12 Salic ace ae. 



What is called the weeping willow here is really a com- 

 plex including not only Salix babylonica but a series of usu- 

 ally hardier hybrids of that species. 



1. Weeping. 2. 



Not markedly weeping. 4. 



2. Twigs very slender, glabrous. 3. 

 Twigs stout: villous. 



(Kilmarnock willow). S. caprea pendula. 



3. Buds alternate. (Weeping willow). (1). S. babylonica. 

 Buds often opposite. (Purple willow). S. purpurea. 



4. Buds large (5X10 mm.). 5. 

 Buds moderate (4-6 mm. long). 7. 

 Buds small (scarcely 3 mm. long). 9. 



5. Buds rather sharply 2-winged. 6. 



Buds plano-convex. (2). S. missouriensis. 



6. Buds green-and-red : planted. 



(Goat willow). (3). S. caprea. 

 Buds blackish: native. (Pussy willow). S. discolor. 



7. Buds frequently opposite. S. purpurea. 

 Buds always alternate. 8. 



8. Twigs glossy olive, glabrous. (Shining willow). S. lucida. 

 Twigs dull, velvety. S. incana.- 



9. Trees: Twigs mostly glabrescent. 10. 

 Shrubs: twigs gray-velvety. 13. 



10. Twigs olive-green. 11. 



Twigs golden. (Golden willow). S. vitellina. 



Twigs red. (Red-twigged willow). 



S. vitellina Britzensis. 



11. Large open trees. 12. 



Slender, pole-like. (Sand-bar willow). S. longifolia. 



12. Trunks mostly clustered. (Black willow). S. nigra. 

 Trunk single: twigs sometimes velvety. 



(White willow). S. alba. 



13. Buds 3 mm. long. (Prairie willow). S. humilis. 

 Buds 2 mm. long. (Dwarf gray willow). (6). S. tristis. 



