia, 403. Nest-fungi, 176. Nettle, 351, 352, 353. Neuradeæ, 457. Neuwiedia, 329. Nicandra, 519, 522. Nicotiana, 520, 522. Nicotine, 522. Nidularia, 176. Nidulariaceæ, 176. Nierembergia, 521. Nigella, 379, 380, 382. Nightshade, 521. Nigritella, 332. Nile-lily, 305. Nipa, 301. Nipplewort, 570. Nitella, 65. Nitelleæ, 67. Nitraria, 438. Nitrifying Bacteria, 5. Nitzchieæ, 21. Noble Pine, 264. Noctiluca, 17. Nodularia, 25. Nolana, 522. Nolanaceæ, 518, 522. Noli-me-tangere, 421. Nonnea, 533. Nonsexual reproduction, 10. Nostoc, 22, 23, 25, 27, 29, 138, 486. Nostocaceæ, 22, 24, 25. Nostocopsis, 26. Nothofagus, 347, 348, 501. Notorhizæ, 400. Nucellus, 235, 241, 243, 247. Nuculiferæ, 505, 515, 531. Nucumentaceæ, 403. Nullipora, 84. Nuphar, 387. Nutmegs, 393. Nutritive-tissue, 248. Nux vomica, 546. Nyctaginiaceæ, 373. Nyctalis, 172. Nyctanthes, 547. Nycterinia, 525, 526. Nymphæa, 387, 388. Nymphæaceæ, 385. Nymphæeæ, 386. Oak, 117, 130, 134, 135, 161, 164, 166, 346, 347, 348. Oat, 113, 151, 292, 294, 296. Oat-grain, 290. Oat-grass, 296. Obdiplostemonous, 336. Obelidium, 103. Obligate parasites, 85. Ochna, 439. Ochnaceæ, 439. Ochroma, 427. Ocimum, 541. Ocrea, 359. Odonthalia, 83. Odontites, 526. Œdogoniaceæ, 47, 55. Œdogonium, 10, 11, 55, 56. Œnanthe, 495, 498. Œnothera, 484, 485, 486. Œnotheraceæ, 484. Oidia, 90. Oidium, 121, 179. Oidium forms, 179. Oil-mould, 99. Oil-palm, 301. Olea, 547. Oleaceæ, 541, 542, 546. Oleander, 544. Oligorus, 166. Olive, 547. Olive-brown Seaweeds, 68. Olive Oil, 547. Olpidiaceæ, 103. Olpidieæ, 103. Olpidium, 103. Olyreæ, 296. Omphalodes, 533, 534. Onagraceæ, 484. Oncidium, 332. Oncobyrsa, 24. Onion, 312. Onobrychis, 472, 473. Ononis, 471. Onopordon, 570. Ooblastema-filaments, 82. Oocystis, 51. Oogamous fertilisation, 13. Oogonium, 13. Oomycetes, 95, 96, 100. Oophyte, 181. Oosphere, 13, 248. Oospore, 14. Operculum, 193. Ophiocytium, 51. Ophioglossaceæ, 209, 210. Ophioglossum, 210, 211, 238. Ophiopogon, 320. Ophrydeæ, 331. Ophrys, 332, 333. Opium-poppy, 395. Oplismenus, 295. Opuntia, 375, 377. Orange, 438. Orchid, diagram of flower, 329. Orchidaceæ, 5, 238, 328. Orchideæ, 277. Orchids, 151. Orchis, 276, 331, 332, 333. Oreobolus, 285. Oreodoxa, 301. Organs of attachment, 4. Origanum, 536, 539, 541. Ornithogalum, 312, 314. Ornithopus, 466, 472. Orobanche, 334, 528, 529. Orontieæ, 303. Orontium, 304. Orris-root, 321. Orseille, 142. Orthoploceæ, 400. Orthospermeæ, 493. Orthothecium, 197. Orthotrichum, 197. Orthotropous, 242, 243. Oryza, 293. Oryzeæ, 293. Oscillaria, 10, 23, 24, 26, 37. Oscillariaceæ, 24. Osiers, 152. Osmunda, 209, 215. Osmundaceæ, 202, 210, 215. Ostioles, 73. Ostropa, 133. Ostropaceæ, 133. Ostrya, 345. Osyris, 500. Ouratea, 439. Ouvirandra, 281. Ovary, 3, 239, 250. Ovule, 241, 242, 248. Ovuliferous scale, 256, 257. Oxalidaceæ, 416. Oxalis, 416. Ox-eye, 572. Oxslip, 513. Oxybaphus, 374. Oxycoccus, 509, 510. Oxyria, 360. Oyster Mushroom, 171. Padina, 76. Pæonia, 379, 381. Pæonieæ, 381. Pæpalanthus, 309. Palaquium, 511. Palava, 429. Paleæ, 209. Pales, 288. Palisander-wood, 529. Paliurus, 448. Palm, 275, 276, 297. Branching of, 298. Inflorescence of, 299. Palm-oil, 301. Palm-wax, 301. Palm-wine, 301. Palmæ, 297. Palmella-stage, 15, 16. Palmyra-palm, 301. Paludella, 197. Pampas-grass, 296. Panama hats, 302. Panax, 491. Pancratium, 317. Pandanaceæ, 302. Pandanus, 302. Pandorina, 45, 48. Paniceæ, 295. Panicum, 295, 296. Pansy, 411. Panus, 171. Papaveraceæ, 394. Papaver, 394, 395. Papaw, 476. Papayaceæ, 476. Paper-mulberry tree, 354, 356. Papilionaceæ, 335, 468. Pappus, 564, 566. Papyrus, 287. Paradise apple, 465. Paraglobulin, 473. Paraphyses, 88. Paraguay tea, 445. Parasites, 5. Parasites, endophytic, 85. endozoic, 85. epiphytic, 85. epizoic, 85. facultative, 84. obligate, 85. pathogenic, 85. Parasitic Bacteria, 38. Parasol-fungus, 171. Pariana, 291. Parietaria, 353. Paris, 309, 314, 316. Paritium, 430. Parkia, 475. Parmelia, 140, 141, 142, 143. Parnassia, 453. Paronychia, 365, 367. Paronychieæ, 366. Parrotia, 455. Parsley, 494, 498. Parsnip, 492, 496, 498. Parthenogenesis, 14. Pasanea, 346, 348. Paspalum, 295. Pasta guaranà, 441. Pastinaca, 493, 496. Passerina, 449. Passiflora, 475, 476. Passifloraceæ, 476. Passiflorinæ, 475. Passion-flower, 476. Patellaria, 134. Patellariaceæ, 134. Patellea, 134. Paternoster peas, 470. Pathogenic Rod-Bacteria, 39. Patrinia, 557. Paullinia, 441. Paulownia, 527. Pavonia, 428. Paxillei, 172. Payena, 511. Paypayroleæ, 411. Pea, 470. Peach, 117, 121, 461. Pear, 130, 464, 465. Pedagnuoli, 355. Pedaliaceæ, 518, 529. Pediastrum, 52. Pedicularis, 151, 526. Peganum, 438. Pelargonium, 418, 419. Peliosanthes, 320. Pellia, 191, 192. Pellitory, 353. Peltigera, 143. Pelvetia, 73. Penicillium, 122, 123. Penium, 43, 44. Pennisetum, 295. Penny-cress, 401. Penny-wort, 493. Pentacyclicæ, 505, 506. Pentadesma, 414. Pentapera, 505. Pentstemon, 524, 527. Peplis, 47, 483. Pepper, 361. Peppermint, 541. Peperomia, 361, 362. Pepperwort, 401. Pereskia, 375, 376. Perianth, 235. Perichætium, 192. Pericarp, 249. Pericallis, 574. Peridermium, 147, 148, 153, 154, 155, 156. Peridinea, 1, 14, 17. Peridinin, 16. Peridinium, 17. Peridiola, 176. Peridium, 88, 89, 147. Perigynium, 189. Perilla, 541. Periphyses, 88. Periplasm, 104. Periploca, 546. Perisperm, 249. Perisporiaceæ, 122. Perisporiales, 95, 116, 118, 119. Peristome, 195. Perithecia, 125. Periwinkle, 543, 544. Perizonium, 20. Pernambuco-tree, 468. Peronocarpic ascocarps, 125. Peronospora, 101, 104, 105, 107. Peronosporaceæ, 104. Persea, 393. Persica, 461. Personatæ, 505, 515, 517. Pertusaria, 140, 142. Petals, 235. Petasites, 153, 569, 571. Petiveria, 372. Petrocelis, 84. Petunia, 518, 521. Peucedaneæ, 496. Peucedanum, 496. Peyssonellia, 84. Peziza, 115, 135, 159. Pezizaceæ, 135. Pezizales, 134. Phacelia, 515. Phacidiales, 133. Phacidium, 133. Phacotus, 48. Phæophyceæ, 1, 14, 68. Phæophyl, 68. Phæosporeæ, 68. Phæothamnion, 54. Phagocytes, 41. Phajus, 332. Phalarideæ, 295. Phalaris, 295. Phallaceæ, 172. Phalloideæ, 96, 145, 172. Phallus, 172, 173. Phanerogams, 3, 234, 236, 249. Pharbitis, 516. Pharus, 291, 293. Phascum, 195. Phaseoleæ, 470. Phaseolus, 134, 469, 471, 473. Phegopteris, 213, 214. Phellodendron, 437. Philadephus, 451, 455. Phillyrea, 547. Philodendron, 303, 305. Philonotis, 197. Phlebia, 163. Phleum, 290, 294, 296. Phloëm, 251. Phlœospora, 70. Phlomis, 538, 541. Phlox, 515. Phœniceæ, 299. Phœnix, 298, 299, 301, 302. Pholiota, 171. Phormium, 312, 313, 314. Phragmidium, 146, 147, 148, 151, 152. Phragmites, 113, 131, 291, 294. Phragmonema, 22, 25. Phrynium, 327. Phycocyan, 22, 77. Phycoerythrin, 22, 77. Phycomyces, 99. Phycomycetes, 1, 5, 95, 96. Phycophæin, 69. Phycopyrrin, 16. Phycoxanthin, 69. Phylica, 448. Phyllachora, 131. Phyllactinia, 122. Phyllactis, 560. Phyllanthus, 431, 432. Phyllitis, 70. Phyllobium, 47, 51. Phyllocactus, 377. Phyllocladus, 260. Phyllodia, 474. Phyllodoce, 509. Phylloglossum, 228. Phyllophora, 83. Phyllosiphon, 8. Phyllosiphonaceæ, 47, 61. Physalis, 521. Physarum, 6, 8. Physcia, 139, 143. Physcomitrium, 188, 197. Physiological