The Project Gutenberg EBook of Studies of Trees, by Jacob Joshua Levison This eBook is for the use of anyone anywhere 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.net Title: Studies of Trees Author: Jacob Joshua Levison Release Date: June 23, 2005 [EBook #16116] Language: English Character set encoding: ISO-8859-1 *** START OF THIS PROJECT GUTENBERG EBOOK STUDIES OF TREES *** Produced by Thaadd, Ben Beasley and the Online Distributed Proofreading Team at http://www.pgdp.net [Illustration: Frontispiece. "Come forth into the light of things, Let Nature be your Teacher." --WORDSWORTH.] STUDIES OF TREES BY J.J. LEVISON, M.F. Lecturer on Ornamental and Shade Trees, Yale University Forest School; Forester to the Department of Parks, Brooklyn, N.Y. FIRST EDITION FIRST THOUSAND 1914 PREFACE In presenting this volume, the author is aware that there are several excellent books, dealing with one phase or another of tree life, already before the public. It is believed, however, that there is still need for an all-round book, adapted to the beginner, which gives in a brief and not too technical way the most important facts concerning the identification, structure and uses of our more common trees, and which considers their habits, enemies and care both when growing alone and when growing in groups or forests. In the chapters on the identification of trees, the aim has been to bring before the student only such characters and facts as shall help him to distinguish the tree readily during all seasons of the year. Special stress is laid in each case on the most striking peculiarities. Possible confusion with other trees of similar appearance is prevented as far as possible through comparisons with trees of like form or habit. Only such information is given concerning the structure and requirements of trees as will enable the reader better to understand the subsequent chapters. In the second half of the book, practical application is made of the student's general knowledge thus acquired, and he is acquainted with the fundamental principles of planting, care, forestry, wood identification and nature study. The author recognizes the vastness of the field he is attempting to cover and the impossibility of even touching, in a small hand-book of this character, on every phase of tree study. He presumes no further; yet he hopes that by adhering to what is salient and by eliminating the less important, though possibly interesting, facts, he is able to offer a general and elementary _résumé_ of the whole subject of value to students, private owners, farmers and teachers. In the preparation of Chapter VIII on "Our Common Woods: Their Identification, Properties and Uses," considerable aid has been received from Prof. Samuel J. Record, author of "Economic Woods of the United States." Acknowledgment is also due to the U.S. Forest Service for the photographs used in Figs. 18, 122 to 138 inclusive and 142; to Dr. George B. Sudworth, Dendrologist of the U.S. Forest Service, for checking up the nomenclature in the lists of trees under Chapter V; to Dr. E.P. Felt, Entomologist of the State of New York, for suggestions in the preparation of the section of the book relating to insects; to Dr. W.A. Murrill, Assistant Director of the New York Botanical Gardens, for Fig. 108; and to Mr. Hermann W. Merkel, Chief Forester of the New York Zoological Park, for Figs. 26, 59 and 60. J.J. LEVISON. BROOKLYN, N.Y. June, 1914. CONTENTS CHAPTER I HOW TO IDENTIFY TREES The Pines The Spruce and Hemlock The Red Cedar and Arbor-vitae CHAPTER II HOW TO IDENTIFY TREES (Continued) The Larch and Cypress The Horsechestnut, Ash, and Maple Trees Told by their Form Trees Told by their Bark or Trunk The Oaks and Chestnut CHAPTER III HOW TO IDENTIFY TREES (Continued) The Hickories, Walnut, and Butternut Tulip Tree, Sweet Gum, Linden, Magnolia, Locust, Catalpa, Dogwood, Mulberry, and Osage Orange CHAPTER IV THE STRUCTURE AND REQUIREMENTS OF TREES CHAPTER V WHAT TREES TO PLANT AND HOW Trees for the Lawn Trees for the Street Trees for Woodland Trees for Screening CHAPTER VI THE CARE OF TREES Insects Injurious to Trees and How to Combat Them Important Insects Tree Diseases Pruning Trees Tree Repair CHAPTER VII FORESTRY What Forestry Is and What It Does Care of the Woodland CHAPTER VIII OUR COMMON WOODS: THEIR IDENTIFICATION, PROPERTIES AND USES Woods Without Pores (Soft woods) Woods with Pores (Hard woods) CHAPTER IX AN OUTDOOR LESSON ON TREES INTRODUCTION A good many popular books on trees have been published in the United States in recent years. The continually increasing demand for books of this character indicates the growing public interest not only in the trees that we pass in our daily walks, but also in the forest considered as a community of trees, because of its aesthetic and protective value and its usefulness as a source of important economic products. As a nation, we are thinking more about trees and woods than we were wont to do in the years gone by. We are growing to love the trees and forests as we turn more and more to outdoor life for recreation and sport. In our ramblings along shady streets, through grassy parks, over wooded valleys, and in mountain wildernesses we find that much more than formerly we are asking ourselves what are these trees, what are the leaf, flower, twig, wood and habit characteristics which distinguish them from other trees; how large do they grow; under what conditions of soil and climate do they thrive best; what are their enemies and how can they be overcome; what is their value for wood and other useful products; what is their protective value; are they useful for planting along streets and in parks and in regenerating forests; how can the trees of our streets and lawns be preserved and repaired as they begin to fail from old age or other causes? All these questions and many more relating to the important native and exotic trees commonly found in the states east of the Great Lakes and north of Maryland Mr. Levison has briefly answered in this book. The author's training as a forester and his experience as a professional arboriculturist has peculiarly fitted him to speak in an authoritative and interesting way about trees and woods. The value of this book is not in new knowledge, but in the simple statement of the most important facts relating to some of our common trees, individually and collectively considered. A knowledge of trees and forests adds vastly to the pleasures of outdoor life. The more we study trees and the more intimate our knowledge of the forest as a unit of vegetation in which each tree, each flower, each animal and insect has its part to play in the complete structure, the greater will be our admiration of the wonderful beauty and variety exhibited in the trees and woods about us. J.W. TOUMEY, Director, Yale University Forest School. NEW HAVEN, CONN., June, 1914. STUDIES OF TREES CHAPTER I HOW TO IDENTIFY TREES There are many ways in which the problem of identifying trees may be approached. The majority attempt to recognize trees by their leaf characters. Leaf characters, however, do not differentiate the trees during the other half of the year when they are bare. In this chapter the characterizations are based, as far as possible, on peculiarities that are evident all year round. In almost every tree there is some one trait that marks its individuality and separates it, at a glance, from all other trees. It may be the general form of the tree, its mode of branching, bark, bud or fruit. It may be some variation in color, or, in case of the evergreen trees, it may be the number and position of the needles or leaves. The species included in the following pages have thus been arranged in groups based on these permanent characters. The individual species are further described by a distinguishing paragraph in which the main character of the tree is emphasized in heavy type. The last paragraph under each species is also important because it classifies all related species and distinguishes those that are liable to be confused with the particular tree under consideration. GROUP I. THE PINES [Illustration: FIG. 1.--Twig of the Austrian Pine.] How to tell them from other trees: The pines belong to the _coniferous_ class of trees; that is, trees which bear cones. The pines may be told from the other coniferous trees by their leaves, which are in the form of _needles_ two inches or more in length. These needles keep green throughout the entire year. This is characteristic of all coniferous trees, except the larch and cypress, which shed their leaves in winter. [Illustration: FIG. 2.--Twig of the White Pine.] The pines are widely distributed throughout the Northern Hemisphere, and include about 80 distinct species with over 600 varieties. The species enumerated here are especially common in the eastern part of the United states, growing either native in the forest or under cultivation in the parks. The pines form a very important class of timber trees, and produce beautiful effects when planted in groups in the parks. How to tell them from each other: The pine needles are arranged in _clusters_; see Fig. 1. Each species has a certain characteristic number of needles to the cluster and this fact generally provides the simplest and most direct way of distinguishing the different pines. In the white pine there are _five_ needles to each cluster, in the pitch pine _three_, and in the Scotch pine _two_. The Austrian pine also has two needles to the cluster, but the difference in size and character of the needles will distinguish this species from the Scotch pine. THE WHITE PINE (_Pinus strobus_) Distinguishing characters: The tree can be told at close range by the number of needles to each cluster, Fig. 2. There are *five* needles to each cluster of the white pine. They are bluish green, slender, and about four inches in length. At a distance the tree may be told by the *right angles* which the branches form with the main trunk, Fig. 3. No other pine shows this character. Form and size: A tall tree, the stateliest of the evergreens. Range: Eastern North America. Soil and location: Prefers a deep, sandy soil, but will grow in almost any soil. Enemies: Sucking insects forming white downy patches on the bark and twigs, the _white pine weevil_, a boring insect, and the _white pine blister rust_, a fungus, are among its principal enemies. [Illustration: FIG. 3.--The White Pine.] Value for planting: Aside from its value as an ornamental tree, the white pine is an excellent tree to plant on abandoned farms and for woodlands and windbreaks throughout the New England States, New York, Pennsylvania, and the Lake States. Commercial value: The wood is easily worked, light, durable, and will not warp. It is used for naval construction, lumber, shingles, laths, interior finish, wooden ware, etc. Other characters: The _fruit_ is a cone, four to six inches long. Comparisons: The tree is apt to be confused with the _Bhotan pine_ (_Pinus excelsa_), which is commonly grown as an ornamental tree. The Bhotan pine, however, has needles much longer and more drooping in appearance. THE PITCH PINE (_Pinus rigida_) Distinguishing characters: Here there are *three* needles to each cluster, Fig. 4. They are dark, yellowish-green needles about four inches long. The rough-looking _branches_ of the tree may be seen _studded with cones_ throughout the year, and _clusters of leaves_ may be seen _sprouting directly from the trunk_ of the tree; see Fig. 5. The last two are very characteristic and will distinguish the tree at a glance. Form and size: It is a low tree of uncertain habit and extremely rough looking at every stage of its life. It is constantly full of dead branches and old cones which persist on the tree throughout the year. Range: Eastern United States. Soil and location: Grows in the poorest and sandiest soils where few other trees will grow. In New Jersey and on Long Island where it is native, it proves so hardy and persistent that it often forms pure stands excluding other trees. [Illustration: FIG. 4.--Twig of the Pitch Pine.] Enemies: None of importance. Value for planting: Well adapted for the sea coast and other exposed places. It is of extremely uncertain habit and is subject to the loss of the lower limbs. It frequently presents a certain picturesqueness of outline, but it could not be used as a specimen tree on the lawn. [Illustration: FIG. 5.--The Pitch Pine.] Commercial value: The wood is coarse grained and is used for rough lumber, fuel, and charcoal. Other characters: The _fruit_ is a cone one to three inches long, persistent on the tree for several years. THE SCOTCH PINE (_Pinus sylvestris_) Distinguishing characters: There are *two* needles to each cluster, and these are _short_ compared with those of the white pine, and _slightly twisted_; see Fig. 6. The _bark_, especially along the upper portion of the trunk, _is reddish_ in color. Form and size: A medium-sized tree with a short crown. Range: Europe, Asia, and eastern United States. Soil and location: Will do best on a deep, rich, sandy soil, but will also grow on a dry, porous soil. Enemies: In Europe the Scotch pine has several insect enemies, but in America it appears to be free from injury. Value for planting: Suitable for windbreaks and woodland planting. Many excellent specimens may also be found in our parks. Commercial value: In the United States, the wood is chiefly used for fuel, though slightly used for barrels, boxes, and carpentry. In Europe, the Scotch pine is an important timber tree. Comparisons: The Scotch pine is apt to be confused with the _Austrian pine_ (_Pinus austriaca_), because they both have two needles to each cluster. The needles of the Austrian pine, however, are much longer, coarser, straighter, and darker than those of the Scotch pine; Fig. 1. The form of the Austrian pine, too, is more symmetrical and compact. [Illustration: FIG. 6.--Twig of the Scotch Pine.] The _red pine_ (_Pinus resinosa_) is another tree that has two needles to each cluster, but these are much longer than those of the Scotch pine (five to six inches) and are straighter. The bark, which is reddish in color, also differentiates the red pine from the Austrian pine. The position of the cones on the red pine, which point outward and downward at maturity, will also help to distinguish this tree from the Scotch and the Austrian varieties. GROUP II. THE SPRUCE AND HEMLOCK How to tell them from other trees: The spruce and hemlock belong to the evergreen class and may be told from the other trees by their _leaves_. The characteristic leaves of the spruce are shown in Fig. 9; those of the hemlock in Fig. 10. These are much shorter than the needles of the pines but are longer than the leaves of the red cedar or arbor vitae. They are neither arranged in clusters like those of the larch, nor in feathery layers like those of the cypress. They adhere to the tree throughout the year, while the leaves of the larch and cypress shed in the fall. The spruces are pyramidal-shaped trees, with tall and tapering trunks, thickly covered with branches, forming a compact crown. They are widely distributed throughout the cold and temperate regions of the northern hemisphere, where they often form thick forests over extended areas. There are eighteen recognized species of spruce. The Norway spruce has been chosen as a type for this group because it is so commonly planted in the northeastern part of the United States. The hemlock is represented by seven species, confined to temperate North America, Japan, and Central and Western China. [Illustration: FIG. 7.