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. .6^. amplifolla^ 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. commutata^ p. 317. 

 Plant prostrate. 



Leaves crenate about the whole margin. 



S, 77iyrtillifolia^ p. 325. 

 Leaves entire or sparingly toothed toward the base. 

 Leaves bright green and shining on both surfaces. 



S. 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 w^anting 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. bebbiana^ 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 S. 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. 



