200 



TREES OF NORTH AMERICA 



states to the valley of the Trinity River, Texas, and through the Mississippi valley 

 to the Indian Territory, eastern Kansas, the bottom-lands of the Missouri River, 

 in eastern Nebraska, central Minnesota, southern Wisconsin, and Ohio; the only 

 semiaquatic species and the only species ripening its seeds in the spring or early 

 summer; attaining its largest size in the damp semitropical lowlands of Florida, 

 Louisiana, and Texas, and the only Birch-tree of such warm regions. 



Often cultivated in the northeastern states as an ornamental tree, and growing 

 rapidly in cultivation, 



**Strohiles cylindrical, pendant or spreading. * 



-i-Scales of the strobiles pubescent, with recurved lateral lobes, the middle lobe 

 nearly as broad as long leaves long-pointed, their petioles slender, elongated. 



4. Betula populifolia, Marsh. Gray Birch. "White Birch. 



Leaves nearly triangular to rhomboidal, long-pointed, coarsely doubly serrate, 

 with stout spreading glandular teeth except at the broad truncate or slightly cordate 

 or wedge-shaped base, thin and firm, dark green and lustrous and somewhat rough- 

 ened on the upper surface early in the season by small pale glands in the axils of 

 the conspicuous reticulate veinlets, 21'-3' long, l^'-2^' wide, with stout yellow 

 midribs covered with minute glands, and raised and rounded on the upper side, and 

 obscure yellow primary veins, turning pale yellow in the autumn; their petioles 

 slender, terete, covered with black glands, often stained with red on the upper side, 

 I'-l' long; stipules broadly ovate, acute, membranaceous, light green slightly tinged 

 with red. Flcwers : staminate aments usually solitary or rarely in pairs, l^'-l^' 



long, about i' thick during the winter, becoming 2^'-4' long, with ovate acute 

 apiculate scales; pistillate aments on glandular peduncles about ^ long, slender, 

 about ^' long, with ovate acute pale green glandular scales, Fruit: strobiles cylin- 

 drical, pubescent, obtuse at the apex, about f long and ^' thick, pendant or spreading 

 on slender stems; nut oval or obovate, acute or rounded at the base, a little narrower i 

 than its obovate wing. 



A short-lived tree, 20'-30' or exceptionally 40 high, with a trunk rarely 18' in 

 diameter, short slender often pendulous more or less contorted branches usually 