--The Norway Spruce.] How to tell them from each other: The needles and branches of the spruce are _coarse_; those of the hemlock are _flat and graceful_. The individual leaves of the spruce, Fig. 9, are four-sided and green or blue on the under side, while those of the hemlock, Fig. 10, are flat and are _marked by two white lines_ on the under side. THE NORWAY SPRUCE (_Picea excelsa_) Distinguishing characters: The characteristic appearance of the full-grown tree is due to the *drooping branchlets* carried on *main branches which bend upward* (Fig. 7). Leaf: The leaves are dark green in color and are _arranged spirally_, thus making the twigs coarser to the touch than the twigs of the hemlock or fir. In cross-section, the individual leaflet is quadrilateral, while that of the pine is triangular. Form and size: A large tree with a straight, undivided trunk and a well-shaped, conical crown (Fig. 7). Range: Northern Europe, Asia, northern North America. Soil and location: Grows in cool, moist situations. Enemies: The foliage of the spruce is sometimes affected by _red spider_, but is apt to be more seriously injured by drought, wind, and late frosts. Value for planting: Commonly planted as an ornamental tree and for hedges. It does well for this purpose in a cool northern climate, but in the vicinity of New York City and further south it does not do as well, losing its lower branches at an early age, and becoming generally scraggly in appearance. [Illustration: FIG. 8.--A Group of Hemlock.] Commercial value: The wood is light and soft and is used for construction timber, paper pulp, and fuel. Other characters: The _fruit_ is a large slender cone, four to seven inches long. Comparisons: The _white spruce_ (_Picea canadensis_) may be told from the Norway spruce by the whitish color on the under side of its leaves and the unpleasant, pungent odor emitted from the needles when bruised. The cones of the white spruce, about two inches long, are shorter than these of the Norway spruce, but are longer than those of the black spruce. It is essentially a northern tree growing in all sorts of locations along the streams and on rocky mountain slopes as far north as the Arctic Sea and Alaska. It often appears as an ornamental tree as far south as New York and Pennsylvania. The _black spruce_ (_Picea mariana_) may be told from the other spruces by its small cone, which is usually only about one inch in length. In New England it seldom grows to as large a size as the other spruce trees. It covers large areas in various parts of northern North America and grows to its largest size in Manitoba. The black spruce has little value as an ornamental tree. The _Colorado blue spruce_ (_Picea parryana_ or _Picea pungens_) which is commonly used as an ornamental tree on lawns and in parks, can be told from the other spruces by its pale-blue or sage-green color and its sharp-pointed, coarse-feeling twigs. Its small size and sharp-pointed conical form are also characteristic. It grows to a large size in Colorado and the Middle West. In the Eastern States and in northern Europe where it is planted as an ornamental tree, it is usually much smaller. [Illustration: FIG. 9.--Twig of the Norway Spruce.] HEMLOCK (_Tsuga canadensis_) Distinguishing characters: Its leaves are arranged in *flat layers*, giving a flat, horizontal and graceful appearance to the whole branch (Fig. 8). The individual leaves are dark green above, lighter colored below, and are *marked by two white lines on the under side* (Fig. 10). The leaves are arranged on little stalks, a characteristic that does not appear in the other evergreen trees. Form and size: A large tree with a broad-based pyramidal head, and a trunk conspicuously tapering toward the apex. The branches extend almost to the ground. Range: The hemlock is a northern tree, growing in Canada and the United States. Soil and location: Grows on all sorts of soils, in the deepest woods as well as on high mountain slopes. Enemies: None of importance. Value for planting: The hemlock makes an excellent hedge because it retains its lowest branches and will stand shearing. In this respect it is preferable to the spruce. It makes a fair tree for the lawn and is especially desirable for underplanting in woodlands, where the shade from the surrounding trees is heavy. In this respect it is like the beech. Commercial value: The wood is soft, brittle, and coarse-grained, and is therefore used mainly for coarse lumber. Its bark is so rich in tannin that it forms one of the chief commercial products of the tree. Other characters: The _fruit_ is a small cone about ¾ of an inch long, which generally hangs on the tree all winter. [Illustration: FIG. 10.--Twig of the Hemlock.] GROUP III. THE RED CEDAR AND ARBOR-VITAE How to tell them from other trees: The red cedar (juniper) and arbor-vitae may be told from other trees by their _leaves_, which remain on the tree and keep green throughout the entire year. These leaves differ from those of the other evergreens in being much shorter and of a distinctive shape as shown in Figs. 12 and 13. The trees themselves are much smaller than the other evergreens enumerated in this book. Altogether, there are thirty-five species of juniper recognized and four of arbor-vitae. The junipers are widely distributed over the northern hemisphere, from the Arctic region down to Mexico in the New World, and in northern Africa, China, and Japan in the Old World. The arbor-vitae is found in northeastern and northwestern America, China, and Japan. The species mentioned here are those commonly found in America. How to tell them from each other: The _twigs_ of the arbor-vitae are _flat and fan-like_ as in Fig. 13; the twigs of the red cedar are _needle-shaped or scale-like_ as in Fig. 12. The foliage of the arbor-vitae is of a lighter color than that of the red cedar, which is sombre green. The arbor-vitae will generally be found growing in moist locations, while the red cedar will grow in dry places as well. The arbor-vitae generally retains its lower branches in open places, while the branches of the red cedar start at some distance from the ground. RED CEDAR (_Juniperus virginiana_) [Illustration: FIG. 11.--The Red Cedar.] Distinguishing characters: The tree can best be told at a glance by its general form, size and leaves. It is a medium-sized tree with a _symmetrical, cone-like form_, Fig. 11, which, however, broadens out somewhat when the tree grows old. Its color throughout the year is dull green with a tinge of brownish red, and its bark peels in thin strips. [Illustration: FIG. 12(a).--Twig of Young Cedar. FIG. 12(b).--Twig of Cedar (Older Tree).] Leaf: In young trees the leaf is needle-shaped, pointed, and marked by a white line on its under side, Fig. 12(a). In older trees it is scale-like, Fig. 12(b), and the white line on its under side is indistinct. Range: Widely distributed over nearly all of eastern and central North America. Soil and location: Grows on poor, gravelly soils as well as in rich bottom lands. Enemies: The "_cedar apple_," commonly found on this tree, represents a stage of the apple rust, and for that reason it is not desirable to plant such trees near orchards. Its wood is also sometimes attacked by small _boring insects_. Value for planting: Its characteristic slender form gives the red cedar an important place as an ornamental tree, but its chief value lies in its commercial use. Commercial value: The wood is durable, light, smooth and fragrant, and is therefore used for making lead-pencils, cabinets, boxes, moth-proof chests, shingles, posts, and telegraph poles. Other characters: The _fruit_ is small, round and berry-like, about the size of a pea, of dark blue color, and carries from one to four bony seeds. Other common names: The red cedar is also often called _juniper_ and _red juniper_. Comparisons: The red cedar is apt to be confused with the _low juniper_ (_Juniperus communis_) which grows in open fields all over the world. The latter, however, is generally of a low form with a flat top. Its leaves are pointed and prickly, never scale-like, and they are whitish above and green below. Its bark shreds and its fruit is a small round berry of agreeable aromatic odor. ARBOR-VITAE; NORTHERN WHITE CEDAR (_Thuja occidentalis_) Distinguishing characters: The *branchlets* are extremely *flat and fan-like*, Fig. 13, and have an agreeable _aromatic odor_ when bruised. The tree is an evergreen with a _narrow conical form_. [Illustration: FIG. 13.--Twig of the Arbor-vitae.] Leaf: Leaves of two kinds, one scale-like and flat, the other keeled, all tightly pressed to the twig (see Fig. 13). Form and size: A close, conical head with dense foliage near the base. Usually a small tree, but in some parts of the northeastern States it grows to medium size with a diameter of two feet. Range: Northern part of North America. Soil and location: Inhabits low, swampy lands; in the State of Maine often forming thick forests. Enemies: Very seldom affected by insects. Value for planting: Is hardy in New England, where it is especially used for hedges. It is also frequently used as a specimen tree on the lawn. Commercial value: The wood is durable for posts, ties, and shingles. The bark contains considerable tannin and the juices from the tree have a medicinal value. Other characters: The _fruit_ is a cone about ½ inch long. Other common names: Arbor-vitae is sometimes called _white cedar_ and _cedar_. Comparisons: The arbor-vitae is apt to be confused with the true _white cedar_ (_Chamaecyparis thyoides_) but the leaves of the latter are sharp-pointed and not flattened or fan-shaped. CHAPTER II HOW TO IDENTIFY TREES--(Continued) GROUP IV. THE LARCH AND CYPRESS How to tell them from other trees: In summer the larch and cypress may easily be told from other trees by their _leaves_. These are needle-shaped and arranged in clusters with numerous leaves to each cluster in the case of the larch, and feathery and flat in the case of the cypress. In winter, when their leaves have dropped off, the trees can be told by their cones, which adhere to the branches. There are nine recognized species of larch and two of bald cypress. The larch is characteristically a northern tree, growing in the northern and mountainous regions of the northern hemisphere from the Arctic circle to Pennsylvania in the New World, and in Central Europe, Asia, and Japan in the Old World. It forms large forests in the Alps of Switzerland and France. The European larch and not the American is the principal species considered here, because it is being planted extensively in this country and in most respects is preferable to the American species. The bald cypress is a southern tree of ancient origin, the well-known cypress of Montezuma in the gardens of Chepultepec having been a species of Taxodium. The tree is now confined to the swamps and river banks of the South Atlantic and Gulf States, where it often forms extensive forests to the exclusion of all other trees. In those regions along the river swamps, the trees are often submerged for several months of the year. How to tell them from each other: In summer the larch may be told from the cypress by its leaves (compare Figs. 14 and 16). In winter the two can be distinguished by their characteristic forms. The larch is a broader tree as compared with the cypress and its form is more conical. The cypress is more slender and it is taller. The two have been grouped together in this study because they are both coniferous trees and, unlike the other Conifers, are both deciduous, their leaves falling in October. [Illustration: FIG. 14.--Twig of the Larch in Summer.] THE EUROPEAN LARCH (_Larix europaea_) Distinguishing characters: Its leaves, which are needle-shaped and about an inch long, are borne in *clusters* close to the twig, Fig. 14. There are many leaves to each cluster. This characteristic together with the *spire-like* form of the crown will distinguish the tree at a glance. Leaf: The leaves are of a light-green color but become darker in the spring and in October turn yellow and drop off. The cypress, which is described below, is another cone-bearing tree which sheds its leaves in winter. [Illustration: FIG. 15.--Twig of the Larch in Winter.] Form and size: A medium-sized tree with a conical head and a straight and tapering trunk. (See Fig. 90.) Range: Central Europe and eastern and central United States. Soil and location: Requires a deep, fresh, well-drained soil and needs plenty of light. It flourishes in places where our native species would die. Grows very rapidly. Enemies: The larch is subject to the attacks of a _sawfly_, which has killed many trees of the American species. A _fungus_ (_Trametes pini_) which causes the tree to break down with ease is another of its enemies. Value for planting: A well-formed tree for the lawn. It is also useful for group planting in the forest. Commercial value: Because its wood is strong and durable the larch is valuable for poles, posts, railroad ties, and in shipbuilding. [Illustration: FIG. 16.--Twig of the Cypress.] Other characters: The _fruit_ is a small cone about one inch long, adhering to the tree throughout the winter. [Illustration: FIG. 17.--The Bald Cypress.] Comparisons: The tree is apt to be confused with the _American larch_, also known as _tamarack_ and _hackmatack_, but differs from it in having longer leaves, cones twice as large and more abundant and branches which are more pendulous. The larch differs from the bald cypress in the broader form of its crown and the cluster-like arrangement of its leaves. The twigs of the bald cypress are flat and feathery. The larch and bald cypress have the common characteristics of both shedding their leaves in winter and preferring to grow in moist or swampy soils. The larch, especially the native species, forms the well-known tamarack swamps of the north. The bald cypress grows in a similar way in groups in the southern swamps. BALD CYPRESS (_Taxodium distichum_) Distinguishing characters: The *feathery character* of the *twigs*, Fig. 16, and the *spire-like form* of the tree, Fig. 17, which is taller and more slender than the larch, will distinguish this species from others. [Illustration: FIG. 18.