20 



9a. Petioles without glands 10. 

 9b. Petioles with glands 11. 



lOa. Petiole short (about 5 mm.), broad and flat 



Black Willow, Salix nigra, 

 lOb. Petiole slender, about 10 20 mm. long 



Peach-leaied Willow, Salix amyg-daloides. 



lla. Leaves green beneath Crack Willow, Salix frag-ilis. 



lib. Leaves pale beneath 12. 



12a. Branches and twigs conspicuously drooping 



Weeping- Willow, Salix babylonica. 

 12b. Branches and twigs not conspicuously drooping, yellow 



Yellow Willow, Salix alba var. vitellina. 

 13a. Shrubs of bogs 14. 



13b. Plants of sand-dunes along the Great Lakes 15. 

 13c. Plants of dry upland hills 16. 

 13d. Plants of wet ground, river-banks, and swamps 17. 



14a. Leaves densely white-tomentose beneath 



Willow, Salix Candida, 

 14b. Leaves pale beneath but Hot tomentose 



Willow, Salix serissima. 

 14c. Leaves glabrous a^nd green beneath 



Willow, Salix pedicellaris. 



15a. Leaves linear Willow, Salix long-ifolia. 



15b. Leaves ovate-lanceolate, tomentose beneath 



Willow, Salix syrticola. 

 15c. Leaves ovate-lanceolate, glabrous Willow, Salix glaucopliylla. 



16a. Leaves about 3 times as long as broad 



Willow, Salix rostrata. 



16b. Leaves narrower, nearly sessile Willow, Salix tristis. 



16c. Leaves narrower, distinctly petioled Willow, Salix humilis. 



17a. Leaves linear or nearly so ^ Willow, Salix longifolia. 



17b. Leaves shining Willow, Salix lucida. 



17c. Leaves silky Willow, Salix sericea. 



17d. Leaves not as in the preceding 3 species 18. 



18a. Leaves rounded at base Willow, Salix cordata. 



18b. Leaves acute at base 19. 



19a. Leaves finely serrulate Willow, Salix petiolaris. 



19b. Leaves remotely serrate or nearly entire Willow, Salix discolor. 



MYKICACEAE, the Sweet Gale Family 



Shrubs, with monoecious or dioecious flowers in catkins, and 

 aromatic foliage. 



la. Leaves pinnately lobed Sweet Fern, Myrica asplenifolia. 



Ib. Leaves merely serrate 2. 