varieties, 41. Physoderma, 103. Physostigma, 471, 473. Phytelephantinæ, 301. Phytelephas, 299, 301, 302. Phyteuma, 562. Phytoamœbæ, 10, 61. Phytolacca, 372. Phytolaccaceæ, 372. Phytomyxa, 8. Phytophthora, 101, 104, 105, 106. Piassava, 297. Picea, 124, 129, 132, 155, 165, 265. Pichurim, 392. Picraena, 438. Picris, 571. Picrotoxine, 390. Pilacraceæ, 157. Pilacre, 157. Pilea, 353. Pilobolus, 99, 100. Pilostyles, 504. Pilularia, 216, 220. Pimelea, 449. Pimenta, 489. Pimento, 489. Pimpernel, 513. Pimpinell, 498. Pimpinella, 494, 498. Pine, 127, 153, 161, 165, 255, 263, 266. Pine-apple, 320. Pine-shoot Fungus, 152. Pinellia, 305. Pinguicula, 334, 528. Pink, 367. Pin-mould, 99. Pinnularia, 19. Pinus, 129, 132, 153, 155, 165, 264, 265, 266, 267, 272. Pinoideæ, 256, 258, 259, 262. Pipe-flower, 500. Piper, 361, 363. Piperaceæ, 361. Pipereæ, 361. Piptocephalidaceæ, 100. Piptocephalis, 100. Pircunia, 372. Pisonia, 374. Pistia, 306. Pistacia, 439. Pistil, 239. Pistillaria, 161. Pistillate, 236. Pisum, 469, 470, 473. Pitcairnia, 320. Pitcher-plant, 409. Pittosporaceæ, 451, 455. Pittosporum, 455. Placenta, 237, 241. Placochromaticæ, 21. Plagiochila, 189, 192. Plagiothecium, 197. Plagiotropideæ, 21. Planera, 351. “Plankton,” 15, 17, 20. Planogametes, 12. Plantago, 335, 530, 531, 536, 559. Plantaginaceæ, 518, 530. Plantain, 530. Plasmodia, 4, 5, 7. Plasmodiophora, 8. Plasmodiophorales, 6. Platanaceæ, 455. Platanus, 456. Platanthera, 332, 333. Plate-cultures, 33. Platonia, 414. Platycerium, 213. Platycodon, 562. Platystemon, 395. Plectonema, 24. Plectranthus, 541. Pleospora, 130. Pleosporaceæ, 130. Pleurandra, 413. Pleuridium, 195. Pleurocarpi, 197. Pleurococcaceæ, 47, 51. Pleurococcus, 10, 51, 138. Pleurorhizæ. 400. Pleurotænium, 44. Pleurothallis, 332. Pleurotus, 171. Plocamium, 83. Plum, 117, 164, 461, 462. Plumbaginaceæ, 514. Plumbago, 514. Plumeria, 544. Plumule, 247. Pneumathodia, 267. Poa, 287, 290, 294, 296. “Pocket-plum,” 85. “Pockets,” 117. Pod, 466. Pod-pepper, 522. Podalyrieæ, 469. Podocarpeæ, 260. Podocarpus, 251, 255, 261, 272. Podophyllum, 390. Podosphæra, 120. Podospora, 129. Podostemaceæ, 451, 456. Pogostemon, 541. Poinciana, 468. Point Caraway, 498. Polanisia, 406. Polemoniaceæ, 509, 515. Polemonium, 515. Polianthes, 318. Pollinarium, 332. Pollinia, 329. Pollinodium, 100, 120. Pollen-chamber, 251. Pollen-grain, 240, 244, 245. Pollen-sac, 235, 237, 240. Pollen-tube, 244, 249. Polycarpicæ, 377. Polycystis, 24. Polydinida, 16, 17, 18. Polyembryony, 247. Polygala, 442, 443. Polygalaceæ, 442. Polygamous, 236. Polygonaceæ, 239, 359. Polygonatum, 314, 316. Polygonifloræ, 358. Polygonum, 359, 360, 361. Polyides, 84. Polykrikos, 17. Polypetalæ, 336. Polyphagus, 103, 104. Polypodiaceæ, 202, 205, 206, 209, 210, 212. Polypodium, 207, 213. Polyporaceæ, 163. Polyporus, 163, 164, 165. Polysiphonia, 79, 83. Polystachya, 332. Polystigma, 125, 127. Polytrichaceæ, 197. Polytrichum, 197. Pomaceæ, 456, 462. Pomaderris, 448. Pomalo, 438. Pomegranate, 488, 489. Pomona-fungus, 171. Pond-weed, 279. Pontederia, 316. Pontederiaceæ, 308, 316. Poplar, 124, 164, 338. Poppies, 394. Populus, 152, 338. Pore-fungus, 163. Porogames, 273. Poronia, 131. Porphyra, 10, 78. Porphyraceæ, 78. Portulaca, 373. Portulacaceæ, 373. Posidonia, 281. Potamogeton, 47, 278, 279. Potamogetonaceæ, 278, 279. Potato-fungus, 104, 107. Potato-plant, 521, 522. Potentilla, 458, 460. Potentilleæ, 458. Poterium, 460. Pothos, 304. Pottia, 196. Pottiaceæ, 196. Pouzolzia, 353. Prasiola, 53. Preissia, 191. Preslia, 539. Primrose, 512. Primula, 511, 512, 513. Primulaceæ, 239, 512, 514. Primulinæ, 505, 511. Pringsheimia, 54. Prionium, 284. Pritchardia, 298. Priva, 535. Privet, 547. Procarpium, 81. Proembryo, 64. Profichi, 355. Promycelium, 94, 146. Pronucleus, 245. Prorocentrum, 17, 18. Protea, 450. Proteaceæ, 450. Prothallium, 198, 244, 248. Secondary, 233. Protistæ, 5. Protium, 438. Protobasidia, 144. Protobasidiomycetes, 96, 145. Protococcaceæ, 47, 48, 51. Protococcoideæ, 8, 47. Protomyces, 108. Protomycetaceæ, 108. Protonema, 181. Provence oil, 547. Prunella, 539. Prunus, 117, 118, 127, 130, 152, 461, 462. Psalliota, 167, 168, 169, 171. Psamma, 295, 296. Pseudophacidiaceæ, 133. Pseudopodium, 10, 193. Pseudotsuga, 264, 265, 266. Psidium, 488, 489. Psilotaceæ, 228. Psilotum, 201, 228. Psychotria, 550. Ptelea, 437. Pteridium, 131, 207, 213, 214. Pteridophyta, 2, 198, 234. Pterigynandrum, 197. Pteris, 199, 203, 213, 214. Pterisanthes, 445. Pterocarpus, 473. Pterocarya, 350. Pterocephalus, 560. Pterogoniaceæ, 197. Pterogyne, 468. Pterostegia, 360. Pterygophyllum, 197. Ptilidium, 192. Ptilota, 84. Ptychogaster, 166. Puccinia, 147, 148, 149, 150. Puff-ball, 174. Pulmonaria, 533, 534. Pulque, 318. Pulsatilla, 384. Pumpkin, 480, 481. Punctaria, 70. Punica, 483, 488, 489, 490. Puniceæ, 488. Puschkinia, 312. Putrefaction, 32. Puya, 319. Pycnidia, 89. Pylaiella, 70. Pyrenoid, 46. Pyrenolichenes, 142. Pyrenomycetes, 95, 116, 118, 125. Pyrenula, 142. Pyrethrum, 572, 574. Pyrola, 334, 506, 507. Pyrolaceæ, 506. Pyrrophyl, 16. Pyrus, 152, 463. Pythium, 101, 106. Quaking-grass, 294, 296. Quassia, 438, 439. Quassine, 438. Quercifloræ, 337, 340. Quercitron-wood, 348. Quercus, 341, 346, 347, 348, 504. Quillaja, 457, 460. Quillajeæ, 457. Quill-wort, 230. Quince, 464, 465. Quinchamalium, 500. Quinine, 550, 553. Racomitrium, 197. Radiatæ, 571. Radicle, 247. Radiola, 418. Radiolarias, 9. Radish, 403, 404, 405. Radula, 192. Rafflesia, 504. Rafflesiaceæ, 499, 504. Raisins, 447. Rajania, 323. Ralfsia, 71. Ralfsiaceæ, 71. Ramalina, 143. Ramenta, 209. Ramié, 353. Rampion, 562. Randia, 550. Ranunculaceæ, 278, 378. Ranunculeæ, 383. Ranunculus, 151, 378, 379, 380, 382, 383, 384. Rapateaceæ, 308. Rape, 404. Raphanus, 400, 403. Raphia, 301. Raphidium, 51. Raphiolepis, 463, 465. Raspberry, 459, 460, 461. Ravenala, 325. Ray-flowers, 567. Reboulia, 191. Receptacle, 210. Red Algæ, 1. Red-beet, 372. Red-cabbage, 405. Red-clover, 466, 517. Red-currant, 455. Red-pine, 264, 266. “Red-rot,” 164, 166. Red Sandalwood, 473. Red Seaweeds, 4, 77. Red Snow, 48. Red-strip, 165. Red-tree, 468. Reed, 151, 294. Reed-mace, 303. Reindeer Moss, 141. Reineckea, 314. Remijia, 550, 553. Renealmia, 326. Replum, 398. Reseda, 407. Resedaceæ, 406. Resin, 266. Rest-harrow, 471. Restiaceæ, 309. Restio, 309. Restrepia, 332. Retama, 472. Reticularia, 8. Retinospora, 268. Rhamnaceæ, 447, 449. Rhamnus, 151, 448. Rhaphidophora, 305. Rhatany, 468. Rheum, 151, 359, 360. Rhinanthaceæ, 153. Rhinantheæ, 525, 526. Rhinanthus, 526. Rhingia, 320. Rhipidium, 320. Rhipsalis, 375, 376, 377. Rhizidiaceæ, 103. Rhizoboleæ, 415. Rhizocarpeæ, 205, 215. Rhizoclonium, 58. Rhizoids, 4, 10. Rhizomorpha, 169, 170. Rhizopaceæ, 99. Rhizophora, 482, 486, 487, 513. Rhizophoraceæ, 482, 486. Rhizophyllidaceæ, 84. Rhizophyllis, 84. Rhizopods, 5. Rhizopogon, 175, 176. Rhizopus, 99. Rhizosolenia, 20. Rhodanthe, 573. Rhodiola, 451, 452. Rhodochiton, 525. Rhododendron, 161, 508. Rhodomela, 83. Rhodomelaceæ, 83. Rhodophyceæ, 1, 14, 77. Rhodophyll, 77. Rhodophyllidaceæ, 83. Rhodophyllis, 83. Rhodoraceæ, 335, 