THE WILLOWS OF ALASKA 3OI 



Catkins terminal on leaf-bearing, though sometimes very short and 

 small-leaved, branches. 

 Plant an erect bush or tree. 



Plant a tree, the leaves without stipules. .^S. amplifolia^ p. 314. 

 Plant a bush, the leaves with toothed stipules. 



Leaves glaucous beneath, the catkin scales black. 



6^. bar clay i^ p. 316. 

 Leaves green beneath, the catkin scales yellowish. 



S. com?nutata^ p. 317- 

 Plant prostrate. 



Leaves crenate about the whole margin. 



S. 7nyrtillifolia^ p. 325. 

 Leaves entire or sparingly toothed toward the base. 

 Leaves bright green and shining on both surfaces. 



vS. leiocarpa^ p. 338. 

 Leaves glaucous beneath. 



Style about 1.5 mm. long S. stolonifera^ p. 333. 



Style about .5 mm. or less in length. 



Pedicels about three times as long as the nectaries, 



style almost wanting S. fuscescens^ p. 329. 



Pedicels not longer than the nectaries, style about .5 



mm. long S. ovalifolia^ p. 331. 



Ovaries hairy. 



Catkin scales several times longer than their hairs, filaments hairy 



below S. reticulata,, p. 340. 



Catkin scales little or not at all longer than their hairs, filaments 

 smooth throughout. 

 Catkin scales yellowish throughout. 



Pedicels several times the length of the nectaries, in fruit ex- 

 ceeding the catkin scales S. bebblana^ p. 306. 



Pedicels at most three times the length of the nectaries, never 

 exceeding the scale. 

 Leaves acute at the base, on petioles several millimeters in 



length S. glauca, p. 321. 



Leaves rounded at the base, on petioles 2 mm. or less in 



length 6'. niphoclada, p. 322. 



Catkin scales black, at least at the apex. 



Leaves finely and evenly serrate or crenate about the whole 

 margin. 

 Plant erect, the leaves oblanceolate, sericeous beneath. 



S. arbusculoides ^ p. 323. 