--Cypress "Knees."] Leaf: The leaves drop off in October, though the tree is of the cone-bearing kind. In this respect it is like the larch. Form and size: Tall and pyramidal. Range: The cypress is a southern tree, but is found under cultivation in parks and on lawns in northern United States. Soil and location: Grows naturally in swamps, but will also do well in ordinary well-drained, good soil. In its natural habitat it sends out special roots above water. These are known as "_cypress knees_" (Fig. 18) and serve to provide air to the submerged roots of the tree. Enemies: None of importance. Value for planting: An excellent tree for park and lawn planting. Commercial value: The wood is light, soft, and easily worked. It is used for general construction, interior finish, railroad ties, posts and cooperage. Other characters: The _bark_ is thin and scaly. The _fruit_ is a cone about an inch in diameter. The general _color_ of the tree is a dull, deep green which, however, turns orange brown in the fall. Comparisons: The cypress and the larch are apt to be confused, especially in the winter, when the leaves of both have dropped. The cypress is more slender and is taller in form. The leaves of each are very different, as will be seen from the accompanying illustrations. GROUP V. THE HORSECHESTNUT, ASH AND MAPLE How to tell them from other trees: The horsechestnut, ash, and maple have their branches and buds arranged on their stems *opposite* each other as shown in Figs. 20, 22 and 24. In other trees, this arrangement is *alternate*, as shown in Fig. 19. How to tell these three from each other. If the bud is large--an inch to an inch and a half long--dark brown, and _sticky_, it is a _horsechestnut_. If the bud is _not sticky_, much smaller, and _rusty brown to black_ in color, and the ultimate twigs, of an olive green color, are _flattened_ at points below the buds, it is an _ash_. [Illustration: FIG. 19.--Alternate Branching (Beech.)] If it is not a horsechestnut nor an ash and its small buds have many scales covering them, the specimen with branches and buds opposite must then be a _maple_. Each of the maples has one character which distinguishes it from all the other maples. For the sugar maple, this distinguishing character is the _sharp point of the bud_. For the silver maple it is the _bend in the terminal twig_. For the red maple it is the _smooth gray-colored bark_. For the Norway maple it is the _reddish brown color of the full, round bud_, and for the box elder it is the _greenish color of its terminal twig_. The form of the tree and the leaves are also characteristic in each of the maples, but for the beginner who does not wish to be burdened with too many of these facts at one time, those just enumerated will be found most certain and most easily followed. [Illustration: FIG. 20.--Opposite Branching (Horsechestnut.)] THE HORSECHESTNUT (_Aesculus hippocastanum_) Distinguishing characters: The *sticky* nature of the *terminal bud* and its *large size* (about an inch long). The bud is dark brown in color. See Fig. 20. Leaf: Five to seven leaflets, usually seven. Fig. 21. Form and size: Medium-sized tree, pyramidal head and coarse twigs. Range: Europe and eastern United States. Soil and location: Prefers a deep, rich soil. Enemies: The leaves are the favorite food of caterpillars and are subject to a blight which turns them brown prematurely. The trunk is often attacked by a disease which causes the flow of a slimy substance. Value for planting: On account of its showy flowers, the horsechestnut is a favorite for the park and lawn. Commercial value: The wood is not durable and is not used commercially. Other characters: The _flowers_ appear in large white clusters in May and June. The _fruit_ is large, round, and prickly. [Illustration: FIG. 21.--Leaf of the Horsechestnut.] Comparisons: The _red horsechestnut_ differs from this tree in having red flowers. The _buckeye_ is similar to the horsechestnut, but its bud is not sticky and is of a lighter gray color, while the leaf generally has only five leaflets. THE WHITE ASH (_Fraxinus americana_) Distinguishing characters: The terminal *twigs* of glossy olive green color are *flattened* below the bud. Fig. 22. The bud is rusty-brown. [Illustration: FIG. 22.--Twig of White Ash.] Leaf: Five to nine leaflets. Fig. 23. Form and size: A large tree with a straight trunk. Range: Eastern North America. Soil and location: Rich, moist soil. Enemies: In cities it is very often attacked by sucking insects. Value for planting: The white ash grows rapidly. On account of its insect enemies in cities, it should be used more for forest planting and only occasionally for ornament. Commercial value: It has a heavy, tough, and strong wood, which is valuable in the manufacture of cooperage stock, agricultural implements, and carriages. It is superior in value to the black ash. Other characters: The _bark_ is gray. The _flowers_ appear in May. Comparisons: The white ash is apt to be confused with the _black ash_ (_Fraxinus nigra_), but differs from the latter in having a lighter-colored bud. The bud of the black ash is black. The bark of the white ash is darker in color and the terminal twigs are more flattened than those of the black ash. [Illustration: FIG. 23.--Leaf of White Ash.] SUGAR MAPLE (_Acer saccharum_) Distinguishing characters: The *bud is sharp-pointed*, scaly, and reddish brown. Fig. 24. [Illustration: FIG. 24.--Twig of the Sugar Maple.] Leaf: Has sharp points and round sinus. Fig. 25. Form and size: The crown is oval when the tree is young and round in old age. Fig. 26. Range: Eastern United States. Soil and location: Moist and deep soil, and cool, shady positions. Enemies: Subject to drouth, especially in cities. Is attacked by the _sugar maple borer_ and the _maple phenacoccus_, a sucking insect. Value for planting: Its rich and yellow color in the fall, and the fine spread of its crown make it a desirable tree for the lawn, especially in the country. Commercial value: Its wood is hard and takes a good polish; used for interior finish and furniture. The tree is also the source of maple sugar. Fig. 27. Other characters: The _bark_ is smooth in young trees and in old trees it shags in large plates. The _flowers_ appear in the early part of April. Other common names: The sugar maple is sometimes called _rock maple_ or _hard maple_. SILVER MAPLE (_Acer saccharinum_) Distinguishing characters: The tips of the *twigs curve upwards* (Fig. 28), the bark is scaly, and the leaves are very deeply cleft and are silvery on the under side. [Illustration: FIG. 25.--Leaf of Sugar Maple.] Leaf: Deeply cleft and silvery under side. Fig. 29. Form and size: A large tree with the main branches separating from the trunk a few feet from the ground. The terminal twigs are long, slender, and drooping. Range: Eastern United States. Soil and location: Moist places. Enemies: The _leopard moth_, a wood-boring insect, and the _cottony-maple scale_, a sucking insect. [Illustration: FIG. 26.--The Sugar Maple.] Value for planting: Grows too rapidly and is too short-lived to be durable. Commercial value: Its wood is soft, weak, and little used. Other characters: The _bark_ is light gray, smooth at first and scaly later on. The scales are free at each end and attached in the center. The _flowers_ appear before the leaves in the latter part of March or early April. [Illustration: FIG. 27.--Tapping the Sugar Maple.] Other common names: The silver maple is sometimes known as _soft maple_ or _white maple_. RED MAPLE (_Acer rubrum_) [Illustration: FIG. 28.--Terminal Twig of Silver Maple.] Distinguishing characters: The *bark is smooth and light gray*, like that of the beech, on the upper branches in older trees, and in young trees over the whole trunk. Fig. 30. The buds are in clusters, and the terminal twigs, Fig. 31, are quite red. [Illustration: FIG. 29.--Leaf of the Silver Maple.] Leaf: Whitish underneath with three-pointed lobes. Fig. 32. Form and size: A medium-sized tree with a narrow, round head. Range: Eastern North America. Soil and location: Prefers moist places. Enemies: Leaf blotches (_Rhytisma acerinum_) which, however, are not very injurious. Value for planting: Suitable as a shade tree for suburban streets. Its rich red leaves in the fall make it attractive for the lawn. [Illustration: FIG. 30.--Bark of the Red Maple.] Commercial value: Its wood is heavy, close-grained, and takes a good polish. Used for furniture and fuel. Other characters: The _bud_ is small, round, and red. The _flowers_ appear before the leaves are out in the early part of April. [Illustration: FIG. 31.--Twig of the Red Maple.] [Illustration: FIG. 32.--Leaf of the Red Maple.] Other common names: The red maple is sometimes known as _swamp maple_. [Illustration: FIG. 33.--Twig of Norway Maple.] Comparisons: The red maple is apt to be confused with the silver maple, but the latter can be distinguished by its turned-up twigs and scaly bark over the whole trunk of the tree, which presents a sharp contrast to the straight twig and smooth bark of the red maple. The latter has a bark similar to the beech, but its branches are _opposite_, while those of the beech are _alternate_. NORWAY MAPLE (_Acer platanoides_) Distinguishing characters: The bud, Fig. 33, is *oval and reddish-brown* in color; when taken off, a *milky juice exudes*. The bark is close. Fig. 34 [Illustration: FIG. 34.--Bark of Norway Maple.] Leaf: Like the leaf of the sugar maple but thicker in texture and darker in color. Fig. 35. Form and size: A tall tree with a broad, round head. Range: Europe and the United States. Soil and location: Will grow in poor soil. Enemies: Very few. Value for planting: One of the best shade trees. Commercial value: None. Other characters: The _bark_ is close like that of the mockernut hickory. Comparisons: The Norway maple is apt to be confused with the _sycamore maple_ (_Acer pseudoplatanus_), but differs from the latter in having a reddish bud instead of a green bud, and a close bark instead of a scaly bark. BOX ELDER (_Acer negundo_) Distinguishing characters: The terminal *twigs are green*, and the buds are round and small. Fig. 36. Leaf: Has three to seven leaflets. [Illustration: FIG. 35.--Leaf of Norway Maple.] Form and size: A medium-sized tree with a short trunk and wide-spreading top. Range: Eastern United States to the Rocky Mountains. Soil and location: Grows rapidly in deep, moist soil and river valleys, but accommodates itself to the dry and poor soil conditions of the city. [Illustration: Figure 36.--Twig of the Box Elder.] Enemies: Few. Value for planting: Used as a shade tree in the Middle West, but the tree is so ill formed and so short-lived that it is not to be recommended. Commercial value: None. The wood is soft. Other characters: The _bark_ of the trunk is smooth and yellowish-green in young trees and grayish brown in older specimens. The _flowers_ appear in the early part of April. The _fruit_ takes the form of yellowish-green keys which hang on the tree till late fall. Other common names: The box elder is also commonly known as the _ash-leaf maple_. GROUP VI. TREES TOLD BY THEIR FORM: ELM, POPLAR, GINGKO AND WILLOW How to tell them from other trees: The trees described in this group are so distinctive in their general _form_ that they may, for the purpose of study, be grouped together, and distinguished from all other trees by this characteristic. How to tell them from each other: The American elm is _vase-like_ in shape; the Lombardy poplar is narrow and _spire-like_; the gingko, or maidenhair tree, is _odd_ in its mode of _branching_; and the weeping willow is extremely _pendulous_. AMERICAN ELM (_Ulmus americana_) Distinguishing characters: The tree can be told at a glance by its general branching habit. The limbs arch out into a wide-spreading *fan or vase-like crown* which loses itself in numerous fine drooping branchlets. See Fig. 37. [Illustration: FIG. 37.--American Elm.] Leaf: The leaves are simple, alternate, and from 2 to 5 inches long. [Illustration: FIG. 38.--English Elm in Winter.] Form and size: It is a tall tree with a trunk that divides a short distance above ground. Its general contour, together with the numerous branches that interlace its massive crown, give the elm an interesting and stately appearance which is unequaled by any other tree. [Illustration: FIG. 39.--Lombardy Poplar.] Range: Eastern North America. Soil and location: The elm prefers a deep, rich and moist soil, but will adapt itself even to the poor soil of the city street. Enemies: _The leopard moth_, a wood-boring insect, and the _elm leaf beetle_, a leaf-eating insect, are the two most important enemies of the tree. Their ravages are very extensive. Value for planting: The tree has a character of its own which cannot be duplicated for avenue or lawn planting. Commercial value: The wood is strong and tough and therefore has a special value for cooperage, agricultural implements, carriages, and shipbuilding. Other characters: The _buds_ are small, brown, and smooth, while those of the European elms are covered with down. The _small side twigs_ come out at almost right angles to the larger terminal twigs, which is not the case in other species of elm. [Illustration: FIG. 40.--Leaf of Carolina Poplar.] Other common names: _White elm_. Comparisons: The _English elm_ (_Ulmus campestris_) is also a tall, dignified tree commonly seen under cultivation in America, but may be told from the American species by the difference in their general contour. The branches of the English species spread out but do not arch like those of the American elm, and the bark of the English elm is darker and coarser, Fig. 38. Little tufts of dead twigs along the main branches and trunk of the tree are characteristic of the English elm and will frequently help to distinguish it from the American elm. The _Camperdown elm_ may be recognized readily by its dwarf size and its low drooping umbrella-shaped crown. LOMBARDY OR ITALIAN POPLAR (_Populus nigra, var. italica_) Distinguishing characters: Its *tall, slender, spire-like form* and rigidly *erect branches*, which commence low on the trunk, make this tree very distinct at all seasons of the year. See Fig. 39. Leaf: Triangular in shape, similar to that of the Carolina poplar but smaller, see Fig. 40. Range: Asia, Europe, and North America. Soil and location: The poplar is easily grown in poor soil, in any location, and is very hardy. Value for planting: The tree has a distinctive form which makes it valuable for special landscape effects. It is also used for shelter belts and screening. Like all poplars it is short lived and will stand pruning well. Commercial value: None. [Illustration: FIG. 41.