508. Rhodotypus, 457. Rhodymenia, 83, 84. Rhodymeniaceæ, 83. Rhodymeniales, 82, 84. Rhœadinæ, 393. Rhopographus, 131. Rhubarb, 359. Rhus, 439. Rhynchosia, 471. Rhynchospora, 285, 286. Rhytisma, 132. Ribbon-grass, 296. Ribes, 121, 152, 153, 241, 454, 455. Ribesiaceæ, 454. Rib-grass, 530. Riccia, 186, 189, 190. Ricciaceæ, 190. Rice, 291, 293, 296. Richardia, 305. Richardsonia, 550. Ricinus, 431. Riella, 192, 231. Ringworm, 180. Rivina, 372. Rivularia, 10, 25. Rivulariaceæ, 22, 24, 25. Robinia, 470, 473. Roccella, 142. Rock-cress, 402. Rock-rose, 412. Rod-bacteria, 39. Roestelia, 147, 148, 151, 152, 153. Roman spinach, 372. Roots, 4. “Ropiness,” 35. Rosa, 148, 459, 460. Rosaceæ, 451, 457. Rose, 121. Rose-mallow, 428. Rose of Jericho, 401, 574. Roseæ, 459. Rosellinia, 130. Rosemary, 540. Oil of, 541. Rosifloræ, 456, 466. Rosmarinus, 536, 540, 541. Rostellum, 329, 332. Rotang, 298. Royal-fern, 209, 215. Rubeæ, 458. Rubia, 551, 552, 553. Rubiaceæ, 542, 546, 548, 549, 553. Rubiales, 490, 505, 548, 556, 564. Rubus, 458, 460, 461. Rudbeckia, 572. Ruellia, 530. Rulingia, 422. Rumex, 151, 359, 360. Ruppia, 278, 279. Ruscus, 316. Rush, 283, 284. Russula, 171. Russulei, 171. Rust of Wheat, 148. Rusts, 146. “Rust spots,” 130. Ruta, 436. Rutaceæ, 436. Ruteæ, 436. Rye, 125, 151. Rye-grass, 295, 296. Rye-stem blight, 113. Sabal, 300. Sabaleæ, 299. Saccharomyces, 177, 178. Saccharomyces-forms, 176. Saccharum, 293. Safflower, 574. Saffron, 321. Sagina, 364, 365, 366. Sagittaria, 281, 282. Sago, 254. Sago-palm, 298. Sainfoin, 472, 473. “Salep,” 333. Salicaceæ, 338. Salicin, 339. Salicifloræ, 337. Salicornia, 369, 371, 503. Salicornieæ, 371. Salisburia, 259. Salix, 122, 337, 338. Salpiglossis, 521. Salsafy, 574. Salsola, 370, 371, 372. Salsoleæ, 370. Saltpetre formation, 35. Saltwort, 370. Salvadora, 547. Salvadoraceæ, 542, 547. Salvia, 536, 540, 541. Salvinia, 201, 216, 217, 218, 245. Salviniaceæ, 210, 218. Sambuceæ, 555, 557. Sambucus, 156, 553, 555. Samolus, 513. Samydaceæ, 476. Sandalwood, 473, 500. Sandarack resin, 269. Sand-box tree, 432. Sand-star, 287. Sanguinaria, 395. Sanguisorba, 460. Sanicula, 493. Sannicle, 493. Sanseviera, 320. Santalaceæ, 500. Santalum, 500. Santolina, 572. Sapindaceæ, 440. Sapindus, 441. Saponaria, 368. Saponin, 460. Sapotaceæ, 510. Saprolegnia, 102, 107, 108. Saprolegniaceæ, 107. Saprophytes, 5. Sapucaia-nuts, 489. Saranthe, 327. Sarcina, 27, 28, 38. Sarcophyte, 504. Sargassum, 4, 10, 73, 75. Sarothamnus, 472. Sarracenia, 409. Sarraceniaceæ, 408. Sarsaparilla, 316. Sassafras, 392. Satureia, 540, 541. Satureieæ, 539. Saurureæ, 362. Saururus, 362. Saussurea, 570. Sauvagesieæ, 411. Saw-wort, 570. Saxifraga, 161, 452. Saxifragaceæ, 451, 452. Saxifrage, 452. Saxifraginæ, 451, 555. Scabiosa, 558, 559, 560. Scævola, 564. Scale-leaves, 235. Scammony, 517. Scandiceæ, 495. Scandix, 495. Scapania, 192. Scarlet-runner, 473. Scenedesmus, 51. Scheuchzeria, 278. Schistostega, 196, 197. Schistostegaceæ, 197. Schizæa, 215. Schizæaceæ, 210, 215. Schizanthus, 521. Schizocarp, 492. Schizocarpeæ, 195. Schizochlamys, 51. Schizomeris, 53. Schizomycetes, 26, 33. Schizopetaleæ, 404. Schizopetalum, 402. Schizophyceæ, 8, 10, 23, 26. Schizophyllum, 171. Schizophyta, 1, 14, 19, 22, 24. Schœnocaulon, 310. Schœnoxiphium, 287. Schœnus, 286. Schwendenerian Theory, 139. Sciadium, 51. Sciadopitys, 267. Scilla, 312, 314. Scirpeæ, 285. Scirpus, 285, 286, 287. Scirrhia, 131. Scitamineæ, 276, 278, 323, 328. Scitonemaceæ, 22, 24, 25, 27. Scleranthus, 365, 367. Scleria, 286. Scleroderma, 175. Sclerodermataceæ, 175. Sclerotinia, 116, 134, 135. Sclerotium, 87, 127. Scolopendrium, 213, 214. Scoparia, 525. Scopolia, 519, 521. Scorodosma, 496. Scorzonera, 571, 574. Scotch Fir, 259, 266. Scotinosphæra, 47, 51. Screw Pine, 302. Scrophularia, 524, 526. Scrophulariaceæ, 518, 521, 522, 527. Scutellaria, 536, 539. Scutellum, 293. Scyballium, 504. Scytonema, 22, 26, 176. Scytonemaceæ, 25. Sea-holly, 493. Sea-kale, 403, 405. Sea-lavender, 514. Sea-milkwort, 513. Seaweed, 4. Sea-wormwood, 574. Sebacina, 156. Secale, 127, 295, 296. cornutum, 127. Sechium, 481. “Sedimentary-yeast,” 178. Sedum, 451, 452. Seed, 247, 248, 249. Seguieria, 372. Selaginaceæ, 532, 541. Selaginella, 200, 203, 228, 229, 230, 232, 233, 245, 254. Selaginellaceæ, 231. Selaginelleæ, 205, 228. Selago, 541. Selenastrum, 51. Selenipedilum, 329, 330. Seligeria, 196. Seligeriaceæ, 196. Semele, 316. Sempervivum, 151, 451, 452. Senebiera, 400, 401. Senecio, 566, 569, 572, 573. Senecioneæ, 572. Senna, 468. Sepals, 235. Sequoia, 267, 272. Serapias, 332. Serjania, 441. Serratula, 570, 574. Serum, 33. Service-tree, 465. Sesamum, 529. Seseli, 495. Seselineæ, 495. Sesleria, 294. Sesuvium, 375. Seta, 186. Setaria, 295. Sexual reproduction, 11. Sheep-seaweed, 84. Shellac, 356, 434. Shepherdia, 450. Shepherd’s-needle, 495. Shepherd’s-purse, 401. Sherardia, 552. “Sichel,” 284. “Sickle,” 284. Sicyos, 481. Sida, 428, 430. Sideritis, 538. Sideroxylon, 511. Sigillariaceæ, 233. Silaus, 495. Sileneæ, 367. Silene, 367. Siler, 495. Siliceous earth, 20. Siliculosæ angustiseptæ, 401. latiseptæ, 400. Siliqua, 398. Siliquosæ, 402. Silk-cotton, 427. Silphium, 498, 572. Silver-leaf, 450. Silybum, 567, 570. Simaba, 439. Simaruba, 439. Simarubaceæ, 438. Sinapeæ, 404. Sinapis, 400, 402. Siphocampylos, 563. Siphoneæ, 4, 9, 47, 59. Siphonia, 434. Siphonocladus, 62. Sirosiphoniaceæ, 22, 24, 26. Sisal hemp, 318. Sisymbriinæ, 404. Sisymbrium, 399, 402, 410. Sisyrinchium, 321. Sium, 494, 498. Skimmia, 437. Skull-cap, 539. Slime-fungi, 1, 4, 5. Sloe, 461, 462. Sloth, 8, 356. Smilaceæ, 316. Smilacina, 314. Smilax, 315, 316. “Smut,” 113, 130. Smut-fungi, 114. Snake cucumber, 481. Snapdragon, 523, 524. Snowberry, 554. Snowdrop, 317. Soapwort, 368. Soft-grass, 296. Soja, 471. Solanaceæ, 514, 518, 520, 522. Solanine, 522. Solanum, 238, 521, 522. Soldanella, 513. Solenia, 162. Solidago, 573. Sollya, 455. Solomon’s seal, 314. Sonchus, 153, 571. Sophora, 469. Sophoreæ, 469. Sorbus, 152, 465. Sordaria, 129. Sordariaceæ, 129. Soredia, 141. Sorghum, 296. Sori, 205. Sorocea, 356. Sorrel, 361. Southernwood, 574. Sow-thistle, 571. Spadicifloræ, 277, 297. Spadix, 297. Sparassis, 161. Sparaxis, 321. Sparganium, 302, 303. Sparmannia, 425. Spartium, 472. Spathe, 297. Spathicarpa, 306. Spathulea, 136. Spearmint, 541. Specularia, 562. Speedwell, 525. Spergula, 366. Spergularia, 366. Spermacoce, 550. Spermacoceæ, 550. Spermagonia, 116. Spermaphyta, 3. Spermatangia, 81. Spermatia, 13, 76, 77, 141, 146. Spermatochnaceæ, 71. Spermatochnus, 71. Spermatozoid, 13, 183. Sperm-nucleus, 245. Spermocarp, 58. Spermogonia, 89, 141, 146, 147, 149. Spermothamnion, 84. Sphacelaria, 70. Sphacelariaceæ, 70. Sphacelia, 125, 126. Sphacelotheca, 110. Sphæralcea, 430. Sphærella, 48, 130. Sphærellaceæ, 130. Sphæriales, 129. Sphærobolaceæ, 173. Sphærobolus, 173. Sphærocarpus, 191, 192. Sphærococcaceæ, 83. Sphærophorus, 142. Sphæroplea, 13, 14, 58. Sphæropleaceæ, 47, 58. Sphærotheca, 120, 121. Sphærozosma, 44. Sphagneæ, 193. Sphagnum, 186, 188, 192, 194, 195, 197. Sphenogyne, 566. Sphenophyllaceæ, 