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                           THE GENUS PINUS

               PUBLICATIONS OF THE ARNOLD ARBORETUM No. 5




                                 THE

                             GENUS PINUS

                                 BY

                         GEORGE RUSSELL SHAW

                  [Illustration: Printer's Logo.]

          Es giebt jedoch auch Arten--und dieses ist
          für den Systematiker wie für den Physiologen
          gleich wichtig--welche sich den wechselnden
          Bedingungen der Feuchtigkeit so vollkommen
          anpassen, dass ihre extremen Formen zu
          ungleichen Arten zu gehören scheinen.

                                        _Schimper._


                              CAMBRIDGE
                     PRINTED AT THE RIVERSIDE PRESS
                                1914

               REPRINTED 1958 BY THE MURRAY PRINTING COMPANY
                      FORGE VILLAGE, MASSACHUSETTS




  CONTENTS

                                                        Page     Plate

  PART 1 CHARACTERS OF THE GENUS                           1

    Cotyledon, Primary Leaf, Bud and Branchlet          1, 2         I

    Secondary Leaves                                       2        II

      External Characters                                  4

      Internal Characters                                  4

    Flowers and Conelet                                    7       III

    Cone                                                   8        IV

      Phyllotaxis                                         12         V

      Cone-tissues and Seeds                           12-16        VI

    Wood                                                  17       VII

    Bark                                                  18

  PART 2 CLASSIFICATION OF THE SPECIES                    22

    Sections, subsections and groups                      25

    Section Haploxylon                                    26

      Subsection Cembra                                   26

        Group Cembrae                                     26

          Pinus Koraiensis, Cembra, Albicaulis        26, 27      VIII

        Group Flexiles                                    28

          Pinus Flexilis, Armandi                     28, 30        IX

        Group Strobi                                      30

          Pinus Ayacahuite, Lambertiana               30, 32         X

                Parviflora, Peuce, Excelsa            32, 34        XI

                Monticola, Strobus                    34, 36       XII

      Subsection Paracembra                               36

        Group Cembroides                                  38

          Pinus Cembroides, Pinceana, Nelsonii        38, 40      XIII

        Group Gerardianae                                 40

          Pinus Bungeana, Gerardiana                  40, 42       XIV

        Group Balfourianae                                42

          Pinus Balfouriana, Aristata                 42, 44        XV

    Section Diploxylon                                    44

      Subsection Parapinaster                             44

        Group Leiophyllae                                 44

          Pinus Leiophylla, Lumholtzii                44, 46       XVI

        Group Longifoliae                                 46

          Pinus Longifolia, Canariensis               46, 48      XVII

        Group Pineae                                      48

          Pinus Pinea                                     48     XVIII

      Subsection Pinaster                                 50

        Group Laricionea                                  51

          Pinus Resinosa, Tropicalis                  51, 52       XIX

                Massoniana, Densiflora                    52        XX

                Sylvestris, Montana                       54       XXI

                Luchuensis, Thunbergii, Nigra         56, 58      XXII

                Merkusii, Sinensis, Insularis         58, 60     XXIII

        Group Australes                                   62

          Pinus Pseudostrobus                             62      XXIV

                Montezumae                                64       XXV

                Ponderosa                                 66      XXVI

                Teocote, Lawsonii                         68     XXVII

                Occidentalis, Palustris                   70    XXVIII

                Caribaea                                  70      XXIX

                Taeda, Glabra, Echinata               72, 74       XXX

        Group Insignes                                    76

          Pinus Pringlei, Oocarpa                     76, 78      XXXI

                Halepensis, Pinaster                  78, 80     XXXII

                Virginiana, Clausa                        80    XXXIII

                Rigida, Serotina, Pungens             82, 84     XXXIV

                Banksiana, Contorta                       84      XXXV

                Greggii, Patula                           86     XXXVI

                Muricata, Attenuata, Radiata          86, 88    XXXVII

        Group Macrocarpae                                 90

          Pinus Torreyana, Sabiniana                      90   XXXVIII

                Coulteri                                  93     XXXIX


  INDEX                                                   94




INTRODUCTION


This discussion of the characters of Pinus is an attempt to determine
their taxonomic significance and their utility for determining the
limits of the species. A systematic arrangement follows, based on the
evolution of the cone and seed from the comparatively primitive
conditions that appear in Pinus cembra to the specialized cone and
peculiar dissemination of Pinus radiata and its associates. This
arrangement involves no radical change in existing systems. The new
associations in which some of the species appear are the natural result
of another point of view.

Experience with Mexican species has led me to believe that a Pine can
adapt itself to various climatic conditions and can modify its growth in
response to them. Variations in dimensions of leaf or cone, the number
of leaves in the fascicle, the presence of pruinose branchlets, etc.,
which have been thought to imply specific distinctions, are often the
evidence of facile adaptability. In fact such variations, in correlation
with climatic variation, may argue, not for specific distinction, but
for specific identity. The remarkable variation in the species may be
attributed partly to this adaptability, partly to a participation, more
or less pronounced, in the evolutionary processes that culminate in the
serotinous Pines.




PART I

CHARACTERS OF THE GENUS


THE COTYLEDON. Plate I, figs. 1-3.

The upper half of the embryo in Pinus is a cylindrical fascicle of 4 to
15 cotyledons (fig. 1). The cross-section of a cotyledon is, therefore,
a triangle whose angles vary with the number composing the fascicle.
Sections from fascicles of 10 and of 5 cotyledons are shown in figs. 2
and 3. Apart from this difference cotyledons are much alike. Their
number varies and is indeterminate for all species, while any given
number is common to so many species that the character is of no value.


THE PRIMARY LEAF. Plate I, figs. 4-6.

Primary leaves follow the cotyledons immediately (fig. 4) and assume the
usual functions of foliage for a limited period, varying from one to
three years, secondary fascicles appearing here and there in their
axils. With the permanent appearance of the secondary leaves the green
primaries disappear and their place is taken by bud-scales, which in the
spring and summer persist as scarious bracts, each subtending a fascicle
of secondary leaves. At this stage the bracts present two important
distinctions.

    1. The bract-base is non-decurrent, like the leaf-base
         of Abies                                                fig. 5.
    2. The bract-base is decurrent, like the leaf-base of Picea  fig. 6.

The two sections of the genus, Haploxylon and Diploxylon, established by
Koehne on the single and double fibro-vascular bundle of the leaf, are
even more accurately characterized by these two forms of
bract-insertion. The difference between them, however, is most obvious
on long branchlets with wide intervals between the leaf-fascicles.

The bracts of spring-shoots are the scarious bud-scales of the previous
winter; but the bracts of summer-shoots have the form and green color of
the primary leaf.


THE BUD. Plate I, figs. 7-11.

The winter-bud is an aggregate of minute buds, each concealed in the
axil of a primary leaf converted into a scarious, more or less
fimbriate, bud-scale. Buds from which normal growth develops appear only
at the nodes of the branches. On uninodal branchlets they form an apical
group consisting of a terminal bud with a whorl of subterminal buds
about its base. On multinodal branchlets the inner nodes bear lateral
buds which may be latent.

Fig. 7 represents a magnified bud of P. resinosa, first immersed in
alcohol to dissolve the resin, then deprived of its scales. This bud
contains both fascicle-buds, destined for secondary leaves, and larger
paler buds at its base. These last are incipient staminate flowers,
sufficiently developed for recognition. Such flower-bearing buds are
characteristic of the Hard Pines in distinction from the Soft Pines
whose staminate flowers cannot be identified in the bud.

The want of complete data leaves the invariability of this distinction
in question, but with all species that I have examined, the flowers of
Hard Pines are further advanced at the end of the summer. In the
following year they open earlier than those of Soft Pines in the same
locality. The staminate flowers of some Hard Pines (resinosa,
sylvestris, etc.,) are not apparent without removing the bud-scales,
but, with most Hard Pines, they form enlargements of the bud (fig. 9).

Invisible or latent buds are present at the nodes and at the apex of
dwarf shoots. The former are the origin of the numerous shoots that
cover the trunk and branches of P. rigida, leiophylla and a few other
species (fig. 10). The latter develop into shoots in the centre of a
leaf-fascicle (fig. 11) when the branchlet, bearing the fascicle, has
been injured.

The size, color and form of buds, the presence of resin in quantity,
etc., assist in the diagnosis of species. Occasionally a peculiar bud,
like that of P. palustris, may be recognized at once.


THE BRANCHLET. Plate I, figs. 12-14.

The branchlet, as here understood, is the whole of a season's growth
from a single bud, and may consist of a single internode (uninodal, fig.
12-a) or of two or more internodes (multinodal, fig. 13), each internode
being defined by a leafless base and a terminal node of buds.

The spring-shoot is uninodal in all Soft Pines and in many Hard Pines,
but, in P. taeda and its allies and in species with serotinous cones, it
is more or less prevalently multinodal.

The uninodal spring-shoot may remain so throughout the growing season
and become a uninodal branchlet. Or a summer-shoot may appear on
vigorous branches of any species with the result of converting a
uninodal spring-shoot into an imperfect multinodal branchlet. The
summer-shoot may be recognized, during growth, by its green, not
scarious bracts and, at the end of the season, by the imperfect growth
of its wood and foliage (fig. 14).

The perfect multinodal branchlet is formed in the winter-bud (fig. 8-a)
and the spring-shoot is multinodal. It is gradually evolved among the
Hard Pines, where it may be absent, rare, frequent or prevalent,
according to the species. In fact there is, in Pinus, an evolutionary
tendency toward multinodal growth, with its beginnings in the
summer-shoot and its culmination in the multinodal winter-bud, most
prevalent among the serotinous Pines.

The multinodal shoot is never invariable in a species, but is rare,
common or prevalent. This condition prevents its employment for grouping
species. For Pines are not sharply divided into multinodal and uninodal
species, and no exact segregation of them, based on this difference, is
possible. In fact the character is unequally developed among closely
related species, such as P. palustris and caribaea. Both produce
multinodal shoots, but the former so rarely that it should be classed as
a uninodal species, while the latter is characteristically multinodal.
The multinodal spring-shoot, however, has a certain correlative value in
its relation to other evolutionary processes that are obvious in the
genus.

The length of the branchlet is much influenced by different soils and
climates. In species able to adapt themselves to great changes, the
length of the internode may vary from 50 cm. or more to 1 cm. or less.
In the latter case the branch is a series of very short leafless joints
terminated by a crowded penicillate tuft of leaves (fig. 12-b). Such a
growth may be seen on any species (ponderosa, albicaulis, resinosa,
etc.) that can survive exposure and poor nourishment.

The presence of wax, as a bloom on the branchlet, is associated with
trees in arid localities, especially Mexico, where it is very common.
With several species the character is inconstant, apparently dependent
on environment, and is a provision against too rapid transpiration.

The branchlet furnishes evidence of the section to which the species
belongs, for the bract-bases persist after the bracts have fallen away.
The color of the branchlet, its lustre, the presence of minute hairs,
etc., are often suggestions for determining species.

[Illustration: PLATE I. PRIMARY LEAF, BUD AND BRANCHLET]


THE SECONDARY LEAF. Plate II.

Secondary leaves, the permanent foliage of Pines, are borne on
dwarf-shoots in the axils of primary leaves. They form cylindrical
fascicles, rarely monophyllous, prevalently of 2, 3 or 5 leaves,
occasionally of 4, 6, 7, or 8 leaves. The scales of the fascicle-bud
elongate into a basal sheath, deciduous (fig. 15) in all Soft Pines
except P. Nelsonii, persistent (fig. 16) in all Hard Pines except P.
leiophylla and Lumholtzii. Inasmuch as these three species are easily
recognized, the fascicle-sheath is useful for sectional distinctions.


EXTERNAL CHARACTERS.

The number of leaves in the fascicle is virtually constant in most
species, the variations being too rare to be worthy of consideration.
With some species, however, heteromerous fascicles are normal. The
influences that cause this variation are not always apparent (echinata,
etc.), but with P. ponderosa, leiophylla, sinensis and others, the
number of leaves in the fascicle is, in some degree, dependent on
climatic conditions, the smaller number occurring in colder regions. In
Mexico, for example, where snow-capped mountains lie on subtropical
table-lands and extremes of temperature are in juxtaposition, the
conditions are favorable for the production of species with heteromerous
fascicles, and the number of leaves in the fascicle possesses often
climatic rather than specific significance.

Among conifers, the leaf of Pinus attains extraordinary length with
great variation, from 5 cm. or less to 50 cm. or more, the maximum for
each species being usually much more than twice the minimum. Climate is
the predominating influence; for the shortest leaves occur on alpine and
boreal species, the longest leaves on species in or near the tropics.

The length of the leaf is complicated by the peculiarities of individual
trees and by pathological influences; as a general rule, however, the
length of leaves is less or greater according to unfavorable or
favorable conditions of temperature, moisture, soil and exposure.
Therefore the dimensions of the leaf may be misleading. It can be said,
however, that certain species always produce short leaves, others leaves
of medium length, and others very long leaves.

Persistence of the leaf varies with the species and with the individual
tree. But it is noteworthy that the longest persistence is associated
with short leaves (Balfouriana, albicaulis, montana, etc.).


INTERNAL CHARACTERS.

Since the leaf-fascicle is cylindrical, the cross-section of a leaf is a
sector, its proportional part, of a circle. Theoretically the leaf, in
section, should indicate the number of leaves composing its fascicle.
This is absolutely true for fascicles of two leaves only. No fascicle of
five leaves, that I have examined, is equally apportioned among its five
members. It may be divided in various ways, one of which is shown in
fig. 18, where the leaf (a) might be mistaken for one of a fascicle of
3, and the leaf (b) for one of a fascicle of 6. Therefore if absolute
certainty is required, a fascicle of triquetral leaves is best
determined by actual count.

The transverse section of a leaf may be conveniently divided into three
distinct parts--1, the dermal tissues, epiderm, hypoderm and stomata
(fig. 17-a)--2, the green tissue, containing the resin-ducts (fig.
17-b)--3, the stelar tissues, enclosed by the endoderm and containing
the fibro-vascular bundle (fig. 17-c).


THE DERMAL TISSUES OF THE LEAF.

The stomata of Pine leaves are depressed below the surface and interrupt
the continuity of epiderm and hypoderm. They are wanting on the dorsal
surface of the leaves of several Soft Pines, constantly in some species,
irregularly in others. In Hard Pines, however, all surfaces of the leaf
are stomatiferous. In several species of the Soft Pines the longitudinal
lines of stomata are very conspicuous from the white bloom which
modifies materially the general color of the foliage.

Under the action of hydrochloric acid the hypoderm is sharply
differentiated from the epiderm by a distinct reddish tint, but without
the aid of a reagent the two tissues do not always differ in appearance.
The cells of epiderm and hypoderm may be so similar that they appear to
form a single tissue. In most species, however, the epiderm is distinct,
while the cells of the hypoderm are either uniform, with equally thin
or thick walls--or biform, with very thin walls in the outer row of
cells and very thick walls in the inner row or rows of cells--or
multiform, with cell-walls gradually thicker toward the centre of the
leaf. These conditions may be tabulated as follows--

    Cells of epiderm and hypoderm similar              fig. 19.
    Cells of epiderm and hypoderm distinct.
      Cells of hypoderm uniform, thin or thick    figs. 20, 21.
      Cells of hypoderm biform                         fig. 22.
      Cells of hypoderm multiform                      fig. 23.

The biform hypoderm is not always obvious (clausa, Banksiana, etc.)
where in some leaves there is but one row of cells. But with the
examination of other leaves one or more cells of a second row will be
found with very thick walls. Among Hard Pines there is no Old World
species with a biform hypoderm. But there are a few American species
with uniform hypoderm (resinosa, tropicalis, patula and Greggii); while,
in some leaves of the few American Hard Pines with multiform hypoderm,
the uniform hypoderm is a variation.


THE GREEN TISSUE.

In this tissue are the resin-ducts, each with a border of cells,
corresponding in appearance and in chemical reaction with the cells of
the hypoderm and with thinner or thicker walls. With reference to the
green tissue the foliar duct may be in one of four positions.

    1. External   against the hypoderm                    fig. 24.
    2. Internal   against the endoderm                    fig. 28.
    3. Medial     in the green tissue, touching neither
                    hypoderm nor endoderm                 fig. 26.
    4. Septal     touching both endoderm and hypoderm,
                    forming a septum                      fig. 30.

Among the Soft Pines the external duct is invariable in the subsection
Paracembra. It is also characteristic of the Strobi, where it is
sometimes associated with a medial duct. In the Cembrae and the
Flexiles, however, the ducts are external in some species, or medial or
both in others, without regard to the affinities of these species.

Among the Hard Pines the external duct is characteristic of the Old
World, there being but two American Pines with this character (resinosa
and tropicalis). The internal duct is peculiar to Hard Pines of the New
World, its presence in Old World species being extremely rare. The
medial duct is common to species of both hemispheres, either alone or in
association with ducts in other positions (figs. 25, 27). The septal
duct is peculiar to a few species (oocarpa, tropicalis, and less
frequently Pringlei and Merkusii). I have also seen it in a leaf of P.
canariensis. The internal and septal ducts appear to be confined to the
species of warm-temperate or tropical countries.

The number of resin-ducts of a single leaf may be limited to two or
three (strobus, koraiensis, etc.), but in many species it is exceedingly
variable and often large (pinaster, sylvestris, etc.). Eighteen or more
ducts in a single leaf have been recorded. Such large numbers are
peculiar to Pinus. Occasionally a single leaf, possibly the leaves of a
single tree, may be without ducts, but this is never true of all the
leaves of a species.


THE STELAR TISSUES.

The walls of the endoderm are, in most species, uniform, but, with P.
albicaulis and some species of western North America, the outer walls of
the cells are conspicuously thickened (fig. 32). Both thin and thick
walls may be found among the leaves of the group Macrocarpae and of the
species longifolia.

The fibro-vascular bundle of the leaf is single in Soft Pines, double in
Hard Pines. This distinction is employed by Koehne as the basis of his
two sections, Haploxylon and Diploxylon. The double bundle is usually
obvious even when the two parts are contiguous, but they are sometimes
completely merged into an apparently single bundle. This condition,
however, is never constant in a Hard Pine, and a little investigation
will discover a leaf with a true double bundle.

Some cells about the fibro-vascular bundle acquire thick walls with the
appearance and chemical reaction of the hypoderm cells. Among the Soft
Pines this condition is most obvious in the group Cembroides. Among the
Hard Pines it appears in all degrees of development, being absent (figs.
24, 25), sometimes in irregular lines above and below the bundle (figs.
26, 27, 30, 31), or forming a conspicuous tissue between and partly
enclosing the two parts of the bundle (figs. 28, 29).

The leaf-section furnishes sectional and other lesser distinctions. It
is often decisive in separating species otherwise difficult to
distinguish (nigra and resinosa or Thunbergii and sinensis, etc.).
Sometimes it is sufficiently distinct to determine a species without
recourse to other characters (tropicalis, oocarpa, Merkusii, etc.). An
intimate knowledge of the leaf-section, with an understanding of the
limits of its variation, is a valuable equipment for recognizing
species.

[Illustration: PLATE II. SECONDARY LEAVES]


THE FLOWERS. Plate III, figs. 33-39.

The flowers in Pinus are monoecious, the pistillate in the position of a
long shoot, taking the place of a subterminal or lateral bud, the
staminate in the position of a dwarf-shoot, taking the place of a
leaf-fascicle but confined to the basal part of the internode.

Pistillate flowers are single or verticillate. On multinodal shoots they
are often multiserial, appearing on two or more nodes of the same
spring-shoot (fig. 33). On uninodal shoots they are necessarily
subterminal (fig. 34), the lateral pistillate flower being possible only
on multinodal shoots (fig. 35) where it is often associated with the
subterminal flower (fig. 33). Like the multinodal shoot, on which its
existence depends, the lateral pistillate flower cannot be employed for
grouping the species. It is merely the frequent, but not the essential,
evidence of condition of growth that is more perfectly characterized by
the shoot itself.

Staminate catkins are in crowded clusters, capitate or elongate (figs.
36, 37), but with much variation in the number of catkins in each
cluster. In P. rigida I have found single catkins or clusters of all
numbers from two to seventy or more. In P. Massoniana and P. densiflora
a cluster attains such unusual length (fig. 37) that this character
becomes a valuable distinction between these species and P. sinensis,
which has short-capitate clusters. The catkins differ much in size, the
largest being found among the Hard Pines.

In the connective of the binate pollen-sacs there is a notable
difference (figs. 38, 39), the smaller form being characteristic of the
Soft Pines. But this is not invariable (excelsa, sylvestris, etc.), and
the absence of complete data does not permit an accurate estimate of its
importance.


THE CONELET. Plate III, figs. 40-45.

After pollination the pistillate flower closes and becomes the conelet,
the staminate flowers withering and falling away. The conelet makes no
appreciable growth until the following year. Like the pistillate flower
it may be subterminal or lateral, but a subterminal pistillate flower
may become a pseudolateral conelet by reason of a summer-growth (fig.
40-a). Such a condition may be recognized on the branchlets of the
present, and of the previous year (fig. 40-b), by the very short
internode and short leaves beyond the fruit.

The conelet offers some distinctions of form, of color, and of length of
peduncle, while in some species (sylvestris, caribaea, etc.) its
reflexed position is an important specific character. The most important
distinctions, however, are found in its scales, which may be

    1. entire             subsection Cembra          fig. 41.
    2. tuberculate        tropicalis, etc.           fig. 42.
    3. short-mucronate    sylvestris, glabra, etc.   fig. 43.
    4. long-mucronate     aristata, contorta, etc.   fig. 44.
    5. spinescent         taeda, pungens, etc.       fig. 45.

[Illustration: PLATE III. FLOWERS AND CONELET]


THE CONE. Plate IV.

The cone of Pinus shows great differences of color, form and tissue;
these are useful for specific and sectional distinctions, while the
gradual change from the primitive conditions of the Cembrae to the
elaborate form, structure and mode of dissemination of some serotinous
species are obvious evidence of an evolution among the species of
remarkable taxonomic range. A form new among Coniferae appears, the
oblique cone, and a new condition, the serotinous cone, both appearing
at first alone and, finally, in constant association.


COLOR OF THE CONE.

With few exceptions the color of the ripe cone may be classified under
one of the following shades of brown or yellow.

    Nut-brown     The stain of the walnut-husk.
    Rufous brown  A pronounced reddish nut-brown.
    Fulvous brown A yellowish nut-brown.
    Tawny yellow  The color of the lion.
    Orange        Ochre-yellow to red-orange.

These colors may be paler or deeper. They may be obscured by a fuscous
shade or may be modified by a dull or lustrous surface. The presence of
two or more of these shades in a single species and the inherent
difficulties of color description lessen the value of the character.
Nevertheless certain allied species, such as P. nigra and Thunbergii, or
P. densiflora and Massoniana, may be distinguished by the prevalent
difference in the color of their cones.


DIMENSIONS OF THE CONE.

The cone is small, medium or large in different species, but varies
greatly under the influences of environment or of individual
peculiarities. The character possesses relative value only, for great
variation is possible in the same locality and even on the same tree.


THE PEDUNCLE.

All conelets are pedunculate, but in some species the peduncle, even
when long (patula), may become overgrown and concealed by the basal
scales of the ripe cone. Articulation usually takes place between the
peduncle and the branch, sometimes with the loss of a few basal scales
which remain temporarily on the tree (ponderosa, palustris, etc.). With
P. Nelsonii, and to a less degree with P. Armandi, there is articulation
between the cone and its peduncle.

There are several species bearing persistent cones with no articulation.
This condition appears in other genera, such as Larix and Picea, but
without obvious significance. In Pinus, however, the gradual appearance
of the persistent cone, for it is rare, common, prevalent or invariable
in different species, and its essential association with the serotinous
cone, suggest an evolution toward a definite end.


THE UMBO.

The exposed part of the scale of the conelet is the umbo of the ripe
cone, a small definite area representing the earlier part of the
biennial growth of the cone. The position of the umbo on the apophysis
is the basis of Koehne's subdivision of the section Haploxylon.

    1. Umbo terminal   Subsection Cembra       fig. 46-a.
    2. Umbo dorsal     Subsection Paracembra   fig. 46-b.

Two other characters assist in establishing these subsections--the
conelet, unarmed in Cembra, armed in Paracembra--the pits of the
ray-cells of the wood, large in Cembra, small in Paracembra.


THE APOPHYSIS.

The apophysis represents the later and larger growth of the cone-scale.
With a terminal umbo the margin of the apophysis is free and may be
rounded (fig. 49) or may taper to a blunt point (fig. 52), and any
extension of the scale is a terminal extension. With the dorsal umbo all
sides of the apophysis are confined between other apophyses, and any
extension is a dorsal thickening of the apophysis or a dorsal
protuberance. The outline of an apophysis with a dorsal umbo is
quadrangular, or it is irregularly pentagonal or hexagonal, the
different forms depending on the arrangement of the contiguous scales,
whether of definite or indefinite phyllotactic order, a distinction to
be considered later.

The two positions of the umbo result from the relative growth of the
dorsal and ventral surfaces of the cone-scale. With the terminal umbo
the growth of both surfaces is uniform, with the dorsal umbo the growth
is unequal. A true terminal umbo rests on the surface of the underlying
scale, although several species with terminal umbos show the first
stages of the dorsal umbo. The umbo of P. Lambertiana or of P. flexilis
does not touch the surface of the scale below, and a small portion of
the under side of the apophysis is brought into view on the closed cone.
The cone of P. albicaulis (Plate VIII, fig. 90) shows all degrees of
development between a terminal umbo near the apex of the cone and a
dorsal umbo near its base.