--Carolina Poplar.] Comparisons: The _Carolina poplar_, or Cottonwood (_Populus deltoides_) can be told from the Lombardy poplar by its wider crown and its more open branching, Fig. 41. It may be recognized by its big terminal twigs, which are light yellow in color and coarser than those of the Lombardy poplar, Fig. 42. Its bark is smooth, light and yellowish-green in young trees, and dark gray and fissured in older specimens. Its large, conical, glossy, chestnut-brown bud is also characteristic, Fig. 42. Its flowers, in the form of large catkins, a peculiarity of all poplars, appear in the early spring. The Carolina poplar is commonly planted in cities because it grows rapidly and is able to withstand the smoke and drouth conditions of the city. Where other trees, however, can be substituted with success, the poplar should be avoided. Its very fast growth is really a point against the tree, because it grows so fast that it becomes too tall for surrounding property, and its wood being extremely soft and brittle, the tree frequently breaks in windstorms. In many cases it is entirely uprooted, because it is not a deep-rooted tree. Its larger roots, which spread near the surface, upset the sidewalk or prevent the growth of other vegetation on the lawn, while its finer rootlets, in their eager search for moisture, penetrate and clog the joints of neighboring water and sewer pipes. The tree is commonly attacked by the _oyster-shell scale_, an insect which sucks the sap from its bark and which readily spreads to other more valuable trees like the elm. The female form of this tree is even more objectionable than the male, because in the early spring the former produces an abundance of cotton from its seeds which litters the ground and often makes walking dangerous. The only justification for planting the Carolina poplar is in places where the conditions for tree growth are so poor that nothing else will grow, and in those cases the tree should be cut back periodically in order to keep it from becoming too tall and scraggly. It is also desirable for screening in factory districts and similar situations. [Illustration: FIG. 42.--Bud of the Carolina Poplar.] The _silver_ or _white poplar_ (_Populus alba_) may be told from the other poplars by its characteristic smooth, _whitish-green bark_, often spotted with dark blotches, Fig. 43. The _leaves are silvery-white_ and downy on the under side. The twigs are dark green in color and densely covered with a white down. It grows to very large size and forms an irregular, wide-spreading, broad head, which is characteristically different from that of any of the other poplars. [Illustration: FIG. 43.--Bark of the Silver Poplar.] The _quaking aspen_ (_Populus tremuloides_), the _large-toothed aspen_ (_Populus grandidentata_) and the _balsam poplar_ or _balm of Gilead_ (_Populus balsamifera_) are other common members of the poplar group. The quaking aspen may be told by its reddish-brown twigs, narrow sharp-pointed buds, and by its small finely toothed leaves. The large-toothed aspen has thicker and rather downy buds and broader and more widely toothed leaves. The balsam poplar has a large bud thickly covered with a sticky, pungent, gelatinous substance. GINGKO OR MAIDENHAIR TREE (_Gingko biloba_) [Illustration: FIG. 44.--Gingko Trees.] Distinguishing characters: The *peculiar branches* of this tree *emerge upward* from a straight tapering trunk *at an angle of about 45°* and give to the whole tree a striking, Oriental appearance, which is quite different from that of any other tree, Fig. 44. Leaf: Like that of a leaflet of maidenhair fern, Fig. 45. Range: A native of northern China and introduced into eastern North America. Soil and location: The gingko will grow in poor soils. Enemies: Practically free from insects and disease. [Illustration: FIG. 45.--Leaves of the Gingko Tree.] Value for planting: It makes a valuable tree for the street where heavy shade is not the object and forms an excellent wide-spreading specimen tree on the lawn. Other characters: The _fruit_ consists of a stone covered by sweet, ill-smelling flesh. The tree is dioecious, there being separate male and female trees. The male tree is preferable for planting in order to avoid the disagreeable odor of the fruit which appears on the female trees when about thirty years old. The male tree has a narrower crown than the female tree. The buds (Fig. 46) are very odd and are conspicuous on the tree throughout the winter. The leaves of the gingko shed in the winter. In this respect the tree is like the larch and the bald cypress. [Illustration: FIG. 46.--Bud of the Gingko Tree.] The gingko belongs to the yew family, which is akin to the pine family. It is therefore a very old tree, the remains of the forests of the ancient world. The gingko in its early life is tall and slender with its few branches close to the stem. But after a time the branches loosen up and form a wide-spreading crown. In the Orient it attains enormous proportions and in this country it also grows to a fairly large size when planted on the open lawn or in groups far apart from other trees so that it can have plenty of room to spread. It then produces a picturesque effect of unusual interest. WEEPING WILLOW (_Salix babylonica_) Distinguishing characters: All the willows have a single cap-like scale to the bud, and this species has an unusually *drooping mass of slender branchlets* which characterizes the tree from all others, Fig. 47. [Illustration: FIG. 47.--Weeping Willow.] Form and size: It grows to large size. Range: Asia and Europe and naturalized in eastern United States. Soil and location: Prefers moist places near streams and ponds. Enemies: None of importance. Value for planting: The weeping willow has a special ornamental effect in cemeteries and along lakes and river banks in parks. Commercial value: It is used in the United States for charcoal and for fuel. Comparisons: The _pussy willow_ (_Salix discolor_) may easily be told from the other willows by its small size; it is often no higher than a tall shrub. Its branches are _reddish green_ and the buds are dark red, smooth and glossy. The predominating color of the twigs and buds in the pussy willow is therefore a shade of _red_, while in the weeping willow it is _yellowish green_. GROUP VII. TREES TOLD BY THEIR BARK OR TRUNK: SYCAMORE, BIRCH, BEECH, BLUE BEECH, IRONWOOD, AND HACKBERRY How to tell them from other trees: The _color of the bark or the form of the trunk_ of each of the trees in this group is distinct from that of any other tree. How to tell them from each other: In the sycamore, the bark is _mottled_; in the white birch, it is _dull white_; in the beech, it is _smooth and gray_; in the hackberry, it is covered with numerous _corky warts_; in the blue beech, the trunk of the tree is _fluted_, as in Fig. 54, and in the ironwood, the bark _peels_ in thin perpendicular strips. [Illustration: FIG. 48.--Bark of the Sycamore Tree.] THE SYCAMORE OR PLANE TREE (_Platanus occidentalis_) Distinguishing characters: The peculiar *mottled appearance* of the *bark* (Fig. 48) in the trunk and large branches is the striking character here. The bark produces this effect by shedding in large, thin, brittle plates. The newly exposed bark is of a yellowish green color which often turns nearly white later on. *Round seed balls*, about an inch in diameter, may be seen hanging on the tree all winter. In this species, the seed balls are usually solitary, while in the Oriental sycamore, a European tree similar to the native one, they appear in clusters of two, or occasionally of three or four. See Fig. 49. [Illustration: FIG. 49.--Seed-balls of the Oriental Sycamore. Note one Seed-ball cut in half.] [Illustration: FIG. 50.--Gray or White Birch Trees.] Leaf: The stem of the leaf completely covers the bud. This is a characteristic peculiar to sycamores. Form and size: A large tree with massive trunk and branches and a broad head. Range: Eastern and southern United States. Soil and location: Prefers a deep rich soil, but will adapt itself even to the poor soil of the city street. Enemies: The sycamore is frequently attacked by a fungus (_Gloeosporium nervisequum_), which curls up the young leaves and kills the tips of the branches. Late frosts also often injure its young twigs. The Oriental sycamore, which is the European species, is more hardy in these respects than the native one and is therefore often chosen as a substitute. Value for planting: The Occidental sycamore is now planted very little, but the Oriental sycamore is used quite extensively in its place, especially as a shade tree. The Oriental sycamore is superior to the native species in many ways. It is more shapely, faster growing, and hardier than the native one. Both sycamores will bear transplanting and pruning well. [Illustration: FIG. 51.--Bark of the Black or Sweet Birch.] Commercial value: The wood of the sycamore is coarse-grained and hard to work; used occasionally for inside finishing in buildings. Other names: _Buttonball_, _buttonwood_. Comparisons: The _Oriental sycamore_ (_Platanus orientalis_) an introduced species, is apt to be confused with the Occidental sycamore, but may be told from the latter by the number of seed balls suspended from the tree. In the case of the Oriental species, the seed balls hang in _pairs_ or (rarely) three or four together. In the Occidental, the seed balls are generally _solitary_ and very rarely in pairs. GRAY OR WHITE BIRCH (_Betula populifolia_) Distinguishing characters: The *dull-white color of the bark* on the trunk and the _dark triangular patches below the insertion of the branches_ distinguish this tree; see Fig. 50. The bark of the young trunks and branches is reddish-brown in color and glossy. The bark adheres closely to the trunk of the tree and does not peel in loose, shaggy strips, as in the case of the yellow or golden birch. It is marked by small raised horizontal lines which are the lenticels or breathing pores. These lenticels are characteristic of all birch and cherry trees. In addition to the distinction in the color of the bark, an important character which distinguishes the gray birch from all other species of birch, is found in the *terminal twigs*, which are *rough* to the touch. Form and size: A small tree. Frequently grows in clumps. Range: Eastern United States. Soil and location: The gray birch does best in a deep, rich soil, but will also grow in poor soils. Enemies: The _bronze-birch borer_, a wood-destroying insect, and _Polyporus betulinus_, a fungus, are its chief enemies. Value for planting: Its graceful habit and attractive bark gives the tree an important place in ornamental planting. It may be used to advantage with evergreens, and produces a charming effect when planted by itself in clumps. [Illustration: FIG. 52.--Bark of the Beech.] [Illustration: FIG. 53.--Buds of the Beech Tree.] Commercial value: The wood is soft and not durable. It is used in the manufacture of small articles and for wood pulp. Other characters: The _fruit is a catkin_. Comparisons: The _paper birch_ (_Betula papyrifera_) is apt to be confused with the gray birch, because both have a white bark. The bark of the paper birch, however, is a clear white and peels off in thin papery layers instead of being close. It very seldom shows any dark triangular markings on the trunk. Its terminal twigs are not rough and its trunk is usually straighter and freer from branches. The _black_ or _sweet birch_ (_Betula lenta_) has a bark similar to the gray birch, except that its color is dark gray. See Fig. 51. The twigs have an aromatic taste. [Illustration: FIG. 54.--Trunk of Blue Beech.] [Illustration: FIG. 55.--Bark of the Ironwood.] The _yellow birch_ (_Betula lutea_) has a yellowish or golden bark which constantly peels in thin, ragged, horizontal films. The _European white birch_ (_Betula alba_) has a dull-white bark like the native white birch, but has smooth terminal twigs instead of rough ones. It is commonly seen in the United States on lawns and in parks. AMERICAN BEECH (_Fagus americana_) Distinguishing characters: The *close-fitting, smooth, gray bark* will tell this tree from all others except the red maple and yellow-wood. See Fig. 52. The red maple may then be easily eliminated by noting whether the branches are alternate or opposite. They are alternate in the beech and opposite in the maple. The yellow-wood may be eliminated by noting the size of the bud. The *bud* in the yellow-wood is hardly noticeable and of a golden yellow color, while that of the beech is very *long, slender, and sharp-pointed*, and chestnut brown in color. See Fig. 53. Form and size: It grows tall in the woods, but on the open lawn spreads out into a massive, round-headed tree. Range: Eastern Canada and United States. Soil and location: Prefers a rich, well-drained soil, but will grow in any good soil. Enemies: _Aphides_ or plant lice that suck the sap from the leaves in spring and early summer are the chief enemies of the tree. Value for planting: The pleasing color of its bark, its fine spread of branches, which gracefully droop down to the ground, and its autumnal coloring, make the beech a favorite for lawn and park planting. The several European species of beech are equally charming. [Illustration: FIG. 56.--Bark of the Hackberry.] Commercial value: The wood is strong, close-grained, and tough. It is used mainly for cooperage, tool handles, shoe lasts, chairs, etc., and for fuel. Other characters: The _fruit_ is a prickly burr encasing a sharply triangular nut which is sweet and edible. Comparisons: The _European beech_ (_Fagus sylvatica_), and its weeping, purple-leaved, and fern-leaved varieties, are frequently met with in parks and may be told from the native species by its darker bark. The weeping form may, of course, be told readily by its drooping branches. The leaves of the European beeches are broader and less serrated than those of the American beech. BLUE BEECH OR HORNBEAM (_Carpinus caroliniana_) Distinguishing characters: The *fluted* or muscular effect of its *trunk* will distinguish the tree at a glance, Fig. 54. Leaf: Doubly serrated; otherwise the same as that of ironwood. Form and size: A low-spreading tree with branches arching out at various angles, forming a flattened head with a fine, slender spray. Range: Very common in the eastern United States. Soil and location: Grows in low wet woods. Enemies: None of importance. Value for planting: Its artistic branching and curious trunk give the tree an important place in park planting. Commercial value: None. Other characters: The bark is smooth and bluish gray in color. Comparisons: The blue beech or hornbeam is often confused with the _ironwood_ or _hop hornbeam_ (_Ostrya virginiana_). The ironwood, however, has a characteristic bark that peels in perpendicular, short, thin segments, often loose at the ends. See Fig. 55. This is entirely different from the close, smooth, and fluted bark of the blue beech. The color of the bark in the ironwood is brownish, while that of the blue beech is bluish-gray. The buds of the ironwood are greenish with brown tips, while the bud of the blue beech shows no green whatever. HACKBERRY (_Celtis occidentalis_) Distinguishing characters: The tree may be told readily from other trees by the *corky tubercles* on the bark of the lower portion of the trunk. See Fig. 56. Leaf: Has three predominating veins and is a bit more developed on one side than on the other. Form and size: A small or medium-sized tree with a single stem and broad conical crown. Range: United States and Canada. Soil and location: Grows naturally in fertile soils, but will adapt itself to almost sterile soils as well. Enemies: The hackberry is usually free from disease, though often its leaves are covered with insect galls. Value for planting: It is extensively planted as a shade tree in the Middle West, and is frequently seen as an ornamental tree in the East. Commercial value: It has little economic value except for fuel. Other characters: The _fruit_ is berry-like, with a hard pit. The fleshy outer part is sweet. Other common names: _Nettle tree_; _sugarberry_. GROUP VIII. THE OAKS AND CHESTNUT How to tell them from other trees: The oaks are rather difficult to identify and, in studying them it will often be necessary to look for more than one distinguishing character. The oaks differ from other trees in bearing _acorns_. Their _leaves_ have many lobes and their upper lateral _buds_ cluster at the top of the twigs. The general contour of each oak presents a characteristic branching and sturdiness uncommon in other trees. The chestnut differs from other trees in bearing _burs_ and its _bark_ is also distinctly characteristic. How to tell them from each other: There are two groups of oaks, the _white oak_ and the _black oak_. The white oaks mature their acorns in one year and, therefore, only acorns of the same year can be found on trees of this group. The black oaks take two years in which to mature their acorns and, therefore, young acorns of the present year and mature acorns of the previous year may be found on the same tree at one time. The _leaves_ of the white oaks have rounded margins and rounded lobes as in Fig. 57, while those of the black oaks have pointed margins and sharp pointed lobes as shown in Figs. 60, 62 and 64. The _bark_ of the white oaks is light colored and breaks up in loose flakes as in Fig. 58, while that of the black oaks is darker and deeply ridged or tight as in Figs. 59 and 61. The white oak is the type of the white oak group and the black, red and pin oaks are types of the other. For the characterization of the individual species, the reader is referred to the following pages. [Illustration: FIG. 57.