233. Sphinctrina, 140. Spigelia, 546. Spikelet, 285, 287, 289. Spikes, 285. Spilanthes, 572. Spinach, 371. Spinacia, 371, 372. Spindle-tree, 444. Spiræa, 151, 451, 456, 457, 460. Spiræeæ, 457. Spiranthes, 331. Spirilla, 27. Spirillum, 30. Spirochætæ, 27. Spirochæte, 28, 38, 40. Spirodela, 307. Spirogyra, 44, 45. Spirolobeæ, 371, 400. Spirotænia, 44. Spirulina, 24. Splachnaceæ, 197. Splachnum, 196, 197. Spondias, 439. Sponges, 8. Sporangia, 239. Sporangial-layers, 88. Sporangiocarp, 88. Sporangio-fructification, 87. Sporangiophore, 88. Spores, 10. Liberation and Distribution of, 91. Germination of, 93. Sporidia, 112. Sporobolus, 295. Sporocarp, 205, 219. Sporochnaceæ, 71. Sporochnus, 71. Sporogonium, 186. Sporophylls, 223, 235, 236. Sporophyte, 181, 186. Spring-spores, 147. Spumaria, 8. Spurge, 431, 432. Spurge-laurel, 449. Spurry, 366. Squamariacæ, 84. “Squills,” 314. Squirting cucumber, 480. Stachydeæ, 538. Stachys, 538, 541. Stachytarpheta, 535. Staehelina, 570. Stag-truffle, 124. Stalk, 186. Stamen, 235, 236. Staminate, 236. Stangeria, 253, 254. Stanhopea, 332. Stanleyinæ, 404. Stapelia, 546. Staphylea, 440. Staphyleaceæ, 440. Staphylococcus, 39. Star-aniseed, 389. Statice, 514. Staurastrum, 42, 43, 44. Steenhammera, 533. Stegocarpeæ, 195. Stellaria, 364, 365, 366. Stellatæ, 550, 552, 553. Stemless Plants, 1. Stemonitis, 7, 8. Stephanospermum, 272. Stephanosphæra, 48. Sterculia, 422. Sterculiaceæ, 422. Stereocaulon, 143. Stereum, 162. Sterigmata, 144, 146. Sterilization, 32. Sticta, 134, 137, 143. Stictidaceæ, 133. Stictidales, 133. Stictis, 133. Stigeoclonium, 54. Stigma, 3, 250. Stigmaria, 233. Stigonema, 26, 142. Stilbaceæ, 532, 541. Stilbe, 541. Stillingia, 434. Stilophora, 71. Stilophoraceæ, 71. Stinkbrand, 113. Stink-horn, 172, 173. Stipa, 291, 294, 296. Stitchwort, 366. St. John’s-wort, 413. Stock, 402, 405. Stonebrand, 113. Stonecrop, 451. Stone-wort, 1, 14. Stork’s-bill, 419. Stratiotes, 282. Strawberry, 458. Strawberry-tree, 508. Strelitzia, 325. Streptocarpus, 528. Streptochæta, 290. Streptococcus, 39. Streptopus, 314. Striaria, 70. Striariaceæ, 70. Strickeria, 129, 130. Stroma, 88. Stromanthe, 327. Strophanthus, 544. Struthiopteris, 209, 214, 254. Struvea, 9, 62. Strychnine, 546. Strychnos, 546. Sturmia, 332. Stylar-column, 328. -brush, 567. Style, 250. Stylidiaceæ, 564. Stylidium, 564. Stylochrysalis, 15. Stylopod, 492. Styphelia, 509. Styracaceæ, 511. Styrax, 511. Styrax-balsam, 455. Subhymenial layer, 167. Subularia, 393, 399, 400, 401. Succisa, 517. Sugar-beet, 372. Sugar-cane, 289, 293, 296. Sugar-root, 498. Sulphur-bacteria, 37, 38. Sumach, 439. Summer-spores, 147. Sundew, 407. Sun-flower, 572. Sunn hemp, 473. “Surface yeast,” 178. Surirayeæ, 21. Suspensor, 233, 246, 247. Swamp cypress, 267. Swarmspores, 10, 87. Swede, 405. Sweet Cicely, 498. Sweet-flag, 303. Sweet-gale, 351. Sweet oil, 547. Sweet-pea, 470. Sweet-potato, 517. Sweet-vernal, 295, 296. Swertia, 542. Swietenia, 436. Swine’s-succory, 571. Sycamore, 133, 442. Symbiosis, 85. Sympetalæ, 336, 504. Symphoricarpus, 554, 556. Symphyandra, 562. Symphyllodium, 257. Symphytopleura, 387. Symphytum, 533, 535. Symploca, 24. Synalissa, 139. Synandrium, 306. Synangium, 212. Syncarp, 278. Syncephalis, 100. Synchytrieæ, 103. Synchytrium, 103. Syncrypta, 15. Synedra, 21. Synergidæ, 248. Syngeneticæ, 1, 14, 15, 17, 48. Syngonium, 306. Synura, 15. Syringa, 455, 546, 547, 550. Systegium, 196. Systematic division of the Algæ, 14. of Filices, 210. of Fungi, 95. of Monocotyledons, 277. of Thallophytes, 4. of Vascular Cryptogams, 204. Tabellaria, 19. Tabellarieæ, 21. Tabernæmontana, 544. Taccarum, 306. Tacona, 284. Tagetes, 564, 572. Takamahaka, 438. Talinum, 373. Talipot, 298. Tallow-tree, 434. Tamaricaceæ, 411. Tamarind, 466, 468. Tamarindus, 467. Tamarisk, 411. Tamarix, 411, 412. Tamus, 323. Tanacetum, 572, 574. Tanghinia, 544. Tannin, 490. Tansy, 572. Tapetum, 203, 239, 240. Taphrina, 116, 117, 118. Taphrinaceæ, 116. Tapioca, 434. Tar, 266. Taraxacum, 571, 566, 574. Targionia, 191. Tassel Pond-weed, 279. Taxaceæ, 259, 272. Taxeæ, 261. Taxodiaceæ, 257, 267, 272. Taxodium, 267. Taxoideæ, 258, 259. Taxus, 237, 238, 255, 257, 259, 261, 262, 272. Tea, 415. Tea-plant, False, 521. Tea-rose, 460. Teak-tree, 535. Tear-Fungus, 166. Teasel, 494, 558, 560. Tecoma, 529. Tectona, 535. Teesdalia, 398, 401. Telegraph-plant, 466. Teleutospores, 146. Tellima, 452. Terebinthinæ, 435. Terfezia, 124. Terminalia, 487. Ternstrœmiaceæ, 414. Testa, 247, 248. Testudinaria, 323. Tetmemorus, 44. Tetracyclicæ, 505, 514. Tetradynamia, 398. Tetragonia, 375. Tetragonolobus, 471. Tetraphis, 195, 196, 197. Tetrapoma, 400. Tetrapteris, 442. Tetraspora, 51. Tetrasporaceæ, 47, 48, 51. Tetraspores, 10, 76. Teucrium, 567. Thalassia, 283. Thalia, 327. Thalictrum, 379, 385. Thallophyta, 1, 4. Thallus, 1, 4. Thamnidiaceæ, 99. Thamnidium, 100. Thea, 414, 415. Thecaphora, 110, 114. Thëin, 374. Thelebolaceæ, 109. Thelebolus, 109, 120. Thelephora, 162, 176. Thelephoraceæ, 162. Thelygonum, 372. Thelypodieæ, 404. Theobroma, 422, 423. Theobromine, 423. Theophrasta, 513. Thesium, 500. Thistle, 569. Thladiantha, 481. Thlaspi, 400, 401, 402. Thomasia, 422. Thorn-apple, 520. Thottea, 499. Thrift, 514. Thrinax, 300. Thrush, 180. Thuidium, 197. Thuja, 241, 268. Thujopsis, 269. Thunbergia, 530. Thyme, 539, 541. Thymelæa, 449. Thymelæaceæ, 449. Thymelæinæ, 448. Thymus, 537, 539, 541. Tiaridium, 533. Tibouchina, 484. Ticorea, 437. Tigridia, 321. Tilia, 424, 425. Tiliaceæ, 423. Tillandsia, 320. Tilletia, 111, 112, 113. Tilletiaceæ, 110, 113. Tilopteridaceæ, 72. Tilopteris, 72. Timothy-grass, 294, 296. Tinnantia, 308. Tmesipteris, 228. Toad-flax, 525. Toad-rush, 284. Toadstools, 159, 166. Tobacco, 520, 529. Virginian, 522. Toddalieæ, 437. Todea, 203. Tofieldia, 310. Tofieldieæ, 310. Tolu, Balsam of, 473. Toluifera, 473. Tolypella, 67. Tolypellopsis, 67. Tolyposporium, 110. Tolypothrix, 26. Tomato, 521. Tomentella, 161. Tomentellaceæ, 161. Tonquin-bean, 466, 472. Tooth-wort, 526. Tordylium, 496. Torenia, 525. Torilis, 497. Torreya, 262, 272. Touchwood, 164. Tournefortia, 533. Trabeculæ, 231. Tracheides, 251. Trachylobium, 468. Tradescantia, 308. Trama, 167, 174. Trametes, 164, 165. Tragacanth, Gum, 473. Tragopogon, 113, 564, 571, 574. Trapa, 485, 486. Travellers’ Palm, 325. Tremandraceæ, 442. Tremella, 156, 157, 159. Tremellaceæ, 146, 156. Trentepohlia, 8, 54. Tribulus, 438. Trichia, 8. Trichocoma, 176. Trichodesmium, 22. Trichogyne, 58, 81. Tricholoma, 168, 171. Trichomanes, 206, 215. Trichophilus, 8, 54. Trichosanthes, 481. Trichosphæria, 129, 130. Trichosphæriaceæ, 129. Trichostomum, 196. Tricoccæ, 430. Tricyrtis, 310. Trientalis, 512, 513. Trifolieæ, 471. Trifolium, 469, 471, 473. Triglochin, 278, 279. Trigoniaceæ, 442. Trillium, 314. Triodia, 294. Triphasia, 438. Triphragmium, 147, 151. Triplaris, 361. Triteleia, 312. Triticum, 288, 295, 296. Tritonia, 321. Triumfetta, 424, 425. Trollius, 379, 381. Tropæolaceæ, 419. Tropæolum, 420. True Ferns, 204, 205. True Laurels, 391. True Mosses, 192. Truffles, 124. Trumpet-tree, 356. Trumpet-wood, 