the trek willows of alaska 277 



Key for use with specimens bearing Pistillate Catkins, 



Ovary smooth ; fully developed leaves broadly oval or obovate, rounded 



at the base S. amplifolia. 



Ovary hairy ; leaves narrower, usually wed<^e-shaped at the base. 

 Ovary short-pedicelled, the pedicel about once or twice the length 

 of the nectary. 

 Hairs of the catkin scales, except sometimes those of the lower 

 ones, extending about a third or a half the length of the scale 

 beyond its apex ; stigmas ovate to lanceolate, entire or 2-lobed ; 

 pistillate catkins seldom exceeding 6 mm. in diameter in flower 

 and 10 mm. in fruit; leaves satiny beneath with straight ap- 



pressed hairs S. sitchensis. 



Hairs of the catkin scales extending about the full length of the 

 scale beyond its apex ; stigmas divided into two very slender 

 divisions, the style therefoi^e apparently surmounted by four 

 filiform stigmas; pistillate catkins commonly about 10 mm. in 

 diameter in flower and 15 to 18 in fruit; leaves densely woolly 



beneath with tangled hairs S. alaxeftsis. 



Ovary long-pedicelled, the pedicel three to several times the length 

 of the nectary. 

 Catkins appearing before the leaves; scales black or sometimes 

 dark brown, obovate to oblanceolate ; stalk of the ovary com- 

 monly 3 to 4 times the length of the nectary, barely elongating 



in fruit S. nuttallii. 



Catkins appearing with the leaves; scales pale, buff, or straw- 

 colored when dry, linear-oblong; stalk of the ovary several 

 times the length of the nectary, in fruit usually exceeding the 

 scale and sometimes becoming twice or three times as long. 



S. bebbiana. 



Key for use with specimens bearing Staminate Catkins. 



Scales of the staminate catkins subtending but a single stamen each* 



S. sttchcnsis' 

 Scales subtending two stamens each. 



Scales pale, buff, or straw-colored when dry ; staminate catkins about 

 4 to 5 mm. in diameter exclusive of the exserted portions of the 



stamens S. bebbiana. 



Scales black to brown ; staminate catkins, exclusive of the exserted 

 portions of the stamens, 8 to 10 mm. or more in diameter. 

 Catkins appearing before the leaves, on twigs entirely devoid of 



leaves or green bracts "S". nuttallii. 



Catkins appearing with the leaves, the twigs always bearing at 

 the time of flowering some young leaves or green herbaceous 

 bracts. 

 Leaves densely white-woolly beneath, smooth or nearly so above. 



S. alaxcnsis. 

 Leaves smooth or with some villous pubescence on either surface. 



S. amplifolia. 