--Leaf and Fruit of White Oak. (Quercus alba.)] WHITE OAK (_Quercus alba_) Distinguishing characters: The massive ramification of its branches is characteristic of this species and often an easy clue to its identification. The *bark* has a *light gray color*--lighter than that of the other oaks--and breaks into soft, loose flakes as in Fig. 58. The *leaves are deeply lobed* as in Fig. 57. The *buds are small, round and congested* at the end of the year's growth. The acorns usually have no stalks and are set in shallow, rough cups. The kernels of the acorns are white and palatable. Form and size: The white oak grows into a large tree with a wide-spreading, massive crown, dissolving into long, heavy, twisted branches. When grown in the open it possesses a short sturdy trunk; in the forest its trunk is tall and stout. Range: Eastern North America. [Illustration: FIG. 58.--Bark of White Oak. (Quercus alba.)] Soil and location: The white oak thrives in almost any well-drained, good, deep soil except in a very cold and wet soil. It requires plenty of light and attains great age. Enemies: The tree is comparatively free from insects and disease except in districts where the Gipsy moth is common, in which case the leaves of the white oak are a favorite food of its caterpillars. [Illustration: FIG. 59.--Bark of Black Oak. (Quercus velutina).] Value for planting: The white oak is one of the most stately trees. Its massive form and its longevity make the tree suitable for both lawn and woodland planting but it is not used much because it is difficult to transplant and grows rather slowly. Commercial value: The wood is of great economic importance. It is heavy, hard, strong and durable and is used in cooperage, construction work, interior finish of buildings and for railroad ties, furniture, agricultural implements and fuel. Comparisons: The _swamp white oak_ (_Quercus platanoides_) is similar to the white oak in general appearance of the bark and form and is therefore liable to be confused with it. It differs from the white oak, however, in possessing a more straggly habit and in the fact that the bark on the under side of its branches shags in loose, large scales. Its buds are smaller, lighter colored and more downy and its acorns are more pointed and with cups more shallow than those of the white oak. The tree also grows in moister ground, generally bordering swamps. [Illustration: FIG. 60.--Leaf and Fruit of Black Oak. (Quercus velutina).] BLACK OAK (_Quercus velutina_) Distinguishing characters: The *bark* is black, rough and cut up into firm *ridges* especially at the base of the tree, see Fig. 59. The _inner bark_ has a _bright yellow color_: the *leaves* have _sharp points_ and are wider at the base than at the tip as shown in Fig. 60. The buds are _large, downy_ and _sharp pointed_. The acorns are small and have deep, scaly cups the inner margins of which are downy. The kernels are yellow and bitter. Form and size: The tree grows in an irregular form to large size, with its branches rather slender as compared with the white oak and with a more open and narrow crown. Range: Eastern North America. Soil and location: It will grow in poor soils but does best where the soil is rich and well drained. Enemies: None of importance. Value for planting: The black oak is the poorest of the oaks for planting and is rarely offered by nurserymen. Commercial value: The wood is heavy, hard and strong, but checks readily and is coarse grained. It is of little value except for fuel. The bark is used for tannin. Other common names: _Yellow oak_. Comparisons: The black oak might sometimes be confused with the _red_ and _scarlet oaks_. The yellow, bitter inner bark will distinguish the black oak from the other two. The light-colored, smooth bark of the red oak and the dark, ridged bark of the black oak will distinguish the two, while the bark of the scarlet oak has an appearance intermediate between the two. The buds of the three species also show marked differences. The buds of the black oak are covered with hairs, those of the scarlet oak have fewer hairs and those of the red are practically free from hairs. The leaves of each of the three species are distinct and the growth habits are different. RED OAK (_Quercus rubra_) Distinguishing characters: The *bark* is perpendicularly fissured into long, _smooth, light gray strips_ giving the trunk a characteristic *pillar effect* as in Figs. 61 and 94. It has the straightest trunk of all the oaks. The leaves possess _more lobes_ than the leaves of any of the other species of the black oak group, see Fig. 62. The acorns, the largest among the oaks, are semispherical with the cups extremely shallow. The buds are large and sharp pointed, but not as large as those of the black oak. They also have a few fine hairs on their scales, but are not nearly as downy as those of the Black oak. [Illustration: FIG. 61--Bark of Red Oak.] Form and size: The red oak is the largest of the oaks and among the largest of the trees in the northern forests. It has a straight trunk, free from branches to a higher point than in the white oak, see Fig. 94. The branches are less twisted and emerge at sharper angles than do those of the white oak. Range: It grows all over Eastern North America and reaches north farther than any of the other oaks. Soil and location: It is less fastidious in its soil and moisture requirements than the other oaks and therefore grows in a great variety of soils. It requires plenty of light. [Illustration: FIG. 62.--Leaf and Fruit of Red Oak.] Enemies: Like most of the other oaks, this species is comparatively free from insects and disease. Value for planting: The red oak grows faster and adapts itself better to poor soil conditions than any of the other oaks and is therefore easy to plant and easy to find in the nurseries. It makes an excellent street tree, is equally desirable for the lawn and is hardly surpassed for woodland planting. Commercial value: The wood is hard and strong but coarse grained, and is used for construction timber, interior finish and furniture. It is inferior to white oak where strength and durability are required. PIN OAK (_Quercus palustris_) Distinguishing characters: Its method of *branching* will characterize the tree at a glance. It develops a well-defined _main_ ascending _stem_ with numerous _drooping_ side _branches_ as in Fig. 63. The buds are very small and sharp pointed and the leaves are small as in Fig. 64. The bark is dark, firm, smooth and in close ridges. The acorn is small and carries a light brown, striped nut, wider than long and bitter. The cup is shallow, enclosing only the base of the nut. [Illustration: FIG. 63.--Pin Oaks in Winter.] Form and size: The pin oak is a medium-sized tree in comparison with other oaks. It develops a tall, straight trunk that tapers continuously through a pyramidal crown of low, drooping tender, branches. Range: Eastern North America. Soil and location: It requires a deep, rich, moist soil and grows naturally near swamps. Its roots are deep and spreading. The tree grows rapidly and is easily transplanted. Enemies: None of importance. Value for planting: The pin oak is an extremely graceful tree and is therefore extensively used for planting on lawns and on certain streets where the tree can find plenty of water and where conditions will permit its branches to droop low. Commercial value: The wood is heavy and hard but coarse grained and liable to check and warp. Its principal use is in the construction of houses and for shingles. [Illustration: FIG. 64.--Leaf and Fruit of Pin Oak.] CHESTNUT (_Castanea dentata_) Distinguishing characters: The *bark* in young trees is smooth and of a marked reddish-bronze color, but when the tree grows older, the bark breaks up into *diamond-shaped ridges*, sufficiently characteristic to distinguish the tree at a glance, see Fig. 65. A close examination of the _terminal twig_ will show _three ridges_ and _two grooves_ running down along the stem from the base of each leaf or leaf-scar. The twig has no true terminal bud. The fruit, a large, round *bur*, prickly without and hairy within and enclosing the familiar dark brown, sweet edible nuts is also a distinguishing mark of the tree. Leaf: The leaves are distinctly long and narrow. They are from 6 to 8 inches long. Form and size: The chestnut is a large tree with a massive trunk and broad spreading crown. The chestnut tree when cut, sprouts readily from the stump and therefore in places where the trees have once been cut, a group of two to six trees may be seen emerging from the old stump. [Illustration: FIG. 65.--Trunk of Chestnut Tree.] Range: Eastern United States. Soil and location: It will grow on rocky as well as on fertile soils and requires plenty of light. Enemies: During the past nine years nearly all the chestnut trees in the United States have been attacked by a fungus disease (_Diaporthe parasitica_, Mur.) which still threatens the entire extinction of the chestnut trees in this country. No remedy has been discovered and all affected trees should be cut down and the wood utilized before it decays and becomes worthless. No species of chestnut tree is entirely immune from this disease, though some species are highly resistant. Value for planting: The chestnut is one of the most rapidly growing hardwood trees but, on account of its disease, which is now prevalent everywhere, it is not wise to plant chestnut trees for the present. Commercial value: The wood is light, not very strong and liable to warp. It is durable when brought in contact with the soil and is therefore used for railroad ties, fence-posts, poles, and mine timbers. It is also valuable for interior finish in houses and for fuel. Its bark is used in the manufacture of tanning extracts and the nuts are sold in cities in large quantities. CHAPTER III HOW TO IDENTIFY TREES--(Continued) GROUP IX. THE HICKORIES, WALNUT AND BUTTERNUT How to tell them from other trees and from each other: The hickory trees, though symmetrical, have a rugged _appearance_ and the _branches_ are so sturdy and black as to give a special distinction to this group. The _buds_ are different from the buds of all other trees and sufficiently characteristic to distinguish the various species of the group. The _bark_ is also a distinguishing character. The walnut and butternut have _chambered piths_ which distinguish them from all other trees and from each other. SHAGBARK HICKORY (_Hicoria ovata_) Distinguishing characters: The yellowish brown *buds* nearly as large as those of the mockernut hickory, _are each provided with two long, dark, outer scales_ which stand out very conspicuously as shown in Fig. 67. The *bark* in older specimens *shags* off in rough strips, sometimes more than a foot long, as shown in Fig. 68. These two characters will readily distinguish the tree at all seasons of the year. [Illustration: FIG. 66.--A Shagbark Hickory Tree.] Leaf: The leaf is compound, consisting of 5 or 7 leaflets, the terminal one generally larger. Form and size: A tall, stately tree--the tallest of the hickories--of rugged form and fine symmetry, see Fig. 66. Range: Eastern North America. Soil and location: The shagbark hickory grows in a great variety of soils, but prefers a deep and rather moist soil. Enemies: The _hickory bark borer_ (_Scolytus quadrispinosus_) is its principal enemy. The insect is now killing thousands of hickory trees in the vicinity of New York City and on several occasions has made its appearance in large numbers in other parts of the country. Value for planting: It is difficult to transplant, grows slowly and is seldom found in nurseries. [Illustration: FIG. 67.--Bud of the Shagbark Hickory.] Commercial value: The wood is extremely tough and hard and is used for agricultural implements and for the manufacture of wagons. It is excellent for fuel and the nuts are of great value as a food. Other characters: The fruit is a nut covered by a thick husk that separates into 4 or 5 segments. The kernel is sweet. Other common names: _Shellbark hickory_. MOCKERNUT HICKORY (_Hicoria alba_) [Illustration: FIG. 68.--Bark of the Shagbark Hickory.] Distinguishing characters: The *bud* is the largest among the hickories--nearly half an inch long--is hard and oval and covered with _yellowish brown_ downy _scales_ which _do not project_ like those of the shagbark hickory, see Fig. 69. The twigs are extremely coarse. The *bark* is very tight on the trunk and branches and has a _close_, hard, _wavy_ appearance as in Fig. 70. Leaf: The leaf consists of 5, 7 or 9 leaflets all of which are large and pubescent and possess a distinct resinous odor. Form and size: A tall tree with a broad spreading head. Range: Eastern North America. Soil and location: The mockernut hickory grows on a great variety of soils, but prefers one which is rich and well-drained. Enemies: The same as for the shagbark hickory. Value for planting: It is not commonly planted. Commercial value: The wood is similar to that of the shagbark hickory and is put to the same uses. Other characters: The fruit is a nut, larger and covered with a shell thicker than that of the shagbark. The husk is also thicker and separates into four segments nearly to the base. The kernel is small and sweet. Other common names: _Bigbud hickory_; _whiteheart hickory_. Comparisons: The _pignut hickory_ (_Hicoria glabra_), sometimes called broom hickory or brown hickory, often has a shaggy bark, but differs from both the shagbark and the mockernut hickory in possessing buds very much smaller, twigs more slender and leaflets fewer. The nut has a thinner husk which does not separate into four or five segments. The tree prefers drier ground than the other hickories. [Illustration: FIG. 69.