SAI.DC 



47 



c. Twigs greenish-yellow 

 (young) to reddish-brown 

 (older) ;introduced trees 



d. Bark gray, thick, rough; 



twigs very brittle at 

 ( base; buds midsized 



to large, 3-7 (-10) mm. 



long 

 d. Bark gray-brown, 



rough, ridged ;twigs 



not brittle; buds small 



to midsized, 1-3 (-5) 



mm. long 



b. Twigs long, pendulous 

 (weeping) 



a. Shrubs, or occasionally small 

 trees (as also is_S^ carolinlana 

 above) 



b. Buds alternate 



6. S. fragilis 



7. S. alba 



8. S. babylonica 



c. Thicket-forming, stoloni- 



ferous shrub, 2-3m. high; 



twigs slender; buds small, 



2-4 mm. long 

 c. Not thicket-forming or 



stoloniferous shrubs 



d. Buds small to midsized, 

 2-6 or rarely 7 mm. 

 long (4-7 (-10) mm. in 

 S. discolor ) 



9. S. interior 



e. Older twigs and 

 buds glabrous (ex- 

 cept in hairy vari- 

 eties, as noted) 



f. Twigs midsized 

 to stout, 2-6 (-7) 

 mm. wide at base 



g. Seasonal twigs 

 yellowish-brown. 



