324 CONTKIBUTIONS FBOM THE NATIONAL HERBARIUM. 



22. Salix vestita Pursh. Cracker Lake and switchbacks near Swiftcurrent Pass, 

 on rocky slopes. Alta. and B. C. to Mont, and eastern Oreg.; also Lab., Newf., 

 Anticosti, and the Gasp^ Peninsula of Que. — Ascending shrub, 0.2 to 1 meter high; 

 leaves broadly elliptic to obovate-oblong or suborbicular, rounded to retuse at the 

 apex, 3 to 5 or 6 cm. long, 2 to 4 cm. wide, thick, deep green and glabrous above, 

 clothed beneath with long white silky hairs, especially on midrib and veins; catkins 

 on short villous peduncles, slender, 2 to 3 or 4 cm. long; capsules ovoid-conic, pointed, 

 4 to 5 cm. long. 



A very handsome shrub because of the striking contrast in the leaves between the 

 bright green, netted upper surface and the silvery-silky under surface. 



22a. Salix vestita erecta Anderss. Abundant above timber line, in meadows and 

 on rock slides; one of the most characteristic plants of alpine situations, frequently 

 forming large dense patches. — More erect, -with narrower, more pointed leaves, longer 

 catkins, and more ovoid -ellipsoid, blunter capsules. 



23. Salix saximontana Rydb. Gunsight Pass, on rock slides and rocky slopes. 

 Alpine summits, Alta. and B. C. to Nev. and N. Mex. — Prostrate, 3 to 6 cm. high; 

 leaves elliptic-oblong to broadly oval, obtuse or acutish at both ends, entire, 1.5 to 3 

 cm. long, 1 to 2 cm. wide, glabrous on both sides; catkins several to many-flowered, 

 1 to 1.5 cm. long; capsules ovoid, 3 to 4 mm. long. 



24. Salix nivalis Hook. Above timber line, Siyeh Pass and Boundary Peak 

 (B. C), 2,280 to 2,400 meters elevation, collected by Vernon Bailey, August, 1917. 

 Alpine summits, Alta. and Mont, and westward. — Scarcely 2 cm. high; leaves as the 

 last but only 7 to 12 mm. long and 4 to 8 mm. wide; catkins few-flowered, less than 

 1 cm. long; capsules 2.5 to 3 mm. long. 



25. Salix cascadensis Cockerell. Sexton Glacier, abundant on rocky slope. 

 Alpine summits, Wyo. and Mont, to Wash. {S. tener a Anderas.) — Prostrate, creeping, 



3 to 5 cm. high; leaves narrowly elliptic to subobovate, mostly acute at both ends, 

 deep green and shining on both sides, glabrous, strongly veined, 8 to 15 mm. long, 



4 to 8 mm. wide; catkins subglobose, 5 to 20-flowered, 7 to 20 mm. long; capsules 

 sessUe, 4 to 5 mm. long, gray-tomentose. 



22. BETTJLACEAE. Birch Family. 



Trees or shrubs; leaves alternate, toothed or somewhat lobed; flowers staminate 

 and pistillate, the staminate ones in slender drooping catkins; pistillate flowers in 

 short catkins, these becoming conelike, inclosing the small nutlike or seedlike fruits. 



Conelike pistillate catkins falling apart when mature, their bracts 3-lobed. 



1. BETULA. 

 Conelike pistillate catkins not falling apart, their bracts not lobed ... 2. ALNITS. 



1. BETULA L. Birch. 

 Trees or shrubs; leaves stalked, small or large; fruit narrowly or broadly winged. 

 Leaves 1 to 2.5 cm. long, rounded at the tip, the teeth rounded . . 1. B. glandulosa. 

 Leaves mostly 3 to 10 cm. long, usually sharp-pointed, the teeth sharp. 



Bark not separating into layers; twigs densely covered vsdth glands, not hairy; 



leaves mostly less than 5 cm. long 2. B. fontinalis. 



Bark separating into thin layers; twigs hairy and often glandular; leaves mostly 

 5 to 10 cm. long. 

 Bark white or yellowish white; twigs usually not glandular . . 3. B. papyrifera. 



Bark reddish brown; tvngs glandular 4. B. occidentalis. 



1. Betula glandulosa Michx. Scrub birch. Frequent on the east slope at nearly 

 all altitudes, in bogs, along streams, or on alpine slopes. Alaska to Colo., Minn., 

 Me., and Greenl.- — Shrub, usually 1 to 2 meters high, with reddish brown, very 

 glandular branchlets; leaves rounded, short-stalked, glabrous; cones 1 to 2 cm. long, 

 the fruit with a narrow wing. 