--Bud of the Mockernut Hickory.] The _bitternut_ (_Hicoria minima_) can be told from the mockernut and other species of hickory by its bud, which has no scales at all. The color of its bud is a characteristic orange yellow. The bark is of a lighter shade than the bark of the mockernut hickory and the leaflets are more numerous than in any of the hickories, varying from 7 to 11. Its nuts are bitter. BLACK WALNUT (_Juglans nigra_) Distinguishing characters: By cutting a twig lengthwise, it will be seen that its *pith* is divided into little _chambers_ as shown in Fig. 71. The bud is dark gray and satiny. The bark is dark brown and deeply ridged and the fruit is the familiar round walnut. [Illustration: FIG. 70.--Bark of the Mockernut Hickory.] Form and size: A tall tree with a spreading crown composed of stout branches. In the open it grows very symmetrically. Range: Eastern United States. Soil and location: The black walnut prefers a deep, rich, fertile soil and requires a great deal of light. Enemies: The tree is a favorite of many caterpillars. Value for planting: It forms a beautiful spreading tree on open ground, but is not planted to any extent because it is hard to transplant. It grows slowly unless the soil is very deep and rich, develops its leaves late in the spring and sheds them early in the fall and produces its fruit in great profusion. Commercial value: The wood is heavy, strong, of chocolate brown color and capable of taking a fine polish. It is used for cabinet making and interior finish of houses. The older the tree, usually, the better the wood, and the consumption of the species in the past has been so heavy that it is becoming rare. The European varieties which are frequently planted in America as substitutes for the native species yield better nuts, but the American species produces better wood. [Illustration: FIG. 71.--Twig of the Black Walnut. Note the large chambers in the pith.] [Illustration: FIG. 72.--Twig of the Butternut. Note the small chambers in the pith.] Other characters: The _fruit_ is a large round nut about two inches in diameter, covered with a smooth husk which at first is dull green in color and later turns brown. The husk does not separate into sections. The kernel is edible and produces an oil of commercial value. The _leaves_ are compound and alternate with 15 to 23 leaflets to each. Comparisons: The _butternut_ (_Juglans cinerea_) is another tree that has the pith divided into little chambers, but the little chambers here are shorter than in the black walnut, as may be seen from a comparison of Figs. 71 and 72. The bark of the butternut is light gray while that of the black walnut is dark. The buds in the butternut are longer than those of the black walnut and are light brown instead of gray in color. The form of the tree is low and spreading as compared with the black walnut. The fruit in the butternut is elongated while that of the black walnut is round. The leaves of the butternut have fewer leaflets and these are lighter in color. GROUP X. TULIP TREE, SWEET GUM, LINDEN, MAGNOLIA, LOCUST, CATALPA, DOGWOOD, MULBERRY AND OSAGE ORANGE TULIP TREE (_Liriodendron tulipifera_) Distinguishing characters: There are four characters that stand out conspicuously in the tulip tree--the *bud*, the *trunk*, the persistent *fruit cups* and the wedged *leaf*. The bud, Fig. 74, about three-quarters of an inch long, is covered by two purplish scales which lend special significance to its whole appearance. The trunk is extremely individual because it rises stout and shaft-like, away above the ground without a branch as shown in Fig. 73. The tree flowers in the latter part of May but the cup that holds the fruit persists throughout the winter. The leaf, Fig. 75, has four lobes, is nearly as broad as it is long and so notched at the upper end that it looks different from any other leaf. [Illustration: FIG. 73.--The Tulip Tree.] [Illustration: FIG. 74.--Bud of the Tulip Tree.] Form and size: The tulip tree is one of the largest, stateliest and tallest of our trees. Range: Eastern United States. Soil and location: Requires a deep, moist soil. Enemies: Comparatively free from insects and disease. Value for planting: The tree has great value as a specimen on the lawn but is undesirable as a street tree because it requires considerable moisture and transplants with difficulty. It should be planted while young and where it can obtain plenty of light. It grows rapidly. Commercial value: The wood is commercially known as _whitewood_ and _yellow poplar_. It is light, soft, not strong and easily worked. It is used in construction, for interior finish of houses, woodenware and shingles. It has a medicinal value. Other characters: The _flower_, shown in Fig. 75, is greenish yellow in color, appears in May and resembles a tulip; hence the name tulip tree. The _fruit_ is a cone. Other common names: _Whitewood_; _yellow poplar_; _poplar_ and _tulip poplar_. SWEET GUM (_Liquidambar styraciflua_) [Illustration: FIG. 75.--Leaf and Flower of the Tulip Tree.] Distinguishing characters: The _persistent, spiny_, long-stemmed round *fruit*; _the corky growths on the_ *twigs*, the characteristic _star-shaped_ *leaves* (Fig. 76) and the very shiny greenish brown buds and the perfect symmetry of the tree are the chief characters by which to identify the species. Form and size: The sweet gum has a beautiful symmetrical shape, forming a true monopodium. [Illustration: FIG. 76.--Leaf and Fruit of the Sweet Gum. Note the corky ridges along the twig.] Range: From Connecticut to Florida and west to Missouri. Soil and location: Grows in any good soil but prefers low wet ground. It grows rapidly and needs plenty of light. Enemies: Is very often a favorite of leaf-eating caterpillars. Value for planting: The tree is sought for the brilliant color of its foliage in the fall, and is suitable for planting both on the lawn and street. In growing the tree for ornamental purposes it is important that it should be frequently transplanted in the nursery and that it be transported with burlap wrapping around its roots. Commercial value: The wood is reddish brown in color, tends to splinter and is inclined to warp in drying. It is used in cooperage, veneer work and for interior finish. Other characters: On the smaller branches there are irregular developments of cork as shown in Fig. 76, projecting in some cases to half an inch in thickness. Other common names: _Red gum_. Comparisons: The _cork elm_ is another tree that possesses corky ridges along its twigs, but this differs from the sweet gum in wanting the spiny fruit and its other distinctive traits. AMERICAN LINDEN (_Tilia Americana_) [Illustration: FIG. 77.--Bud of the Linden Tree.] Distinguishing characters: The great distinguishing feature of any linden is the *one-sided* character of its *bud* and *leaf*. The bud, dark red and conical, carries a sort of protuberance which makes it extremely one sided as shown in Fig. 77. The leaf, Fig. 78, is heart-shaped with the side nearest the branch largest. [Illustration: FIG. 78.--Leaves and Flowers of the European Linden.] Form and size: The American Linden is a medium-sized tree with a broad round head. Range: Eastern North America and more common in the north than in the south. Soil and location: Requires a rich, moist soil. [Illustration: FIG. 79.--European Linden Tree.] [Illustration: FIG. 80.--Bud of the Umbrella Tree.] Enemies: Its leaves are a favorite food of caterpillars and its wood is frequently attacked by a boring insect known as the _linden borer_ (_Saperda vestita_). Value for planting: The linden is easily transplanted and grows rapidly. It is used for lawn and street planting but is less desirable for these purposes than the European species. Commercial value: The wood is light and soft and used for paper pulp, woodenware, cooperage and furniture. The tree is a favorite with bee keepers on account of the large quantities of nectar contained in its flowers. Other characters: The _fruit_ is like a pea, gray and woody. The _flowers_ appear in early July, are greenish-yellow and very fragrant. Other common names: _Bass-wood_; _lime-tree_; _whitewood_. Comparisons: The _European lindens_, Fig. 79, of which there are several species under cultivation, differ from the native species in having buds and leaves smaller in size, more numerous and darker in color. THE MAGNOLIAS The various species of magnolia trees are readily distinguished by their buds. They all prefer moist, rich soil and have their principal value as decorative trees on the lawn. They are distinctly southern trees; some species under cultivation in the United States come from Asia, but the two most commonly grown in the Eastern States are the cucumber tree and the umbrella tree. [Illustration: FIG. 81.--Bark of the Black Locust.] CUCUMBER TREE (_Magnolia acuminata_) Distinguishing characters: The *buds* are _small_ and _slender_ compared with those of the other magnolia trees and are _covered_ with small silvery silky _hairs_. The *habit* of the tree is to form a straight axis of great height with a symmetrical mass of branches, producing a perfect monopodial crown. The tree is sometimes known as _mountain magnolia_. UMBRELLA TREE (_Magnolia tripetala_) Distinguishing characters: The _buds_, Fig. 80, are extremely _long_, often one and a half inches, have a _purple color_ and _are smooth_. The tree does not grow to large size and produces an open spreading head. Its leaves, twelve to eighteen inches long, are larger than those of the other magnolia trees. The tree is sometimes called _elkwood_. BLACK LOCUST (_Robinia pseudacacia_) Distinguishing characters: The *bark* of the trunk is _rough_ and _deeply ridged_, as shown in Fig. 81. The *buds* are _hardly noticeable_; the twigs sometimes bear small spines on one side. The leaves are large, compound, and fern-like. The individual leaflets are small and delicate. Form and size: The locust is a medium-sized tree developing a slender straight trunk when grown alongside of others; see Fig. 82. Range: Canada and United States. Soil and location: The locust will grow on almost any soil except a wet, heavy one. It requires plenty of light. Enemies: The _locust borer_ has done serious damage to this tree. The grubs of this insect burrow in the sapwood and kill the tree or make it unfit for commercial use. The _locust miner_ is a beetle which is now annually defoliating trees of this species in large numbers. Value for planting: It has little value for ornamental planting. Commercial value: Though short-lived, the locust grows very rapidly. It is extremely durable in contact with the soil and possesses great strength. It is therefore extensively grown for fence-posts and railroad ties. Locust posts will last from fifteen to twenty years. The wood is valuable for fuel. [Illustration: FIG. 82.--Black Locust Trees.] Other characters: The _flowers_ are showy pea-shaped panicles appearing in May and June. The _fruit_ is a small pod. Other common names: _Yellow locust_; _common locust_; _locust_. Comparisons: The _honey locust_ (_Gleditsia triacanthos_) can be told from the black locust by the differences in their bark. In the honey locust the bark is not ridged, has a sort of dark iron-gray color and is often covered with clusters of stout, sharp-pointed thorns as in Fig. 83. The fruit is a large pod often remaining on the tree through the winter. This tree has an ornamental, but no commercial value. [Illustration: FIG. 83.--Bark of the Honey Locust.] HARDY CATALPA (_Catalpa speciosa_) Distinguishing characters: The tree may be told by its *fruit*, which hang in long slender pods all winter. The leaf-scars appear on the stem in whorls of three and rarely opposite each other. Form and size: The catalpa has a short, thick and twisted trunk with an irregular head. Range: Central and eastern United States. [Illustration: FIG. 84.--Hardy Catalpa Trees.] [Illustration: FIG. 85.--Bark of the Flowering Dogwood.] Soil and location: It grows naturally on low bottom-lands but will also do well in poor, dry soils. Enemies: Practically free from disease and insects. Value for planting: The catalpa grows very rapidly and is cultivated in parks for ornament and in groves for commercial purposes. The _hardy catalpa_ is preferable to the _common catalpa_ for planting. Commercial value: The wood is extremely durable in contact with the soil and is consequently used for posts and railroad ties. Other characters: The _flowers_, which appear in late June and early July, are large, white and very showy. Other common names: _Indian bean_; _western catalpa_. Comparisons: The _white flowering dogwood_ (_Cornus florida_) is a small tree which also has its leaves in whorls of three or sometimes opposite. It can be readily told from other trees, however, by the small square plates into which the outer bark on the trunk divides itself, see Fig. 85, and by the characteristic drooping character of its branches. It is one of the most common plants in our eastern deciduous forests. It is extremely beautiful both in the spring and in the fall and is frequently planted for ornament. There are many varieties of dogwood in common use. WHITE MULBERRY (_Morus alba_) A small tree recognized by its _small round reddish brown buds_ and _light brown, finely furrowed_ (wavy looking) _bark_. The tree, probably a native of China, is grown under cultivation in eastern Canada and United States. It grows rapidly in moist soil and is not fastidious in its light requirements. Its chief value is for screening and for underplanting in woodlands. The _red mulberry_ (_Morus rubra_) is apt to be confused with the white mulberry, but differs in the following characters: The leaves of the red mulberry are rough on the upper side and downy on the under side, whereas the leaves of the white mulberry are smooth and shiny. The buds in the red are larger and more shiny than those of the white. The _Osage orange_ (_Toxylon pomiferum_) is similar to the mulberry in the light, golden color of its bark, but differs from it in possessing conspicuous spines along the twigs and branches and a more ridged bark. CHAPTER IV THE STRUCTURE AND REQUIREMENTS OF TREES To be able fully to appreciate trees, their mode of life, their enemies and their care, one must know something of their structure and life requirements. Structure of trees: Among the lower forms of plants there is very little distinction between the various parts--no differentiation into root, stem, or crown. Often the lower forms of animal and vegetable life are so similar that one cannot discriminate between them. But as we ascend in the scale, the various plant forms become more and more complex until we reach the tree, which is the largest and highest form of all plants. The tree is a living organism composed of cells like any other living organism. It has many parts, every one of which has a definite purpose. The three principal parts are: the stem, the crown, and the root. The stem: If we examine the cross-section of a tree, Fig. 86, we will notice that it is made up of numerous rings arranged in sections of different color and structure. The central part is known as the _pith_. Around the pith comes a dark, close-grained series of rings known as the _heartwood_, and outside the heartwood comes a lighter layer, the _sapwood_. The _cambium layer_ surrounds the sapwood and the _bark_ covers all. The cambium layer is the most important tissue of the tree and, together with part of the sapwood, transports the water and food of the tree. It is for this reason that a tree may be hollow, without heart and sapwood, and still produce foliage and fruit. [Illustration: FIG. 86.