Salix Salicaceae 359 



sparsely pubescent; blades rounded at the base, stipules per- 

 sistent at least on vigorous branchlets 18. S. cordata. 



Leaves glabrous and glaucous beneath, oblong-lanceolate or narrow- 

 lanceolate, mostly 6-9 times as long as wide, rounded at the base; 



shrubs of streams near the Ohio Eiver 5. S. longipes var. Wardi. 



Margins of leaves entire, remotely dentate or serrulate, mostly revolute. 



Leaves strictly glabrous, oblanceolate, rarely obovate or narrowly to broadly 

 elliptic, 2-4 or up to 6 cm long, 1-2 cm wide, closely reticulate on both 

 surfaces, thin, entire, often bluish beneath; apex obtuse, rounded or rarely 



acute (see also no. 12) ; small shrubs of a bog habitat 



15. S. pedicellaris var. hypoglauca. 



Leaves not as above. 



Serrations (not undulations) of margins, if any, generally more than 0.3 mm 

 deep; leaves large, mostly elliptic-oblanceolate, elliptic or obovate, mostly 

 5-10 cm long, 2-3 cm wide; petioles generally 5-20 mm long. 



Branchlets of previous year and leaves entirely glabrous 9. S. discolor. 



Branchlets of previous year and at least some of the leaves pubescent. 

 Blades rarely impressed-nerved above, some or most of them nearly 

 glabrous beneath, the pubescence straight or woolly, all or at least 

 some of the leaves with a few tawny hairs; petioles mostly 8-25 mm 



l on g 9a. S. discolor var. latifolia. 



Blades generally impressed-nerved above and strongly rugose-veined be- 

 neath, lower surface of all more or less densely woolly-pubescent; 



petioles mostly 4-12 mm long 14. S. Bebbiana. 



Serrations (not undulations), if any, mostly less than 0.3 mm deep; leaves 

 linear-oblanceolate or oblanceolate, rarely wider, tomentose or glabrate 

 beneath; petioles 2-6 mm long. 

 Leaves generally 7-16 times as long as wide, usually densely tomentose 

 beneath; midrib deeply impressed above; plants of a bog habitat. 



Leaves pubescent above 16. S. Candida. 



Leaves glabrous above 16a. S. Candida var. denudata. 



Leaves generally less than 7 times as long as wide; midrib not deeply im- 

 pressed above; plants of a dry or prairie habitat. 



Blades mostly 5-10 cm long 12. S. humilis. 



Blades mostly 3-7 cm long, thicker and more tomentose beneath 



13. S. tristis. 



1. Salix nigra Marsh. BLACK Willow. Map 733. Infrequent to fre- 

 quent throughout the state in low ground mostly along streams and about 

 lakes. In southwestern Indiana along old river channels it often becomes 

 a large tree. 



The leaves of this species vary much in outline but I do not think the 

 variations have any taxonomic value. The form with narrow and falcate 

 leaves is known as var. falcata (Pursh) Torr. 



N. B. to N. Dak., southw. to Fla. and Tex. 



2. Salix amygdaloides Anders. Peachleaf Willow. Map 734. The 

 habitat of this willow is low ground along streams and about lakes. This 

 species is restricted to the lake area with two outposts south of that area 

 where it was found in swamps. It is usually infrequent and only locally 

 frequent. 



Cent. N. Y. and Ont. to B. C. and the Rocky Mts., southw. to Tex. 

 and N. Mex. 