529. Tryblidiaceæ, 133. Tryblidiales, 133. Tryblidium, 133. Tsuga, 265, 266. Tuber, 124. Tuberaceæ, 124. Tubercles, 8, 466. Tubercularia, 127. Tuberose, 318. Tubifloræ, 505, 514, 532. Tuburcinia, 110, 111, 113. Tulip, 312. Tulipa, 312, 314. Tulipeæ, 312. Tupa, 563. Turkish-millet, 296. Turmeric, 326. Turneraceæ, 476. Turnip, 405. Turpentine, 266, 439. Turritinæ, 404. Tussilago, 151, 569, 571, 574. Tydæa, 528. Tylostoma, 174. Tylostomaceæ, 174. Typha, 302, 303. Typhaceæ, 302. Typhula, 161. Ulex, 472. Ullucus, 371, 372. Ulmaceæ, 351. Ulmeæ, 351. Ulmus, 351. Ulothricaceæ, 47, 53. Ulothrix, 12, 14, 53, 54. Ulva, 10, 53. Ulvaceæ, 47, 53. Umbelliferæ, 491. Umbellifloræ, 490. Umbilicaria, 143. Umbilicus, 451. Uncaria, 553. Uncinia, 287. Uncinula, 122. Upas-tree, 356. Urare, 546. Uredinaceæ, 145, 146. Uredo, 148. Urena, 428. Ureneæ, 428. Urginea, 312, 314. Urocystis, 113. Uroglena, 15. Uromyces, 148, 151. Urophlyctis, 103. Urospora, 58. Urtica, 134, 151, 351, 353. Urticaceæ, 352. Urticifloræ, 351. Usnea, 143. Ustilaginaceæ, 110, 113. Ustilagineæ, 109. Ustilago, 111, 113. Ustulina, 131. Utricularia, 527, 528. Utriculariaceæ, 518, 527. Utriculus, 287. Uvularia, 310. Vaccines, 41. Vacciniaceæ, 451, 508, 509. Vaccinium, 134, 160, 161, 509, 510. Vaginula, 189. Vahea, 544. Vaillantia, 552. Valeriana, 557, 558. Valerianaceæ, 549, 556. Valerianella, 557, 558. Vallisneria, 282, 283. Valloons, 348. Vallota, 318. Valonia, 59, 62. Valoniaceæ, 47, 62. Valsa, 130. Valsaceæ, 130. Vanda, 332. Vandellia, 525. Vandeæ, 332. Vanilla, 331, 333. Vascular Cryptogams, 2, 198, 240. Isosporous, 200. Heterosporous, 200. Vateria, 415. Vaucheria, 10, 33, 61. Vaucheriaceæ, 47, 60. Vegetable-ivory, 301, 302. Vegetable-silk, 545. Velamen, 332. Vella, 400. Vellinæ, 404. Vellosia, 318. Vellosieæ, 318. Ve11theimia, 312. Velum partiale, 167, 168. universale, 167. Venter, 184. Ventral-canal-cell, 185. Venturia, 130. Veratreæ, 310. Veratrin, 311. Veratrum, 310, 311. Verbascum, 523, 525, 527. Verbena, 535. Verbenaceæ, 532, 535, 537. Vernonia, 571. Veronica, 335, 523, 525, 526, 527, 530, 536, 559. Verpa, 136. Verrucaria, 140, 142. Vesicaria, 400. Vetch, 470. Vibriones, 27. Viburnum, 455, 553, 555, 556. Vicia, 469, 470, 473. Vicieæ, 469, 470. Victoria, 386, 387. Vigna, 471. Vinca, 544. Vincetoxicum, 155, 546. Vine, 121, 444. Vinegar-bacterium, 31, 32, 35. Viola, 410, 411. Violaceæ, 410. Violets, 114, 410. Violet-stone, 54. Viper’s-bugloss, 533. Virginian-creeper, 447. Viscaria, 364, 367. Viscoideæ, 501. Viscum, 501, 502, 504. Vismia, 414. Vitex, 535. Vitis, 445, 446, 447. Vochysiaceæ, 442. Volkmannia, 225. Volva, 167. Volvaria, 171. Volvocaceæ, 14, 47, 48. Volvox, 48, 50. Vomic nut, 546. “Vorblatt,” 275. Wahlenbergia, 562. Wallflower, 402, 405. Wall-lichen, 143. Wall-rue, 213. Walnut, 165, 349, 350. Water-cress, 402, 405. Water-dropwort, 498. Water-ferns, 205, 215. Water-fungi, 96. Water-hyssop, 525. Water-lilies, 385. Water-melon, 481. Water-milfoil, 486. Water-net, 52. Water-purslane, 483. Water-soldier, 282. Water-wort, 413. Water-violet, 512. Wax-flower, 546. Weberia, 197. Weigelia, 554. Weingærtneria, 294. Weisia, 196. Weisiaceæ, 196. Wellingtonia, 267. Welwitschia, 270, 271. “Wendungszellen,” 67. West-Indian arrowroot, 327. Weymouth Pine, 266, 267. Wheat, 113, 291, 292, 295, 296. Wheat-grain, 292. Wheat, seedling of, 292. White-beam, 465. White Bryony, 481. White-cabbage, 405. White-mustard, 405. White Pine, 266. White-pepper, 363. White-rot, 164, 165. White Water-lily, 387. Whitlavia, 515. Whortleberry, 509. Wig-tree, 439. Wild Basil, 540. Wild Cabbage, 404. Willow, 124, 133, 338. Willow-herb, 484. Winter-aconite, 382. Winter-cherry, 521. Winter-cress, 402. Winter-green, 507. Winter-spores, 146. Wistaria, 470, 473. Witches’-brooms, 85, 117, 155. Woad, 403, 405. Wolffia, 307. Wood, 251. Wood-rush, 284. Wood-sorrel, 416. Woodruff, 552, 553. Woodsia, 214. Wormwood, 572, 574. Woundwort, 538. Xanthellaceæ, 15. Xanthidium, 44. Xanthium, 569, 573. Xanthorhiza, 379, 383. Xanthorrhæa, 312. Xeranthemum, 566, 570. Xerotes, 312. Xylaria, 131. Xylariaceæ, 131. Xylem, 251. Xylopia, 388. Xylophylla, 431, 432. Xylosteum, 554. Xyridaceæ, 308. Yam, 323. Yeast-formation, 94. Yeast-fungi, 31, 36. Yellow bird’s-nest, 507. Yellow-rattle, 525, 526. Yellow Water-lily, 387. Yellow-wort, 543. Yew, 259, 261, 266. Ylang-ylang, 388. Yorkshire-fog, 294, 296. Yucca, 312, 313, 316. Zamia, 253. Zannardinia, 12, 72. Zannichellia, 278, 279. Zantedeschia, 305, 306. Zanthoxyleæ, 436. Zanthoxylum, 436. Zea, 290, 293. Zelkova, 351. Zingiber, 326. Zingiberaceæ, 277, 323, 325. Zinnia, 572. Zizania, 293. Zizyphus, 448. Zoochlorella, 9. Zoogametes, 12. Zooglœa, 27. Zoogonicæ, 68, 70. Zoosporangia, 10. Zoospores, 10, 87. Zooxantella, 9. Zostera, 279, 280, 306, 316. Zostereæ, 278. Zygadenus, 310. Zygochytriaceæ, 103. Zygomorphy, 277. Zygomycetes, 95, 96. Zygophyllaceæ, 438. Zygophyllum, 438. Zygospore, 12. Zygote, 12. Zygnema, 44, 45. Zygnemaceæ, 44. Butler & Tanner, The Selwood Printing Works, Frome, and London. FOOTNOTES: [1] See Angiospermæ. [2] According to the recent investigations of Winogradsky some micro-organisms (Nitrifying-bacteria) can build organic from inorganic matter. Sachs’ hypothesis that the first organisms must necessarily have contained chlorophyll is therefore untenable. [3] Myxogasteres, Engler’s Syllabus, p. 1. [4] Acrasieæ and Plasmodiophorales, _ibid._ [5] Myxophyceæ, Cyanophyceæ. [6] The Bacteria are more usually included under Fungi. It seems better, however, to place them under the Algæ in a separate class with the Schizophyceæ. [7] See Marshall Ward, “On the Characters or Marks employed for Classifying the Schizomycetes,” _Annals of Botany_, 1892. [8] According to Hansen these are not disease forms, but occur regularly under certain conditions, _e.g._ temperature. [9] Before fertilisation the oosphere divides and cuts off at the base one or more cells (polar bodies?), termed “wendungszellen.” [10] From the Greek μὐκης = Fungus, hence “mycology.” [11] This term is adopted as a translation of the German “anlage.” [12] Also termed Water-Fungi (Wasserpilzen). [13] Antheridium is preferred in this sub-class as keeping a more uniform term (Kn). [14] In the _resupinate_ fruit-bodies a fertile and sterile surface cannot be distinguished (_cf._ Polyporaceæ and some _Stereum_-species). [15] The two last genera are identical, the Algal part being a _Scytonema_, that of _Cora_ a _Chroococcus_; while the same Fungus--a _Thelephora_--takes part in the formation of all three (A. Möller, Flora, 1893). [16] Formerly termed _oophyte_. [17] The oospore divides by a wall transverse or oblique to the longer axis of the archegonium. From the upper (epibasal) cell, the capsule (and seta) is derived, while the lower (hypobasal) gives rise to the _foot_. In _Riccia_ the hypobasal half takes part in the formation of the sporangium. [18] In the Polypodiaceæ unisexual prothallia as distinct as those of _Equisetum_ are of common occurrence. [19] The position of the annulus varies in the different orders; longitudinal in