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. Resin. 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.

[Ill.u.s.tration: 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 p.u.b.escent. 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 Carriere, Trait. Conif. 305.

1862 P. alba-canadensis Provancher, Fl. Canad. ii. 554.

1903 Strobus strobus Small, Fl. Southeast. U. S. 29.

Spring-shoots p.u.b.escent. 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 a.s.sociated with it. It is also recognized by the color and horizontal ma.s.sing 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 ill.u.s.trate 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 Ma.s.sachusetts.

[Ill.u.s.tration: 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. Munch. i. 392.

1838 P. Llaveana Schiede in Linnaea, xii. 488.

1845 P. monophylla Torrey in Fremont'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, x.x.xiv. 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 p.r.i.c.kle. Cones from 4 to 6 cm. long, subglobose, subsessile; apophyses l.u.s.trous ochre-yellow, crowned with a quadrilateral umbo bearing the minute p.r.i.c.kle 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.