320 CONTPJBUTIOIS^S FROM THE NATIONAL HERBARIUM. 



Plants low, creeping, alpine, less than 10 cm. high. 



Leaves pale beneath 15. S. petrophila. 



Leaves glaucous beneath 16. S. anglorum. 



Leaves densely silvery -silky beneath. Capsules silvery-silky. 

 Leaves lanceolate to oblanceolate, pubescent; styles 0.8 to 1.5 mm. long; 



twdgs often pruinose 17. S. subcoerulea. 



Leaves obovate or obovate-oblong, tomentose; style 0.5 to 1 mm. long; twigs 



never pruinose 18. S. drummondiana. 



Styles short, obsolete or only 0.2 to 0.3 mm. long. 



Plants erect shrubs, mostly tall; capsules slender, 6 to 10 mm. long, on pedicels 

 1 to 5 mm. long. 

 Catkins dense, sessile or nearly so; scales black, densely silky with long 



hairs; stigmas long, slender 19. S. scouleriana. 



Catkins loose, leafy-peduncled ; scales yellowish, thinly hairy; stigmas very 

 short. 

 Leaves elliptic-oval, strongly net-veined beneath. 



Leaves more or less tomentose 20. S. bebbiana. 



Leaves glabrate 20a. S. bebbiana perrostrata. 



Leaves linear-oblanceolate, not net-veined beneath ... 21. S. geyeriana. 

 Plants low or creeping alpine shrubs; capsules ovate, 3 to 5 mm. long, sessile. 

 Plants ascending, 0.3 to 1 meter tall; leaves long-hairy beneath. 



Leaves thick, broadly oval; capsules somewhat pointed . . 22. S. vestita. 



Leaves thinner, narrower; capsules blunter 22a. S. vestita erecta. 



Plants creeping, 5 to 10 cm. tall; leaves glabrous beneath. 

 Leaves roundish-oval, glaucous beneath. 



Blades 1.5 to 2.5 cm. long; aments usually many-flowered. 



23. S. saximontana. 



Blades 7 to 12 mm. long; aments usually few-flowered . . 24. S. nivalis. 



Leaves narrowly elliptic, green beneath 25. S. cascadensis. 



1. Salix caudata (Nutt.) Heller. Pare; at low altitudes, in wet thickets. Moun- 

 tain streams from B. C. and Alta. to N. Mex. and Calif.— Stems few, 3 to 5 meters 

 high; twigs chestnut, sliining; leaves narrowly to broadly lanceolate, 6 to 13 cm. 

 long, tapering to a long slender point; catkins stout, 1.2 to 2 cm. wide, 2 to 5 cm. 

 long, becoming 3 to 6 cm. long in fruit; capsules thin-walled, 6 to 7 mm. long, 

 yellowish. 



2. Salix serissima (Bailey) Femald. In cold bog about spring near Swiftcurrent 

 Creek below Lake McDermott. East of the Divide, in southern Alta. and northern 

 Mont, (the only other Montana specimen collected near Chouteau), eastward to 

 northern Ohio, N. Eng., and Lower Can. — Plant similar to the last; leaves 

 elliptic-lanceolate, acute or only short-pointed at the apex; capsules thick-walled, 

 7 to 9 mm. long, shining, olive-brown or darker. 



Remarkable for its flowering in midsummer or later and producing fruit in late 

 summer and autumn. 



3. Salix amygdaloides Anderss. Peachleaf willow. Belton, in thicket along 

 the river. Along streams at low elevations, east of the Cascades from B. C. to Oreg., 

 east to northwest Tex., central N. Y., and Que. — Tall shrub or small tree, yellowish 

 green; twigs slender, yello-ndsh, often drooping; petioles 1 to 2 cm. long, slender, 

 twisted; leaves lanceolate or broadly lanceolate, 5 to 12 cm. long, long-pointed; 

 catkins about 1 cm. wide, 3 to 5 cm. long, the pistillate becoming 4 to 7 cm. long in 

 fruit; pedicels 2 mm. long, slender. 



4. Salix interior Rowlee. Sandbar willow. East entrance, along the edge of 

 Two Medicine Creek, at the foot of a steep shale slide. Alaska to Idaho and N. Mex., 

 eastward to La., Del., and N. B.; not common west of the Divide, but abundant in 



