Il8 SALICACEAE. 



Salix nivalis Hook. A low creeping shrub, 2-3 cm. high, similar to S. 

 saximontana but smaller in every way; leaves elliptic or somewhat obovate, 

 mostly obtuse, glabrous, entire with revolute margins, 7-12 mm. long, green 

 and shining above, glaucous and strongly net-veined beneath; aments very 

 small, 3-6-flowered, on naked peduncles; scales oblanceolate, yellowish, gla- 

 brous or nearly so; capsule 2.5-3 mm. long, sessile, tomentose; stigmas short, 

 sessile, divided. 



On the higher peaks of the Cascade Mountains. Mount Rainier, Flett. 



145. POPULUS. 



Trees with scaly resinous buds and rounded or angled twigs; 

 leaves long-petioled, broad or narrow; bracts of the aments 

 fimbriate or incised; disk cup-shaped, oblique, lobed or entire; 

 staminate aments dense, pendulous; pistillate aments sometimes 

 raceme-like by the elongation of the pedicels, pendulous, erect 

 or spreading; staminate flowers with 4-60 stamens; filaments 

 distinct; ovary sessile; seed with a very conspicuous tuft of hair. 



Bark smooth; petioles flattened; capsules oblong-conic, 



smooth. P. vancouveriana. 



Bark rough; petioles terete; capsules globose, hairy. P. trichocarpa. 



Populus vancouveriana Trelease n. sp.* Tree 5-10 m. high; bark smooth, 

 whitish; twigs chestnut colored to dark purplish; buds smooth, conical, 

 gummy, dark purple; leaves broadly ovate to suborbicular, acute or abruptly 

 acuminate, undulate-crenulate, somewhat silky pubescent beneath when 

 young, glabrous in age, mostly 4-6 cm. long; petioles equalling or slightly 

 longer than the blades; staminate aments 4-5 cm. long, the bracts 5 mm. long, 

 cleft into numerous ciliate filiform lobes; stamens many; pistillate aments 

 and fruit unknown. 



Vancouver Island, Lyall, 1858-9 (type in Gray Herbarium); Victoria, 

 Macoun, nos. 2131, 2132; Seattle, E. S. Meany (staminate aments described 

 from this specimen in United States National Herbarium). Apparently 

 confined to the region west of the Cascade Mountains from Vancouver 

 Island southward at least to the head of Puget Sound. This aspen is easily 

 distinguished from the eastern P. tremuloides Michx. and the Rocky Moun- 

 tain P, aurea Tidestrom by the peculiar dentition of the leaves. The teeth 

 are much larger than in any of its immediate allies and besides being crenu- 

 late are depressed so that each tooth viewed from the edge forms a double 

 curve. Herbarium material of this aspen is very scanty and complete speci- 

 mens showing pistillate flowers, fruit and the leaves of the sterile shoots are 

 much desired. 



Populus trichocarpa T. & G. Cottonwood. Large tree, 10-30 m. tall, 

 with rough fissured pale gray bark; leaves broadly ovate, rounded at the base, 

 acuminate, 5-12 cm. long, puberulent when young, whitish beneath; petioles 

 slender, terete, about equalling the blades; staminate aments dense, the bracts 

 long-hairy; stamens 50-60; pistillate aments becoming loose; capsules nearly 

 sessile, globose, puberulent or glabrate. 



Banks of streams and lake shores. 



Family 26. MYRICACEAE. SWEET GALE FAMILY. 



Shrubs or small trees with alternate usually waxy-dotted and 

 fragrant leaves; flowers solitary in the axils of bracts, monoecious 

 * Description by Mr. Ivar Tidestrom. 