The growth of the apophysis may be limited and constant (strobus,
echinata, etc.) or exceedingly variable, ranging from a slight thickness
to a long protuberance (pseudostrobus, montana, etc.). The protuberance
is usually reflexed from the unequal growth of the two surfaces. With
the terminal umbo the protuberance lengthens the scale, with the dorsal
umbo it thickens the scale. It is sometimes a specific character
(ayacahuite, longifolia) appearing on all cones of the species,
sometimes a varietal form, associated in the same species with an
unprolonged apophysis (sylvestris, montana).

On different parts of the same cone, base, centre or apex, the
dimensions of the apophyses differ, but at each level the scales may be
uniform on all sides of the cone. That is to say, the cone is
symmetrical with reference to any plane passing through its axis. This,
the symmetrical cone, is characteristic of all other genera of the
Abietineae, and is invariable among the Soft Pines and in many Hard
Pines (figs. 47, 48, 52, 54). But among the Hard Pines there is
gradually developed a new form of cone with smaller flatter apophyses on
the anterior, and larger thicker apophyses on the posterior surface.
This is the peculiar oblique cone of Pinus (figs. 50, 51, 53),
symmetrical with reference to one plane only, which includes the axis of
both cone and branch. The oblique cone is a gradual development among
the Hard Pines; in some species it is associated as a varietal form with
the symmetrical cone, and finally, in some serotinous species, it is the
constant form.


THE OBLIQUE CONE.

When the oblique cone is merely a varietal form (halepensis, etc.), it
gives the impression of an accident, resulting from the reflexed
position of the cone and the consequent greater development of the
scales receiving a greater amount of light and air. But with the
serotinous cones (radiata, attenuata), the advantages of this form
become apparent. The cones of these species are in crowded nodal
clusters, reflexed against the branch (fig. 50). The inner, anterior
scales are perfectly protected by their position, while the outer,
posterior scales are exposed to the weather. These last only are very
thick; that is to say, there is an economical distribution of protective
tissue, with the greatest amount where it is most needed. The oblique
form is peculiarly adapted for a cone destined to remain on the tree for
twenty years or more and to preserve its seeds unimpaired. Like the
persistent cone, the oblique cone finds in association with the
serotinous cone a definite reason for existence.

[Illustration: PLATE IV. THE CONE]


PHYLLOTAXIS. Plate V.

There is an obvious difference between the cones of the two sections of
the genus. Those of the Soft Pines (figs. 55, 56) have larger and fewer
scales, those of the Hard Pines (figs. 57, 58) have more numerous and
smaller scales, in proportion to the size of the cone. The former
condition represents a lower, the latter condition represents a higher,
order of phyllotaxis.


DEFINITE PHYLLOTAXIS.

On a cylindrical axis with scales of the same size, the spiral
arrangement would appear as in fig. 62, where the scales are
quadrangular and any four adjacent scales are in mutual contact at their
sides or angles. These four scales lie on four obvious secondary spirals
(fig. 59, a-a, b-b, c-c, d-d). According to the phyllotactic order of
the scales these may be the spirals of 2, 3, 5, 8 or of 3, 5, 8, 13 or
of 5, 8, 13, 21 etc., etc., from which combinations the primary spiral,
on which the scales are inserted on the cone-axis, can be easily
deduced. Four quadrangular scales in mutual contact represent the
condition of definite phyllotaxis. If the cone is conical, definite
phyllotaxis would be possible among all the scales only when the size of
the scales diminishes in equal measure with the gradual diminution of
the cone's diameter. Such a hypothetical cone is shown in fig. 61.


INDEFINITE PHYLLOTAXIS.

On an imaginary cone of conical form and with scales of equal size
throughout, there must be more scales about the base than about the apex
of the cone. The phyllotactic conditions must differ, and the obvious
spirals, in passing from base to apex, must undergo readjustment. If the
scales at the base are in definite phyllotactic order and those at the
apex are in the next lower order, it is evident that intermediate
scales, in the gradual change from one condition to the other, must
represent different conditions of indefinite phyllotaxis, while those in
a central position on the cone may belong equally to either of two
orders.

A Pine cone is never absolutely cylindrical nor do its scales vary in
size proportionately to the change of diameter. Most of the scales of a
cone are in indefinite phyllotactic relation, while definite phyllotaxis
is found only at points on the cone.

As an extreme illustration, the cone of P. pinaster (fig. 60) shows four
mutually contiguous quadrangular apophyses at (a), lying on the obvious
spirals 5, 8, 13, 21, at (b) four similar apophyses on the spirals 3, 5,
8, 13, and at (c) four others on the spirals 2, 3, 5, 8. Between these
three points are apophyses of irregular pentagonal or hexagonal outline,
with three scales only in mutual contact (figs. 63, 64). Such are the
majority of the scales of the cone and represent more or less indefinite
conditions of phyllotaxis.

The cones of Hard Pines, by reason of relatively more and smaller scales
and of a more conical form, attain a higher phyllotaxis and a more
complex condition, two or even three orders being represented on a
single cone; while the cones of Soft Pines, by reason of relatively
fewer and larger scales and a more cylindrical form, are of lower
phyllotaxis, with one order only more or less definitely presented.
Therefore phyllotaxis furnishes another distinction between the two
sections of the genus, but its further employment is exceedingly
restricted on account of the constant repetition of the same orders
among the species.

[Illustration: PLATE V. PHYLLOTAXIS OF THE CONE]


THE CONE-TISSUES. Plate VI.

The axis of the cone is a woody shell, enclosing a wide pith and covered
by a thick cortex traversed by resin-ducts. By removing the scales and
cortex from the axis (fig. 65) the wood is seen to be in sinuous strands
uniting above and below fusiform openings, the points of insertion of
the cone-scales. From the wood, at each insertion, three stout strands
enter the scale, dividing and subdividing into smaller tapering
strands whose delicate tips converge toward the umbo. Fig. 70 represents
a magnified cross-section of half the cone-scale of P. Greggii; at (a)
is a compact dorsal plate of bast cells; at (e) is a ventral plate of
the same tissue but of less amount; at (b) is the softer brown tissue
enclosing the wood-strands (d, d) (the last much more magnified in fig.
69) and the resin-ducts (e, e).


WOOD STRANDS.

The wood-strands, forming the axis of the cone, differ in tenacity in
the two sections of the genus. Those of the Soft Pines are easily pulled
apart by the fingers, those of the Hard Pines are tougher in various
degrees and cannot be torn apart without the aid of a tool. This
difference is correlated with differences in other tissues, all of them
combining in a gradual change from a cone of soft yielding texture to
one of great hardness and durability.

If a cone scale of P. ayacahuite is stripped of its brown and bast
tissues (fig. 66) and is immersed in water and subsequently dried, there
is at first a flexion toward the cone-axis (fig. 67) and then away from
it (fig. 68). The wood-strands are hygroscopic and coöperate with the
bast tissues in opening and closing the cone. This appears to be true of
all species excepting the three species of the Cembrae, whose strands
are so small and weak that they are not obviously affected by
hygrometric changes.


BAST TISSUE.

With the exception of the three species of the Cembrae the inner part of
the cone-scales is protected by sclerenchymatous cells forming hard
dorsal and ventral plates (fig. 70, a, c). In Soft Pines these cells are
subordinate to the more numerous parenchymatous cells, but in Hard Pines
the sclerenchyma increases in amount until, among the serotinous
species, it is the predominating tissue of the cone-scale, giving to
these cones their remarkable strength and durability.

This bast tissue is hygroscopic and, with its greater thickness on the
dorsal surface, there is a much greater strain on that side of the
scale, tending to force the scales apart when they are ripe and dry, and
subsequently closing and opening the cone on rainy and sunny days.

The cone, during the second season's growth, is completely closed, its
scales adhering together with more or less tenacity. In most species the
hygroscopic energy of the scales is sufficient to open the cone under
the dry condition of its maturity, but with several species the adhesion
is so persistent that some of the cones remain closed for many years.
These are the peculiar serotinous cones of the genus.


THE SEROTINOUS CONE.

As an illustration of the area to which the adhesion is confined, a
section may be sawed from a cone of P. attenuata (fig. 71). The axis and
the scales that have been severed from their apophyses (b) can be easily
pushed out of the annulus (a), which is composed wholly of apophyses so
firmly adherent that they will successfully resist a strong effort to
break them apart. When immersed in boiling water, however, the ring
falls to pieces. An examination of these pieces discovers adhesion only
on a narrow ventral border under the apophysis and on a corresponding
dorsal border back of the apophysis. The rest of the scale is not
adherent, so that the seed is free to fall at the opening of the cone.

The serotinous cone is a gradual development, wanting in most species,
rare in a few, less or more frequent in others. A similar evolution of
the persistent cone, of the oblique cone and of the cone-tissues has
been already discussed. All these progressive characters culminate in
mutual association in P. radiata and its allies. The result is a highly
specialized fruit that should convey taxonomic significance of some
kind.

With all serotinous species that I have seen, some of the trees open
their cones at maturity, others at indefinite intervals. That is to say,
the seed of a prolific year is not at the mercy of a single, perhaps
unfavorable season. The chances of successful germination are much
increased by the intermittent seed-release peculiar to these Pines. Such
a method of dissemination must accrue to the advantage of a species. In
other words, this intermittent dissemination and the oblique form of
cone with its perfected tissues all mark the highest development of the
genus.


THE SEED. Plate VI. Figs. 72-79.

The seed of Pinus contains an embryo, with the cotyledons clearly
defined, embedded in albumen, which is protected by a bony testa with an
external membranous spermoderm, produced, in most species, into an
effective wing. While the seed of other genera of the Abietineae shows
no striking difference among the species, that of Pinus is remarkably
variable, presenting alike the most primitive and the most elaborate
forms among the Conifers. These differences are valuable for the
segregation of kindred species and for some specific distinctions.


WINGLESS SEEDS.

With wingless seeds the main distinction is found in the spermoderm,
which is entire in one species only, P. koraiensis. In P. cembra it is
wanting on the ventral surface of the nut, but on the dorsal surface, it
is adnate partly to the nut, partly to the cone-scale. The nut of P.
albicaulis and that of P. cembroides are quite bare of membranous cover.
The spermoderm of P. flexilis is reduced to a marginal border, slightly
produced into a rudimentary wing adnate to the nut.


THE ADNATE WING.

In P. strobus, longifolia and their allies and in P. Balfouriana the
spermoderm is prolonged into an effective wing-blade from a marginal
adnate base like that of P. flexilis. This adnate wing cannot be
detached without injury.


THE ARTICULATE WING.

The articulate wing can be removed from the nut and can be replaced
without injury. An ineffective form of this wing is seen in the
Gerardianae and in P. pinea, where the blade is very short and the base
has no effective grasp on the nut.

The base of the effective articulate wing contains hygroscopic tissue
which acts with the hygroscopic tissue of the cone-scales. The dry
conditions that open the cone and release the seeds cause the bifurcate
base of the wing to grasp the nut more firmly.

This articulate wing is found in P. aristata and in all Hard Pines
except P. pinea, longifolia and canariensis. The wing-blade is usually
membranous throughout, but in some species there is a thickening of the
base of the blade that meets the membranous apical part in an oblique
line along which the wing is easily broken apart. This last condition
attains in P. Coulteri and its associates a remarkable development.

Plate VI, fig. 72 shows the wingless seed of P. cembroides; fig. 73
represents the seed of P. flexilis, with a rudimentary wing; fig. 74
shows two seeds of P. strobus, intact and with the wing broken away;
fig. 75 represents the articulate wing, whose bifurcate base when wet
(fig. 76) tends to open and release the nut. When dry (fig. 77) the
forks of the base, in the absence of the nut, close together and cross
their tips; figs. 78, 79 show the peculiar reinforced articulate wing of
P. Coulteri.

Such wide variation in so important an organ suggests generic
difference. But here we are met by the association of the different
forms in species evidently closely allied. The two Foxtail Pines are so
similar in most characters that they have been considered, with good
reason, to be specifically identical; yet the seed-wing of P.
Balfouriana is adnate, that of P. aristata articulate. P. Ayacahuite
produces not only the characteristic wing of the Strobi, adnate, long
and effective, but also, in the northern variety, a seed with a
rudimentary wing, the exact counterpart of the seed of P. flexilis. In
both sections of the genus are found the effective adnate wing (Strobi
and Longifoliae) and the inefficient articulate wing (Gerardianae and
Pineae). A little examination of all forms of the seed will show that
they blend gradually one into another.

The color of the wing is occasionally peculiar, as in the group
Longifoliae. There is usually no constancy in this character, for the
wing may be uniform in color or variously striated in seeds of the same
species. The length and breadth of the seed-wing, being dependent on the
varying sizes of the cone-scale, differ in the same cone. They are also
inconstant in different cones of the same species, and of this
inconstancy the seed of P. ayacahuite furnishes the most notable
example.

[Illustration: PLATE VI. CONE-TISSUES AND SEEDS]


THE WOOD. Plate VII.

With the exception of the medullary rays, a very small proportion of the
whole, the wood of Pinus, as seen in cross-section (fig. 82), is a
homogeneous tissue of wood-tracheids with interspersed resin-ducts. In
tangential section the medullary rays appear in two forms, linear,
without a resin-duct, and fusiform, with a central resin-duct. In radial
section the cells of the linear rays are of two kinds, ray-tracheids,
forming the upper and lower limits of the ray, characterized by small
bordered pits, and ray-cells, between the tracheids, characterized by
simple pits.

The walls of the ray-tracheids may be smooth or dentate; the pits of the
ray-cells may be large or small. These conditions admit of four
combinations, all of which appear in the medullary rays of Pinus, and of
which a schematic representation is given in Plate VII. These
combinations are

    Ray-tracheids with smooth walls. Soft Pines.
      Ray-cells with large pits    Subsection Cembra        fig. 80.
      Ray-cells with small pits    Subsection Paracembra    fig. 81.

    Ray-tracheids with dentate walls. Hard Pines.
      Ray-cells with large pits    Group Lariciones         fig. 83.
      Ray-cells with small pits    Other Hard Pines         fig. 84.

This, the simplest classification of Pine-wood, is not without
exceptions. P. pinea of the Hard Pines resembles, in its
wood-characters, P. Gerardiana and P. Bungeana of the Soft Pines. The
dentate ray-tracheids of P. longifolia are not always obvious. The
tracheids of P. luchuensis, according to Bergerstein (Wiesner Festschr.
112), have smooth walls. My specimen shows dentate tracheids. There is
also evidence of transition from small to large pits (I. W. Bailey in
Am. Nat. xliv. 292). Both large and small pits appear in my specimen of
P. Merkusii.

Of other wood-characters, the presence or absence of tangential pits in
the tracheids of the late wood establishes a distinction between Soft
and Hard Pines. These pits, however, while always present in Soft Pines,
are not always absent in Hard Pines. The single and multiple rows of
resin-ducts in the wood of the first year may prove to be a reliable
sectional distinction, but this character has not been sufficiently
investigated to test its constancy. The wood-characters, therefore,
however decisive they may be for establishing the phylogenetic relations
of different genera, must be employed in the classification of the Pines
with the same reservations that apply to external characters.

Ray-tracheids with dentate walls and ray-cells with large pits are
peculiar to Pinus. Therefore the presence of these characters, alone or
in combination, is sufficient evidence for the recognition of Pine-wood.
But the combination of smooth tracheids with small pits (subsection
Paracembra) Pinus shares with Picea, Larix and Pseudotsuga.

Among Hard Pines the size of the pits has a certain geographical
significance. The large pits are found in all species of the Old World
except P. halepensis and P. pinaster; the small pits in all species of
the New World except P. resinosa and P. tropicalis. The Asiatic P.
Merkusii with both large and small pits is not strictly an exception to
this geographical distinction. The four exceptional species by this and
by other characters unite the Hard Pines of the two hemispheres.


THE BARK.

Bark is the outer part of the cortex that has perished, having been cut
off from nourishment by the thin hard plates of the bark-scales. In the
late and early bark-formation is found a general but by no means an
exact distinction between Soft and Hard Pines. In the Soft Pines the
cortex remains alive for many years, adjusting itself by growth to the
increasing thickness of the wood. The trunks of young trees remain
smooth and without rifts. In the Hard Pines the bark-formation begins
early and the trunks of young trees are covered with a scaly or rifted
bark. The smooth upper trunk of older trees is invariable in Soft Pines,
but in Hard Pines there are several exceptions to early bark-formation.
These exceptions are easily recognized in the field, and the character
is of decisive specific importance (glabra, halepensis, etc.).

Among species with early bark-formation are two forms of bark: 1,
cumulative, sufficiently persistent to acquire thickness and the
familiar dark gray and fuscous-brown shades of bark long exposed to the
weather; 2, deciduous, constantly falling away in thin scales and
exposing fresh red inner surfaces. The latter are commonly known as Red
Pines, as distinguished from Black Pines with dark cumulative bark.
Deciduous bark changes after some years to cumulative bark, and the
upper trunk only of mature trees is red. Red Pines, although usually
recognizable by their bark, are by no means constant in this character.
Oecological or pathological influences may check the fall of the
bark-scales, and then the distinction between the upper and lower parts
of the trunk becomes lost.

[Illustration: PLATE VII. THE WOOD]



SUMMARY

The various characters that have been considered in the previous pages
may be classified under different heads, some of them applicable to the
whole genus, others to larger or smaller groups of species.


GENERIC CHARACTERS

Several characters, quite distinct from those of other genera, are
common to all the species.

    1. The primary leaf--appearing as a scale or bract throughout the
         life of the tree.
    2. The bud--its constant position at the nodes.
    3. The internode--its three distinct divisions.
    4. The secondary leaves--in cylindrical fascicles with a basal
         sheath.
    5. The pistillate flower--its constant nodal position and its
         verticillate clusters.
    6. The staminate flower--its constant basal position on the
         internode and its compact clusters.
    7. The cone--its clearly defined annual growths.

Pinus is also peculiar in the dimorphism of shoots and leaves and in
their constant interrelations with the diclinous flowers. Evolutionary
processes develop features peculiar to Pinus alone (the oblique cone,
etc.), but confined to a limited number of species.


SECTIONAL CHARACTERS

There are several characters that actually or potentially divide the
genus into two distinct sections, popularly known as Soft and Hard
Pines.

    1. The fibro-vascular bundle of the leaf, single or double.
    2. The base of the bract subtending the leaf-fascicle, non-decurrent
         or decurrent
    3. The phyllotaxis of the cone, simple or complex.
    4. The flower-bud, its less or greater development.

Some characters indicate the same distinction but are subject each to a
few exceptions.

    5. The fascicle-sheath, deciduous or persistent.
    6. The walls of the ray-tracheids, smooth or dentate.
    7. The connective of the pollen-sacs, large or small.
    8. The formation of bark, late or early.

SUBSECTIONAL CHARACTERS

An exact subdivision of the Soft Pines is possible on the following
characters.

    1. The umbo of the cone-scales, terminal or dorsal.
    2. The scales of the conelet, mutic or armed.
    3. The pits of the ray-cells, large or small.


EVOLUTIONAL CHARACTERS

The progressive evolution of the fruit of Pinus, from a symmetrical cone
of weak tissues, bearing a wingless seed, to an indurated oblique cone
with an elaborate form of winged seed and an intermittent dissemination,
appears among the species in various degrees of development as follows--

    The seed

      1. wingless.
      2. with a rudimentary wing.
      3. with an effective adnate wing.
      4. with an ineffective articulate wing.
      5. with an effective articulate wing.
      6. with an articulate wing, thickened at the base of the blade.

    The cone

      1. indehiscent.
      2. dehiscent and deciduous.
      3. dehiscent and persistent.
      4. persistent and serotinous.

                    and as to its form

      5. symmetrical.
      6. subsymmetrical.
      7. oblique.

These different forms of the seed and, to some extent, of the cone, are
available for segregating the species into groups of closely related
members; while the gradual progression of the fruit, from a primitive to
a highly specialized form of cone and method of dissemination, points to
a veritable taxonomic evolution which is here utilized as the
fundamental motive of the systematic classification of the species.


SPECIFIC CHARACTERS

All aspects of vegetative and reproductive organs may contribute toward
a determination of species, but the importance of each character is
often relative, being conclusive with one group of species, useless with
another. Characters considered by earlier authors to be invariable with
species, such as the dimensions of leaf or cone, the number of leaves in
the fascicle, the position of the resin-ducts, the presence of pruinose
branchlets, etc., prove to be inconstant in some species. In fact, as
the botanical horizon enlarges, the varietal limits of the species
broaden and many restrictions imposed by earlier systems are gradually
disappearing.

Variation is the preliminary step toward the creation of species, which
come into being with the elimination of intermediate forms. Variation in
a species may be the result of its participation in the evolutionary
processes culminating in the serotinous Pines, or it may result from the
ability of the species to adapt itself to various environments by
sympathetic modifications of growth, or it may arise from some
peculiarity of the individual tree.

Evolutionary variation is associated with the gradual appearance of the
persistent, the oblique and the serotinous cone, and of the multinodal
spring-shoot. For these conditions appear in less or greater prevalence
among the species of the genus.

Variation induced by environment finds familiar illustrations among the
species that can survive at the limits of vegetation and can meet these
inhospitable conditions by a radical change of all growing parts. Such
variations are mainly of dimensions, but, with some species, the number
of fascicle-leaves is affected and the shorter growing-season may modify
the cone-tissues. In Mexico and Central America are found extremes of
climate within small areas and easily within the range of dissemination
from a single tree. The cause of the bewildering host of varietal forms,
connecting widely contrasted extremes, seems to lie in the facile
adaptability of those Pines, which are able to spread from the tropical
base of a mountain to a less or greater distance toward its snow-capped
summit.

The peculiarities of individual trees that induce abnormally short or
long growths, the dwarf or other monstrous forms, the variegations in
leaf-coloring, etc., etc., are not available for classification, for
they may appear in any species, in fact in any genus of Conifers. These
variations are artificially multiplied for commercial and decorative
purposes. But inasmuch as they are repeated in all species and genera of
the Coniferae that have been long under the observation of skillful
gardeners, their significance has a broader scope than that imposed by
the study of a single genus.




PART II

CLASSIFICATION OF THE SPECIES


The following classification is based on the gradual evolution of the
fruit from a cone symmetrical in form, parenchymatous in tissue,
indehiscent and deciduous at maturity, releasing its wingless seed by
disintegration--to a cone oblique in form, very strong and durable in
tissue, persistent on the tree, intermittently dehiscent, releasing its
winged seeds partly at maturity, partly at indefinite intervals during
several years. This evolution embraces two extreme forms of fruit, one
the most primitive, the other the most elaborate, among Conifers.

Two sections of the genus, Soft and Hard Pines, are distinguished by
several correlated characters, and moreover are distinct by obvious
differences in the tissues of their cones as well as in the quality and
appearance of their wood.

With the Soft Pines the species group naturally under two subsections on
the position of the umbo, the anatomy of the wood and the armature of
the conelet. In one subsection (Cembra) are found three species, P.
cembra and its allies, with the cone-tissues so completely
parenchymatous that the cones cannot release the seeds except by
disintegration. In both subsections there is a gradual evolution from a
wingless nut to one with an effective wing, adnate in one subsection,
adnate and articulate in the other. The different stages of this
evolution are so distinct that the Soft Pines are easily separated into
definite groups.

Among the Hard Pines a few species show characters that are peculiar to
the Soft Pines. These exceptional species form a subsection
(Parapinaster) by themselves.

With the remaining species, the majority of the Pines, the distinctions
that obtain among Soft Pines have disappeared. The dorsal umbo, the
articulate seed-wing, the persistent fascicle-sheath, the dorsal and
ventral stomata of the leaf and its serrate margins, the dentate walls
of the ray-tracheids have become fixed and constant. But a new form of
seed-wing appears, with a thickened blade, assuming such proportions in
P. Sabiniana and its two allies that these three constitute a distinct
group, remarkable also for the size of its cones.

Here also appear a new form of fruit, the oblique cone, and a new method
of dissemination, the serotinous cone. Associated with the latter are
the persistent cone and the multinodal spring-shoot. These characters do
not develop in such perfect sequence and regularity that they can be
employed for grouping the species without forcing some of them into
unnatural association. The oblique cone first appears sporadically here
and there and without obvious reason. The persistent cone, the first
stage of the serotinous cone, is equally sporadic in the earlier stages
of evolution. The same may be said of the multinodal shoot.

Nevertheless these characters show an obvious progression toward a
definite goal, where they are all united in a small group of species
remarkable for the form and texture of their cones, for a peculiar
seed-release and for the vigor and rapidity of their growth. It is
possible, with the assistance of other characters, to segregate these
species in three groups in which the affinities are respected and the
general trend of their evolution is preserved.

The first group, the Lariciones, contains species with large ray-pits,
cones dehiscent at maturity, and uninodal spring-shoots. They are, with
two exceptions, P. resinosa and P. tropicalis, Old World species.

The second group, the Australes, contains species with small ray-pits,
cones dehiscent at maturity and spring-shoots gradually changing, among
the species, from a uninodal to a multinodal form. They are, without
exception, species of the New World.

