48 BETULACEAE (BIRCH FAMILY) 



ovate, taper-pointed, very sharply double-serrate, downy beneath, 11-15 

 principal veins. Rich woods. 



CARPINUS 



Trees or tall shrubs with gray bark which has the appearance 

 of being very tight-fitting to the wood, giving the stems and 

 branches a "hard-muscled" appearance. The slender buds and 

 straight-veined leaves resemble those of beech. 



C. caroliniana, BLUE BEECH. Leaves ovate-oblong, pointed, sharply 

 double-serrate. Along streams. 



BETULA 



Trees or shrubs with the outer bark often separable in sheets 

 and that of the smaller branches dotted. Buds sessile and scaly. 

 Staminate catkins terminal and lateral, sessile, formed in summer, 

 remaining naked through winter, and expanding in early spring. 

 They appear with or precede the leaves. The pistillate catkins are 

 ovoid to cylindrical and usually terminate the very short 2-leaved 

 early lateral branches. 



B. lenta, SWEET BIRCH. Bark and 

 twigs sweet-aromatic. Leaves green on 

 both sides. Bark of trunk dark brown 

 and tight, in age becoming ashy-brown 

 and furrowed. The fruiting catkins 

 short-cylindric. Rich woods. 



B. lutea, YELLOW BIRCH. Bark and 

 twigs sweet-aromatic, but less so than in 

 preceding species. Leaves green on both 

 sides. Bark of trunk yellowish- or silvery- 

 gray, detaching in very thin filmy layers. 

 The fruiting catkins narrow-ovoid to sub- 

 globose. Rich moist woods. 



Betula lutea. Yellow birch; a, 

 branch with staminate and 

 pistillate catkins; b, single 

 staminate flowers; c, leaf. 



B. nigra, RIVER BIRCH. Bark not aro- 

 matic. Leaves whitish beneath. Bark 

 greenish-brown. Twigs reddish. Leaves 

 acutish at both ends, downy beneath when young. Petioles and pe- 

 duncles and the thick-cylindric catkins woolly-pubescent. Banks of 

 streams and swamps. 