--The Cross-Section of a Tree.] The crown: The crown varies in form in different species and is developed by the growth of new shoots from buds. The bud grows out to a certain length and forms the branch. Afterwards it thickens only and does not increase in length. New branches will then form from other buds on the same branch. This explains in part the characteristic branching of trees, Fig. 87. [Illustration: FIG. 87.--Characteristic Form and Branching of Trees. The trees in the photograph are pin oaks.] The leaves are the stomach and lungs of the tree. Their broad blades are a device to catch the sunlight which is needed in the process of digesting the food of the tree. The leaves are arranged on the twigs in such a way as to catch the most sunlight. The leaves take up the carbonic acid gas from the air, decompose it under the influence of light and combine it with the minerals and water brought up by the roots from the soil. The resulting chemical combinations are the sugars and starches used by the cambium layer in building up the body of the tree. A green pigment, _chlorophyll_, in the leaf is the medium by which, with the aid of sunlight, the sugars are manufactured. [Illustration: FIG. 88.--Roots of a Hemlock Tree in their Search for Water.] The chlorophyll gives the leaf its green color, and this explains why a tree pales when it is in a dying condition or when its life processes are interfered with. The other colors of the leaf--the reds, browns and yellows of the fall or spring--are due to other pigments. These are angular crystals of different hues, which at certain times of the year become more conspicuous than at others, a phenomenon which explains the variation in the colors of the leaves during the different seasons. It is evident that a tree is greatly dependent upon its leaves for the manufacture of food and one can, therefore, readily see why it is important to prevent destruction of the leaves by insects or through over-trimming. The root: The root develops in much the same manner as the crown. Its depth and spread will vary with the species but will also depend somewhat upon the condition of the soil around it. A deep or a dry soil will tend to develop a deep root, while a shallow or moist soil will produce a shallow root, Fig. 88. The numerous fine hairs which cover the roots serve the purpose of taking up food and water from the soil, while the heavy roots help to support the tree. The root-hairs are extremely tender, are easily dried out when exposed to the sun and wind, and are apt to become overheated when permitted to remain tightly packed for any length of time. These considerations are of practical importance in the planting of trees and in the application of fertilizers. It is these fine rootlets far away from the trunk of the tree that have to be fed, and all fertilizers must, therefore, be applied at points some distance from the trunk and not close to it, where merely the large, supporting roots are located. In the cultivation of trees the same principle holds true. Requirements of trees: Trees are dependent upon certain soil and atmospheric conditions which influence their growth and development. (1) Influence of moisture: The form of the tree and its growth and structure depend greatly upon the supply of moisture. Botanists have taken the moisture factor as the basis of classification and have subdivided trees into those that grow in moist places (_hydrophytes_), those that grow in medium soils (_mesophytes_), and those that grow in dry places (_xerophytes_). Water is taken up by the roots of the tree from the soil. The liquid absorbed by the roots carries in solution the mineral salts--the food of the tree--and no food can be taken up unless it is in solution. Much of the water is used by the tree and an enormous amount is given off in the process of evaporation. [Illustration: FIG. 89.--Dead Branches at the Top Caused by Insufficient Water.] These facts will explain some of the fundamental principles in the care of trees. To a tree growing on a city street or on a lawn where nature fails to supply the requisite amount of water, the latter must be supplied artificially, especially during the hot summer months, or else dead branches may result as seen in Fig. 89. Too much thinning out of the crown causes excessive evaporation, and too much cutting out in woodlands causes the soil to dry and the trees to suffer for the want of moisture. This also explains why it is essential, in wooded areas, to retain on the ground the fallen leaves. In decomposing and mixing with the soil, the fallen leaves not only supply the trees with food material, but also tend to conserve moisture in the ground and to prevent the drying out of the soil. Raking off the leaves from wooded areas, a practice common in parks and on private estates--hurts the trees seriously. Some soils may have plenty of moisture, but may also be so heavily saturated with acids or salts that the tree cannot utilize the moisture, and it suffers from drought just the same as if there had been no moisture at all in the soil. Such soils are said to be "physiologically dry" and need treatment. In the development of disease, moisture is a contributing factor and, therefore, in cavities or underneath bandages where there is likely to be an accumulation of moisture, decay will do more damage than in places that are dry and exposed to the sun. (2) Influence of soil: Soil is made up of fine particles of sand and rock and of vegetable matter called _humus_. A tree will require a certain soil, and unsuitable soils can be very often modified to suit the needs of the tree. A deep, moderately loose, sandy loam, however, which is sufficiently aerated and well supplied with water, will support almost any tree. Too much of any one constituent will make a soil unfit for the production of trees. If too much clay is present the soil becomes "stiff." If too much vegetable matter is present, the soil becomes "sour." The physical character of the soil is also important. By physical character is meant the porosity which results from breaking up the soil. This is accomplished by ploughing or cultivation. In nature, worms help to do this for the soil, but on streets an occasional digging up of the soil about the base of the tree is essential. Humus or the organic matter in the soil is composed of litter, leaves and animal ingredients that have decayed under the influence of bacteria. The more vegetable matter in the humus, the darker the soil; and therefore a good soil such as one finds on the upper surface of a well-tilled farm has quite a dark color. When, however, a soil contains an unusual quantity of humus, it is known as "muck," and when there is still more humus present we find _peat_. Neither of these two soils is suitable for proper tree growth. [Illustration: FIG. 90.--A Tree in the Open. Note the full development of the wide crown with branches starting near the ground. The tree is the European larch.] (3) Influence of light: Light is required by the leaves in the process of assimilation. Cutting off some of the light from a tree affects its form. This is why trees grown in the open have wide-spreading crowns with branches starting near the ground as in Fig. 90, while the same species growing in the forest produces tall, lanky trees, free from branches to but a few feet from the top as in Fig. 91. Some trees can endure more shade than others, but all will grow in full light. This explains why trees like the beech, hemlock, sugar maple, spruce, holly and dogwood can grow in the shade, while the poplar, birch and willow require light. It also explains why, in the forest, the lower branches die and fall off--a process known in Forestry as "natural pruning," The influence of light on the form of trees should be well understood by all those who plant trees and by those designing landscape effects. [Illustration: FIG. 91.--A Tree in The Forest. Note the tall stem free from branches and the small, narrow crown.] (4) Influence of heat: Trees require a certain amount of heat. They receive it partly from the sun and partly from the soil. Evaporation prevents the overheating of the crown. The main stem of the tree is heated by water from the soil; therefore trees in the open begin growth in the spring earlier than trees in the forest because the soil in the open is warmer. Shrubs begin their growth earlier than trees because of the nearness of their crowns to their root systems. This also explains why a warm rain will start vegetation quickly. Too much heat will naturally cause excessive drying of the roots or excessive evaporation from the leaves and therefore more water is needed by the tree in summer than in winter. (5) Influence of season and frost: The life processes of a tree are checked when the temperature sinks below a certain point. The tree is thus, during the winter, in a period of rest and only a few chemical changes take place which lead up to the starting of vegetation. In eastern United States, growth starts in April and ceases during the latter part of August or in early September. The different parts of a tree may freeze solid during the winter without injury, provided the tree is a native one. Exotic trees may suffer greatly from extreme cold. This is one of the main reasons why it is always advisable to plant native trees rather than those that are imported and have not yet been acclimatized. Frosts during mid-winter are not quite as injurious as early and late frosts and, therefore, if one is going to protect plants from the winter's cold, it is well to apply the covering early enough and to keep it on late enough to overcome this difficulty. The mechanical injuries from frost are also important. Snow and sleet will weigh down branches but rarely break them, while frost will cause them to become brittle and to break easily. Those who climb and prune trees should be especially cautious on frosty days. (6) Influence of air: On the under side of leaves and on other surfaces of a tree little pores known as _stomata_ may be found. In the bark of birch and cherry trees these openings are very conspicuous and are there known as _lenticels_. These pores are necessary for the breathing of the tree (respiration), whereby carbonic acid gas is taken in from the air and oxygen given out. The process of assimilation depends upon this breathing process and it is therefore evident that when the stomata are clogged as may occur where a tree is subjected to smoke or dust, the life processes of the tree will be interfered with. The same injurious effect results when the stomata of the roots are interfered with. Such interference may occur in cases where a heavy layer of soil is piled around the base of a tree, where the soil about the base of a tree is allowed to become compact, where a tree is planted too deep, or where the roots are submerged under water for any length of time. In any case the air cannot get to the roots and the tree suffers. Nature takes special cognizance of this important requirement in the case of cypress trees, which habitually grow under water. Here the trees are provided with special woody protuberances known as "cypress knees," which emerge above water and take the necessary air. See Fig. 18. Conclusions: From the foregoing it will be seen that trees have certain needs that nature or man must supply. These requirements differ with the different species, and in all work of planting and care as well as in the natural distribution of trees it is both interesting and necessary to observe these individual wants, to select species in accordance with local conditions and to care for trees in conformity with their natural needs. CHAPTER V WHAT TREES TO PLANT AND HOW The following classification will show the value of the more important trees for different kinds of planting. The species are arranged in the order of their merit for the particular object under consideration and the comments accompanying each tree are intended to bring out its special qualifications for that purpose. Conditions for tree growth in one part of the country differ from those of another and these lists, especially applicable to the Eastern States, may not at all fit some other locality. TREES BEST FOR THE LAWN DECIDUOUS 1. American elm (_Ulmus americana_) One of the noblest of trees. Possesses a majestic, wide-spreading, umbrella-shaped crown; is easily transplanted, and is suited to a variety of soils. 2. Pin oak (_Quercus palustris_) Has a symmetrical crown with low-drooping branches; requires a moist situation. 3. European linden (_Tilia microphylla_) Possesses a beautiful shade-bearing crown; grows well in ordinary soil. 4. Red maple (_Acer rubrum_) Shows pleasing colors at all seasons; grows best in a fairly rich, moist soil. 5. Copper beech (_Fagus sylvatica_, _alropurpurea_) Exceedingly beautiful in form, bark, and foliage and possesses great longevity and sturdiness. It is difficult to transplant and therefore only small trees from 6 to 10 feet in height should be used. 6. Coffee tree (_Gymnocladus dioicus_) A unique and interesting effect is produced by its coarse branches and leaves. It is free from insects and disease; requires plenty of light; will grow in poor soils. 7. European white birch (_Belula alba_) A graceful tree and very effective as a single specimen on the lawn, or in a group among evergreens; should be planted in early spring, and special care taken to protect its tender rootlets. 8. Gingko or Maiden-hair tree (_Gingko biloba_) Where there is plenty of room for the spread of its odd branches, the gingko makes a picturesque specimen tree. It is hardy and free from insect pests and disease. 9. Horsechestnut (_Aesculus hippocastanum_) Carries beautiful, showy flowers, and has a compact, symmetrical low-branched crown; is frequently subject to insects and disease. The red flowering horsechestnut (_A. rubicunda_) is equally attractive. [Illustration: FIG. 92.