The third group, the Insignes, contains the serotinous species. The
ray-pits are small and the spring-shoots are, with two exceptions,
multinodal. With two exceptions, P. halepensis and P. pinaster, they are
New World species.

These three groups, being the progressive sequence of a lineal
evolution, are not absolutely circumscribed, but are more or less
connected through a few intermediate species of each group. The
systematic position of these intermediate species is determined by their
obvious affinities. It cannot be expected that the variations, which
take an important part in the evolution of the species, progress with
equal step or in perfect correlation with each other.

As to specific determinations, a little experience in the field
discloses an amount of variation in species that does not always appear
in the descriptions of authors; and species that are under the closest
scrutiny of botanists, foresters or horticulturalists, attest by their
multiple synonymy their wide variation. The possibilities of variation
are indefinite and, with adaptable Pines, the range of variation is
somewhat proportionate to change of climate. In mountainous countries,
where there are warm sheltered valleys with rich soil below cold barren
ledges, the most variable Pines are found. The western species of North
America, for instance, are much more variable than the eastern species,
while in Mexico, a tropical country with snow-capped mountains, the
variation is greatest.

Therefore in the limitation of species undue importance should not be
given to characters responsive to environment, such as the dimensions of
leaf or cone, the number of leaves in the fascicle, etc. Moreover, there
are familiar examples (P. sylvestris, etc.) that show the possibility of
wide differences in the cone of the same species.

In the following classification species only are considered without
attempting to determine varietal or other subspecific forms. But
varieties are often mentioned as one of the factors illustrating the
scope of species. Synonymy serves a like purpose, but synonyms not
conveying useful information are omitted, Roezl's list of Mexican
species, for instance, and variations in the orthography of specific
names.


PINUS

    1755 Pinus Duhamel, Traité des Arbres, ii. 121.
    1790 Apinus Necker, Elem. Bot. iii. 269.
    1852 Cembra Opiz, Seznam, 27.
    1854 Strobus Opiz, Lotos, iv. 94.
    1903 Caryopitys Small, Fl. Southeast. U. S. 29.

Leaves and shoots dimorphous, primary leaves on long shoots, secondary
leaves on dwarf shoots. Flowers diclinous, the pistillate taking the
place of long shoots, the staminate taking the place of dwarf shoots.
Growth of wood and fruit emanating from the nodes; buds, branchlets and
cones, therefore, in verticillate association. Leaves and staminate
flowers in internodal position, the primary leaves along the whole
length of the internode, subtending secondary leaf-fascicles on the
apical, staminate flowers on the basal part. Buds compounded of minute
buds in the axils of bud-scales, becoming the bracts of the
spring-shoot. Branchlets of one or more internodes, each internode in
three parts--a length without leaves, a length bearing leaves and a node
of buds. Cone requiring two, rarely three years to mature, displaying
its annual growths by distinct areas on each scale. Seeds wingless or
winged, edible and nutritious.

The Pines are confined to the northern hemisphere, but grow in all
climates and under all conditions of soil, temperature and humidity
where trees can grow. Some of the species are of very restricted range,
but others are adaptable and can cover wide areas. The sixty-six species
are distributed as follows--

    Eastern Hemisphere, 23.

      1 exclusively African (Canary Islands).
      2 exclusively European.
      3 about the Mediterranean Basin.
      2 common to Europe and northern Asia.
      14 exclusively Asiatic.

    Western Hemisphere, 43.

      28 in western North America, of which 12 are confined to Mexico
           and Central America.
      15 in eastern North America, of which 2 are exclusively West Indian.

The two sections of the genus correspond with those of Koehne (Deutsch.
Dendrol. 28 [1893]) and his two names, Haploxylon and Diploxylon, are
adopted here, together with his two subsections of Haploxylon, Cembra
and Paracembra.

Of the two subsections of Diploxylon, Pinaster has been employed by
Endlicher (Syn. Conif. 166 [1847]) and later authors for smaller or
larger groups of Hard Pines. The subsection Parapinaster is now
proposed.

The names of groups, Cembrae, Strobi, Cembroides, Gerardianae,
Balfourianae, Pineae, Lariciones and Australes, are taken from
Engelmann's Revision of the Genus Pinus (Trans. Acad. Sci. St. Louis,
iv. 175-178 [1880]). The remainder, Flexiles, Leiophyllae, Longifoliae,
Insignes and Macrocarpae, are here proposed.

In order to bring the illustrations within the limits of the page the
dimensions of cone and leaf, as shown on the plates, are a little
smaller than life. In plates X and XXV the reproductions of the cones
are reduced to 2/5 life-size.


SECTIONS, SUBSECTIONS, AND GROUPS

  Bases of the fascicle-bracts non-decurrent   A--HAPLOXYLON

    Umbo of the cone-scale terminal              a--Cembra

      Seeds wingless.
        Cones indehiscent                          I.     Cembrae
        Cones dehiscent                            II.    Flexiles
      Seed with an adnate wing                     III.   Strobi

    Umbo of the cone-scale dorsal                b--Paracembra

      Seeds wingless                               IV.    Cembroides
      Seed-wing short, ineffective                 V.     Gerardianae
      Seed-wing long, effective                    VI.    Balfourianae

  Bases of the fascicle-bracts decurrent       B--DIPLOXYLON

    Fascicle-sheath or seed of Haploxylon        c--Parapinaster

      Fascicle-sheath deciduous                    VII.   Leiophyllae
      Fascicle-sheath persistent.
        Seed-wing of the Strobi                    VIII.  Longifoliae
        Seed-wing of the Gerardianae               IX.    Pineae

    Fascicle-sheath persistent, seed-wing
        articulate, effective                    d--Pinaster

      Base of wing-blade thin or slightly
          thickened.
        Cones dehiscent at maturity.
          Pits of ray-cells large                  X.    Lariciones
          Pits of ray-cells small                  XI.   Australes
        Cones serotinous, pits of ray-cells small  XII.  Insignes
      Base of wing-blade very thick                XIII. Macrocarpae




HAPLOXYLON


Bases of the bracts subtending leaf-fascicles not decurrent. Staminate
flowers not sufficiently developed in the bud to be apparent.
Spring-shoots uninodal. Fibro-vascular bundle of the leaf single. Cone
symmetrical, of relatively fewer larger scales, its tissues softer.
Bark-formation late, the trunks of young trees smooth. Wood soft and
with little resin, of uniform color and with relatively obscure
definition of the annual rings. Tracheids of the medullary rays with
smooth walls.

  All the species of this section, except P. Nelsonii, have deciduous
  fascicle-sheaths. There are but two species of Diploxylon with
  deciduous sheaths, P. leiophylla and P. Lumholtzii, both of them
  easily recognized. The deciduous sheath, therefore, is an obvious and
  useful means for recognizing the Soft Pines. On the characters of the
  fruit and the wood Haploxylon can be divided into two subsections.

    a. Cembra      Umbo of the cone-scale terminal.
    b. Paracembra  Umbo of the cone-scale dorsal.

=Cembra=

Umbo of the cone-scale terminal. Scales of the conelet unarmed. Leaves
in fascicles of 5, the sheath deciduous, the two dermal tissues
distinct, the hypoderm-cells uniform. Pits of the cells of the wood-rays
large.

    Seeds wingless.
      Cones indehiscent            I.   Cembrae.
      Cones dehiscent              II.  Flexiles.
    Seeds with an adnate wing      III. Strobi.


=I. CEMBRAE=

Seeds wingless. Cones indehiscent, deciduous at maturity.

  In this group of species there is no segregation of sclerenchyma into
  an effective tissue. The cones are inert under hygrometric changes and
  may always be recognized in herbaria by their persistent occlusion and
  soft tissues. The seeds are released only by the disintegration of the
  fallen cone. There is, however, a vicarious dissemination by predatory
  crows (genus Nucifraga) and rodents.

    Leaves serrulate, their stomata ventral only.
      Cones relatively larger, the apophyses protuberant  1. koraiensis.
      Cones relatively smaller, the apophyses appressed   2. cembra.
    Leaves entire, their stomata ventral and dorsal       3. albicaulis.



1. PINUS KORAIENSIS

    1784 P. strobus Thunberg, Fl. Jap. 275 (not Linnaeus).
    1842 P. koraiensis Siebold & Zuccarini, Fl. Jap. ii. 38.
    1857 P. mandschurica Ruprecht in Bull. Acad. Sci. St. Pétersb. xv. 382.

Spring-shoots more or less densely tomentose. Leaves from 8 to 12 cm.
long, serrulate, stomata ventral only, resin-ducts medial and confined
to the angles. Conelets large, subterminal, or on young trees often
pseudolateral. Cones indehiscent, from 9 to 14 cm. long,
short-pedunculate, ovoid-conical or subcylindrical; apophyses dull pale
nut-brown, rugose, shrinking much in drying and exposing the seeds,
prolonged and tapering to a more or less reflexed tip, the umbo
inconspicuous; seeds large, wingless, the spermoderm entire.

  A species of the mountains of northeastern Asia with valuable wood and
  large edible nuts; hardy and often cultivated in cool-temperate
  climates.

  The P. koraiensis of Beissner (in Nuov. Giorn. Bot. Ital. n. ser. iv.
  184) and of Masters (in Gard. Chron. ser. 3, xxxiii. 34, ff.) are P.
  Armandi and have led to an erroneous extension of the range of this
  species into Shensi and Hupeh. In the original description of the
  species the authors call attention to an error in the plate, where a
  cone of another species has been substituted.

  P. koraiensis resembles P. cembra in leaf and branchlet but not in the
  cone. It is often confused with P. Armandi, but can easily be
  distinguished by its tomentose branchlets, indehiscent cone and
  peculiar seed. The two species, moreover, do not always agree in the
  position of the foliar resin-ducts.

    Plate VIII.

    Fig. 85, Cone and seed. Fig. 86, Leaf-fascicle and magnified
    leaf-section.


2. PINUS CEMBRA

    1753 P. cembra Linnaeus, Sp. Pl. 1000.
    1778 P. montana Lamarck, Fl. Franç. iii. 651 (not Miller).
    1858 P. pumila Regel in Index Sem. Hort. Petrop. 23.
    1884 P. mandschurica Lawson, Pinet. Brit. i. 61, ff. (not Ruprecht).
    1906 P. sibirica Mayr, Fremdl. Wald- & Parkb. 388.
    1913 P. coronans Litvinof in Trav. Mus. Bot. Acad. St. Pétersb.
              xi. 23, f.

Spring-shoots densely tomentose. Leaves from 5 to 12 cm. long,
serrulate; stomata ventral only; resin-ducts medial or, in the dwarf
form, often external. Conelets short-pedunculate, purple during their
second season. Cone from 5 to 8 cm. long, ovate or subglobose,
subsessile; apophyses dull nut-brown, thick, slightly convex, the margin
often a little reflexed, the umbo inconspicuous; seeds wingless, large,
the dorsal spermoderm adnate partly to the nut, partly to the
cone-scale, the ventral spermoderm wanting.

  The Swiss Stone Pine attains a height of 15 or 25 metres and occupies
  two distinct areas, the Alps, from Savoy to the Carpathians at high
  altitudes, and the plains and mountain-slopes throughout the vast area
  from northeastern Russia through Siberia. Beyond the Lena and Lake
  Baikal it becomes a dwarf (var. pumila) with its eastern limit in
  northern Nippon and in Kamchatka. It is successfully cultivated in the
  cool-temperate climates of Europe and America. The wood is of even,
  close grain, peculiarly adapted to carving. The nuts are gathered for
  food and confections, but are destroyed in great numbers by squirrels,
  mice and a jay-like crow, the European Nutcracker. It is generally
  conceded, however, that these enemies assist in dissemination.

    Plate VIII.

    Fig. 87, Cone, seed and magnified leaf-section. Fig. 88, Tree at
    Arolla, Switzerland. Fig. 89, Cone, leaf-fascicle and magnified
    leaf-section of var. pumila.


3. PINUS ALBICAULIS

    1853 P. flexilis Balfour in Bot. Exped. Oregon, 1, f. (not James).
    1857 P. cembroides Newberry in Pacif. R. R. Rep. vi-3, 44, f.
              (not Zuccarini).
    1863 P. albicaulis Engelmann in Trans. Acad. Sci. St. Louis, ii. 209.
    1867 P. shasta Carrière, Trait. Conif. ed. 2, 390.

Spring-shoots glabrous or pubescent. Branchlets pliant and tough. Leaves
from 4 to 7 cm. long, entire, stout, persistent for several years;
stomata dorsal and ventral; resin-ducts external. Conelets
short-pedunculate, dark purple during the second season, their scales
often tapering to an acute apex. Cones from 5 to 7 cm. long, subsessile,
oval or subglobose; apophyses nut-brown or fulvous brown, dull or
slightly lustrous, very thick, the under surface conspicuous, meeting
the upper surface in an acute margin, and terminated by a salient,
often acute umbo; seed wingless, the testa bare of spermoderm.

  This species ranges from British Columbia through Washington and
  Oregon, over the mountains of northern California and the Sierras as
  far south as Mt. Whitney, and, on the Rocky Mountains, through Idaho
  and Montana to northern Wyoming. It is found at the timber-line of
  many stations and forms, in exposed situations, flat table-like masses
  close to the ground. It is a species of no economical importance and
  is too inaccessible for the profitable gathering of its large nuts,
  which are devoured in quantity by squirrels and by Clark's crow, a
  bird of the same genus with the pinivorous Nutcracker of Europe.

  P. albicaulis is distinguished from its allies by its entire leaves
  with both dorsal and ventral stomata, from P. flexilis by its
  indehiscent cone, and from all of these species by its seed without
  membranous cover or rudimentary wing. It was united with P. flexilis
  by Parlatore and Gordon, and, later, was referred to that species as a
  varietal form by Engelmann (in Brewer & Watson, Bot. Calif. ii. 124).
  Parrish's P. albicaulis (in Zoe, iv. 350), extending its range to the
  mountains of southern California, proves to be P. flexilis (Jepson,
  Silva Calif. 74).

    Plate VIII.

    Fig. 90, Two cones and seed. Fig. 91, Leaf-fascicle. Fig. 92,
    Magnified leaf-section.

[Illustration: PLATE VIII. P. KORAIENSIS (85, 86), CEMBRA (87-89),
ALBICAULIS (90-92)]


=II. FLEXILES=

Seeds wingless, the spermoderm forming a narrow border with a
rudimentary prolongation. Cones dehiscent at maturity.

  The dehiscent cone distinguishes this group from the Cembrae.
  Therefore confusion of P. koraiensis with P. Armandi, or P. albicaulis
  with P. flexilis should be impossible. The peculiar seed is found
  again only in the northern variety of P. ayacahuite.

    Leaves usually entire, the stomata dorsal and ventral  4. flexilis.
    Leaves serrulate, the stomata ventral only             5. Armandi.


4. PINUS FLEXILIS

    1823 P. flexilis James in Long's Exped. ii. 34.
    1882 P. reflexa Engelmann in Bot. Gaz. vii. 4.
    1897 P. strobiformis Sargent, Silva N. Am. xi. 33, tt. 544, 545
              (not Engelmann).

Spring-shoots pubescent; branchlets very tough and pliant. Leaves from 3
to 9 cm. long, entire, or serrulate in the southern variety, persistent
for five or six years; stomata dorsal and ventral or, in the south,
sometimes ventral only; resin-ducts external. Cones from 6 to 25 cm.
long, ovate or subcylindrical, short-pedunculate; apophyses pale tawny
yellow, or yellow ochre, lustrous, often prolonged and more or less
reflexed, thick, the margin together with the umbo raised above the
surface of the cone.

  This species grows on the Rocky Mountains from Alberta in the Dominion
  of Canada to Chihuahua in northern Mexico and ranges westward to the
  eastern slope of the Sierras and to the southern mountains of
  California. The wood, where accessible, is manufactured into lumber.
  It may be seen in the Arnold Arboretum and in the Royal Gardens at
  Kew.

  P. flexilis is recognized by its lustrous yellow cones. This and the
  constantly external ducts of its usually entire leaves distinguish it
  from P. Armandi. From P. albicaulis, with similar leaves, it differs
  by its dehiscent cone. At one extreme the cone of P. flexilis is not
  unlike that of P. albicaulis, at the other extreme it approaches the
  characteristic cone of P. ayacahuite, with prolonged reflexed scales.
  Hence the confusion of P. albicaulis with P. flexilis (Murray,
  Parlatore and others) and of P. flexilis with Engelmann's P.
  strobiformis. Sargent's P. strobiformis, illustrated in the Silva of
  North America, is the form of this species known as var. reflexa of
  Engelmann.

    Plate IX.

    Fig. 93, Two cones and seed. Fig. 94, Leaf-fascicle. Fig. 95,
    Magnified leaf-section.


5. PINUS ARMANDI

    1884 P. Armandi Franchet in Nouv. Arch. Mus. Paris, sér. 2,
              vii. 95, 96, t. 12.
    1898 P. scipioniformis Masters in Bull. Herb. Boiss. vi. 270.
    1903 P. koraiensis Masters in Gard. Chron. ser. 3, xxxiii. 34,
              ff. 18, 19 (not Siebold & Zuccarini).
    1908 P. Mastersiana Hayata in Gard. Chron. ser. 3, xliii, 194.

Spring-shoots glabrous; branches and most of the trunk covered with a
smooth gray cortex. Leaves from 8 to 15 cm. long, serrulate; stomata
ventral only; resin-ducts external, external and medial, or medial, all
three conditions sometimes occurring in leaves of the same branchlet.
Cones from 6 to 20 cm. in length, pendent on peduncles of various
lengths, the peduncle often remaining on the tree after the fall of the
cone; apophyses fulvous brown, dull or sublustrous, the margin rounded
or tapering to an acute apex, sometimes a little prolonged and reflexed,
the umbo inconspicuous.

  A tree of the mountains of central, southern and western China with an
  outlying station on the Island of Formosa. Recently planted in Europe
  and America, it has so far proved hardy. The nuts are gathered for
  food and some use is made of the wood.

  The glabrous shoots of P. Armandi distinguish it from P. flexilis and
  P. koraiensis. From the latter it is also distinct in its dehiscent
  cone and in its seed. The section of its leaf, with dorsal ducts often
  in two positions, is peculiar to this species among Soft Pines.

    Plate IX.

    Fig. 96, Two cones and seed. Fig. 97, Leaf-fascicle. Figs. 98, 99,
    Magnified sections of three leaves.

[Illustration: PLATE IX. P. FLEXILIS (93-95), ARMANDI (96-99)]


=III. STROBI=

Seed with a long effective wing adnate to the nut.

The base of the seed-wing corresponds to the marginal spermoderm of the
Flexiles but is prolonged into an effective adnate wing. This form of
wing appears again in the species Balfouriana and in the group
Longifoliae.

    Cones very long, usually exceeding 25 cm.
      Cone-scales prolonged and reflexed                 6. ayacahuite.
      Cone-scales appressed                              7. Lambertiana.
    Cones less than 25 cm. long.
      Cone-scales prominently convex.
        Leaves less than 7 cm. long                      8. parviflora.
        Leaves 9-12 cm. long                             9. peuce.
        Leaves 12-18 cm. long                           10. excelsa.
      Cone-scales thin, conforming to the surface of
          the cone.
        Cone relatively longer, its phyllotaxis 8/21    11. monticola.
        Cone relatively shorter, its phyllotaxis 5/13   12. strobus.


6. PINUS AYACAHUITE

    1838 P. ayacahuite Ehrenberg in Linnaea, xii. 492.
    1848 P. strobiformis Engelmann in Wislizenus, Tour Mex. 102.
    1857 P. Veitchii Roezl, Cat. Graines Conif. Mex. 32.
    1858 P. Bonapartea Roezl in Gard. Chron. 358.
    1858 P. Loudoniana Gordon, Pinet. 230.

Spring-shoots glabrous or pubescent. Leaves from 10 to 20 cm. long,
serrulate, their stomata ventral only, their resin-ducts external, often
numerous. Cones from 25 to 45 cm. long, pendent on long stalks,
subcylindrical or tapering, often curved; apophyses pale nut-brown, dull
or sublustrous, varying much in thickness, prolonged in various degrees,
the prolongations patulous, reflexed, recurved or revolute; seeds of
the southern typical form with a long wing, the wing diminishing and the
nut increasing in relative size northward.

  The White Pine of Mexico and Guatemala grows on mountain-slopes and at
  the head of ravines. It is not very hardy in cultivation except in the
  milder parts of Great Britain and in northern Italy, where the forms
  of central and northern Mexico have been very successful. The species
  is best recognized by the prolonged apophyses of its large cone.

  The variations in the size of the cone and in the prolongations of its
  scales are many, but of far more significance is the remarkable
  variation of the seed-wing, which is long in the southern part of the
  range, short and broad in central Mexico, and rudimentary, like the
  seed of P. flexilis, in the north. This makes it possible to establish
  two well defined varieties--Veitchii and brachyptera. The three forms
  of the species present a gradation from the long effective wing of the
  Strobi to the rudimentary form of the Flexiles. Many of the seed-wings
  of the var. Veitchii correspond, in their short broad form and opaque
  coloring, with the characteristic wing of P. Lambertiana.

    Plate X. (leaves and cones much reduced).

    Fig. 103, Cone and cone-scale of var. Veitchii. Fig. 104, Cone and
    seed of var. brachyptera. Fig. 105, Cone-scale of the typical form.
    Figs. 106, 107, Leaf-fascicles and magnified leaf-sections.


7. PINUS LAMBERTIANA

    1827 P. Lambertiana Douglas in Trans. Linn. Soc. xv. 497.

Spring-shoots pubescent. Leaves from 7 to 10 cm. long, serrulate;
stomata dorsal and ventral; resin-ducts external or with one or two
ventral medial ducts. Cones from 30 to 50 cm. long, pendent,
subcylindrical, tapering to a rounded apex; apophyses pale nut-brown,
thick, a narrow border of the under surface showing on the closed cone,
the margin rounded or tapering to a blunt slightly reflexed tip; seed
with a large nut and a broad short opaque wing.

  The Sugar Pine is the tallest of the genus and attains a height of 50
  or 60 metres. It grows on mountain slopes and the sides of ravines.
  Its southern limit is in Lower California on the plateau of San Pedro
  Martir, its northern limit is in western Oregon. The wood is valuable,
  its nuts are eaten by native Indians, and the sweet exudation, which
  gives the tree its popular name, is a manna-like substance of some
  officinal value. P. Lambertiana is recognized by its long cone and by
  the constant dorsal stomata of its leaves.

    Plate X. (leaves and cone much reduced).

    Fig. 100, Cone and seed. Fig. 101, Conelet. Fig. 102, Leaf-fascicle
    and magnified leaf-section.

[Illustration: PLATE X. P. LAMBERTIANA (100-102), AYACAHUITE (103-107)]


8. PINUS PARVIFLORA

    1784 P. cembra Thunberg, Fl. Jap. 274. (not Linnaeus).
    1842 P. parviflora Siebold and Zuccarini, Fl. Jap. ii. 27, t. 115.
    1890 P. pentaphylla Mayr, Mon. Abiet. Jap. 78, 94, t. 6.
    1908 P. morrisonicola Hayata in Gard. Chron. ser. 3, xliii. 194.
    1908 P. formosana Hayata in Jour. Linn. Soc. xxxviii. 297, t. 22.

Spring-shoots pubescent or glabrous; branches becoming studded with
prominent resin-cells of the cortex. Leaves from 3 to 8 cm. long,
slender, serrulate; stomata ventral only; resin-ducts external and
dorsal. Cones subsessile, often persistent, from 5 to 10 cm. long,
patulous or horizontal, short-ovate, or elongate and slightly conical;
apophyses nut-brown, abruptly convex near the apex, or irregularly
warped, varying much in size, the umbo confluent with the thin margin of
the scale and resting on the apophysis beneath; seeds with a large nut
and a short broad wing, often temporarily adherent to the cone-scale and
breaking apart at the fall of the nut.

  A tree of the mountains of Japan and Formosa, cultivated extensively.
  It is recognized by its very short quinate leaves and by its nearly
  sessile cones. The frequent but not invariable retention of the
  seed-wing in the cone is due to adhesion. Many seeds fall with their
  wings intact, others break away from the wing which, after a while,
  loosens and also falls.

    Plate XI.

    Figs. 114, 115, Three cones and seed. Fig. 116, Leaf-fascicle and
    magnified leaf-section.


9. PINUS PEUCE

    1844 P. peuce Grisebach, Spicil. Fl. Rumel. ii. 349.
    1865 P. excelsa Hooker in Jour. Linn. Soc. viii. 145. (not Wallich).

Spring-shoots glabrous. Leaves from 7 to 10 cm. long, erect, serrulate;
stomata ventral only; resin-ducts external. Connective of pollen-sacs
small and narrow. Cones deciduous, from 8 to 15 cm. long,
subcylindrical, often curved, the peduncle short; apophyses tawny
yellow, prominently and abruptly convex, the umbo against the scale
beneath; seed-wing long.

  A tree of the Balkan Mountains, very hardy and bearing abundant fruit
  in the gardens of both hemispheres. The cone resembles that of P.
  excelsa, but is prevalently much shorter and with a relatively shorter
  peduncle. Its leaves are also much shorter and are always erect. A
  curious difference is found in the connectives of the pollen-sacs,
  small in peuce (fig. 113), large in excelsa (fig. 110). The convexity
  of its apophyses distinguishes the cone from those of P. monticola and
  P. strobus. Beissner followed Hooker and named this species excelsa,
  var. peuce, in the first edition of his Handbuch (1891), but in the
  second edition he restored the Balkan Pine to specific standing.

