SUMMER KEY TO THE SPECIES OF BETULA 
a. Bark of trunk white, separating freely into thin, papery 
layers; twigs without wintergreen taste; leaves usually soli- 
tary; not aromatics..s¢sis eesessw vas B. alba papyrifera, p. gt. 
aa. Bark of trunk not white, usually dark colored, not separating 
freely into papery layers; twigs with more or less hiien: 
green taste; leaves solitary or in pairs, aromatic. 
b. Bark dirty-yellow, breaking into strips more or less curled 
at the edges; leaves solitary or in pairs, slightly aromatic; 
twigs with slight wintergreen taste......... B. lutea, p. 89. 
bb. Bark dark red-brown, cleaving off in thick, irregular plates 
(resembles bark of Black Cherry); leaves in pairs, 
strongly aromatic; twigs with strong wintergreen taste.. 
Desde cated Sood aes Oden eS Oe B. lenta, p. 87. 
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