Polypodiaceæ, Hymenophyllaceæ, and Cyatheaceæ; transverse in Schizæaceæ, Gleicheniaceæ; indistinct or apical in Osmundaceæ, Ophioglossaceæ, Marattiaceæ, Salviniaceæ, Marsiliaceæ. [20] The former genus _Pteris_ is divided into _Pteris_ and _Pteridium_. [21] Floral-leaves (hypsophyllary leaves) are here adopted as an equivalent of the term “Hochblätter,” to signify leaves on the floral-shoot other than foliage or sporangia-bearing leaves. The term _bract_ is applied only to leaves in whose axil a flower is borne, and _bracteoles_ to leaves borne on the flower-stalk (_pedicel_). [22] It may be here remarked that another explanation is possible, based on the study of the development (_K_). [23] Piperaceæ, Nymphæaceæ. [24] “Fore-leaf” is adopted as a translation of “Vorblatt.” [25] Regarding these and other abbreviations see the appendix in the book. [26] Syncarp = cluster of fruits belonging to one flower. [27] “Fan” and “sickle” are adopted as terms for these inflorescences from the German “_fæchel_” and “_sichel_.” [28] [Although unbranched stems are characteristic of the Palms, yet branched specimens are recorded from some eleven genera. The branches are developed from lateral buds, which in many instances only develope when the terminal bud has been destroyed. A few Palms develope axillary branches at the base of the stem; these form rhizomes, and give rise to clusters of aerial stems.] [29] The aggregation of the fruits of several distinct flowers into one mass. [30] According to Pfitzer, the column is the prolongation of the floral axis beyond the insertion of the perianth, and is not formed by the coalescence of sporophylls (filament and style). [31] _Cypripedilum_ = _Cypripedium_. [32] _Corallorhiza_ = _Coralliorrhiza_. [33] This is Eichler’s view.--According to Drude the perianth is absent; at the base of the bracts, a nectary or cup-like disc. Prantl holds the same view. According to Pax the perianth is absent, but there is a disc cup-like, or reduced to a single toothed scale. [34] The fruit of the Walnut is thus a false fruit; and the term drupe must therefore not be used in the same sense as in the Rosaceæ. [35] The pollen-tube in _Ulmus_ does not enter the ovule through the micropyle. [36] According to Prantl, some species of _Trollius_ (_T. europæus_, and _asiatiacus_) have a perianth, differentiated into calyx and corolla, which does not pass over into the honey-leaves. The outer leaves of the perianth have frequently an incised apex, the intermediate ones sometimes present transitional forms to the inner, and sometimes there is a distinct boundary between them. [37] If we suppose a spiral line drawn through the leaves _upwards_ on a stem with scattered leaves (in the shortest way), then the side of the leaf first touched is the catodic, or descending, and the other the anodic, or ascending side. [38] Those marked [+] are officinal, and when no home is stated, the plant is a native. [39] Those which are officinal are indicated by [+]. [40] Those marked with a [+] are officinal. [41] For further reference see Sachs, _History of Botany_; Lindley, _Vegetable Kingdom_; Le Maout and Decaisne, _General System of Botany_, etc. Transcriber’s Notes: 1. Obvious printers’, punctuation and spelling errors have been corrected silently. 2. Where hyphenation is in doubt, it has been retained as in the original. 3. Some hyphenated and non-hyphenated versions of the same words have been retained as in the original. 4. Superscripts are represented using the caret character, e.g. D^r. or X^{xx}. Subscripts are shown as _{1}. 5. Italics are shown as _xxx_. 6. Smaller font is shown as ~xxx~. 7. Bold print is shown as =xxx=. 8. The corrigenda have been corrected. *** END OF THE PROJECT GUTENBERG EBOOK A HANDBOOK OF SYSTEMATIC BOTANY *** Updated editions will replace the previous one—the old editions will be renamed. Creating the works from print editions not protected by U.S. copyright law means that no one owns a United States copyright in these works, so the Foundation (and you!) can copy and distribute it in the United States without permission and without paying copyright royalties. Special rules, set forth in the General Terms of Use part of this license, apply to copying and distributing Project Gutenberg™ electronic works to protect the PROJECT GUTENBERG™ concept and trademark. Project Gutenberg is a registered trademark, and may not be used if you charge for an eBook, except by following the terms of the trademark license, including paying royalties for use of the Project Gutenberg trademark. If you do not charge anything for copies of this eBook, complying with the trademark license is very easy. You may use this eBook for nearly any purpose such as creation of derivative works, reports, performances and research. Project Gutenberg eBooks may be modified and printed and given away—you may do practically ANYTHING in the United States with eBooks not protected by U.S. copyright law. Redistribution is subject to the trademark license, especially commercial redistribution. START: FULL LICENSE THE FULL PROJECT GUTENBERG LICENSE PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK To protect the Project Gutenberg™ mission of promoting the free distribution of electronic works, by using or distributing this work (or any other work associated in any way with the phrase “Project Gutenberg”), you agree to comply with all the terms of the Full Project Gutenberg™ License available with this file or online at www.gutenberg.org/license. Section 1. General Terms of Use and Redistributing Project Gutenberg™ electronic works 1.A. By reading or using any part of this Project Gutenberg™ electronic work, you indicate that you have read, understand, agree to and accept all the terms of this license and intellectual property (trademark/copyright) agreement. If you do not agree to abide by all the terms of this agreement, you must cease using and return or destroy all copies of Project Gutenberg™ electronic works in your possession. If you paid a fee for obtaining a copy of or access to a Project Gutenberg™ electronic work and you do not agree to be bound by the terms of this agreement, you may obtain a refund from the person or entity to whom you paid the fee as set forth in paragraph 1.E.8. 1.B. “Project Gutenberg” is a registered trademark. It may only be used on or associated in any way with an electronic work by people who agree to be bound by the terms of this agreement. There are a few things that you can do with most Project Gutenberg™ electronic works even without complying with the full terms of this agreement. See paragraph 1.C below. There are a lot of things you can do with Project Gutenberg™ electronic works if you follow the terms of this agreement and help preserve free future access to Project Gutenberg™ electronic works. See paragraph 1.E below. 