    Plate XI.

    Fig. 111, Cone and seed. Fig. 112, Leaf-fascicle and magnified
    leaf-section. Fig. 113, Pollen-sacs and connective magnified.


10. PINUS EXCELSA

    1824 P. excelsa Wallich ex Lambert, Gen. Pin. ii, 5, t. 3.
    1845 P. nepalensis De Chambray, Arbr. Résin. 342.
    1854 P. Griffithii McClelland in Griffith, Notul. Pl. Asiat. iv, 17;
              Icon. Pl. Asiat. t. 365.

Spring-shoots glabrous. Leaves from 10 to 18 cm. long, drooping,
serrulate; stomata ventral only; resin-ducts external but often with a
medial ventral duct. Connective of the pollen-sacs large. Cones from 15
to 25 cm. long, narrow-cylindrical; apophyses tawny yellow or pale
fulvous brown, prominently convex, the umbo against the apophysis
beneath; seeds with a long wing.

  A tree with gray-green drooping foliage, found, with some
  interruptions, along the Himalayas. It furnishes resin, tar and wood
  of considerable value. It is cultivated in all temperate climates and
  is a familiar tree of American and European gardens. Madden states
  that the foliage of P. excelsa is sometimes erect and is occasionally
  bright green. Such variations are often met in other species of Pinus.
  Usually the drooping gray-green foliage and the peculiar cone are
  sufficient for the recognition of this species. The not infrequent
  presence of a medial duct and the large connective are valuable aids
  for identifying it.

    Plate XI.

    Fig. 108, Cone and seed. Fig. 109, Leaf-fascicle and magnified
    section of two leaves. Fig. 110, Pollen-sacs and connective
    magnified.

[Illustration: PLATE XI. P. EXCELSA (108-110), PEUCE (111-113),
PARVIFLORA (114-116)]


11. PINUS MONTICOLA

    1837 P. monticola Douglas ex Lambert, Gen. Pin. iii. t.
    1884 P. porphyrocarpa Lawson, Pinet. Brit. i, 83, ff.

Spring-shouts pubescent. Leaves from 4 to 10 cm. long, serrulate;
stomata ventral or rarely with a few dorsal stomata; resin-ducts
external. Cones from 10 to 25 cm. long, cylindrical or tapering,
sometimes curved; apophyses brown-ochre or fulvous brown, thin, smooth,
conforming to the surface of the cone, the apex sometimes slightly
prolonged and reflexed, the umbo not quite touching the surface of the
scale below.

  The western White Pine grows in southern British Columbia and on
  Vancouver Island, on the Rocky Mountains of Montana and Idaho, in
  Washington, on the Blue Mountains, Cascades and Coast Range of Oregon,
  across northern California and along the Sierras to the mountains of
  southern California. Where it is abundant and accessible it furnishes
  valuable timber. It is hardy in New England and in northern and
  central Europe.

  It differs from P. strobus in the higher phyllotaxis of its cone, an
  obvious difference that may be seen by comparing cones of the two
  species of the same length (figs. 117, 119), the number of scales on
  the cone of P. monticola being much greater than that on the cone of
  P. strobus. Nuttall (Sylva, iii, 118) followed Hooker in considering
  it to be a variety of P. strobus.

    Plate XII.

    Fig. 117, Cone and cone-scale. Fig. 118, Leaf-fascicle and magnified
    leaf-section.


12. PINUS STROBUS

    1753 P. strobus Linnaeus, Sp. Pl. 1001.
    1855 P. nivea Booth ex Carrière, Trait. Conif. 305.
    1862 P. alba-canadensis Provancher, Fl. Canad. ii. 554.
    1903 Strobus strobus Small, Fl. Southeast. U. S. 29.

Spring-shoots pubescent. Leaves from 6 to 14 cm. long, serrulate;
stomata ventral only; resin-ducts external. Cones from 8 to 24 cm. long,
narrow cylindrical, sometimes curved; apophyses fulvous brown, or rufous
brown, thin, the smooth or slightly rugose surface conforming to the
general surface of the cone; seed with a long wing.

  A valuable timber-tree of singular beauty and rapid growth. The
  northern limit of its range extends from Newfoundland to Manitoba; it
  grows throughout the northern states from Minnesota to the Atlantic,
  and, south of Pennsylvania, along the Appalachians to northern
  Georgia. Its tractable and reliable wood, its adaptability to various
  soils and climates, its early maturity and stately habit, recommend it
  to the forester and gardener.

  Mature trees of P. strobus tower above the evergreens associated with
  it. It is also recognized by the color and horizontal massing of its
  foliage. The cone, when closed, is very narrow; its thin flat scales
  distinguish it from the cone of P. peuce, and its phyllotaxis from the
  cone of P. monticola. To illustrate the possibilities of variation in
  the size of Pine cones, I once collected several in Tamworth, N. H.,
  on the estate of Mr. Augustus Hemenway, on the same slope and within
  an area of one square kilometre. These cones varied in length from 6
  to 24 cm., with all intermediate sizes. Also on each tree were cones
  of various lengths, but the longest were confined to two or three
  trees among the several hundred examined. Dimensions of leaves also
  varied with individual trees; not infrequently the leaves of a tree
  were twice the length of those of an adjacent tree. Such variations
  appear in many species and in many localities.

    Plate XII.

    Fig. 119, Two cones. Fig. 120, Leaf-fascicle. Fig. 121, Magnified
    leaf-section. Fig. 122, Conelets. Fig. 123, A cultivated tree in
    Massachusetts.

[Illustration: PLATE XII. P. MONTICOLA (117, 118), STROBUS (119-123)]

=Paracembra=

Umbo of the cone-scale dorsal. Scales of the conelet mucronate or
aristate. Epiderm and hypoderm of the leaf similar, appearing as a
single tissue; resin-ducts external. Pits of the ray-cells small.

  The wood of this subsection differs from that of other species, except
  that of P. pinea, in the Picea-like characters of the medullary
  rays--tracheids with smooth walls combined with the thick walls and
  small pits of the ray-cells. On the character of the seeds the species
  may be divided into three groups.

    Seeds wingless                                    IV. Cembroides.
    Seeds with a short, ineffective, articulate wing   V. Gerardianae.
    Seeds with a long and effective wing              VI. Balfourianae.


=IV. CEMBROIDES=

Seeds wingless, the nut large, wholly or partly bare of membranous
cover. Cones varying from yellow-ochre to deep red-orange in color.

  These are the Nut Pines, growing on the arid slopes and table-lands
  above the great plateau of northern Mexico and its extension into the
  southwestern United States. There are three distinct species.

    Leaves entire, the sheath deciduous.
      Cones subglobose, subsessile                  13. cembroides.
      Cones cylindrical, pedunculate                14. Pinceana.
    Leaves serrulate, the sheath persistent         15. Nelsonii.


13. PINUS CEMBROIDES

    1832 P. cembroides Zuccarini in Abh. Akad. Münch. i. 392.
    1838 P. Llaveana Schiede in Linnaea, xii. 488.
    1845 P. monophylla Torrey in Frémont's Rep. 319, t. 4.
    1847 P. Fremontiana Endlicher, Syn. Conif. 183.
    1848 P. edulis Engelmann in Wislizenus, Tour. Mex. 88.
    1848 P. osteosperma Engelmann in Wislizenus, Tour. Mex. 89.
    1862 P. Parryana Engelmann in Am. Jour. Sci. ser. 2, xxxiv. 332
              (not Gordon).
    1897 P. quadrifolia Sudworth, Bull. 14, U. S. Dep. Agric. 17.
    1903 Caryopitys edulus Small, Fl. Southeast. U. S. 29.

Spring-shoots pruinose. Leaves from 2 to 6 cm. long, in fascicles of 1
to 5, the sheath-scales revolute at the apex, then deciduous; stomata
ventral, or ventral and dorsal; resin-ducts external. Scales of the
conelet armed with a minute prickle. Cones from 4 to 6 cm. long,
subglobose, subsessile; apophyses lustrous ochre-yellow, crowned with a
quadrilateral umbo bearing the minute prickle of the conelet; seed
flaxen yellow when fresh, its testa bare, the spermoderm adnate to the
cone-scale.

  A broad tree with a round head, similar in size and form, but not in
  ramification, to the cultivated Apple-tree; growing on arid slopes and
  table-lands. Its eastern limit is in southwestern Wyoming, central
  Colorado, Texas, western Tamaulipas and northwestern Vera Cruz. It
  ranges over Utah, Nevada, Arizona and the northern states of Mexico to
  the southern Sierras of California and to the northern and southern
  extremities of Lower California. It is recognized by its small cone,
  which expands, when open, into an irregular flat aggregate of loosely
  attached scales. The leaves are shorter than those of the other Pines
  of this group.

  The cone of this species always retains its peculiar character. The
  variations are mainly in the number of leaves in the fascicle. On this
  character this Nut Pine is divided by many authors into four
  species--cembroides, with three slender leaves--edulis, with two stout
  leaves--monophylla, with one leaf and--Parryana, with four stout
  leaves. But there are intermediate forms that may be either cembroides
  or edulis, edulis or monophylla etc., and Voss's reduction of the four
  to a single species with three varieties seems to be justified (Mitt.
  Deutsch. Dendrol. Ges. xvi. 95).

    Plate XIII.

    Fig. 130, Cone, cone-scale and seed. Fig. 131, Open cone. Fig. 132,
    Branchlet with leaves and magnified leaf-section.

14. PINUS PINCEANA

    1846 P. cembroides Gordon in Jour. Hort. Soc. Lond. i. 236, f.
              (not Zuccarini).
    1858 P. Pinceana Gordon, Pinet. 204.
    1882 P. latisquama Engelmann in Gard. Chron. ser. 2, xviii. 712.
              f. 125 (as to cone only).

Spring-shoots slender, pruinose. Leaves in fascicles of three, the
sheath revolute at the base, then deciduous; stomata ventral, or ventral
and dorsal; resin-ducts external. Scales of the conelet minutely
mucronate. Cones from 6 to 9 cm. long, cylindrical, pendent on long
peduncles; apophyses lustrous ochre-yellow, elevated in the centre,
the umbo usually retaining the small prickle; seed large, bearing on its
dorsal surface remnants of the spermoderm.

  A small bushy tree with long slender branchlets, clear gray cortex,
  persistently smooth except on the lower part of the trunk, and
  glaucous-green foliage. It grows along water-courses, dry in autumn
  and winter, from southern Coahuila to central Hidalgo, and is
  associated with P. cembroides, from which it may be distinguished by
  its longer leaves and much longer cylindrical cone.

    Plate XIII.

    Fig. 127, Cone, cone-scale and seed. Fig. 128, Branchlet with
    leaves. Fig. 129, Magnified leaf-section.


15. PINUS NELSONII

    1904 P. Nelsonii Shaw in Gard. Chron. ser. 3, xxxvi. 122, f. 49.

Spring-shoots slender, pruinose; branchlets very pliant and tough,
summer-shoots abundant. Leaves with a persistent sheath, from 6 to 9 cm.
long, united in threes along a portion of their ventral surface into
pseudomonophyllous fascicles, serrulate on the two margins of the dorsal
surface, entire on the ventral margin; stomata dorsal and with one row
along the free portion of each ventral face. Conelets usually, if not
always, pseudolateral by reason of the summer growth of the branchlets,
and attaining in their first season an unusually large size. Cones from
6 to 12 cm. long, on very long stout and curved peduncles, cylindrical,
deciduous by an articulation between the cone and its peduncle, leaving
the latter for several years on the tree; apophyses dark lustrous
orange-red, rugose, elevated along a sharp transverse keel, the umbo
obscurely defined, the mucro usually broken away; nuts large, flaxen
yellow, the spermoderm adnate to the cone-scale.

  A small bushy tree with long pliant branches, clear gray cortex all
  over the limbs and trunk, and sparse gray-green foliage. It grows,
  together with P. cembroides, on the lower slopes of the northeastern
  Sierras of Mexico, near the boundary between the states of Tamaulipas
  and Nuevo Leon. It is apparently confined to a small area near the
  latitude of the city of Victoria, the capital of Tamaulipas, where its
  nuts are often exposed for sale.

  In many characters this species is unique. It can be recognized at
  once by the connate leaves that form the fascicle or by the remarkable
  stout curved peduncle of its cone. Such seeds as I have seen differ
  from those of P. cembroides by a reddish area at one end, but this can
  be seen with fresh seeds only.

    Plate XIII.

    Fig. 124, Cone, cone scale and seed. Fig. 125, Branchlet with
    leaves. Fig. 126, Magnified section of a leaf-fascicle.

[Illustration: PLATE XIII. P. NELSONII (124-126), PINCEANA (127-129),
CEMBROIDES (130-132)]


=V. GERARDIANAE=

Seeds with a very short ineffective articulate wing. Leaves in fascicles
of 3, serrulate, the sheath deciduous. Bark exfoliating in large scales,
leaving parti-colored areas.

  These Asiatic Nut Pines are alike in leaf and cortex as well as in the
  peculiar seed-wing. The last often remains in the cone after the nut
  falls. The mechanical nature of this adhesion is apparent in P.
  Gerardiana, where the wing adheres not to its own, but to the adjacent
  scale. The two species are alike in their leaves but distinct in their
  cones and seeds.

    Cones smaller, the nut short-ovate              16. Bungeana.
    Cones larger, the nut long-cylindrical          17. Gerardiana.


16. PINUS BUNGEANA

    1847 P. Bungeana Zuccarini ex Endlicher, Syn. Conif. 166.

Spring-shoots glabrous, summer-shoots common on fruiting branches of
young trees. Leaves from 6 to 10 cm. long, serrulate; stomata dorsal and
ventral; resin-ducts external. Conelets subterminal or often
pseudolateral, their scales gradually narrowed into a spine. Cones from
5 to 7 cm. long, short-pedunculate, short-ovate; apophyses dull pale
nut-brown, elevated along a transverse keel, the dark brown umbo forming
a spine with a broad base; seeds with a short loosely attached wing,
sometimes remaining in the cone when the short-ovate nut falls.

  A tree cultivated about the temples of China and recently found by
  Wilson growing on the mountains of Hupeh. The earlier parti-colored
  bark changes to chalky white on old trunks, by which the tree is
  recognized from a great distance. The stem of the tree is often
  multiple by the vertical growth of some of the lower branches. It is
  very hardy and is cultivated in Europe and America, although these
  cultivated trees are not yet of sufficient age to show the remarkable
  white trunk.

    Plate XIV.

    Fig. 138, Cone and cone-scale with adhering wing. Fig. 139, Seed and
    wing. Fig. 140, Leaf-fascicle and magnified leaf-section. Fig. 141,
    Parti-colored bark. Fig. 142, Tree with white trunk.


17. PINUS GERARDIANA

    1832 P. Gerardiana Wallich ex Lambert, Gen. Pin. ed. 8vo, ii. t. 79.

Spring-shoots glabrous. Leaves from 6 to 10 cm. long, serrulate; stomata
dorsal and ventral; resin-ducts external. Scales of the conelet armed
with a short spine. Cones from 9 to 15 cm. long, short-pedunculate,
ovoid or oblong; apophyses fulvous brown, very thick, with a prominent
reflexed or erect protuberance culminating in an umbo on which the spine
is more or less persistent; nuts remarkably long, narrow, terete, the
shell fragile, the short wing falling with the nut or adhering to the
adjacent scale.

  A tree of the northwestern Himalayas found on the borders of Cashmere
  and Thibet and in Kafiristan and north Afghanistan, and so highly
  prized for its nuts that it is rarely felled for its wood. It grows in
  dry regions and rarely attains a height of 20 metres. Attempts to
  cultivate this species, even in the milder parts of Great Britain,
  have generally failed.

  The apophysis of the cone varies much in prominence (figs. 134, 135),
  but the peculiar seed is invariable and quite unlike that of any other
  Pine. The general color of the trunk at a distance is silver-gray.

    Plate XIV.

    Fig. 133, Cone. Fig. 134, Cone-scale with adhering seed-wing. Fig.
    135, Cone-scale of flatter form. Fig. 136, Seed and wing. Fig. 137,
    Leaf-fascicle and magnified leaf-section.

[Illustration: PLATE XIV. P. GERARDIANA (133-137), BUNGEANA (138-142)]


=VI. BALFOURIANAE=

Seeds with long effective wings. Leaves entire, in fascicles of 5, the
sheath deciduous.

  The two species known as Foxtail Pines are alike in their short entire
  falcate leaves, persisting for many years and forming long dense
  foliage-masses. They differ in the armature of their cones and in
  their seed-wings. The presence of both adnate and articulate wings in
  these closely related species suggests that these two forms of wing
  are not fundamentally distinct.

    Cone-scales short-mucronate, the seed-wing adnate   18. Balfouriana.
    Cone-scales long-aristate, the seed-wing articulate 19. aristata.


18. PINUS BALFOURIANA

    1853 P. Balfouriana Balfour in Bot. Exp. Oregon, 1, f.

Spring-shoots somewhat puberulent. Leaves from 2 to 4 cm. long,
persistent for many years; stomata ventral only; resin-ducts external.
Scales of the conelet short-mucronate. Cones from 7 to 12 cm. long,
tapering to a rounded apex, short-pedunculate; apophyses dark
terracotta-brown, tumid, the umbo bearing a short recumbent prickle;
seed with a long adnate wing.

  An alpine species growing often at the timber-limit. It is found in
  two distinct stations in California, on the northern Coast Range and
  on the southern Sierras. It is not often cultivated, but young plants
  may be seen in the Arnold Arboretum and in the Royal Gardens at Kew.

    Plate XV.

    Fig. 147, Cone, seed and enlarged cone-scale. Fig. 148,
    Leaf-fascicle. Fig. 149, Magnified leaf-section. Fig. 150, A branch
    with persistent leaves.


19. PINUS ARISTATA

    1862 P. aristata Engelmann in Am. Jour. Sci. ser. 2, xxxiv. 331.
    1871 P. Balfouriana Watson in King's Rep. v. 331 (not Balfour).

Spring-shoots glabrous or temporarily pubescent. Leaves from 2 to 4 cm.
long, persistent for many years; stomata ventral only; resin-ducts
external. Scales of the conelet prolonged into long slender bristles.
Cones from 4 to 9 cm. long, subcylindrical or tapering to a rounded
apex, short-pedunculate; apophyses terracotta or purple-brown, tumid,
the long bristles of the umbo often partly or wholly broken away; seeds
with a long articulate wing.

  A bushy tree, similar in foliage to the preceding species, growing at
  the timber-limit from Colorado through Utah, central and southern
  Nevada and northern Arizona into southeastern California, but
  separated from the nearest station of P. Balfouriana by an arid
  treeless desert. Engelmann (in Brewer and Watson, Bot. Calif. ii. 125)
  considered it to be a variety of P. Balfouriana.

    Plate XV.

    Fig. 143, Cone. Fig. 144, Seed and enlarged cone-scale. Fig. 145,
    Leaf-fascicle and magnified leaf-section. Fig. 146, Conelet.

[Illustration: PLATE XV. P. ARISTATA (143-146), BALFOURIANA (147-150)]




DIPLOXYLON


Bases of the bracts subtending leaf-fascicles decurrent. Leaves
serrulate; fibro-vascular bundle double; stomata dorsal and ventral.
Cones with a dorsal umbo, the phyllotaxis complex. Wood hard, with dark
resinous bands, the annual rings clearly defined.

  In this section there are a few species combining the essential
  characters of Diploxylon with important characters of Haploxylon. A
  subsection, Parapinaster, is established for these exceptional
  species.

    c. Parapinaster  Species with the fascicle-sheath or seed-wing of
                       Haploxylon.
    d. Pinaster      Sheath persistent, seed-wing articulate, effective.

=Parapinaster=

    Sheath of the leaf-fascicle deciduous          VII.  Leiophyllae.
    Sheath of the leaf-fascicle persistent.
      Seed-wing of the Strobi                     VIII.  Longifoliae.
      Seed-wing of the Gerardianae                  IX.  Pineae.


=VII. LEIOPHYLLAE=

    Sheath of the leaf-fascicles deciduous.
      Leaves short, erect, the fructification triennial  20. leiophylla.
      Leaves long, pendent, the fructification biennial  21. Lumholtzii.


20. PINUS LEIOPHYLLA

    1831 P. leiophylla Schlechtendal and Chamisso in Linnaea, vi. 354.
    1848 P. chihuahuana Engelmann in Wislizenus, Tour. Mex. 103.

Spring-shoots uninodal. Leaves in fascicles of 3, 4 or 5, the sheath
deciduous, from 8 to 14 cm. long; resin-ducts medial with an occasional
internal duct. Conelets single or verticillate, their scales mucronate;
conelets of the second year only slightly enlarged. Cones maturing the
third year, not exceeding 7 cm. in length, ovate or ovate-conic,
subsymmetrical, more or less reflexed, persistent for several years on
some trees, sometimes serotinous; apophyses lighter or darker brown,
often with an olive or fuscous shade, thin or tumid, the umbo double,
the mucro more persistent near the apex of the cone.

  This species grows at subtropical or warm-temperate altitudes in
  Mexico, from Oaxaca through the central and western states to southern
  Arizona and New Mexico. As it approaches the northern part of its
  range the leaves become thicker and more rigid and the number in the
  fascicle is reduced to 3 or 4 (var. chihuahuana, Shaw, Pines Mex. 14).
  Like P. rigida it sprouts freely along the branches and trunk, and
  stumps of felled trees put out shoots in great numbers. The species is
  easily recognized by the deciduous sheath and triennial cone.

    Plate XVI.

    Fig. 151, Branch with fruit of first, second and third years. Fig.
    152, Leaf-fascicles. Fig. 153, Magnified leaf-section of the
    species. Fig. 154, Magnified leaf-section of the variety.


21. PINUS LUMHOLTZII

    1894 P. Lumholtzii Robinson & Fernald in Proc. Am. Acad. xxx. 122.

Spring-shoots uninodal, sometimes multinodal. Leaves in fascicles of 3,
the sheath deciduous, from 20 to 30 cm. long, absolutely pendent;
resin-ducts medial and internal. Conelets subterminal, or lateral and
subterminal, mucronate. Cones not exceeding 7 cm. in length,
symmetrical, pendent on slender peduncles, ovate-conic, early deciduous;
apophyses sublustrous, nut-brown, tumid at the margins, flat on the
surface, the umbo large, the mucro rarely persistent.

  A remarkable Pine with long pendent bright green foliage, confined to
  the western states of Mexico and ranging on the mountains from
  southern Jalisco to the latitude of the city of Chihuahua. Each
  season's growth of leaves hangs from the branchlet like a long beard,
  from which the tree receives, in some localities, the name "Pino barba
  caida." In the herbarium the long leaves, deciduous sheaths, and the
  decurrent bases of the bracts, present a combination of characters not
  found in other species.

    Plate XVI.

    Fig. 155, Cone. Fig. 156, Cone. Fig. 157, Leaf-fascicle. Fig. 158,
    Magnified leaf-section. Fig. 159, Tree at Ferraria de Tula.

[Illustration: PLATE XVI. P. LEIOPHYLLA (151-154), LUMHOLTZII
(155-159)]


=VIII. LONGIFOLIAE=

Seed-wing adnate to the nut. Leaves long, in fascicles of 3, the sheath
persistent.

    Apophysis of the cone prolonged and reflexed       22. longifolia.
    Apophysis of the cone low-pyramidal                23. canariensis.


22. PINUS LONGIFOLIA

    1803 P. longifolia Roxburgh ex Lambert, Gen. Pin. i. 29, t. 21.
    1897 P. Roxburghii Sargent, Silva N. Am. xi. 9.

Spring-shoots uninodal. Leaves in fascicles of 3, the sheath persistent,
from 20 to 30 cm. long; resin-ducts external, the hypoderm often in
large masses, some or all of the endoderm cells with thick outer walls.
Cones from 10 to 17 cm. long, short-pedunculate, ovoid-conic; apophyses
lustrous brown-ochre or fuscous brown, elevated into thick, often
reflexed, beaks with obtuse mutic umbos; seeds with large nuts and
adnate striated dark gray or fuscous brown wings.

  Of the three Pines of the Himalayas this species is the most
  important. It grows on the outer slopes and foot-hills from Bhotan to
  Afghanistan. The wood is used for construction and for the manufacture
  of charcoal, the thick soft bark is valuable for tanning, the resin is
  abundant and of commercial importance, and the nuts are gathered for
  food. The tree is not hardy in cool-temperate climates, but has been
  successfully grown in northern Italy.

  It differs from P. canariensis in the usually protuberant apophysis of
  the cone, in the thick outer walls of the leaf-endoderm and in the
  nearly smooth walls of the ray-tracheids of the wood. In the
  dimensions of cone and leaf, in the dermal tissues and resin-ducts of
  the leaf and in the peculiar coloring of the seed-wing, the two
  species are alike.

    Plate XVII.

    Fig. 160, Cone. Fig. 161, Leaf-fascicle. Fig. 162, Magnified
    leaf-section.


