Black Willow 



183 



Leaves lanceolate, oblong-lanceolate or oblanceolate, three 

 times or more as long as wide. 

 Leaves slightly serrate, green on both sides; northwestern 



tree. 

 Leaves whitish or canescent beneath. 



Leaves acute; filaments distinct; tree of the Central 



States. 

 Leaves acuminate; filaments united below; tree of Cali- 

 fornia and Arizona. 

 Leaves obovate to elliptic-obovate or ovate-oval, less than three 

 times as long as wide. 

 Twigs glabrous, or merely puberulent when very young; 



eastern tree or shrub. 

 Twigs villous-pubescent or tomentose; western trees or shrubs 

 Style three to five times longer than the stigmas; Alaskan 



tree. 

 Style as long or twice as long as the stigmas; northwestern 

 tree. 

 B. Capsule pubescent, silky or tomentose (nearly glabrous in Texan 

 specimens of Salix taxijolia). 



a. Filaments distinct. 



Leaves linear-lanceolate to narrowly lanceolate. 



Leaves dark green above, 7 to 15 cm. long; silvery-white 



beneath; style long; European introduced tree. 

 Leaves not dark green above, only i to 4 mm. long; style short 

 or none; southwestern and Mexican tree. 

 Leaves lanceolate to oblong, oblanceolate or obovate. 



Stamen only i; pedicels of capsules very short; far western tree 



with leaves satiny beneath. 

 Stamens 2; leaves not satiny, but often pubescent or tomen- 

 tose beneath. 

 Capsule distinctly pedicelled; leaves not white-felty beneath. 

 Bracts of the catkins yellow. 



Style none, or very short; northern tree or shrub. 

 Style slender, distinct; California tree or shrub. 

 Bracts of the catkins black or brown. 



Leaves distinctly toothed; eastern tree or shrub. 

 Leaves nearly or quite entire; western tree or shrub. 

 Capsule ver)'^ short-pedicelled; leaves densely white-felty 

 beneath; Alaskan tree. 



b. Filaments united; ovary and stigmas sessile; European introduced 



tree. 



17. 6". M ackenzieana. 



19. 



S. missouriensis. 

 S. lasiolepis. 



20. 5. balsamijera. 



21. 



22. 



S. amplijolia. 

 S. Hookeriana. 



23- 



24. 



S. viminalis. 

 S. taxijolia. 



25. 5". sitchensis. 



I. BLACK WILLOW - Salix nigra Marshall 



Salix marginata Wimmer 



The Black willow is the largest native species of eastern North America, some- 

 times attaining a height of 40 meters, with a trunk a meter in diameter in the 

 central States, usually much smaller, however, and commonly 10 to 20 meters 

 high, with the trunk not over s dm. thick; the trunks are often two to five together 