--A Lawn Tree. European Weeping Beech.] 10. Sugar maple (_Acer saccharum_) Has a symmetrical crown and colors beautifully in the fall; requires a rich soil and considerable moisture. 11. Soulange's magnolia (_Magnolia soulangeana_) Extremely hard and flowers in early spring before the leaves appear. 12. Flowering dogwood (_Cornus florida_) Popular for its beautiful white flowers in the early spring and the rich coloring of its leaves in the fall; does not grow to large size. The red-flowering variety of this tree, though sometimes not quite as hardy, is extremely beautiful. 13. Japanese maple (_Acer polymorphum_) It has several varieties of different hues and it colors beautifully in the fall; it does not grow to large size. CONIFEROUS 14. Oriental spruce (_Picea orientalis_) Forms a dignified, large tree with a compact crown and low branches; is hardy. 15. Austrian pine (_Pinus austriaca_) Is very hardy; possesses a compact crown; will grow in soils of medium quality. 16. Bhotan pine (_Pinus excelsa_) Grows luxuriantly; is dignified and beautiful; requires a good soil, and in youth needs some protection from extreme cold. 17. White pine (_Pinus strobus_) Branches gracefully and forms a large, dignified tree; will thrive on a variety of soils. 18. European larch (_Larix europaea_) Has a beautiful appearance; thrives best in moist situations. 19. Blue spruce (_Picea pungens_) Extremely hardy; forms a perfect specimen plant for the lawn. 20. Japanese umbrella pine (_Sciadopitys verlicillata_) Very hardy; retains a compact crown. An excellent specimen plant when grouped with other evergreens on the lawn. Does not grow to large size. 21. Mugho pine (_Pinus mughus_) A low-growing evergreen; hardy; important in group planting. 22. Obtuse leaf Japanese cypress (_Retinospora obtusa_) Beautiful evergreen of small size; hardy; desirable for group planting. 23. English yew (_Taxus baccata_) An excellent evergreen usually of low form; suitable for the lawn, massed with others or as a specimen plant; will grow in the shade of other trees. There are various forms of this species of distinctive value. TREES BEST FOR THE STREET 1. Oriental sycamore (_Platanus orientalis_) Very hardy; will adapt itself to city conditions; grows fairly fast and is highly resistant to insects and disease. 2. Norway maple (_Acer platanoides_) Very hardy; possesses a straight trunk and symmetrical crown; is comparatively free from insects and disease and will withstand the average city conditions. 3. Red oak (_Quercus rubra_) Fastest growing of the oaks; very durable and highly resistant to insects and disease; will grow in the average soil of the city street. [Illustration: FIG. 93.--Street Trees. Norway Maples.] 4. Gingko (_Gingko biloba_) Hardy and absolutely free from insects and disease; suited for narrow streets, and will permit of close planting. 5. European linden (_Tilia microphylla_) Beautiful shade-bearing crown; is very responsive to good soil and plenty of moisture. 6. American elm (_Ulmus americana_) When planted in rows along an avenue, it forms a tall majestic archway of great beauty. It is best suited for wide streets and should be planted further apart than the other trees listed above. Requires a fairly good soil and plenty of moisture, and is therefore not suited for planting in the heart of a large city. 7. Pin oak (_Quercus palustris_) This tree exhibits its greatest beauty when its branches are allowed to droop fairly low. It, moreover, needs plenty of moisture to thrive and the tree is therefore best suited for streets in suburban sections, where these conditions can be more readily met. 8. Red maple (_Acer rubrum_) Beautiful in all seasons of the year; requires a rich soil and considerable moisture. TREES BEST FOR WOODLAND FOR OPEN PLACES 1. Red oak (_Quercus rubra_) Grows rapidly to large size and produces valuable wood; will grow in poor soil. 2. White pine (_Pinus strobus_) Rapid grower; endures but little shade; wood valuable; will do well on large range of soils. 3. Red pine (_Pinus resinosa_) Very hardy; fairly rapid growing tree. 4. Tulip tree (_Liriodendron tulipifera_) Grows rapidly into a stately forest tree with a clear tall trunk; wood valuable; requires a fairly moist soil. Use a small tree, plant in the spring, and pay special attention to the protection of the roots in planting. 5. Black locust (_Robinia pseudacacia_) Grows rapidly; adapts itself to poor, sandy soils. The wood is suitable for posts and ties. 6. White ash (_Fraxinus americana_) Grows rapidly; prefers moist situations. Wood valuable. 7. American elm (_Ulmus americana_) Grows rapidly to great height; will not endure too much shade; does best in a deep fertile soil. Wood valuable. 8. European larch (_Larix europaea_) Grows rapidly; prefers moist situations. [Illustration: FIG. 94.--Woodland Trees. Red Oaks.] FOR PLANTING UNDER THE SHADE OF OTHER TREES 9. Beech (_Fagus_) Will stand heavy shade; holds the soil well along banks and steep slopes. Both the American and the English species are desirable. 10. Hemlock (_Tsuga canadensis_) Will stand heavy shade and look effective in winter as well as in summer. 11. Dogwood (_Cornus florida_) Will grow under other trees; flowers beautifully in the spring and colors richly in the fall. 12. Blue beech (_Carpinus caroliniana_) Native to the woodlands of the Eastern States; looks well in spring and fall. TREES BEST FOR SCREENING 1. Hemlock (_Tsuga canadensis_) Will stand shearing and will screen in winter as well as in summer. Plant from 2 to 4 feet apart to form a hedge. 2. Osage orange (_Toxylon pomiferum_) Very hardy. Plant close. 3. English hawthorn (_Crataegus oxyacantha_) Flowers beautifully and grows in compact masses. Plant close. 4. Lombardy poplar (_Populus nigra var. italica_) Forms a tall screen and grows under the most unfavorable conditions. Plant 8 to 12 feet apart. Quality of trees: Trees grown in a nursery are preferable for transplanting to trees grown in the forest. Nursery-grown trees possess a well-developed root system with numerous fibrous rootlets, a straight stem, a symmetrical crown, and a well-defined leader. Trees grown in neighboring nurseries are preferable to those grown at great distances, because they will be better adapted to local climatic and soil conditions. The short distances over which they must be transported also will entail less danger to the roots through drying. For lawn planting, the branches should reach low to the ground, while for street purposes the branches should start at about seven feet from the ground. For street planting, it is also important that the stem should be perfectly straight and about two inches in diameter. For woodland planting, the form of the tree is of minor consideration, though it is well to have the leader well defined here as well as in the other cases. See Fig. 95. When and how to procure the trees: The trees should be selected in the nursery personally. Some persons prefer to seal the more valuable specimens with leaden seals. Fall is the best time to make the selection, because at that time one can have a wider choice of material. Selecting thus early will also prevent delay in delivery at the time when it is desired to plant. When to plant: The best time to plant trees is early spring, just before growth begins, and after the frost is out of the ground. From the latter part of March to the early part of May is generally the planting period in the Eastern States. Where one has to plant both coniferous and deciduous trees, it is best to get the deciduous in first, and then the conifers. How to plant: The location of the trees with relation to each other should be carefully considered. On the lawn, they should be separated far enough to allow for the full spread of the tree. On streets, trees should be planted thirty to thirty-five feet apart and in case of the elm, forty to fifty feet. In woodlands, it is well to plant as close as six feet apart where small seedlings are used and about twelve feet apart in the case of trees an inch or more in diameter. An abundance of good soil (one to two cubic yards) is essential with each tree where the specimens used are an inch or two in diameter. A rich mellow loam, such as one finds on the surface of a well-tilled farm, is the ideal soil. Manure should never be placed in direct contact with the roots or stem of the tree. Protection of the roots from drying is the chief precaution to be observed during the planting process, and for this reason a cloudy day is preferable to a sunny day for planting. In case of evergreens, the least exposure of the roots is liable to result disastrously, even more so than in case of deciduous trees. This is why evergreens are lifted from the nursery with a ball of soil around the roots. All bruised roots should be cut off before the tree is planted, and the crown of the tree of the deciduous species should be slightly trimmed in order to equalize the loss of roots by a corresponding decrease in leaf surface. The tree should be set into the tree hole at the same depth that it stood in the nursery. Its roots, where there is no ball of soil around them, should be carefully spread out and good soil should be worked in carefully with the fingers among the fine rootlets. Every root fibre is thus brought into close contact with the soil. More good soil should be added (in layers) and firmly packed about the roots. The last layer should remain loose so that it may act as a mulch or as an absorbent of moisture. The tree should then be thoroughly watered. [Illustration: FIG. 95.--Specifications for a Street Tree.] After care: During the first season the tree should be watered and the soil around its base slightly loosened at least once a week, especially on hot summer days. Where trees are planted on streets, near the curb, they should also be fastened to stakes and protected with a wire guard six feet high. See Fig. 95. Wire netting of ½-inch mesh and 17 gauge is the most desirable material. [Illustration: FIG. 96.--A Home Nursery. (Austrian pines in front.)] Suggestions for a home or school nursery: Schools, farms, and private estates may conveniently start a tree nursery on the premises and raise their own trees. Two-year seedling trees or four-year transplants are best suited for this purpose. These may be obtained from several reliable nurseries in various parts of the country that make a specialty of raising small trees for such purposes. The cost of such trees should be from three to fifteen dollars per thousand. The little trees, which range from one to two feet in height, will be shipped in bundles. Immediately upon arrival, the bundles should be untied and the trees immersed in a pail containing water mixed with soil. The bundles should then be placed in the ground temporarily, until they can be set out in their proper places. In this process, the individual bundles should be slanted with their tops toward the south, and the spot chosen should be cool and shady. At no time should the roots of these plants be exposed, even for a moment, to sun and wind, and they should always be kept moist. The little trees may remain in this trench for two weeks without injury. They should then be planted out in rows, each row one foot apart for conifers and two feet for broadleaf trees. The individual trees should be set ten inches apart in the row. Careful weeding and watering is the necessary attention later on. CHAPTER VI THE CARE OF TREES STUDY I. INSECTS INJURIOUS TO TREES AND HOW TO COMBAT THEM In a general way, trees are attacked by three classes of insects, and the remedy to be employed in each case depends upon the class to which the insect belongs. The three classes of insects are: 1. Those that *chew* and swallow some portion of the leaf; as, for example, the elm leaf beetle, and the tussock, gipsy, and brown-tail moths. 2. Those that *suck* the plant juices from the leaf or bark; such as the San José scale, oyster-shell, and scurfy scales, the cottony maple scale, the maple phenacoccus on the sugar maples, and the various aphides on beech, Norway maple, etc. 3. Those that *bore* inside of the wood or inner bark. The principal members of this class are the leopard moth, the hickory-bark borer, the sugar-maple borer, the elm borer, and the bronze-birch borer. The chewing insects are destroyed by spraying the leaves with arsenate of lead or Paris green. The insects feed upon the poisoned foliage and thus are themselves poisoned. The sucking insects are killed by a contact poison: that is, by spraying or washing the affected parts of the tree with a solution which acts externally on the bodies of the insects, smothering or stifling them. The standard solutions for this purpose are kerosene emulsion, soap and water, tobacco extract, or lime-sulfur wash. [Illustration: FIG. 97.--A Gas-power Spraying Apparatus.] The boring insects are eliminated by cutting out the insect with a knife, by injecting carbon bisulphide into the burrow and clogging the orifice immediately after injection with putty or soap, or in some cases where the tree is hopelessly infested, by cutting down and burning the entire tree. [Illustration: FIG. 98.--A Barrel Hand-pump Spraying Outfit.] For information regarding the one of these three classes to which any particular insect belongs, and for specific instructions on the application of a remedy, the reader is advised to write to his State Entomologist or to the U.S. Bureau of Entomology at Washington, D.C. The letter should state the name of the tree affected, together with the character of the injury, and should be accompanied by a specimen of the insect, or by a piece of the affected leaf or bark, preferably by both. The advice received will be authentic and will be given without charge. [Illustration: FIG. 99.--Egg-masses of the Tussock Moth.] When to spray: _In the case of chewing insects_, the latter part of May is the time to spray. The caterpillars hatch from their eggs, and the elm leaf beetle leaves its winter quarters at that time. _In the case of sucking insects_, the instructions will have to be more specific, depending upon the particular insect in question. Some sucking insects can best be handled in May or early June when their young emerge, others can be effectively treated in the fall or winter when the trees are dormant. How to spray: Thoroughness is the essential principle in all spraying. In the case of leaf-eating insects, this means covering every leaf with the poison and applying it to the under side of the leaves, where the insects generally feed. In the case of sucking insects, thoroughness means an effort to touch every insect with the spray. It should be borne in mind that the insect can be killed only when hit with the chemical. The solution should be well stirred, and should be applied by means of a nozzle that will coat every leaf with a fine, mist-like spray. Mere drenching or too prolonged an application will cause the solution to run off. Special precautions should be taken with contact poisons to see that the formula is correct. Too strong a solution