S8 GENUS PDSrUS 



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 south- 

 em 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. PI. 1001. 



1855 P. NiVEA Booth ex Carrifere, Trait. Conif. 305. 



1862 P. ALBA-CANADENSis Provauchcr, 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 ex- 

 tends 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 trac- 

 table 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. pence, 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 infre- 

 quently the leaves of a tree were twice the length of those of an adjacent tree. Such variations ap- 

 pear in many species and in many localities. 



Plate Xn. 



Fig. 119, Two cones. Fig. 120, Leaf -fascicle. Fig. 121, Magnified leaf -section. Fig. 122, 

 Conelets. Fig. 123, A cultivated tree in Massachusetts. 



Paracembra 



Umbo of the cone-scale dorsal. Scales of the conelet mucronate or aristate. Epiderm and hypo- 

 derm 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. 