1.C. The Project Gutenberg Literary Archive Foundation (“the Foundation” or PGLAF), owns a compilation copyright in the collection of Project Gutenberg™ electronic works. Nearly all the individual works in the collection are in the public domain in the United States. If an individual work is unprotected by copyright law in the United States and you are located in the United States, we do not claim a right to prevent you from copying, distributing, performing, displaying or creating derivative works based on the work as long as all references to Project Gutenberg are removed. Of course, we hope that you will support the Project Gutenberg™ mission of promoting free access to electronic works by freely sharing Project Gutenberg™ works in compliance with the terms of this agreement for keeping the Project Gutenberg™ name associated with the work. You can easily comply with the terms of this agreement by keeping this work in the same format with its attached full Project Gutenberg™ License when you share it without charge with others. 1.D. The copyright laws of the place where you are located also govern what you can do with this work. Copyright laws in most countries are in a constant state of change. If you are outside the United States, check the laws of your country in addition to the terms of this agreement before downloading, copying, displaying, performing, distributing or creating derivative works based on this work or any other Project Gutenberg™ work. The Foundation makes no representations concerning the copyright status of any work in any country other than the United States. 1.E. Unless you have removed all references to Project Gutenberg: 1.E.1. The following sentence, with active links to, or other immediate access to, the full Project Gutenberg™ License must appear prominently whenever any copy of a Project Gutenberg™ work (any work on which the phrase “Project Gutenberg” appears, or with which the phrase “Project Gutenberg” is associated) is accessed, displayed, performed, viewed, copied or distributed: This eBook is for the use of anyone anywhere in the United States and most other parts of the world at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org. If you are not located in the United States, you will have to check the laws of the country where you are located before using this eBook. 1.E.2. If an individual Project Gutenberg™ electronic work is derived from texts not protected by U.S. copyright law (does not contain a notice indicating that it is posted with permission of the copyright holder), the work can be copied and distributed to anyone in the United States without paying any fees or charges. If you are redistributing or providing access to a work with the phrase “Project Gutenberg” associated with or appearing on the work, you must comply either with the requirements of paragraphs 1.E.1 through 1.E.7 or obtain permission for the use of the work and the Project Gutenberg™ trademark as set forth in paragraphs 1.E.8 or 1.E.9. 1.E.3. If an individual Project Gutenberg™ electronic work is posted with the permission of the copyright holder, your use and distribution must comply with both paragraphs 1.E.1 through 1.E.7 and any additional terms imposed by the copyright holder. Additional terms will be linked to the Project Gutenberg™ License for all works posted with the permission of the copyright holder found at the beginning of this work. 1.E.4. Do not unlink or detach or remove the full Project Gutenberg™ License terms from this work, or any files containing a part of this work or any other work associated with Project Gutenberg™. 1.E.5. Do not copy, display, perform, distribute or redistribute this electronic work, or any part of this electronic work, without prominently displaying the sentence set forth in paragraph 1.E.1 with active links or immediate access to the full terms of the Project Gutenberg™ License. 1.E.6. You may convert to and distribute this work in any binary, compressed, marked up, nonproprietary or proprietary form, including any word processing or hypertext form. However, if you provide access to or distribute copies of a Project Gutenberg™ work in a format other than “Plain Vanilla ASCII” or other format used in the official version posted on the official Project Gutenberg™ website (www.gutenberg.org), you must, at no additional cost, fee or expense to the user, provide a copy, a means of exporting a copy, or a means of obtaining a copy upon request, of the work in its original “Plain Vanilla ASCII” or other form. Any alternate format must include the full Project Gutenberg™ License as specified in paragraph 1.E.1. 1.E.7. Do not charge a fee for access to, viewing, displaying, performing, copying or distributing any Project Gutenberg™ works unless you comply with paragraph 1.E.8 or 1.E.9. 1.E.8. You may charge a reasonable fee for copies of or providing access to or distributing Project Gutenberg™ electronic works provided that: • You pay a royalty fee of 20% of the gross profits you derive from the use of Project Gutenberg™ works calculated using the method you already use to calculate your applicable taxes. The fee is owed to the owner of the Project Gutenberg™ trademark, but he has agreed to donate royalties under this paragraph to the Project Gutenberg Literary Archive Foundation. Royalty payments must be paid within 60 days following each date on which you prepare (or are legally required to prepare) your periodic tax returns. Royalty payments should be clearly marked as such and sent to the Project Gutenberg Literary Archive Foundation at the address specified in Section 4, “Information about donations to the Project Gutenberg Literary Archive Foundation.” • You provide a full refund of any money paid by a user who notifies you in writing (or by e-mail) within 30 days of receipt that s/he does not agree to the terms of the full Project Gutenberg™ License. You must require such a user to return or destroy all copies of the works possessed in a physical medium and discontinue all use of and all access to other copies of Project Gutenberg™ works. • You provide, in accordance with paragraph 1.F.3, a full refund of any money paid for a work or a replacement copy, if a defect in the electronic work is discovered and reported to you within 90 days of receipt of the work. • You comply with all other terms of this agreement for free distribution of Project Gutenberg™ works. 1.E.9. If you wish to charge a fee or distribute a Project Gutenberg™ electronic work or group of works on different terms than are set forth in this agreement, you must obtain permission in writing from the Project Gutenberg Literary Archive Foundation, the manager of the Project Gutenberg™ trademark. Contact the Foundation as set forth in Section 3 below. 1.F. 1.F.1. Project Gutenberg volunteers and employees expend considerable effort to identify, do copyright research on, transcribe and proofread works not protected by U.S. copyright law in creating the Project Gutenberg™ collection. Despite these efforts, Project Gutenberg™ electronic works, and the medium on which they may be stored, may contain “Defects,” such as, but not limited to, incomplete, inaccurate or corrupt data, transcription errors, a copyright or other intellectual property infringement, a defective or damaged disk or other medium, a computer virus, or computer codes that damage or cannot be read by your equipment. 