ee. Upper surface of leaves usually dull; lowermost 

 branches of trees growing in the open not drooping; 



nut about i inch long Q. rubra, p. 109. 



bb. Leaf-lobes rounded, not bristle-tipped; fruit maturing 

 in the first season. 



c. Leaves cut nearly to the midrib by a pair of deep sinuses 

 near the middle of the leaf; branches corky-ridged; nut 

 l /2-i l /2 inches long, deeply seated in a large, conspic- 

 uously fringed cup '. .Q. macrocarpa, p. 103. 



cc. Leaves not cut by a pair of deep sinuses; branches not 

 corky-ridged ; nut about 24 inch long, about one-fourth 

 covered by a thin, tomentose, warty cup. .Q. alba, p. 101. 

 aa. Leaves not deeply cut nor lobed. 



b. Margin of leaf entire to sinuate-crenate, but not toothed ; 

 acorns on stalks ^2-4 inches long. 



c. Margin of leaf entire, or only slightly undulate; acorns 

 on peduncles l /2 inch long, the nut about Y-I inch long; 

 bark on branches not breaking into large, papery scales 



Q. imbricaria, p. 121. 



cc. Margin of leaf sinuate-crenate, rarely lobed; acorns on 

 stems 1-4 inches long, the nut about I inch long; bark 

 on branches breaking into large, papery scales which 



curl back Q. bicolor, p. 105. 



bb. Margin of leaf coarsely toothed; acorns sessile or on 

 stalks less than l / 2 inch long Q. mnhlenbergii, p, 107. 



97 



