a 1> c d 4 e ? f 5 16 



g2 Winged both sides and borne in the axils of scales which form a cone; 



scales 

 h 3-lobed, thin and falling away at maturity of seed; 



i Bark chalky white and peeling in strips around the trunk; Ivs. 

 j Ovate, rounded or obtuse b., acuminate a.; bark peeling readily. 



CANOE BIRCH (Betula papyrifera). 



32 Deltoid, long-acuminate, petioles long and slender; bark peeling 

 with some difficulty WHITE BIRCH (Betula populifolia). 



12 Bark smooth, lustrous reddish brown; Ivs. broad ovate. 



WESTERN RED BIRCH (B. fontinalis). 



13 Bark scaly, gray-brown; Ivs. ovate-oblong, narrow and rounded or 



subcordate b., aromatic when bruised. 



SWEET BIRCH (Betula lenta). 



1 4 Bark silvery yellow, separating in thin layers and hanging in curls; 



Ivs. ovate-oblong, narrow and mostly heart shaped b., aromatic. 



YELLOW BIRCH (Betula lutea). 

 i Bark reddish brown, separating in thin persistent scales; Ivs. rhombic 



ovate RIVER BIRCH (B. nigra) . 



h2 Thickened, woody and persistent; Ivs. 



i Ovate-oblong, mostly acute or acuminate a., lustrous dark green ab.; 



fls. in late summer SEA-SIDE ALDER ( Alnus maritima). 



12 Orbicular-obovate, rounded to notched a., dull green ab. ; fls. in early 

 spring EUROPEAN ALDZR (Almis glutinosa). 