23. PINUS CANARIENSIS

    1825 P. canariensis Smith in Buch, Canar. Ins. 159.

Spring-shoots uninodal, pruinose. Bud-scales with conspicuously long
free fimbriate margins. Leaves in fascicles of 3, the sheath persistent,
from 20 to 30 cm. long; the hypoderm often in large masses, the
resin-ducts external, the endoderm with thin outer walls. Cones from 10
to 17 cm. long, short-pedunculate, ovoid-conic; apophyses lustrous or
sublustrous nut-brown, more or less pyramidal, the umbo unarmed; seeds
as in the last species.

  A species confined to the Canary Islands, but cultivated in northern
  Italy. The stately habit of this tree is seen in Schröter's portrait
  (Exc. Canar. Ins. t. 15).

    Plate XVII.

    Fig. 163, Cone and seed. Fig. 164, Magnified leaf-section. Fig. 165,
    Habit of the tree.

[Illustration: PLATE XVII. P. LONGIFOLIA (160-162), CANARIENSIS
(163-165)]


=IX. PINEAE=

Seed-wing articulate, short, ineffective. Leaves binate, the sheath
persistent. One species only.


24. PINUS PINEA

    1753 P. pinea Linnaeus, Sp. Pl. 1000.
    1778 P. sativa Lamarck, Fl. Franç. ii. 200.
    1854 P. maderiensis Tenore in Ann. Sci. Nat. sér. 4, ii. 379.

Spring-shoots uninodal. Leaves from 12 to 20 cm. long; resin-ducts
external. Conelet mutic, slightly larger in the second year. Cones
triennial, from 10 to 14 cm. long, ovoid or subglobose; apophyses
lustrous nut-brown, convex, of large size, the umbo double; seeds large
with a short, loosely articulated, deciduous wing.

  A species of the Mediterranean Basin, from Portugal to Syria. Its
  northern limit is in southern France and northern Italy, but it is
  cultivated in the southern parts of the British Isles and is a
  familiar ornament of park and garden in southern Europe, and is valued
  for its peculiar beauty and for its large savory nuts. In wood anatomy
  as well as in the seed it agrees with the Gerardianae of the Soft
  Pines.

    Plate XVIII.

    Fig. 166, Fruit of three seasons. Fig. 167, Cone-scales and seed.
    Fig. 168, Magnified leaf-section. Fig. 169, Habit of the tree.

[Illustration: PLATE XVIII. PINUS PINEA]

=Pinaster=

Bases of the bracts subtending leaf-fascicles decurrent. Seeds with an
effective articulate wing. Umbo of the cone-scales dorsal. Leaves
serrulate, stomatiferous on all faces, the sheath persistent. Walls of
the tracheids of the medullary rays dentate.

  Forty-two of the sixty-six species of Pinus are included in this
  subsection. As a group they are clearly circumscribed by several
  correlated characters and are more closely interrelated than the
  twenty-four species previously described. The distinctions of umbo and
  seed have disappeared. The umbo here is invariably dorsal, the
  seed-wing invariably articulate.

  New forms, however, are gradually evolved--the seed with a thick
  wing-blade, the indurated oblique cone, the serotinous cone with its
  intermittent seed-release, and the multinodal spring-shoot. There are,
  moreover, new forms of leaf-hypoderm and a new position of the
  resin-duct.

  Of these new characters, the thick wing-blade attains such proportions
  in the three species of the Macrocarpae that they can be grouped
  apart. But the characters that finally culminate in a lateral oblique
  serotinous cone are so gradually and irregularly developed that they
  offer no divisional distinctions. With the aid of wood and leaf
  characters, however, groups can be established which preserve the
  evolutionary sequence and, at the same time, the obvious affinity of
  the species.

    Wing-blade thin or slightly thickened at the base.
     Cones dehiscent at maturity.
      Pits of the ray-cells large                      X.    Lariciones
      Pits of the ray-cells small                      XI.   Australes
     Cones serotinous, pits of the ray-cells small     XII.  Insignes
    Wing-blade very thick                              XIII. Macrocarpae

  The species of this subsection are very difficult, if not impossible,
  to classify by the usual method, which groups all species under a few
  characters assumed to be invariable and of fundamental importance.
  Such a method can be successfully applied to the Soft Pines and to
  some of the Hard Pines, but cannot be applied to all the Hard Pines
  without forcing some of them into unnatural associations.

  To take an example, the group Pseudostrobus, characterized by
  pentamerous leaf-fascicles, appears in many systems. In this group are
  placed P. Torreyana and P. leiophylla. Another group, with trimerous
  fascicles, contains P. Sabiniana and P. taeda. Now there are no two
  species more obviously related by important peculiarities than P.
  Torreyana and P. Sabiniana; nevertheless they are, by this method,
  kept apart and associated with species which they resemble in no
  important particular.

  An attempt is made here to avoid such incongruities. Groups X, XI and
  XII represent different stages of evolution. In the Lariciones the
  cone is symmetrical, and dehiscent and deciduous at maturity, while
  the spring-shoot is uninodal. In the Australes there is a similar
  cone, but the spring-shoot gradually becomes multinodal. In the
  Insignes the cone is oblique, persistent and serotinous, and the
  spring-shoot is multinodal.

  These definitions state the degree of evolution attained by each
  group, but not all the species of a group conform exactly with its
  definition. In each group are species with a characteristic of another
  group. Among the Lariciones are a few species with both symmetrical
  and oblique cones, and two with persistent cones. Similar exceptions
  occur among the Australes. Among the Insignes are a few species with
  symmetrical cones, and two with cones that are rarely, if ever,
  serotinous.

  There is, however, no difficulty in fixing the systematic position of
  these exceptional species through other characters which show their
  true affinity. They are placed with the species which they most
  resemble. Their exceptional characters are merely the evidence of the
  evolution that pervades and unites the groups. Therefore the
  definition of a group is not necessarily the exact definition of its
  species, and a species is placed in a group because all its
  characters, specific and evolutional, show a closer affinity with that
  group than with the species of any other.


=X. LARICIONES=

Pits of the ray-cells large. Cells of the leaf-hypoderm uniform.
Spring-shoots uninodal. Cones dehiscent at maturity.

  This group represents the first stage in the evolution of the Hard
  Pines. All the species, like the Soft Pines, are uninodal and the
  cones are dehiscent at maturity, but the trend toward the serotinous
  species is shown in the occasional appearance of the oblique cone as a
  varietal form of a few species, and in the persistent cone of the last
  two species of this group.

  All the species of this group are of the Old World except P. resinosa
  and P. tropicalis. These two are the only American Pines combining
  large pits with dentate tracheids, and are the only American Hard
  Pines with external resin-ducts of the leaf.

    Cones deciduous at maturity.
      Cones ovate or ovate-conic.
        Conelet with tuberculate or entire scales.
          Resin-ducts external and medial          25. resinosa
          Resin-ducts septal and external          26. tropicalis
        Conelet with mucronate scales.
          Resin-ducts mostly external.
            Conelet pedunculate, erect.
              Cone nut-brown                       27. Massoniana
              Cone dull tawny yellow               28. densiflora
            Conelet pedunculate, reflexed          29. sylvestris
            Conelet subsessile, erect              30. montana
          Resin-ducts mostly medial.
            Bark-formation late                    31. luchuensis
            Bark-formation early.
              Cone nut-brown                       32. Thunbergii
              Cone lustrous tawny yellow           33. nigra
      Cones narrow cylindrical                     34. Merkusii
    Cones tenaciously persistent.
      Leaves stout, relatively short               35. sinensis
      Leaves slender, relatively long              36. insularis


25. PINUS RESINOSA

    1789 P. resinosa Aiton, Hort. Kew. iii. 367.
    1810 P. rubra Michaux f. Hist. Arbr. Am. i. 45, t. 1.

Spring-shoots uninodal. Leaves binate, from 12 to 17 cm. long;
resin-ducts external or external and medial; hypoderm uniform and
inconspicuous. Scales of the conelet mutic. Cones from 4 to 6 cm. long,
subsessile, symmetrical, deciduous the third year, leaving a few basal
scales on the tree; apophyses sublustrous, nut-brown, somewhat thickened
along a transverse keel.

  From Nova Scotia and Lake St. John this species ranges westward to the
  Winnipeg River and southward into Minnesota, Michigan, northern New
  York and eastern Massachusetts, with rare occurrence on the mountains
  of Pennsylvania. Under cultivation it is a beautiful tree, adapted to
  cold-temperate climates. It was considered by Loiseleur (1812) and by
  Spach (1842) to be a variety of P. nigra (laricio). The two species
  vary in the color of the cone, the anatomy of the leaves, the buds,
  and in the armature of the conelet. A fallen cone of this species is
  moreover usually imperfect from the loss of a few basal scales.

    Plate XIX.

    Fig. 170, Cone and enlarged conelet. Fig. 171, Leaf-fascicle and
    magnified leaf-section.


26. PINUS TROPICALIS

    1851 P. tropicalis Morelet in Rev. Hort. Côte d'Or, i. 105.
    1904 P. terthrocarpa Shaw in Gard. Chron. ser. 3, xxxv. 179, f. 74.

Spring-shoots uninodal. Leaves binate, sometimes ternate, from 15 to 30
cm. long, rigid, erect; hypoderm of uniform thick-walled cells;
resin-ducts of remarkable size, septal, or not quite touching the
endoderm and technically external. Scales of the conelet minutely
tuberculate. Cones from 5 to 8 cm. long, short-pedunculate, erect or
patulous; ovate-conic, symmetrical; apophyses rufous brown,
low-pyramidal, the umbo mutic.

  Growing at sea-level within the tropics and confined to western Cuba
  and the Isle of Pines. On the island it is associated with P.
  caribaea. This species needs no other means of identification than its
  peculiar leaf-section. Septal ducts are found in P. oocarpa, Pringlei,
  Merkusii and rarely in other species, but they never attain the
  extraordinary size that appears to be invariable in P. tropicalis.

    Plate XIX.

    Fig. 172, Cone and enlarged conelet. Fig. 173, Branch with leaves,
    much reduced. Fig. 174, Leaf-fascicle and magnified leaf-section.
    Fig. 175, Trees on the Isle of Pines.

[Illustration: PLATE XIX. P. RESINOSA (170, 171), TROPICALIS (172-175)]


27. PINUS MASSONIANA

1803 P. Massoniana Lambert, Gen. Pin. i. 17, t. 12. 1861 P. canaliculata
Miquel in Jour. Bot. Neerland. i. 86.

Spring-shoots uninodal. Leaves binate, rarely ternate, from 12 to 20 cm.
long, slender and pliant; hypoderm inconspicuous; resin-ducts external.
Staminate catkins often in long dense clusters. Conelets partly
tuberculate or mucronate, partly mutic. Cones symmetrical, from 4 to 7
cm. long, ovate-conic, short-pedunculate, early deciduous; apophyses
sublustrous, nut-brown, flat or somewhat elevated, the umbo usually
mutic.

  The Chinese Red Pine is found in warm-temperate climates. It is native
  to southeastern China and follows the valley of the Yangtse River into
  Szech'uan. It has been confused by London with P. pinaster, which it
  resembles in no respect, by Siebold with P. Thunbergii, from which it
  differs in leaf-dimensions and in leaf-section, and by Mayr with his
  P. luchuensis, whose peculiar cortex and whose leaf-section has no
  counterpart among Chinese Hard Pines. Its nearest relative is P.
  densiflora, from which it differs in its longer leaves, in the color
  of its cone and in its conelet (Plate XX, figs. 176, 179).

    Plate XX.

    Fig. 176, Cone and enlarged conelet. Fig. 177, Two leaf-fascicles.
    Fig. 178, Magnified leaf-section.


28. PINUS DENSIFLORA

    1842 P. densiflora Siebold & Zuccarini, Fl. Jap. ii. 22, t. 112.
    1854 P. scopifera Miquel in Zollinger, Syst. Verz. Ind. Archip. 82.

Spring-shoots more or less pruinose, uninodal. Leaves binate, from 8 to
12 cm. long, slender; hypoderm of few inconspicuous cells; resin-ducts
external. Staminate catkins in long dense clusters. Scales of the
conelet conspicuously mucronate. Cones symmetrical, from 3 to 5 cm.
long, ovate-conic, often persistent for a few years but with a weak hold
on the branch; apophyses dull pale tawny yellow, flat or slightly
elevated, the mucro more or less persistent.

  The Japanese Red Pine forms extensive forests on the mountains of
  central Japan. It is perfectly hardy in cold-temperate climates. Wild
  specimens of China, ascribed to this species, are forms of the
  variable P. sinensis. From P. Massoniana it differs in its shorter
  leaves and yellow cone, but particularly in the more prominent
  prickles and thicker scales of its conelet (figs. 176, 179).

    Plate XX.

    Fig. 179, Cones and enlarged conelet. Fig. 180, Leaf-fascicles. Fig.
    181, Magnified leaf-section and more magnified dermal tissues of the
    leaf.

[Illustration: PLATE XX. P. MASSONIANA (176-178), DENSIFLORA (179-181)]

29. PINUS SYLVESTRIS

    1753 P. sylvestris Linnaeus, Sp. Pl. 1000 (excl. var.).
    1768 P. rubra Miller, Gard. Dict. ed. 8.
    1768 P. tatarica Miller, Gard. Dict. ed. 8.
    1781 P. mughus Jacquin, Icon. Pl. Rar. i. t. 193 (not Scopoli).
    1798 P. resinosa Savi, Fl. Pisa. ii. 354 (not Aiton).
    1827 P. humilis Link in Abhandl. Akad. Berlin, 171.
    1849 P. Kochiana Klotzsch in Linnaea, xxii. 296.
    1849 P. armena Koch in Linnaea, xxii. 297.
    1849 P. pontica Koch in Linnaea, xxii. 297.
    1859 P. Frieseana Wichura in Flora, xlii. 409.
    1906 P. lapponica Mayr, Fremdl. Wald- & Parkb. 348.

Spring-shoots uninodal. Leaves binate, from 3 to 7 cm. long; hypoderm
inconspicuous; resin-ducts external. Conelet reflexed, minutely
mucronate. Cones from 3 to 6 cm. long, reflexed, symmetrical or
sometimes oblique, ovate-conic, deciduous; apophyses dull pale tawny
yellow of a gray or greenish shade, flat, elevated or protuberant and
often much more prominent on the posterior face of the cone, the umbo
with a minute prickle or its remnant.

  A tree of great commercial value, with a very extended range, from
  Norway, Scotland and southern Spain to northeastern Siberia. A
  vigorous hardy species and extensively cultivated. The red upper
  trunk, characteristic of this Pine, is not invariable. The dark upper
  trunk is sufficiently common to be considered a varietal form
  (Mathieu, Flore Forest. ed. 4, 582). In various localities may be
  found trees bearing oblique cones, their apophyses showing various
  degrees of protuberance up to the extreme development represented in
  Loudon's illustration of the variety uncinata (Arb. Brit. iv, f.
  2047). This cone is the beginning of the changes that culminate in
  species with oblique cones only. In P. sylvestris, however, the
  purpose of this form of cone is not apparent except in connection with
  this evolution.

    Plate XXI.

    Figs. 182, 183, Cones. Fig. 184, Leaf-fascicle, magnified
    leaf-section and more magnified dermal tissues of the leaf. Fig.
    185, Habit of the tree.

30. PINUS MONTANA

    1768 P. montana Miller, Gard. Dict. ed. 8.
    1772 P. mughus Scopoli, Fl. Carn. ii. 247.
    1791 P. pumilio Haenke in Jirasek, Beobacht. 68.
    1804 P. mugho Poiret in Lamarck, Encycl. Méth. v. 336.
    1805 P. uncinata Ramond ex De Candolle, Lamarck, Fl. Franç. ed. 3,
              iii. 726.
    1813 P. sanguinea Lapeyrouse, Hist. Pl. Pyren. 587.
    1827 P. rotundata Link in Abhandl. Akad. Berlin, 168.
    1830 P. obliqua Sauter ex Reichenbach, Fl. Germ. Exc. 159.
    1837 P. uliginosa Neumann ex Wimmer, Arb. Schles. Ges. 95.

Spring-shoots uninodal. Leaves binate, from 3 to 8 cm. long, the epiderm
very thick, hypoderm weak; resin-ducts external. Conelets mucronate,
nearly sessile. Cones from 2 to 7 cm. long, subsessile, ovate or
ovate-conic, symmetrical or oblique, often persistent; apophyses
lustrous tawny-yellow or dark brown, both colors often shading into each
other on the same cone, flat, prominent or prolonged into uncinate
beaks of various lengths, the last much more developed on the posterior
face of the cone, the umbo bordered by a narrow dark ring and bearing
the remnant of the mucro.

  P. montana grows as a bush or as a small tree, the two forms often
  associated. It ranges from central Spain through the Pyrenees, Alps
  and Apennines to the Balkan Mountains, associated with P. cembra at
  higher, with P. sylvestris at lower altitudes. It grows indifferently
  in bogs and on rocky slopes. Its dwarf form, under the name of the
  Mugho Pine, is extensively cultivated as a garden ornament.

  On the differences of the cone this species has been divided into
  three subspecies: uncinata, with an oblique cone and protuberant
  apophyses; pumilio, with a symmetrical cone and an excentric umbo;
  mughus, with a symmetrical cone and a concentric umbo. Other
  segregations based on the degree of development of the apophysis and
  on the size and color of the cone, have received names of four or even
  five terms--Pinus montana pumilio applanata--or Pinus montana uncinata
  rostrata castanea etc., etc. These elaborations may be seen in the
  Tharand Jahrbuch of 1861, p. 166, and with them appear also Hartig's
  specifications of 60 forms of this species, each dignified with a
  Latin name.

    Plate XXI.

    Fig. 186, Cone of var. uncinata. Figs. 187, 188, Cones. Fig. 189,
    Leaf-fascicles, magnified leaf-section and more magnified dermal
    tissues of the leaf. Fig. 190, Tree and dwarf-form of the Pyrenees.

[Illustration: PLATE XXI. P. SYLVESTRIS (182-185), MONTANA (186-190)]

31. PINUS LUCHUENSIS

1894 P. luchuensis Mayr in Bot. Centralbl. lviii. 149, f.

Spring-shoots uninodal. Bark-formation late, the upper trunk covered
with a smooth cortex. Leaves binate, from 12 to 16 cm. long, the epiderm
thick, hypoderm of two or three rows of cells; resin-ducts medial or
with an occasional external duct. Conelets mucronate toward the apex.
Cones from 3 to 6 cm. long, ovate-conic, symmetrical; apophyses lustrous
nut-brown, transversely carinate, the umbo unarmed.

  This Pine is known to me through Mayr's description and a single dried
  specimen. The smooth cortex of young trees distinguishes it from all
  other east-Asiatic Hard Pines. Mayr includes under this species the
  Pine of Hong Kong. But in this he must be mistaken, for there is no
  species yet found in China that agrees with the description of P.
  luchuensis.

    Plate XXII.

    Fig. 191, Cone. Fig. 192, Leaf-fascicle and magnified leaf-section.

32. PINUS THUNBERGII

    1784 P. sylvestris Thunberg, Fl. Jap. 274 (not Linnaeus).
    1842 P. Massoniana Siebold & Zuccarini. Fl. Jap. ii. 24, t. 113
              (not Lambert).
    1868 P. Thunbergii Parlatore in DC. Prodr. xvi-2, 388.

Spring-shoots uninodal. Buds of leading-shoots white and conspicuous.
Leaves binate, from 6 to 11 cm. long, the epiderm thick, hypoderm
strong, resin-ducts medial. Conelets with short-mucronate scales. Cones
from 4 to 6 cm. long, ovate or ovate-conic, symmetrical; apophyses
nut-brown, flat or convex and transversely carinate, the prickle of the
umbo more or less persistent.

  The Black Pine of Japan has been cultivated for centuries, and by
  skillful Japanese gardeners has been trained into dwarf and other
  curious forms. It is hardy in cold-temperate climates. It is distinct
  from P. densiflora by the medial ducts of its leaf, from P. nigra by
  the fewer, larger, brown scales of its cone, and from P. resinosa by
  the armature of its conelet. It appears in most determinations of
  Chinese collections, but there is no Chinese Pine with the white buds
  and the medial leaf-ducts of this species.

    Plate XXII.

    Fig. 196, Two cones. Fig. 197, Leaf-fascicle and magnified
    leaf-section.


33. PINUS NIGRA

    1785 P. nigra Arnold, Reise n. Mariaz. 8, t.
    1804 P. laricio Poiret in Lamarck, Encycl. Méth. v. 339.
    1808 P. halepensis Bieberstein, Fl. Taur. Cauc. ii. 408 (not Miller).
    1809 P. pinaster Besser, Fl. Galic. ii. 294 (not Aiton).
    1813 P. maritima Aiton, f. Hort. Kew. v. 315 (not Lambert).
    1816 P. sylvestris Baumgarten, Stirp. Transsilv. ii. 304
              (not Linnaeus).
    1818 P. pyrenaica Lapeyrouse, Hist. Pl. Pyren. Suppl. 146.
    1824 P. Pallasiana Lambert, Gen. Pin. ii. 1, t. 1.
    1825 P. austriaca Höss in Flora, viii-1, Beil. 113.
    1831 P. nigricans Host, Fl. Austr. ii. 628.
    1842 P. dalmatica Visiani, Fl. Dalmal. 199, note.
    1851 P. Salzmanni Dunal in Mém. Acad. Montp. ii. 82, tt.
    1863 P. Heldreichii Christ in Verh. Nat. Ges. Basel, iii. 549.
    1864 P. leucodermis Antoine in Oesterr. Bot. Zeitschr. xiv. 366.
    1896 P. pindica Formanek in Verh. Nat. Ver. Brünn, xxxiv. 272.

Spring-shoots uninodal. Leaves binate, from 9 to 16 cm. long, the
epiderm thick, hypoderm conspicuous, resin-ducts medial. Conelets
mucronate. Cones from 4 to 8 cm. long, subsessile, symmetrical;
apophyses lustrous, tawny yellow, transversely carinate, the keel
strongly convex, the mucro of the umbo more or less persistent.

  A valuable tree unequally distributed over the mountain slopes of
  central and southern Europe and Asia Minor. The typical form, under
  the name of the Austrian Pine, is a familiar exotic of the Middle and
  Eastern States of America. As Mathieu states (Flore Forest., ed. 4,
  597), this species is quite constant in cone and bark. It may be added
  that the anatomy of the leaf is also constant, while the dimensions of
  both leaf and cone present no unusual variations. The varieties
  generally accepted are founded on the habit of the tree, a character
  of forestal or horticultural rather than of botanical importance.

    Plate XXII.

    Fig. 193, Two cones. Fig. 194, Leaf-fascicle and magnified
    leaf-section. Fig. 195, Magnified dermal tissues of the leaf.

[Illustration: PLATE XXII. P. LUCHUENSIS (191, 192), NIGRA (193-195),
THUNBERGII (196, 197)]


34. PINUS MERKUSII

    1790 P. sylvestris Loureiro, Fl. Cochinch. ii. 579 (not Linnaeus).
    1845 P. Merkusii De Vriese, Pl. Nov. Ind. Bat. 5, t. 2.
    1847 P. Finlaysoniana Wallich ex Blume, Rumphia, iii. 210.
    1849 P. Latteri Mason in Jour. Asiat. Soc. i. 74.

Spring-shoots uninodal. Leaves binate, slender, from 15 to 20 cm. long,
the hypoderm of uniform thick-walled cells, resin-ducts medial, or with
internal or septal ducts, endoderm-cells very unequal in size, some of
them large. Conelets unarmed. Cones from 5 to 8 cm. long, peculiarly
narrow-cylindrical, symmetrical; apophyses lustrous, rufous brown,
radially carinate, the transverse keel prominent.

  Of the habit of this Pine I know nothing. As a species it is very
  clearly defined by its peculiar cone and leaf-section. It grows in the
  Philippines, Sumatra, Lower Burmah and western Indo-China. In my
  specimen the pits of the ray-cells of the wood are both large and
  small. In this particular it may belong in either of two groups of
  species. Its uniform leaf-hypoderm associates it with this group or
  with P. halepensis of the Insignes. I have assumed the cone to be
  dehiscent at maturity and have placed it with the Lariciones, but if
  further information shows the cone to be serotinous, this species
  should be transferred to the serotinous group.

    Plate XXIII.

    Fig. 198, Cone. Fig. 199, Magnified sections of two leaves. Fig.
    200, Leaf-fascicle.


35. PINUS SINENSIS

    1832 P. sinensis Lambert, Gen. Pin. ed. 8vo. i. 47, t. 29.
    1867 P. tabulaeformis Carrière, Trait. Conif. ed. 2, 510.
    1881 P. leucosperma Maximowicz in Bull. Acad. St. Pétersb. xxvii. 558.
    1899 P. yunnanensis Franchet in Jour. de Bot. xiii. 253.
    1901 P. funebris Komarow in Act. Hort. Petrop. xx. 177.
    1902 P. Henryi Masters in Jour. Linn. Soc. xxvi. 550.
    1906 P. densata Masters in Jour. Linn. Soc. xxxvii. 416.
    1906 P. prominens Masters in Jour. Linn. Soc. xxxvii. 417.
    1911 P. Wilsonii Shaw in Sargent, Pl. Wilson. i. 3.

