60 WILLOW FAMILY 



Key to the Species 



1. Leaves smooth, or nearly so, on both sides when 

 mature. 



a. Leaves linear, linear-oblong, or linear-lance- 



olate S. ftuviatilis 



b. Leaves broader, lanceolate to ovate 



( 1 ) Branches drooping S. babylonica 



(2) Branches more or less ascending, not 



drooping 



(a) Shrubs or low trees, less than 20 ft. 



high 

 x. Twigs purplish, leaves oblanceolate 



or spatulate .V. purpurea 



y. Twigs brownish or yellowish ; leaves 

 lanceolate to ovate 

 (x) Petioles and stipules glandular .V. lucid a 

 (y) Petioles and stipules not glandu- 

 lar 

 m. Leaves entire, elliptic; 1-3 ft. 



high S. myrtilloides 



n. Leaves more or less toothed 

 (m) Leaves green on both sides. 

 at least not glaucous be- 

 low S. cordata 

 (n) Leaves glaucous or white 

 below 

 r. Leaves elliptic to ovate, the 



fine teeth glandular S. balsatnifera 



s. Leaves lanceolate to oblong- 

 lanceolate 

 (r) Young leaves densely 



silky S. sericea 



(s) Young leaves only slight- 

 ly silky or hairy 

 h. Leaves lanceolate, acu- 

 minate S. petiolaris 

 i. Leaves oblong-lanceo- 

 late acute 5. discolor 



(b) Trees, 20-70 ft. high 



