j. Leaves 3-5 inches long, very lustrous 

 beneath; bark close, smooth, steel-gray 



FAGUS, p. 93- 



jj. Leaves 6-8 inches long, not lustrous be- 

 neath ; bark fissured, brownish 



CASTANEA, p. 95- 



ii. Leaves pubescent or white-tomentose, at 

 least beneath ; fruit not a prickly bur. 

 j. Leaves 2-4 inches long, broadly ovate to 

 suborbicular ; fruit a very small capsule, 



falling in spring POPULUS, p. 44. 



jj. Leaves 4-7 inches long, oblong-lanceolate 

 to obovate; fruit an acorn, falling in 



autumn QUERCUS, p. 96. 



hh. Teeth fine, 6-many per inch of margin. 



i. Leaf-petioles laterally compressed; leaves 



tremulous POPULUS, p. 44- 



ii. Leaf-petioles terete; leaves not tremulous, 

 j. Leaf -blades at least 3 times as long as 

 they are broad. 



k. Twigs brittle; fruit a very small cap- 

 sule, falling in spring SALIX, p. 34. 



kk. Twigs tough ; fruit a fleshy drupe, fall- 

 ing in late summer or autumn 



PRUNUS, p. 152. 



jj. Leaf-blades not more than twice as long 

 as they are broad. 



k. Leaf-blades about twice as long as they 

 are broad. 



1. Margin of leaves singly serrate; fruit 

 fleshy. 



m. Lenticels conspicuous; pith whit- 

 ish or brownish ; bark easily peeled 

 off in papery layers; buds ovate.. 



PRUNUS, p. 152. 



mm. Lenticels inconspicuous ; pith 

 greenish ; bark not separable into 

 papery layers ; buds narrow-con- 

 ical. .. .AMJELANCHIER, p. 149. 

 11. Margin of leaves doubly serrate; fruit 

 not fleshy. 

 xxm 



