302 COVILLE 



Plant prostrate, the leaves obovate, smooth beneath. 



.S. chamissonis, p. 325. 

 Leaves entire or remotely denticulate. 

 Plant prostrate. 



Leaves bright green on both sides. 



^S". phlebophylla^ p. 336. 

 Leaves pale or glaucous beneath. 



Twigs barely i mm. in diameter, rooting in the second 



year S. polaris^ p. 335. 



Twigs thicker, seldom rooting. 



Catkin ovoid-globose, style almost none. 



S. glacialis^ p. 329. 

 Catkin cylindrical, style well developed. 



S. arctica^ p. 326. 

 Plant an erect bush or tree. 



Leaf smooth on both surfaces S. pulchra^ p. 319. 



Leaf with some permanent pubescence beneath. 



Leaf with a white tomentum of curled hairs beneath. 



S. alaxensis^ p. 311. 



Leaf with dense or scanty short appressed hairs beneath. 



Catkins appearing before the leaves, the permanent 



pubescence of the latter beneath very scanty, stamens 



2 in each flower 6". mittallii^ p. 310. 



Catkins appearing with the leaves, the permanent pu- 

 bescence of the latter beneath dense and satiny, 

 stamens i in each flower S. sitchensis^ p. 307. 



Key to Alaska Willows, Based on Pistillate Leaf- 

 bearing Specimens. 

 Leaves obovate, usually wedge-shaped at the base, glabrous, usually 

 glaucous beneath, minutely and closely glandular-serrate, not crenate, 

 about the whole margin ; plant prostrate. 



6". chamissonis^ p. 325. 

 Leaves not with all the characters given above, particularly with refer- 

 ence to the serration ; plant often erect. 

 Leaves not exceeding 2 cm. in length, without stipules, bright green 

 and shining on both surfaces, not glaucous beneath, entire, 

 glabrous, except for the few long hairs usually present on the 

 margin, a few of the principal veins standing out very conspic- 

 uously on the fresh leaves and often forming a skeleton after 

 a few years from the weathering of the softer matter of the 

 persistent dead leaves. 