Spring-shoots uninodal, pruinose. Leaves binate, ternate, or both, from
10 to 15 cm. long, stout and rigid; resin-ducts external, or external
and medial. Staminate catkins in short capitate clusters. Conelets
mucronate. Cones from 4 to 9 cm. long, ovate, symmetrical or oblique,
tenaciously persistent, dehiscent at maturity; apophyses lustrous, pale
tawny yellow at first, gradually changing to a dark nut-brown, tumid,
the posterior scales often larger and more prominent.

  A tree of cold-temperate and subalpine levels, growing on the
  mountains of central and western China, and at lower altitudes in the
  north and in Corea. It is recognized by its tenaciously persistent
  cones with a remarkable change in color. It is constantly confused
  with P. Thunbergii and P. densiflora, neither of which grows
  spontaneously in China. From the former it differs in leaf-section and
  bud (the bud of P. sinensis is never white), from the latter in the
  lustre and the color variation of its cone, and from both in the
  frequent obliquity of its cone and in the frequent presence of
  trimerous leaf-fascicles.

  Of the two varieties of this species, densata and yunnanensis (Shaw in
  Sargent, Pl. Wilson. ii. 17), the former represents the extreme
  oblique form of cone, the latter represents the longest dimensions of
  cone and leaf. The effect of environment on this species can be seen
  in figs. 202, 203, from a lower slope and rich soil, and fig. 204,
  from a high rocky ledge in the same locality.

    Plate XXIII.

    Fig. 201, Cone of var. densata. Fig. 202, Cone of var. yunnanensis.
    Fig. 203, Leaf-fascicle and magnified leaf-section of var.
    yunnanensis. Fig. 204, Cone and leaf-fascicle from a rocky ledge.
    Fig. 205, Cone, leaf-fascicle and magnified leaf-section of the
    typical form. Fig. 206, Seeds. Fig. 207, Conelet and its enlarged
    scale.

36. PINUS INSULARIS

    1837 P. taeda Blanco, Fl. Filip. 767 (not Linnaeus).
    1847 P. insularis Endlicher, Syn. Conif. 157.
    1854 P. khasiana Griffith, Notul. Pl. Asiat. iv. 18; Icon. Pl.
              Asiat. tt. 367, 368.
    1868 P. kasya Royle ex Parlatore in DC. Prodr. xvi-2, 390.

Spring-shoots uninodal, glabrous. Leaves from 12 to 24 cm. long, in
fascicles of 3, rarely of 2, very slender; resin-ducts external, rarely
with a medial duct. Conelets mucronate. Cones from 5 to 10 cm. long,
ovate-conic, symmetrical or oblique, tenaciously persistent; apophyses
lustrous, nut-brown, convex or elevated along a transverse keel, the
posterior scales of some cones larger and more prominent than the
anterior scales, the mucro usually deciduous.

  A species of the Philippines and of northern Burmah. In both countries
  it is locally exploited for wood and resin. It differs from the common
  form of P. sinensis by its much longer leaves, and from its var.
  yunnanensis, which it more resembles, by its much more slender and
  pliant leaves. Moreover its cone, so far as I can learn, is not yellow
  at maturity, but brown.

    Plate XXIII.

    Figs. 208, 209, Three cones. Fig. 210, Leaf-fascicle and magnified
    leaf-section.

[Illustration: PLATE XXIII. P. MERKUSII (198-200), SINENSIS (201-207),
INSULARIS (208-210)]


=XI. AUSTRALES=

Pits of the ray-cells small. Leaf-hypoderm biform or variable.
Spring-shoots uninodal in some, multinodal in other species. Cones
dehiscent at maturity.

  This group combines the dehiscent cone of the Lariciones with the
  wood-anatomy of the serotinous Pines. Also the multinodal spring-shoot
  first appears here and is gradually developed among the species,
  absent in Nos. 37-39, sometimes present in Nos. 40-43, and prevalent
  in Nos. 44-47.

  All the species are of the Western Hemisphere, and among them may be
  found the biform hypoderm of the leaf, the internal resin-duct, and
  the total absence of external resin-ducts, characters common in
  American Hard Pines. The eastern species are quite constant in their
  characters and present no varietal forms; the western species, on the
  other hand, are very variable. This difference may be due to the even
  level and slight climatic differences of the Atlantic states and to
  the remarkable diversity of altitude and climate of the western states
  and Mexico.

    Outer walls of the leaf-endoderm thick.
      Cones large, attaining 12 cm. or more in length.
        Prickles of the cone inconspicuous.
          Bark-formation late                          37. pseudostrobus
          Bark-formation early                         38. Montezumae
        Prickle of the cone conspicuous                39. ponderosa
      Cones small, 7 cm. or less in length             40. teocote
    Outer walls of the leaf-endoderm thin.
      Spring-shoots mostly uninodal.
        Prickle of the cone slender, sometimes deciduous.
          Cones mostly oblique                         41. Lawsonii
          Cones symmetrical                            42. occidentalis
        Prickles of the cone stout and persistent      43. palustris
      Spring-shoots multinodal.
        Resin-ducts internal                           44. caribaea.
        Resin-ducts mostly medial.
          Prickle of the cone stout                    45. taeda
          Prickle of the cone slender.
            Bark-formation late                        46. glabra
            Bark-formation early                       47. echinata


37. PINUS PSEUDOSTROBUS

    1839 P. pseudostrobus Lindley in Bot. Reg. xxv. Misc. 63.
    1839 P. apulcensis Lindley in Bot. Reg. xxv. Misc. 63.
    1842 P. tenuifolia Bentham, Pl. Hartw. 92.
    1846 P. orizabae Gordon in Jour. Hort. Soc. Lond. i. 237, f.

Spring-shoots uninodal, conspicuously pruinose. Bark-formation late, the
cortex of young trees smooth. Leaves in fascicles of 5, sometimes of 6,
from 15 to 30 cm. long, drooping; resin-ducts medial, hypoderm variable
in amount, often in very large masses, the outer walls of the endoderm
thick. Conelets mucronate. Cones from 7 to 14 cm. long, ovate or
ovate-conic, symmetrical or oblique, deciduous and often leaving a few
basal scales on the trees; apophyses rufous or fulvous brown, flat,
elevated or, in one variety, prolonged in various degrees, the
prolongations nearly uniform or much more prominent on the posterior
face of the cone, the mucro usually deciduous.

  A species of the subtropical and warm-temperate altitudes of Mexico
  and Central America. Its range includes both eastern and western
  slopes of the northern plateau. Its northern limit is in Nuevo Leon,
  and it probably reaches in Nicaragua the southern limit of pines in
  the Western Hemisphere. It is distinguished from all its associates by
  the smooth gray trunk of the young trees, by their long internodes,
  and by their drooping gray-green foliage.

  Some cones of this species develop protuberances of all degrees of
  prominence up to the curious cone collected in Oaxaca by Nelson (var.
  apulcensis, Shaw, Pines Mex. t. 12, fig. 8). There is also a
  remarkable difference in the amount of leaf-hypoderm. On many trees of
  the western part of the range this tissue forms septa across the green
  mesophyll. Such partitions are sometimes met in other species, P.
  Pringlei or P. canariensis, where the hypoderm is abundant. But in P.
  pseudostrobus they appear in some leaves of weak, as well as of strong
  hypoderm (var. tenuifolia, Shaw, Pines Mex. t. 13, ff. 2, 4, 5, 7, 8).

    Plate XXIV.

    Fig. 211, Cone. Fig. 212, Two cones of var. tenuifolia. Figs. 213,
    214, Two cones of var. apulcensis. Fig. 215, Magnified section of 3
    leaves of var. tenuifolia. Fig. 216, Magnified section of 2 leaves
    of the species. Fig. 217, Bud destined to produce staminate flowers.
    Fig. 218, Ten-year old branch showing smooth cortex. Fig. 219, Young
    and mature trees in open growth.

[Illustration: PLATE XXIV. PINUS PSEUDOSTROBUS]


38. PINUS MONTEZUMAE

    1817 P. occidentalis H. B. & K. Nov. Gen. ii. 4 (not Swartz).
    1832 P. Montezumae Lambert, Gen. Pin. ed. 8vo, i. 39, t. 22.
    1839 P. Devoniana Lindley in Bot. Reg. xxv. Misc. 62.
    1839 P. Hartwegii Lindley in Bot. Reg. xxv. Misc. 62.
    1839 P. Russelliana Lindley in Bot. Reg. xxv. Misc. 63.
    1839 P. macrophylla Lindley in Bot. Reg. xxv. Misc. 63.
    1840 P. filifolia Lindley in Bot. Reg. xxvi. Misc. 61.
    1841 P. Sinclairii Hooker & Arnott, Bot. Beechy Voy. 392, t. 93
              (as to cone).
    1841 P. radiata Hooker & Arnott, Bot. Beechy Voy. 443 (as to leaves).
    1847 P. Grenvilleae Gordon in Jour. Hort. Soc. Lond. ii. 77, f.
    1847 P. Gordoniana Hartweg in Jour. Hort. Soc. Lond. ii. 79, f.
    1847 P. Wincesteriana Gordon in Jour. Hort. Soc. Lond. ii. 158, f.
    1847 P. rudis Endlicher, Syn. Conif. 151.
    1847 P. Ehrenbergii Endlicher, Syn. Conif. 151.
    1858 P. Lindleyana Gordon, Pinet. 229.
    1891 P. Donnell-Smithii Masters in Bot. Gaz. xvi. 199.

Spring-shoots uninodal, slightly or not at all pruinose. Bark-formation
early, the branches becoming dark and rough. Leaves prevalently in
fascicles of 5, but varying from 3 to 8, extremely variable in length,
attaining 45 cm. at subtropical levels; resin-ducts medial, hypoderm
sometimes uniform, more commonly multiform, the outer walls of the
endoderm thick. Conelet mucronate, the prickle often reflexed. Cones of
many sizes, attaining in warm localities 30 cm. in length, ovate-conic
or long-conic, symmetrical, often curved, deciduous and often leaving a
few scales on the tree; apophyses dull, rarely lustrous, nut-brown, or
of various shades of fuscous brown to nearly black, flat, tumid,
pyramidal or sometimes slightly protuberant, the prickle rarely
persistent.

  This species ranges from the mountains of northern Durango to the
  volcanoes of Guatemala, or possibly farther south. It is found at all
  altitudes where Pines can grow except on the tropical levels of
  Guatemala. Its more hardy forms have been successfully grown in the
  milder parts of Great Britain and northern Italy. It is felled for
  lumber in many parts of Mexico.

  This sturdy Pine and its numberless variations present the most
  remarkable example of adaptation in the genus. The variations are
  mostly those associated with changes of environment--dimensions of
  cone and leaf and the number of leaves in the fascicle. These are so
  accurately correlated with altitude and exposure, and are so
  imperceptibly graded, that no specific segregations among them have
  yet been successfully established.

  The type-specimen figured by Lambert does not show the longest cone
  and leaf of this species. They are better represented by specimens
  which have been named P. filifolia. Such dimensions prevail in
  subtropical localities. At temperate altitudes these dimensions are
  much reduced, but here are found a longer form of cone and leaf (var.
  Lindleyi, Loudon) and a shorter form (var. rudis, Shaw). At still
  higher altitudes and up to the timber-limit the var. Hartwegii,
  Engelmann, with short leaves and a small nearly black cone is found.
  Among these varieties there is no such sharp distinction as these
  definitions imply. All dimensions of fruit and foliage and the various
  brown and black shades of the cone blend into each other through
  endless intergradations. A monograph of this species, by one who could
  devote some years to it on the superb volcanoes and in the delightful
  climates where this tree abounds, would be a valuable contribution to
  science.

    Plate XXV. (Cones and leaves much reduced.)

    Fig. 220, Cone and leaves of Lambert's plate. Figs. 221, 222, Longer
    cones and leaves of the species. Fig. 223, Cone and leaves of var.
    Lindleyi. Fig. 224, Cones and leaves of var. rudis. Fig. 225, Cone
    and leaves of var. Hartwegii. Fig. 226, Magnified leaf-sections.
    Figs. 227, 228, Two forms of the dermal tissues of the leaf,
    magnified. Fig. 229, Habit of the tree.

[Illustration: PLATE XXV. PINUS MONTEZUMAE]


39. PINUS PONDEROSA

    1836 P. ponderosa Douglas ex Lawson's Agric. Man. 354.
    1847 P. Benthamiana Hartweg in Jour. Hort. Soc. Lond. ii. 189.
    1848 P. brachyptera Engelmann in Wislizenus, Tour Mex. 89.
    1848 P. macrophylla Engelmann in Wislizenus, Tour Mex. 103
              (not Lindley).
    1853 P. Jeffreyi Balfour in Bot. Exp. Oregon, 2, f.
    1854 P. Engelmanni Carrière in Rev. Hort. 227.
    1855 P. Beardsleyi Murray in Edinb. Phil. Jour. ser. 2, i. 286, t. 6.
    1855 P. Craigana Murray in Edinb. Phil. Jour. ser. 2, i. 288, t. 7.
    1858 P. Parryana Gordon, Pinet. 202 (not Engelmann).
    1859 P. deflexa Torrey in Emory's Rep. ii. 1, 209, t. 56.
    1878 P. arizonica Engelmann in Wheeler's Rep. vi. 260.
    1889 P. latifolia Sargent in Gar. & For. ii. 496, f. 135.
    1894 P. apacheca Lemmon in Erythea, ii. 103, t. 3.
    1897 P. Mayriana Sudworth in Bull. 14, U. S. Dept. Agric. 21.
    1897 P. scopulorum Lemmon in Gar. & For. x. 183.
    1900 P. peninsularis Lemmon, W. Am. Conebear. 114.

Spring-shoots uninodal, sometimes pruinose. Bark-formation early. Leaves
prevalently in fascicles of 3, but varying from 2 to 5 or more, from 12
to 36 cm. long; resin-ducts medial, hypoderm uniform or multiform, outer
walls of the endoderm thick. Conelet mucronate, the mucro often
reflexed. Cones from 8 to 20 cm. long, ovate-conic, symmetrical,
deciduous and usually leaving a few basal scales on the tree; apophyses
tawny yellow to fuscous brown, lustrous, elevated along a transverse
keel, sometimes protuberant and reflexed, the umbo salient and forming
the base of a pungent, persistent prickle.

  This species ranges from southern British Columbia over the mountains
  between the Pacific and the eastern foot-hills of the Rocky Mountains,
  including the Black Hills of South Dakota, to the northeastern Sierras
  of Mexico, to northern Jalisco and Lower California, forming, in many
  localities, large forests and furnishing the best Hard Pine timber of
  the western United States. It attains its best growth on the Sierras
  of California and is, next to P. Lambertiana, the tallest of the
  Pines.

  Like P. Montezumae, and under like influences, it shows much
  dimensional variation, and the leaf-fascicles are heteromerous, with
  the larger number in the southern part of its range. Many authors
  consider the variety Jeffreyi Vasey to be a distinct species; but
  here, it seems to me, too much importance is attached to the pruinose
  branchlet, clearly a provision against transpiration and associated
  rather with a dry environment than with a species. Most observers
  discover many intermediate forms between this variety and the species.
  The var. scopulorum Engelm. is the Rocky Mountain form with leaves in
  2's and 3's and with small cones passing into P. arizonica, Engelm., a
  more southern form with small cones and leaves in fascicles of 3 to 5.
  The var. macrophylla (Shaw, Pines Mex. 24), in addition to its long
  and stout leaves, bears a cone with protuberant apophyses, somewhat
  comparable to the intermediate forms of P. pseudostrobus var.
  apulcensis Shaw (l. c.). Fascicles of 6 and 7 leaves are sometimes
  found, and specimens that I have collected in Sandia, Durango (issued
  by Pringle, through a misunderstanding, under the name P. Roseana,
  ined.) show such fascicles on the fertile branches.

    Plate XXVI.

    Fig. 230, Cone and seed of var. Jeffreyi. Fig. 231, Cone of var.
    macrophylla. Fig. 232, Cone of var. scopulorum. Fig. 233, Magnified
    leaf-section and cells of leaf-endoderm. Fig. 234, Magnified dermal
    tissues of the leaf, showing uniform and multiform hypoderm.

[Illustration: PLATE XXVI. PINUS PONDEROSA]


40. PINUS TEOCOTE

    1830 P. teocote Schlechtendal & Chamisso in Linnaea, v. 76.

Spring-shoots uninodal, or sometimes multinodal. Leaves prevalently in
fascicles of 3, but varying from 3 to 5, from 10 to 20 cm. long;
resin-ducts medial, sometimes with an internal duct, hypoderm biform,
endoderm with thick outer walls. Conelets mucronate. Cones usually very
small, from 4 to 6 cm. long, but with a larger varietal form, ovate to
long-conic, symmetrical; apophyses nut-brown, flat or tumid, the mucro
usually deciduous.

  This species grows at temperate altitudes from Chiapas to Nuevo Leon,
  associated with temperate Mexican species such as P. patula, P.
  leiophylla and others, and is easily recognized by its small cone. The
  variety with a larger cone (var. macrocarpa, Shaw, Pines Mex. t. 10) I
  have found growing in mixed groves of P. teocote and P. leiophylla. It
  resembles the latter in cone and leaf, but lacks the peculiar
  character that distinguishes P. leiophylla from all other Mexican
  species--the triennial cone. Some of the specimens of Hartweg No. 441
  belong here, as well as Pringle's specimens, Nos. 10013, 10018,
  distributed as P. eslavae, ined.

    Plate XXVII.

    Fig. 235, Two cones of the species and the larger cone of the
    variety. Fig. 236, Leaf-fascicle and magnified sections of two
    leaves. Fig. 237 a, Dermal tissues of the leaf magnified; b,
    magnified cells of the leaf-endoderm. Fig. 238, Habit of the tree.


41. PINUS LAWSONII

    1862 P. Lawsonii Roezl ex Gordon, Pinet. Suppl. 64.
    1905 P. Altamirani Shaw in Sargent, Trees & Shrubs, i. 209, t. 99.

Spring-shoots conspicuously pruinose, uninodal or not infrequently
multinodal. Leaves in fascicles of 3, 4 or 5, not exceeding 24 cm. in
length; resin-ducts internal, often with one or two medial ducts,
hypoderm biform, endoderm usually with thin outer walls. Conelets
mucronate. Cones from 5 to 7 cm. long on pliant peduncles, ovate or
ovate-conic, oblique or sometimes symmetrical, deciduous, or persistent
with a weak hold on the branch; apophyses nut-brown, flat or tumid,
often protuberant on the posterior face of the cone, the umbo usually
large and salient, forming a rounded button-like projection, on which
the mucro is wanting.

  A subtropical species of central and western Mexico, growing alone or
  associated with P. oocarpa, P. Pringlei and the subtropical forms of
  P. Montezumae and P. pseudostrobus. It is recognized among its
  associate species by its conspicuously glaucous foliage. The cone is
  very variable on trees of the same grove, both in size and in the
  protuberance of its apophyses. Gordon's specimen in the Kew herbarium
  consists of a single detached cone and a few leaves. The leaves differ
  from all that I have examined in showing thick-walled endoderm cells,
  but the cone corresponds with many of my own collection.

    Plate XXVII.

    Fig. 239, Three cones. Fig. 240, Leaf-fascicle and magnified
    leaf-section. Fig. 241, Magnified cells of the leaf-endoderm.

[Illustration: PLATE XXVII. P. TEOCOTE (235-238), LAWSONII (239-241)]


42. PINUS OCCIDENTALIS

    1788 P. occidentalis Swartz, Nov. Gen. & Sp. Pl. 103.
    1862 P. cubensis Grisebach in Mem. Am. Acad. ser. 2, viii. 530.
    1880 P. Wrightii Engelmann in Trans. Acad. Sci. St. Louis, iv. 185.

Spring-shoots uninodal, pruinose. Leaves in fascicles of 2 to 5, from 15
to 22 cm. long; resin-ducts internal, hypoderm biform, endoderm with
thin outer walls. Conelets erect, aristate. Cones from 5 to 8 cm. long,
reflexed, ovate, symmetrical, deciduous; apophyses nut-brown, lustrous,
flat or tumid, the umbo often thin and, together with the slender
prickle, bent sharply downward.

  This species is confined to San Domingo, Hayti and eastern Cuba. Its
  erect conelet and reflexed cone distinguish it from P. caribaea, which
  has both its conelet and cone reflexed. Moreover the conelet is
  usually, perhaps always, subterminal in P. occidentalis.

    Plate XXVIII.

    Fig. 247, Cone. Fig. 248, Conelet and enlarged aristate scales. Fig.
    249, Magnified sections of two leaves and more magnified dermal
    tissues.


43. PINUS PALUSTRIS

    1768 P. palustris Miller, Gard. Dict. ed. 8.
    1810 P. australis Michaux f. Hist. Arbr. Am. i. 64, t. 6.

Spring-shoots uninodal, rarely multinodal. Buds peculiarly large, white,
and conspicuously fringed with the long free cilia of the bud-scales.
Leaves in fascicles of 3, from 20 to 45 cm. long, rigid; resin-ducts
internal, hypoderm biform, endoderm with thin outer walls. Conelets
short-mucronate. Cones from 15 to 20 cm. long, narrow, tapering from a
rounded base to a blunt point, symmetrical, deciduous and usually
leaving a few scales on the tree; apophyses dull nut-brown, elevated
along a transverse keel, the umbo salient and forming the broad base of
a small persistent prickle.

  Its thin sap-wood, its very strong heavy wood of large dimensions with
  abundant resin of excellent quality make this the most valuable
  species of the genus. It ranges over the sandy plain that borders the
  Atlantic and the Gulf of Mexico, from southeastern Virginia to eastern
  Texas. The northern limit is approximately the centre of the Southern
  and Gulf States, with a northern extension in Alabama to the base of
  the Appalachian Mountains and to northwestern Louisiana. Its southern
  limit lies near the centre of the Florida peninsula.

  Among its associates this species is recognized by its large white
  fringed bud and its elongated cone. Its leaves attain, on vigorous
  trees, the maximum length among Pines, but on most trees the leaves do
  not differ in length from the longer forms of those of P. caribaea or
  P. taeda. A peculiarity, which it shares with P. caribaea, is the
  deciduous scaly bark of mature trees, constantly falling away in thin
  irregular scales.

    Plate XXVIII.

    Figs. 242, 243, Cones and seed. Fig. 244, Bud. Fig. 245, Magnified
    leaf-section. Fig. 246, Magnified cells of the leaf-endoderm. The
    dermal tissues of fig. 249 also apply to this species.

[Illustration: PLATE XXVIII. P. PALUSTRIS (242-246), OCCIDENTALIS
(247-249)]


44. PINUS CARIBAEA

    1851 P. caribaea Morelet in Rev. Hort. Côte d'Or, i. 105.
    1864 P. bahamensis Grisebach, Fl. Brit. W. Ind. 503.
    1880 P. Elliottii Engelmann in Trans. Acad. St. Louis, iv. 186,
              tt. 1-3.
    1884 P. cubensis Sargent in Rep. 10th. Cens. U. S. ix. 202
              (not Grisebach).
    1893 P. heterophylla Sudworth in Bull. Torrey Bot. Club, xx. 45.
    1903 P. recurvata Rowley in Bull. Torrey Bot. Club, xxx. 107.

Spring-shoots multinodal, more or less pruinose. Buds pale
chestnut-brown. Leaves in fascicles of 2 and 3, or more in its southern
range, from 12 to 25 cm. long; resin-ducts internal, hypoderm biform,
endoderm with thin outer walls. Conelets reflexed on long peduncles,
mucronate. Cones from 5 to 15 cm. long, ovate or oblong-ovate,
symmetrical, deciduous and leaving often a few basal scales on the
branch; apophyses lustrous, rufous-brown, tumid, the umbo somewhat
salient and minutely mucronate.

  The northern limit of the range of P. caribaea extends from the coast
  of southeastern S. Carolina through southeastern Georgia and southern
  Alabama to southeastern Louisiana. It is associated with P. palustris,
  taeda, serotina, echinata and glabra in this part of its range. It
  continues through Florida, where it encounters P. clausa. On the
  Bahamas it is the only Pine. On the Isle of Pines it finds in P.
  tropicalis another associate. It also grows in Honduras and Guatemala.
  The wood and resin of this species are of such excellent quality that
  no commercial distinction is made between P. caribaea and P.
  palustris.

    Plate XXIX.

    Fig. 250, Cone from the Isle of Pines. Fig. 251, Small form of cone.
    Fig. 252, Large form of cone and binate leaf-fascicle. Fig. 253,
    Conelet. Fig. 254, Magnified sections of leaves from binate and
    ternate fascicles. Fig. 255, Habit of the tree, contrasted with a
    tree of P. palustris in the middle-distance.

[Illustration: PLATE XXIX. PINUS CARIBAEA]


45. PINUS TAEDA

    1753 P. taeda Linnaeus, Sp. Pl. 1000.
    1788 P. lutea Walter Fl. Carol. 237.
    1903 P. heterophylla Small, Fl. Southeast. U. S. 28 (not Sudworth).

Spring-shoots multinodal. Leaves in fascicles of 3, from 12 to 25 cm.
long; resin-ducts medial, sometimes with an internal duct, hypoderm
biform, endoderm with thin outer walls. Conelets erect, their scales
prolonged into a sharp point. Cones from 6 to 10 cm. long, ovate-conic,
symmetrical; apophyses dull pale nut-brown, rarely lustrous, elevated
along a transverse keel, the whole umbo forming a stout triangular spine
with slightly concave sides.