1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right of Replacement or Refund” described in paragraph 1.F.3, the Project Gutenberg Literary Archive Foundation, the owner of the Project Gutenberg™ trademark, and any other party distributing a Project Gutenberg™ electronic work under this agreement, disclaim all liability to you for damages, costs and expenses, including legal fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH DAMAGE. 1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a defect in this electronic work within 90 days of receiving it, you can receive a refund of the money (if any) you paid for it by sending a written explanation to the person you received the work from. If you received the work on a physical medium, you must return the medium with your written explanation. The person or entity that provided you with the defective work may elect to provide a replacement copy in lieu of a refund. If you received the work electronically, the person or entity providing it to you may choose to give you a second opportunity to receive the work electronically in lieu of a refund. If the second copy is also defective, you may demand a refund in writing without further opportunities to fix the problem. 1.F.4. Except for the limited right of replacement or refund set forth in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. 1.F.5. Some states do not allow disclaimers of certain implied warranties or the exclusion or limitation of certain types of damages. If any disclaimer or limitation set forth in this agreement violates the law of the state applicable to this agreement, the agreement shall be interpreted to make the maximum disclaimer or limitation permitted by the applicable state law. The invalidity or unenforceability of any provision of this agreement shall not void the remaining provisions. 1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the trademark owner, any agent or employee of the Foundation, anyone providing copies of Project Gutenberg™ electronic works in accordance with this agreement, and any volunteers associated with the production, promotion and distribution of Project Gutenberg™ electronic works, harmless from all liability, costs and expenses, including legal fees, that arise directly or indirectly from any of the following which you do or cause to occur: (a) distribution of this or any Project Gutenberg™ work, (b) alteration, modification, or additions or deletions to any Project Gutenberg™ work, and (c) any Defect you cause. Section 2. Information about the Mission of Project Gutenberg™ Project Gutenberg™ is synonymous with the free distribution of electronic works in formats readable by the widest variety of computers including obsolete, old, middle-aged and new computers. It exists because of the efforts of hundreds of volunteers and donations from people in all walks of life. Volunteers and financial support to provide volunteers with the assistance they need are critical to reaching Project Gutenberg™’s goals and ensuring that the Project Gutenberg™ collection will remain freely available for generations to come. In 2001, the Project Gutenberg Literary Archive Foundation was created to provide a secure and permanent future for Project Gutenberg™ and future generations. To learn more about the Project Gutenberg Literary Archive Foundation and how your efforts and donations can help, see Sections 3 and 4 and the Foundation information page at www.gutenberg.org. Section 3. Information about the Project Gutenberg Literary Archive Foundation The Project Gutenberg Literary Archive Foundation is a non-profit 501(c)(3) educational corporation organized under the laws of the state of Mississippi and granted tax exempt status by the Internal Revenue Service. The Foundation’s EIN or federal tax identification number is 64-6221541. Contributions to the Project Gutenberg Literary Archive Foundation are tax deductible to the full extent permitted by U.S. federal laws and your state’s laws. The Foundation’s business office is located at 809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up to date contact information can be found at the Foundation’s website and official page at www.gutenberg.org/contact Section 4. Information about Donations to the Project Gutenberg Literary Archive Foundation Project Gutenberg™ depends upon and cannot survive without widespread public support and donations to carry out its mission of increasing the number of public domain and licensed works that can be freely distributed in machine-readable form accessible by the widest array of equipment including outdated equipment. Many small donations ($1 to $5,000) are particularly important to maintaining tax exempt status with the IRS. The Foundation is committed to complying with the laws regulating charities and charitable donations in all 50 states of the United States. Compliance requirements are not uniform and it takes a considerable effort, much paperwork and many fees to meet and keep up with these requirements. We do not solicit donations in locations where we have not received written confirmation of compliance. To SEND DONATIONS or determine the status of compliance for any particular state visit www.gutenberg.org/donate. While we cannot and do not solicit contributions from states where we have not met the solicitation requirements, we know of no prohibition against accepting unsolicited donations from donors in such states who approach us with offers to donate. International donations are gratefully accepted, but we cannot make any statements concerning tax treatment of donations received from outside the United States. U.S. laws alone swamp our small staff. Please check the Project Gutenberg web pages for current donation methods and addresses. Donations are accepted in a number of other ways including checks, online payments and credit card donations. To donate, please visit: www.gutenberg.org/donate. Section 5. General Information About Project Gutenberg™ electronic works Professor Michael S. Hart was the originator of the Project Gutenberg™ concept of a library of electronic works that could be freely shared with anyone. For forty years, he produced and distributed Project Gutenberg™ eBooks with only a loose network of volunteer support. Project Gutenberg™ eBooks are often created from several printed editions, all of which are confirmed as not protected by copyright in the U.S. unless a copyright notice is included. Thus, we do not necessarily keep eBooks in compliance with any particular paper edition. Most people start at our website which has the main PG search facility: www.gutenberg.org. This website includes information about Project Gutenberg™, including how to make donations to the Project Gutenberg Literary Archive Foundation, how to help produce our new eBooks, and how to subscribe to our email newsletter to hear about new eBooks.