George Russell Shaw

“ 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, 16perhaps 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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) . ”

“ 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. ”

“ 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. ”

“ 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 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,6 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ Several characters, quite distinct from those of other genera, are common to all the species.
The primary leaf—appearing as a scale or bract throughout the life of the tree. The bud—its constant position at the nodes. The internode—its three distinct divisions. The secondary leaves—in cylindrical fascicles with a basal sheath. The pistillate flower—its constant nodal position and its verticillate clusters. The staminate flower—its constant basal position on the internode and its compact clusters. The cone—its clearly defined annual growths. ”

“ 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. ”