  The species ranges from southern New Jersey to southern Arkansas,
  Oklahoma, eastern Texas and southwestern Tennessee, but does not occur
  in the lower half of the Florida peninsula. It is an important
  timber-tree, manufactured into all descriptions of scantlings,
  boarding and finish, but the wood is of various qualities. It may be
  recognized by the spine of its cone in both years of growth. Excepting
  the formidable armature of the cone of P. pungens, the spines are the
  strongest and most persistent of all the species of eastern North
  America.

    Plate XXX.

    Fig. 264, Cone. Fig. 265, Leaf-fascicle. Fig. 266, Magnified
    leaf-section. Fig. 267. Magnified scales of the conelet.


46. PINUS GLABRA

    1788 P. glabra Walter, Fl. Carol. 237.

Spring-shoots multinodal. Bark-formation late, the upper trunks of
mature trees smooth. Leaves in fascicles of 2, from 9 to 12 cm. long;
resin-ducts medial, hypoderm weak, sometimes of a single row, biform
when of two rows, endoderm with thin outer walls. Conelets reflexed,
mucronate. Cones from 4 to 7 cm. long, reflexed, ovate, symmetrical,
deciduous on some trees, persistent on others; apophyses pale dull
nut-brown, thin or slightly thickened, the prickle usually deciduous.

  A tree that sometimes attains important dimensions, growing singly or
  in small groves from the neighborhood of Charleston, S. C., to eastern
  Louisiana and central Mississippi, most abundant in a strip of
  territory on either side of the northern boundary of Florida. Among
  the Pines of the southeastern United States it is the only species
  with late bark-formation, and is therefore easily identified.

    Plate XXX.

    Fig. 256, Cone. Fig. 257, Enlarged scale of the conelet. Fig. 258,
    Leaf-fascicle and magnified leaf-section. Fig. 259, Dermal tissues
    of the leaf magnified, with a double row of hypoderm cells.


47. PINUS ECHINATA

    1768 P. echinata Miller, Gard. Dict. ed. 8.
    1788 P. squarrosa Walter, Fl. Carol. 237.
    1803 P. mitis Michaux, Fl. Bor. Am. ii. 204.
    1803 P. variabilis Lambert, Gen. Pin. i. 22, t. 15.
    1854 P. Royleana Jamieson in Jour. Hort. Soc. Lond. ix. 52, f.

Spring-shoots multinodal, somewhat pruinose. Bark forming early, rough
on the upper trunk. Leaves in fascicles of 2 and 3, from 7 to 12 cm.
long; resin-ducts medial, with an occasional internal duct, hypoderm
weak, biform when of two rows of cells, endoderm with thin outer walls.
Conelets mucronate. Cones from 4 to 6 cm. long, ovate-conic,
symmetrical, often persistent; apophyses dull pale nut-brown, thin or
somewhat thickened along a transverse keel, the umbo salient, the mucro
more or less persistent.

  This species ranges from southeastern New York to northern Florida, to
  West Virginia and eastern Tennessee, and through the Gulf States to
  eastern Louisiana, eastern Texas, southern Missouri and southwestern
  Illinois. It is extensively manufactured into material of all kinds
  that enters into the construction of buildings. It differs from P.
  virginiana in its longer leaves, brittle branches, and much greater
  height, from P. glabra in its rough upper trunk, and from both by the
  frequent presence of trimerous leaf-fascicles.

  Of the six or seven pines of the southeastern United States, this
  species covers a larger area and ascends the slopes of the Alleghany
  Mountains far enough to meet the northern species, P. virginiana, P.
  rigida, and P. strobus. Unlike the western members of this group, P.
  echinata and its associates are not variable. Their characters are
  singularly constant, as their limited synonymy and total lack of
  varietal names attest.

    Plate XXX.

    Fig. 260, Cone. Fig. 261, Leaf-fascicle and magnified leaf-section
    from a ternate fascicle. Fig. 262, Magnified leaf-section from a
    binate fascicle. Fig. 263, Multinodal branchlet bearing lateral and
    subterminal conelets and a ripe cone. Figs. 257, showing mucronate
    scales of the conelet, and 259, showing dermal tissues of the leaf,
    are applicable also to this species.

[Illustration: PLATE XXX. P. GLABRA (256-259), ECHINATA (260-263), TAEDA
(264-267)]


=XII. INSIGNES=

Pits of the ray-cells small. Cones tenaciously persistent, serotinous in
various degrees. Conelets mucronate or spinose.

    Spring-shoots uninodal.
      Resin-ducts mostly internal                        48. Pringlei
      Resin-ducts mostly septal                          49. oocarpa
    Spring-shoots multinodal.
      Cones symmetrical.
        Leaf-hypoderm not biform.
          Bark-formation late                            50. halepensis
          Bark-formation early                           51. pinaster
        Leaf-hypoderm biform.
          Cones with slender spines.
            Leaves binate.
              Cones dehiscent at maturity                52. virginiana
              Cones serotinous                           53. clausa
            Leaves ternate.
              Cones dehiscent at maturity                54. rigida
              Cones serotinous                           55. serotina
          Cones with stout spines                        56. pungens
      Cones oblique or unsymmetrical.
        Cones and leaves very short, not exceeding 6 cm.
          Cones curved or warped                         57. Banksiana
          Cones straight                                 58. contorta
        Cones and leaves much longer, more than 7 cm.
          Posterior cone-scales gradually larger than
              anterior scales.
            Bark-formation late                          59. Greggii
            Bark-formation early                         60. patula
          Posterior cone-scales abruptly larger than
              anterior scales.
            Cones with very stout spines                 61. muricata
            Cones with minute or deciduous prickles.
              Bark-formation late                        62. attenuata
              Bark-formation early                       63. radiata


48. PINUS PRINGLEI

    1905 P. Pringlei Shaw in Sargent, Trees & Shrubs, i. 211, t. 100.

Spring-shoots uninodal, sometimes pruinose. Leaves ternate, from 15 to
25 cm. long; resin-ducts internal or with an occasional septal duct,
hypoderm biform, in thick masses, often projecting far into the green
tissue and sometimes touching the endoderm. Conelets mucronate. Cones
from 5 to 10 cm. long, reflexed on a rigid peduncle, subsymmetrical or
more or less oblique, tenaciously persistent, often serotinous;
apophyses sublustrous tawny yellow or fulvous brown, convex, the
posterior scales often more prominently developed, the mucro usually
wanting; seed with a perceptibly thickened wing-blade.

  A tree with long erect bright green foliage, confined, so far as
  known, to the subtropical altitudes of western Mexico. As it grows in
  Uruapan, Michoacan, there are two forms of the cone, large and small,
  both with the same long rigid leaf.

    Plate XXXI.

    Figs. 268, 269. Three cones and seed. Fig. 270, Leaf-fascicle and
    magnified leaf-section.


49. PINUS OOCARPA

    1838 P. oocarpa Schiede in Linnaea, xii. 491.
    1842 P. oocarpoides Lindley ex Loudon, Encycl. 1118.

Spring-shoots uninodal, pruinose. Leaves in fascicles of 3, 4 or 5, from
15 to 30 cm. long, erect; resin-ducts mostly septal, sometimes internal,
hypoderm biform or multiform. Conelets on very long peduncles,
mucronate. Cones from 4 to 10 cm. long, long-pedunculate, broad-ovate to
ovate-conic, symmetrical or sometimes oblique, persistent, more or less
serotinous; apophysis gray-yellow or greenish yellow of high lustre,
flat or variously convex, delicately and radially carinate, the umbo
often salient, the prickle usually broken away; seed-wing appreciably
thickened at the base of the blade.

  A subtropical species, ranging from Guatemala to the northern border
  of Sinaloa in northern Mexico; remarkable for the length of the
  peduncle of the cone and for the prevalence of septal resin-ducts in
  the leaf.

    Plate XXXI.

    Fig. 271, Three cones and seed. Fig. 272, Leaf-fascicle and
    magnified leaf-section. Fig. 273, Cone from northern part of the
    range. Fig. 274, Leaf-fascicle and magnified leaf-section from near
    the northern limit.

[Illustration: PLATE XXXI. P. PRINGLEI (268-270), OOCARPA (271-274)]


50. PINUS HALEPENSIS

    1762 P. sylvestris Gouan, Hort. Reg. Monspel. 494 (not Linnaeus).
    1768 P. halepensis Miller, Gard. Dict. ed. 8.
    1803 P. maritima Lambert, Gen. Pin. i. 13, t. 10.
    1812 P. resinosa Loiseleur, Nouv. Duham. v. 237, t. 77 (not Aiton).
    1815 P. brutia Tenore, Cat. Hort. Neap. Appx. 1, 75.
    1826 P. arabica Sieber ex Sprengel, Syst. Veg. iii. 886.
    1833 P. pyrenaica David in Ann. Soc. Hort. Paris, 186
              (not Lapeyrouse).
    1834 P. hispanica Cook, Sketches in Spain, ii. 337.
    1838 P. pityusa Steven in Bull. Soc. Nat. Mosc. xi. 49.
    1841 P. carica Don in Ann. Mag. Nat. Hist. vii. 459.
    1847 P. persica Strangways ex Endlicher, Syn. Conif. 157.
    1855 P. abasica Carrière, Trait. Conif. 352.
    1855 P. Loiseleuriana Carrière, Trait. Conif. 382.
    1856 P. Parolinii Visiani in Mem. Ist. Venet. vi. 243, t. 1.
    1902 P. eldarica Medwejew in Act. Hort. Tiflis. vi-2, 21, f.

Spring-shoots often multinodal. Bark-formation late, the branches ashen
gray and smooth for several years. Leaves binate, from 6 to 15 cm. long;
resin-ducts external, hypoderm uniform. Conelets obscurely mucronate
near the apex. Cones from 8 to 12 cm. long, ovate-conic, symmetrical or
subsymmetrical, persistent, often serotinous; apophyses red with a
lighter or deeper brownish shade, lustrous, flat, convex or
low-pyramidal, radially carinate, the umbo often ashen gray and unarmed.

  A tree ranging from Portugal to Afghanistan, and from Algeria to
  Dalmatia and to northern Italy and Southern France. It is a vigorous
  species in its own home, growing readily in poor soils, but not
  successful in colder climates. The wood is resinous and valuable for
  fuel. The turpentine industry, once associated with this species, has
  gradually been abandoned for the more copious product of P. pinaster.

  It is recognized by its lustrous red cones and by the ashen gray
  cortex of its branches and upper trunk. Tenore's P. brutia (pyrenaica
  of some authors) is founded on a difference in the length of the leaf
  and on an erect cone with a shorter peduncle. To recognize species on
  such distinctions would not be consistent with the purpose and spirit
  of this discussion.

    Plate XXXII.

    Fig. 279, Two cones. Fig. 280, Cone. Fig. 281, Lateral conelet. Fig.
    282, Magnified leaf-section. Fig. 283, Dermal tissues of the leaf
    magnified.


51. PINUS PINASTER

    1768 P. sylvestris Miller, Gard. Dict. ed. 8 (not Linnaeus).
    1789 P. pinaster Aiton, Hort. Kew. iii. 367.
    1798 P. laricio Savi, Fl. Pisa. ii. 353 (not Poiret).
    1804 P. maritima Poiret in Lamarck, Encycl. Méth. v. 337
              (not Lambert).
    1826 P. escarena Risso, Hist. Nat. ii. 340.
    1835 P. Lemoniana Bentham in Trans. Hort. Soc. Lond. ser. 2,
              i. 512, t.
    1845 P. Hamiltonii Tenore, Cat. Ort. Nap. 90.

Spring-shoots sometimes multinodal. Bark-formation early. Leaves binate,
from 10 to 20 cm. long, stout and rigid; resin-ducts medial, hypoderm
multiform, the inner cells gradually larger, remarkably large in the
angles of the leaf. Conelets minutely mucronate. Cones from 9 to 18 cm.
long, nearly sessile, ovate-conic, symmetrical or subsymmetrical,
persistent, sometimes serotinous; apophyses lustrous nut-brown or rufous
brown, conspicuously pyramidal, the umbo salient and pungent.

  A maritime tree corresponding nearly, in its range, with the preceding
  species, but more hardy in cooler climates. It grows from Portugal to
  Greece, and from Algeria to Dalmatia, but its area has been much
  extended by cultivation. Under favorable conditions it attains large
  dimensions, but its exploitation for resin and turpentine tends to
  diminish its size and disfigure its habit (Mathieu, Fl. Forest, ed. 4,
  611). Its rapid growth, strong root-system, and its ability to thrive
  on poor sandy soil, have led to the employment of this species for the
  forestation of sand-dunes in France.

  The tree can be recognized by its long stout leaves and persistent
  brown cones. Its leaf-section is peculiar in the remarkable size of
  the inner cells of the hypoderm, especially in the angles of the leaf.

    Plate XXXII.

    Figs. 275, 276, Cones. Fig. 277, Magnified leaf-section. Fig. 278,
    Magnified dermal tissues in the angle of the leaf.

[Illustration: PLATE XXXII. P. PINASTER (275-278), HALEPENSIS
(279-283)]


52. PINUS VIRGINIANA

    1768 P. virginiana Miller, Gard. Dict. ed. 8.
    1789 P. inops Aiton, Hort. Kew. iii. 367.

Spring-shoots multinodal, pruinose; branchlets pliant and tough.
Bark-formation slow, the cortex not rifted for some years. Leaves
binate, from 4 to 8 cm. long; resin-ducts medial, or with an occasional
internal duct; hypoderm biform. Conelets with long tapering sharp
scales. Cones from 4 to 6 cm. long, ovate or oblong-ovate, symmetrical,
persistent, dehiscent at maturity; apophyses lustrous nut-brown,
somewhat elevated along a transverse keel, the umbo salient, forming a
long slender prickle with a broad base.

  Western Long Island to central Georgia and north Alabama, and from
  eastern Tennessee to southern Indiana and southeastern Ohio. It is a
  low bushy tree in the north, but in the south and west it attains
  small timber-size and is locally exploited. It is hardy beyond the
  limits of its natural range, growing readily in the vicinity of
  Boston. Its short binate leaves, the persistent long prickles of its
  cone, and its tough branches, combine to distinguish this Pine from
  its associates. The obvious relationship of P. virginiana and P.
  clausa places the former in this, rather than in the preceding group.

    Plate XXXIII.

    Fig. 284, Cones. Fig. 285, Conelet and its enlarged spinose scale.
    Fig. 286, Leaf-fascicle, magnified leaf-section and more magnified
    dermal tissues of the leaf. Fig. 287, Buds.


53. PINUS CLAUSA

    1884 P. clausa Vasey ex Sargent, Rep. 10th Cens. U. S. ix. 199.

Spring-shoots multinodal. Bark-formation slow, as in the preceding
species. Leaves binate, from 5 to 9 cm. long; resin-ducts medial, or
with an occasional internal duct, hypoderm biform when of two rows of
cells. Conelets with long tapering acute scales. Cones from 5 to 8 cm.
long, reflexed, ovate-conic, symmetrical, persistent, often serotinous;
apophyses lustrous nut-brown, elevated along a transverse keel, the umbo
forming a triangular persistent spine.

  A species of limited range, confined to the sandy coast of Alabama and
  to Florida. It sometimes attains timber-size, but is usually a low
  spreading tree of no commercial importance and never seen in
  cultivation. It is recognized by its smooth branches, binate leaves
  and numerous, often multiserial, clusters of persistent, often closed,
  cones. It is associated with P. caribaea and, in the northern part of
  its range, it grows with the other Southern species. By its close
  resemblance it may be considered the serotinous form of P. virginiana.

    Plate XXXIII.

    Fig. 288, Three nodal groups of cones of the same year. Fig. 289,
    Conelet and its enlarged scale. Fig. 290, Leaf-fascicle and
    magnified leaf-section. Fig. 291, Larger form of the tree.

[Illustration: PLATE XXXIII. P. VIRGINIANA (284-287), CLAUSA (288-291)]


54. PINUS RIGIDA

    1768 P. rigida Miller, Gard. Dict. ed. 8.
    1909 P. serotina Long, in Bartonia, ii. 17 (not Michaux).

Spring-shoots multinodal. Leaves ternate, from 7 to 14 cm. long;
resin-ducts medial, or with an occasional internal duct, hypoderm
biform. Scales of the conelet abruptly prolonged into a spine. Cones
from 3 to 7 cm. long, ovate-conic, symmetrical, persistent, dehiscent at
maturity or rarely serotinous; apophyses lustrous tawny yellow, elevated
along a transverse keel, the umbo salient and forming the broad base of
a slender sharp prickle.

  A tree with bright green foliage in spreading tufts. The northern
  limit of its range is in southwestern New Brunswick, southern Maine,
  central New Hampshire and Vermont, the Thousand Islands of the St.
  Lawrence River and central Ohio. It ranges into Pennsylvania and
  Delaware at low levels and thence over the Alleghanies into northern
  Georgia. It is associated with P. strobus and P. resinosa and, further
  south, with P. virginiana. The cones are rarely serotinous, but it is
  remarkably like P. serotina in many characters, and is therefore
  placed in this group.

    Plate XXXIV.

    Fig. 292, Cones. Fig. 293, Leaf-fascicle, magnified section through
    a fascicle, and magnified dermal tissues of the leaf. Fig. 294,
    Upper part of a tree.


55. PINUS SEROTINA

    1803 P. serotina Michaux, Fl. Bor. Am. ii. 205.

Spring-shoots multinodal. Leaves ternate, from 12 to 20 cm. long;
resin-ducts medial or medial and internal, hypoderm biform. Conelet
long-mucronate. Cones from 5 to 7 cm. long, subglobose or short-ovate,
symmetrical, persistent, serotinous; apophyses lustrous tawny yellow,
slightly elevated along a transverse keel, the umbo forming the broad
base of a slender, rather fragile prickle.

  This species is confined to low wet lands from southeastern Virginia
  to northern Florida and central Alabama. It is one of the associated
  six timber-Pines of the Southern States and the only one of them with
  serotinous cones. Its wood is of like value with that of P. taeda, the
  two species being constantly confused by lumbermen. It is never
  associated with P. rigida, but its resemblance to that Pine is so
  great that it may be regarded as its serotinous form. Its leaf is
  longer, its cone usually more orbicular and the prickle weaker.

    Plate XXXIV.

    Fig. 295, Cone. Fig. 296, Conelet and its enlarged scale. Fig. 297,
    Leaf-fascicle and magnified leaf-section.


56. PINUS PUNGENS

    1803 P. taeda Lambert, Gen. Pin. i. t. 16, (as to cone).
              (not Linnaeus).
    1806 P. pungens Lambert in Ann. Bot. ii. 198.
    1852 P. montana Noll, Bot. Class Book, 340. (not Miller).

Spring-shoots multinodal. Leaves binate or ternate, from 3 to 7 cm.
long; resin-ducts medial, or with an occasional internal duct, hypoderm
biform. Scales of the conelet much prolonged into a very acute triangle.
Cones from 5 to 9 cm. long, symmetrical or subsymmetrical, tenaciously
persistent, serotinous; apophyses lustrous or sublustrous fulvous brown,
much elevated along a transverse keel, the umbo forming a stout
formidable spine, uniform or nearly uniform on all faces of the cone.

  A mountain species ranging from central Pennsylvania to northern
  Georgia, with isolated stations in western New Jersey and Maryland. It
  is remarkable among the Pines of eastern North America for the size
  and strength of the spines of its cone. The armature resembles that of
  the cone of the western P. muricata, but with the difference that the
  western cone is strongly oblique, the anterior and posterior spines
  varying greatly in size.

    Plate XXXIV.

    Fig. 298, Cone. Fig. 299, Conelet and its enlarged scale. Fig. 300,
    Leaf-fascicle and magnified leaf-section.

[Illustration: PLATE XXXIV. P. RIGIDA (292-294), SEROTINA (295-297),
PUNGENS (298-300)]


57. PINUS BANKSIANA

    1803 P. Banksiana Lambert, Gen. Pin. i. 7. t. 3.
    1804 P. hudsonia Poiret in Lamarck, Encycl. Méth. v. 339.
    1810 P. rupestris Michaux f. Hist. Arbr. Am. i. 49, t. 2.
    1811 P. divaricata Dumont de Courset, Bot. Cult. ed. 2, vi. 457.

Spring-shoots multinodal. Leaves binate, from 2 to 4 cm. long;
resin-ducts medial, hypoderm biform. Conelets minutely mucronate. Cones
from 3 to 5 cm. long, erect, ovate-conic, oblique, much curved or
variously warped from the irregular development of the scales,
serotinous; apophyses lustrous tawny yellow, concave, flat or convex,
the umbo small and unarmed.

  The most northern American Pine, growing near the Arctic Circle in the
  valley of the Mackenzie River, whence it ranges southeasterly to
  central Minnesota and the south shore of Lake Michigan, and easterly
  through the Dominion of Canada to northern Vermont, southern Maine,
  and Nova Scotia. In the northern part of its range it is the only
  Pine, but further south it is associated with P. strobus and P.
  resinosa. It is easily identified by its curious curved or deformed
  cones.

    Plate XXXV.

    Fig. 301, Cones. Fig. 302, Biserial cones of the same year.
    Fig. 303, Leaf-fascicle and magnified leaf-section. Fig. 304,
    Habit of the tree.



58. PINUS CONTORTA

    1833 P. inops Bongard in Mém. Acad. Sci. St. Pétersb. ii. 163,
              (not Aiton).
    1838 P. contorta Douglas ex Loudon, Arb. Brit. iv. 2292, f. 2211.
    1853 P. Murrayana Balfour in Bot. Exp. Oregon, 2, f.
    1854 P. Boursieri Carrière in Rev. Hort. 225, ff. 16, 17.
    1868 P. Bolanderi Parlatore in DC. Prodr. xvi-2, 379.
    1869 P. tamrac Murray in Gard. Chron. 191, ff. 1-9.
    1898 P. tenuis Lemmon in Erythea, vi. 77.

Spring-shoots multinodal. Leaves binate, from 3 to 5 cm. long;
resin-ducts medial, hypoderm biform. Conelets long-mucronate. Cones from
2 to 5 cm. long, sessile, ovate-conic, symmetrical or very oblique,
persistent, serotinous; apophyses lustrous tawny-yellow, flat or
protuberant, on oblique cones abruptly larger on the posterior face; the
umbo armed with a slender fragile prickle.

  It grows from the valley of the Yukon, near the Alaskan boundary,
  along the Pacific coast to Mendocino county, California. It covers the
  plains and slopes of British Columbia and follows the Rocky Mountains
  into western Colorado, with an outlying station on the Black Hills of
  South Dakota. It grows on the Sierras and mountains of southern
  California and in northern Lower California. On the seashore this Pine
  is of low dense growth, but inland it is a slender tree with a long
  tapering stem. It is easily recognized by its very short leaves and
  very small cone.

    Plate XXXV.

    Fig. 305, Cones. Fig. 306, Leaf-fascicle and magnified leaf-section.

[Illustration: PLATE XXXV. P. BANKSIANA (301-304), CONTORTA (305, 306)]


59. PINUS GREGGII

    1868 P. Greggii Engelmann ex Parlatore in DC. Prodr. xvi-2, 396.

Spring-shoots uninodal and multinodal, pruinose. Bark-formation late,
the branches and upper trunk smooth. Leaves ternate, from 7 to 10 cm.
long, erect; resin-ducts medial, hypoderm of uniform thin-walled cells.
Conelets mucronate. Cones from 6 to 12 cm. long, ovate-conic, oblique,
serotinous, reflexed; apophyses lustrous tawny yellow, convex, the
posterior gradually larger and more prominent than the anterior scales,
the umbo flat or depressed, the mucro deciduous.

  This species is known, at present, from specimens collected in the
  vicinity of the city of Saltillo, in northeastern Mexico. Were it not
  for the difference of bark it might be considered to be a northern
  variety of P. patula with shorter erect leaves. With both species the
  long peduncle of the conelet becomes overgrown by the basal scales of
  the ripe cone, which appears to be sessile. With both, the cones are
  in crowded nodal clusters, reflexed against the branch. They are so
  much alike that earlier descriptions of P. patula included the smooth
  gray bark of P. Greggii. The first correct description of the scaly
  red bark of P. patula appeared in the second edition of Veitch's
  Manual of Conifers.

    Plate XXXVI.

    Fig. 311, Cone. Fig. 312, Conelet. Fig. 313, Leaf-fascicle and
    magnified leaf-section. Fig. 314, Branch showing erect leaves.


60. PINUS PATULA

    1831 P. patula Schlechtendal & Chamisso in Linnaea, vi. 354.

Spring-shoots multinodal, more or less pruinose. Bark-formation early,
the scales deciduous, the upper trunk and branches red. Leaves
prevalently ternate but sometimes in fascicles of 4 or 5, from 15 to 30
cm. long, slender and gracefully drooping; resin-ducts medial or with an
occasional internal duct, hypoderm weak, of uniform thin-walled cells.
Conelets mucronate. Cones from 6 to 11 cm. long, in crowded verticillate
clusters, sessile, reflexed, ovate-conic, oblique, persistent and
serotinous; apophyses lustrous nut-brown, more or less tumid, the
posterior gradually larger than the anterior scales, the umbo flat or
depressed, the mucro wanting.

