BETULACE.E 



207 



A tree, with aromatic bark and leaves, 70-80 high, with a trunk 2-5 in diameter, 

 slender branches spreading almost at right angles, becoming pendulous toward the ends 

 and gradually forming a narrow round-topped open graceful head, and branchlets light 

 green, slightly viscid and pilose when they first appear, soon turning dark orange-brown, 

 lustrous during the summer, bright red-brown in their first winter, becoming darker and 

 finally dark dull brown slightly tinged with red. Winter-buds ovoid, acute, about \' 

 long, with ovate acute light chestnut-brown loosely imbricated scales, those of the inner 

 ranks becoming \'-\' long. Bark on young stems and branches close, smooth, lustrous, 

 dark brown tinged with red, and marked by elongated horizontal pale lenticels, becoming 

 on old trunks '-' thick, dull, deeply furrowed and broken into large thick irregular plates 



Fig. 194 



covered with closely appressed scales. Wood heavy, very strong and hard, close-grained, 

 dark brown tinged with red, with thin light brown or yellow sapwood of 70-80 layers of 

 annual growth; largely used for floors, in the manufacture of furniture and for fuel, and 

 occasionally in ship and boatbuilding. Sweet birch-oil distilled from the wood and bark is 

 used for medicinal purposes and for flavoring as a substitute for oil of wintergreen, and 

 beer is obtained by fermenting the sugary sap. 



Distribution. Rich uplands from southern Maine to northwestern Vermont, and eastern 

 Ohio and southward to northern Delaware and along the Appalachian Mountains up to al- 

 titudes of 4000 to northern Georgia; in Alabama, and in eastern Kentucky and Tennes- 

 see; a common forest tree at the north, and of its largest size on the western slopes of the 

 southern Alleghany Mountains. 



X Betula Jackii Schn., a natural hybrid of B. lenta with B. pumila Michx., has appeared 

 in the Arnold Arboretum. 



2. Betula lutea Michx. Yellow Birch. Gray Birch. 



Leaves ovate to oblong-ovate, acuminate or acute at apex, gradually narrowed to the 

 rounded cuneate or rarely heart-shaped usually oblique base, sharply doubly serrate, 

 when they unfold bronze-green or red, and pilose with long pale hairs above and on the 

 under side of the midrib and veins, at maturity dull dark green above, yellow-green below, 



4^' long, l|'-2' wide, with a stout midrib and primary veins covered below near the 

 base of the leaf with short pale or rufous hairs; turning clear bright yellow in the autumn; 

 petioles slender, pale yellow, hairy, i'-l' long; stipules ovate, acute, light green tinged with 

 pink above the middle, about \' long. Flowers: staminate aments during the winter f'-l' 

 long, about ' thick, with ovate rounded scales light chestnut-brown and lustrous above 

 the middle, ciliate on the margins, becoming 3'-8i' long and \' thick; pistillate aments 



