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 aromatic B. alba papyrifera, p. 91. 



aa. Bark of trunk not white, usually dark colored, not separating 

 freely into papery layers; twigs with more or less winter- 

 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 



B. lenta, p. 87. 



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