  Patula grows in the warm-temperate climates of Hidalgo, Puebla and
  Vera Cruz, in eastern and central Mexico. It can be at once recognized
  by its slender drooping foliage, its persistent cones, and its red
  upper trunk. It is cultivated in northern Italy and in the warmer
  parts of Great Britain.

    Plate XXXVI.

    Fig. 307, Cone. Fig. 308, Conelet. Fig. 309, Leaf-fascicle and
    magnified leaf-section. Fig. 310, Branchlet with drooping leaves.

[Illustration: PLATE XXXVI. P. PATULA (307-310), GREGGII (311-314)]


61. PINUS MURICATA

    1837 P. muricata D. Don in Trans. Linn. Soc. xvii. 441.
    1848 P. Edgariana Hartweg in Jour. Hort. Soc. Lond. iii. 217.

Spring-shoots multinodal. Leaves binate, from 10 to 15 cm. long;
resin-ducts medial, hypoderm biform. Scales of the conelet prolonged
into a triangular spine. Cones from 5 to 9 cm. long, in verticillate
clusters, sessile, reflexed, ovate-conic, oblique, serotinous; apophyses
lustrous nut-brown, abruptly much larger on the posterior face of the
cone, each armed with a formidable spine varying in size with the
varying size of the apophysis.

  This species grows on the coast of California, in scattered stations
  between Mendocino and San Luis Obispo Counties, and on the northwest
  coast of Lower California and on Cedros Island. It is recognized by
  its oblique cones, conspicuously spinose, indefinitely persistent and
  very serotinous. The unequal development of its cone-scales
  distinguishes the cone from the more symmetrically developed cone of
  P. pungens. Fruiting trees of P. muricata may be seen in the Royal
  Gardens at Kew.

    Plate XXXVII.

    Fig. 315, Cone. Fig. 316, Leaf-fascicle and magnified leaf-section.


62. PINUS ATTENUATA

    1847 P. californica Hartweg in Jour. Hort. Soc. Lond. ii. 189,
              (not? P. CALIFORNIANA, Loiseleur).
    1849 P. tuberculata Gordon in Jour. Hort. Soc. Lond. iv. 218,
              f. (not D. Don).
    1892 P. attenuata Lemmon in Mining & Sci. Press, lxiv. 45.

Spring-shoots multinodal. Bark-formation late, the branches and upper
trunk smooth. Leaves ternate, from 8 to 16 cm. long; resin-ducts medial
or with one or more internal ducts, hypoderm biform. Scales of the
conelet prolonged into a triangular spine. Cones from 8 to 16 cm. long,
in verticillate clusters, sessile, reflexed, long-ovate, oblique,
persistent and remarkably serotinous; apophyses lustrous tawny yellow,
abruptly larger and more prominent on the posterior face of the cone,
where they are usually prolonged into acute pyramids with a small
incurved spine.

  A tree of slender habit and gray-green foliage, the trunk studded with
  persistent nodal cone-clusters; growing on dry mountain slopes, from
  southwestern Oregon over the foot-hills of the northern mountains of
  California and its coastal ranges as far as the southern slopes of the
  San Bernardino Mountains. It attains its best development in the
  northern part of its range, but is never a tree of importance. The
  serotinous habit is more pronounced in this than in any other species.
  It is distinct from P. radiata, its nearest relative, by the color of
  the cone, by its smooth upper trunk and by its much smaller size.

  The possibility of identifying P. californiana Loiseleur (Nouv. Duham.
  v. 293), through a cone said to have been sent to the Museum at Paris,
  may cause this name to be applied, by reason of its early date (1812),
  to some existing species. Don's radiata and tuberculata, although
  considered to be the same species, were nevertheless founded on
  different forms of the cone. Under a very narrow conception of
  specific limits tuberculata Don might therefore acquire specific rank.
  These considerations seem to make it advisable to abandon for this
  species the names californica Hartw. and tuberculata Gord. for the
  later name attenuata.

    Plate XXXVII.

    Fig. 317, Cone. Fig. 318, Magnified leaf-section.


63. PINUS RADIATA

    1837 P. radiata D. Don in Trans. Linn. Soc. xvii. 442.
    1837 P. tuberculata D. Don in Trans. Linn. Soc. xvii. 442.
    1838 P. insignis Douglas ex Loudon, Arb. Brit. iv. 2265, f. 2171.
    1841 P. Sinclairii Hooker & Arnott in Bot. Beechy Voy. 392, t. 93
              (as to leaves).

Spring-shoots multinodal. Bark formation early, the branches and upper
trunk rough. Leaves ternate or binate, from 10 to 15 cm. long;
resin-ducts medial or with an occasional internal duct, hypoderm biform.
Conelets mucronate, the mucro small and dorsal. Cones from 7 to 14 cm.
long, in verticillate clusters, sessile, reflexed, ovate or oblong,
oblique, serotinous; apophyses nut-brown, lustrous, tumid in various
degrees, the posterior scales abruptly larger and very prominent, the
umbo bearing the minute prickle or its remnant.

  A tall tree with rich green foliage, growing on a strip of coast south
  of San Francisco, particularly in Monterey County. It grows also on
  the islands forming the Santa Barbara Channel and on the Island of
  Guadeloupe, Lower California. It is remarkably successful in the
  warmer climates of Europe and of Australasia. The species is distinct
  in its peculiar cone with rounded apophyses.

    Plate XXXVII.

    Figs. 319, 320, Cones. Fig. 321, Leaf-fascicle and magnified
    leaf-section. Fig. 322, Leaf-section from a binate fascicle. Fig.
    323, Magnified dermal tissues of the leaf.

[Illustration: PLATE XXXVII. P. MURICATA (315, 316), ATTENUATA (317,
318), RADIATA (319-323)]


=XIII. MACROCARPAE=

Pits of the ray-cells small. Wing-blade of the seed thick. Cones large.
Leaves long and stout.

This group is remarkable for the size of leaf, conelet, and cone. The
peculiar thick seed-wing is more or less obscurely present among the
species of the Insignes, but never attains the development that
differentiates this group from all other Pines. The leaf-section is
notable for the large amount of hypoderm and for the presence of both
thick and thin outer walls of the endoderm-cells, both forms appearing
in the same leaf.

    Wing-blade with a short membranous extension.
      Leaves in fascicles of 5                            64. Torreyana
      Leaves in fascicles of 3                            65. Sabiniana
    Wing-blade with a long membranous extension, leaves
        in fascicles of 3                                 66. Coulteri


64. PINUS TORREYANA

    1855 P. Torreyana Parry ex Carrière, Trait. Conif. 326.
    1860 P. lophosperma Lindley in Gard. Chron. 46.

Spring-shoots uninodal, pruinose. Leaves in fascicles of 5, from 20 to
33 cm. long, very stout; resin-ducts medial, hypoderm uniform or
somewhat multiform and of many cells. Conelets large, mucronate. Cones
from 10 to 15 cm. long, on stout peduncles, broad-ovate, symmetrical,
somewhat persistent; apophyses chocolate-brown, prominently pyramidal,
the umbo salient and capped with a small mucro; seed-wing short, very
thick, the dorsal surface of the nut spotted with the black remnants of
the spermoderm.

  A tree 10 or 12 metres high, often semi-prostrate in exposed
  positions, confined to a restricted area on the coast north of San
  Diego, California, and to the Island of Santa Rosa. This species
  resembles P. Sabiniana in the length of its seed-wing and in the color
  of its cone, but is distinct in the short triangular umbo, in its
  pentamerous leaf-fascicles and in the mottled dorsal surface of its
  nut.

    Plate XXXVIII.

    Fig. 324, Cone and seed. Fig. 325, Magnified leaf-section.


65. PINUS SABINIANA

    1833 P. Sabiniana Douglas in Trans. Linn. Soc. xvi. 747.

Spring-shoots multinodal, pruinose. Leaves in fascicles of 3, from 20 to
30 cm. long; resin-ducts medial, hypoderm multiform. Conelets large,
their scales tapering to a sharp point. Cones from 15 to 25 cm. long,
reflexed, ovate, slightly oblique, persistent; apophyses
chocolate-brown, very prominent, the curved umbo confluent with the
apophysis and with it forming a very large talon-like armature with a
sharp apex and a broad thick base; seed-wing very thick, with a short
membranous margin, the dorsal surface of the nut uniform in color.

  A tree with sparse gray-green foliage, growing in small groves on the
  foot-hills of the Sierra Nevada and Coast Ranges of California. Its
  three leaves and the uniform color of the nut distinguish it from
  P. Torreyana. From P. Coulteri it differs in the length of the
  membranous portion of the seed-wing and in its gray-green leaves.

    Plate XXXVIII.

    Fig. 326, Cone. Fig. 327, Seed, nut and wing. Fig. 328, Magnified
    leaf-section.

[Illustration: PLATE XXXVIII. P. TORREYANA (324, 325), SABINIANA
(326-328)]


66. PINUS COULTERI

    1837 P. Coulteri D. Don in Trans. Linn. Soc. xvii. 440.
    1840 P. macrocarpa Lindley in Bot. Reg. xxvi. Misc. 62.

Spring-shoots multinodal, pruinose. Leaves in fascicles of 3, from 15 to
30 cm. long, very stout; resin-ducts medial, or with an occasional
internal duct, hypoderm multiform and of many cells. Conelet very large,
the scales tapering to a long sharp point. Cones from 25 to 35 cm. long,
reflexed, ovate or oblong-ovate, somewhat oblique, persistent; apophyses
sublustrous tawny yellow, very protuberant, with a narrow shoulder from
which springs the umbo in the form of a large stout curved talon;
seed-wing nearly equally divided between the very thick base and the
membranous apex.

  Remarkable among Pines for the size and weight of its cones, many
  times heavier than the longer cones of P. Lambertiana, illustrating
  the great change that the cone-tissues undergo in the gradual
  evolution of the species. It is a tree with dark-green foliage,
  growing from northern Lower California over the mountains of southern
  California to the Santa Lucia range and to Mt. Diablo. It is of no
  value except for fuel and for its large nuts. It is best recognized by
  its seed. The cone differs from the others of this group in its yellow
  color, not unlike that of boxwood.

    Plate XXXIX.

    Fig. 329, Cone of small size. Fig. 330, Seed, nut and wing. Fig.
    331, Magnified leaf-section. Fig. 332, Conelet.

[Illustration: PLATE XXXIX. PINUS COULTERI]




INDEX


  Adnate wing, 16
  Apinus, Neck.--Pinus, 24
  Apophysis of cone, 10
  Armature of conelet, 7
  Articulate wing, 16
  Australes-Group, 62

  Balfourianae-Group, 42
  Bark, 18
  Bases of bracts decurrent and non-decurrent, 1
  Bast-tissue of cone, 14
  Biform hypoderm, 6
  Bloom on branchlet, 2
  Bracts, bases of, 1
  Branchlet, multinodal, 2
    uninodal, 2
  Bud, latent, 2
    leaf, 1
    staminate, 1

  Caryopitys, Small = Pinus, 24
  Caryopitys edulis Small = Pinus cembroides, 38
  Cembra, Opiz = Pinus, 24
  Cembra-Subsection, 26
  Cembrae-Group, 26
  Cembroides-Group, 38
  Characters of the genus, 1
  Classification of species, 22
  Color of cone, 8
  Cone, apophysis of, 10
    bast tissues of, 14
    color of, 8
    dimensions of, 8
    oblique, 10
    peduncle of, 8
    persistent, 8
    phyllotaxis of, 12
    serotinous, 14
    symmetrical, 10
  Conelet, lateral, 7
    pseudolateral, 7
    subterminal, 7
  Conspectus of Sections &c., 25
  Connective of pollen-sacs, 7
  Cotyledons, 1

  Decurrent bases, 1
  Definite phyllotaxis, 12
  Dermal tissue of leaf, 4
  Dimensions of cone, 8
    leaf, 4
  Diploxylon-Section, 44
  Dorsal umbo, 8

  Endoderm, 8
  Evolutional characters, 20
  External resin-ducts, 6

  Fibro-vascular bundle, 6
  Flexiles-Group, 28
  Flowers, lateral, 7
    pistillate, 7
    staminate, 7
    subterminal, 7

  Generic characters, 18
  Genus, characters of, 1
  Geographical distribution, 24
  Gerardianae-Group, 40
  Green tissue of leaf, 6

  Haploxylon-Section, 26
  Hypoderm, biform, 6
    multiform, 6
    uniform, 6

  Indefinite phyllotaxis, 12
  Insignes-Group, 76
  Internal resin-ducts, 6

  Lariciones-Group, 51
  Latent buds, 2
  Lateral flowers, 7
    conelet, 7
  Leaf, dermal tissues of, 4
    dimensions of, 4
    fibro-vascular bundle of, 6
    green tissue of, 6
    persistence of, 4
    primary, 1
    resin-ducts of, 6
    secondary, 2
    stelar tissues of, 6
    stomata of, 4
    tissues of, 4
  Leiophyllae-Group, 44
  Longifoliae-Group, 46

  Macrocarpae-Group, 90
  Medial resin-ducts, 6
  Multiform hypoderm, 6
  Multinodal branchlet, 2
    spring-shoot, 2

  Non-decurrent bases, 1

  Oblique cone, 10

  Paracembra-Subsection, 36
  Parapinaster-Subsection, 44
  Peduncle of cone, 8
  Persistence of leaf, 4
  Persistent cone, 8
  Phyllotaxis, of cone, 12
    definite, 12
    indefinite, 12
  Pinaster-Subsection, 50
  Pineae-Group, 48
  Pinus, 24
  Pinus abasica Carr. = halepensis, 78
    alba-canadensis Prov. = strobus, 36
    albicaulis Engelm., 27
    Altamirani Shaw = Lawsonii, 68
    apacheca Lemm. = ponderosa, 66
    apulcensis Lindl. = pseudostrobus, 62
    arabica Sieb. = halepensis, 78
    aristata Engelm., 44
    arizonica Engelm. = ponderosa, 66
    Armandi Franch., 30
    armena Koch = sylvestris, 54
    attenuata Lemm., 88
    australis Michx. = palustris, 70
    austriaca Höss = nigra, 58
    ayacahuite Ehrenb., 30
    bahamensis Grise. = caribaea, 70
    Balfouriana Balf., 42
    Balfouriana Wats. = aristata, 44
    Banksiana Lamb., 84
    Beardsleyi Murr. = ponderosa, 66
    Benthamiana Hartw. = ponderosa, 66
    Bolanderi Parl. = contorta, 84
    Bonapartea Roezl = ayacahuite, 30
    Boursieri Carr. = contorta, 84
    brachyptera Engelm. = ponderosa, 66
    brutia Ten. = halepensis, 78
    Bungeana Zucc., 40
    californica Hartw. = attenuata, 88
    canaliculata Miq. = Massoniana, 52
    canariensis Smith, 48
    caribaea Mor., 70
    carica Don = halepensis, 78
    cembra L., 27
    cembra Thunb. = parviflora, 32
    cembroides Gord. = Pinceana, 38
    cembroides Newb. = albicaulis, 27
    cembroides Zucc., 38
    chihuahuana Engelm. = leiophylla, 44
    clausa Vasey, 80
    contorta Dougl., 84
    coronans Litv. = cembra, 27
    Coulteri D. Don, 93
    Craigana Murr. = ponderosa, 66
    cubensis Grise. = occidentalis, 70
    cubensis Sarg. = caribaea, 70
    dalmatica Vis. = nigra, 58
    deflexa Torr. = ponderosa, 66
    densata Mast. = sinensis, 60
    densiflora Sieb. & Zucc., 52
    Devoniana Lindl. = Montezumae, 64
    divaricata Dum. Cours. = Banksiana, 84
    Donnell-Smithii Mast. = Montezumae, 64
    echinata Mill., 74
    Edgariana Hartw. = muricata, 86
    edulis Engelm. = cembroides, 38
    Ehrenbergii Endl. = Montezumae, 64
    eldarica Medw. = halepensis, 78
    Elliottii Engelm. = caribaea, 70
    Engelmanni Carr. = ponderosa, 66
    escarena Riss. = pinaster, 80
    excelsa Hook. = peuce, 34
    excelsa Wall., 34
    filifolia Lindl. = Montezumae, 64
    Finlaysoniana Wall. = Merkusii, 58
    flexilis James, 28
    flexilis Balf. = albicaulis, 27
    formosana Hay. = parviflora, 32
    Fremontiana Endl. = cembroides, 38
    Frieseana Wich. = sylvestris, 54
    funebris Kom. = sinensis, 60
    Gerardiana Wall., 42
    glabra Walt., 72
    Gordoniana Hartw. = Montezumae, 64
    Greggii Engelm., 86
    Grenvilleae Gord. = Montezumae, 64
    Griffithii McClell. = excelsa, 34
    halepensis Bieb. = nigra, 58
    halepensis Mill., 78
    Hamiltonii Ten. = pinaster, 80
    Hartwegii Lindl. = Montezumae, 64
    Heldreichii Chr. = nigra, 58
    Henryi Mast. = sinensis, 60
    heterophylla Small = taeda, 72
    heterophylla Sudw. = caribaea, 70
    hispanica Cook = halepensis, 78
    hudsonia Poir. = Banksiana, 84
    humilis Link = sylvestris, 54
    inops Ait. = virginiana, 80
    inops Bong. = contorta, 84
    insignis Dougl. = radiata, 88
    insularis Endl., 60
    Jeffreyi Balf. = ponderosa, 66
    kasya Royle = insularis, 60
    khasiana Griff. = insularis, 60
    Kochiana Klotzsch = sylvestris, 54
    koraiensis Mast. = Armandi, 30
    koraiensis Sieb. & Zucc., 26
    Lambertiana Dougl., 32
    lapponica Mayr = sylvestris, 54
    laricio Poir. = nigra, 58
    laricio Savi = pinaster, 80
    latifolia Sarg. = ponderosa, 66
    latisquama Engelm. = Pinceana, 38
    latteri Mason = Merkusii, 58
    Lawsonii Roezl., 68
    leiophylla Schl. & Cham., 44
    Lemoniana Benth. = pinaster, 80
    leucodermis Ant. = nigra, 58
    leucosperma Max. = sinensis, 60
    Lindleyana Gord. = Montezumae, 64
    Llaveana Schiede = cembroides, 38
    Loiseleuriana Carr. = halepensis, 78
    longifolia Roxb., 46
    lophosperma Lindl. = Torreyana, 90
    Loudoniana Gord. = ayacahuite, 30
    luchuensis Mayr, 56
    Lumholtzii Rob. & Fern., 46
    lutea Walt. = taeda, 72
    macrocarpa Lindl. = Coulteri, 93
    macrophylla Engelm. = ponderosa, 66
    macrophylla Lindl. = Montezumae, 64
    maderiensis Ten. = pinea, 48
    mandschurica Laws. = cembra, 27
    mandschurica Rupr. = koraiensis, 26
    maritima Ait. = nigra, 58
    maritima Lamb. = halepensis, 78
    maritima Poir. = pinaster, 80
    Massoniana Lamb., 52
    Massoniana Sieb. & Zucc. = Thunbergii, 56
    Mastersiana Hay. = Armandi, 30
    Mayriana Sudw. = ponderosa, 66
    Merkusii De Vriese, 58
    mitis Michx. = echinata, 74
    monophylla Torr. = cembroides, 38
    montana Lam. = cembra, 27
    montana Mill., 54
    montana Noll = pungens, 84
    Montezumae Lamb., 64
    monticola Dougl., 34
    morrisonicola Hay. = parviflora, 32
    mugho Poir. = montana, 54
    mughus Jacq. = sylvestris, 54
    mughus Scop. = montana, 54
    muricata D. Don, 86
    Murrayana Balf. = contorta, 84
    Nelsonii Shaw, 40
    nepalensis De Chamb. = excelsa, 34
    nigra Arnold, 58
    nigricans Host = nigra, 58
    nivea Booth = strobus, 36
    obliqua Saut. = montana, 54
    occidentalis H. B. K. = Montezumae, 64
    occidentalis Swartz, 70
    oocarpa Schiede, 78
    oocarpoides Lindl. = oocarpa, 78
    orizabae Gord. = pseudostrobus, 62
    osteosperma Engelm. = cembroides, 38
    Pallasiana Lamb. = nigra, 58
    palustris Miller, 70
    Parolinii Vis. = halepensis, 78
    Parryana Engelm. = cembroides, 38
    Parryana Gord. = ponderosa, 66
    parviflora Sieb. Zucc., 32
    patula Schl. & Cham., 86
    peninsularis Lemm. = ponderosa, 66
    pentaphylla Mayr = parviflora, 32
    persica Strangw. = halepensis, 78
    peuce Grise., 34
    pinaster Ait., 80
    pinaster Bess. = nigra, 58
    Pinceana Gord., 38
    pindica Form. = nigra, 58
    pinea Linn., 48
    pityusa Stev. = halepensis, 78
    ponderosa Dougl., 66
    pontica Koch = sylvestris, 54
    porphyrocarpa Laws. = monticola, 34
    Pringlei Shaw, 76
    prominens Mast. = sinensis, 60
    pseudostrobus Lindl., 62
    pumila Regel = cembra, 27
    pumilio Haenke = montana, 54
    pungens Lamb., 84
    pyrenaica David = halepensis, 78
    pyrenaica Lap. = nigra, 58
    quadrifolia Sudw. = cembroides, 38
    radiata D. Don, 88
    radiata Hook. & Arn. = Montezumae, 64
    recurvata Rowl. = caribaea, 70
    reflexa Engelm. = flexilis, 28
    resinosa Ait., 51
    resinosa Loise. = halepensis, 78
    resinosa Savi = sylvestris, 54
    rigida Mill., 82
    rotundata Link = montana, 54
    Roxburghii Sarg. = longifolia, 46
    Royleana Jam. = echinata, 74
    rubra Michx.= resinosa, 51
    rubra Mill. = sylvestris, 54
    rudis Endl. = Montezumae, 64
    rupestris Michx. = Banksiana, 84
    Russelliana Lindl. = Montezumae, 64
    Sabiniana Dougl., 90
    Salzmanni Dun. = nigra, 58
    sanguinea Lap. = montana, 54
    sativa Lam. = pinea, 48
    scipioniformis Mast. = Armandi, 30
    scopifera Miq. = densiflora, 52
    scopulorum Lemm. = ponderosa, 66
    serotina Long = rigida, 82
    serotina Michx., 82
    shasta Carr. = albicaulis, 27
    sibirica Mayr = cembra, 27
    Sinclairii Hook. & Arn. = Montezumae, 64
                            = radiata, 88
    sinensis Lamb., 60
    squarrosa Walt. = echinata, 74
    strobiformis Engelm. = ayacahuite, 30
    strobiformis Sarg. = flexilis 28
    strobus Linn., 36
    strobus Thunb. = koraiensis, 26
    sylvestris Baumg. = nigra, 58
    sylvestris Gouan = halepensis, 78
    sylvestris Linn., 54
    sylvestris Lour. = Merkusii, 58
    sylvestris Mill. = pinaster, 80
    sylvestris Thunb. = Thunbergii, 56
    tabulaeformis Carr. = sinensis, 60
    taeda Blanco = insularis, 60
    taeda Lamb. = pungens, 84
    taeda Linn., 72
    tamrac Murr. = contorta, 84
    tatarica Mill. = sylvestris, 54
    tenuifolia Benth. = pseudostrobus, 62
    tenuis Lemm. = contorta, 84
    teocote Schl. & Cham., 68
    terthrocarpa Shaw = tropicalis, 52
    Thunbergii Parl., 56
    Torreyana Parry, 90
    tropicalis Mor., 52
    tuberculata D. Don = radiata, 88
    tuberculata Gord. = attenuata, 88
    uliginosa Neum. = montana, 54
    uncinata Ram. = montana, 54
    variabilis Lamb. = echinata, 74
    Veitchii Roezl = ayacahuite, 30
    virginiana Mill., 80
    Wilsonii Shaw = sinensis, 60
    Wincesteriana Gord. = Montezumae, 64
    Wrightii Engelm. = occidentalis, 70
    yunnanensis Franch. = sinensis, 60
  Pistillate flower, 7
  Primary leaf, 1
  Pseudolateral conelet, 7

  Resin-ducts of the leaf external, 6
    internal, 6
    medial, 6
    septal, 6

  Secondary leaf, 2
  Sectional characters, 18
  Seed, wing of, 16
    winged, 16
    wingless, 16
  Septal resin-ducts, 6
  Serotinous cone, 14
  Species, classification of, 22
  Specific characters, 20
  Spring-shoot, 2
  Staminate flowers, 7
  Stelar tissues of leaf, 6
  Stomata of leaf, 4
  Strobi-Group, 30
  Strobus, Opiz = Pinus, 24
  Strobus strobus Small = Pinus strobus, 36
  Subsectional characters, 20
  Subterminal conelet, 7
    flower, 7
  Symmetrical cone, 10

  Terminal umbo, 8
  Tissues of the cone, 12
    leaf, 4
    wood, 17

  Umbo of the cone dorsal, 8
    terminal, 8
  Uninodal branchlet, 2
    spring-shoot, 2
  Uniform hypoderm, 6

  Variation, 21

  Wing of seed, adnate, 16
    articulate, 16
  Winged seed, 16
  Wingless seed, 16
  Wood, 17
  Wood-strands of the cone, 14
  Wood-tissues, 17


Transcriber's Notes:

1. The position of Plates was changed to the end of the section
   referencing each.

2. Species names appear to be Capitalized when they are names of persons
   or places in this book, as in other material of this period.