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, x.x.xiv. 331.

1871 P. Balfouriana Watson in King's Rep. v. 331 (not Balfour).

Spring-shoots glabrous or temporarily p.u.b.escent. 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.

[Ill.u.s.tration: 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 alt.i.tudes 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. x.x.x. 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 subl.u.s.trous, 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 lat.i.tude 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.

[Ill.u.s.tration: 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 ma.s.ses, some or all of the endoderm cells with thick outer walls.

Cones from 10 to 17 cm. long, short-pedunculate, ovoid-conic; apophyses l.u.s.trous 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.