210 



TREES OF NORTH AMERICA 



coast, through the Gulf states to the valley of the Navasota River, Brazos County, Texas, 

 and through Arkansas, eastern Oklahoma, southeastern Kansas, and Missouri to Tennessee 

 and Kentucky, southern and eastern Iowa, southern Minnesota, the valley of the Eau 

 Claire River, Eau Claire County, Wisconsin, southern Illinois, the valley of the Kankakee 

 River, Indiana, and southern 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; the only Birch-tree of such warm 

 regions. 



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

 cultivation. 



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



Leaves nearly triangular to rhombic, long-pointed, coarsely doubly serrate with stout 

 spreading glandular teeth except at the broad truncate or slightly cordate or cuneate base, 

 thin and firm, dark green and lustrous and somewhat roughened on the upper surface early 

 in the season by small pale glands in the axils of the conspicuous reticulate veinlets, 2|'-3' 

 long, 1|'-2|' wide, with a stout yellow midrib covered with minute glands, and raised and 

 rounded on the upper side, and obscure yellow primary veins; turning pale yellow in the 

 autumn; petioles slender, terete, covered with black glands, often stained with red on the 

 upper side*, f'-l' long; stipules broadly ovate, acute, membranaceous, light green slightly 

 tinged with red. Flowers: staminate aments usually solitary or rarely in pairs, 1^'-1' 

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

 scales; pistillate aments slender, as long as their glandular peduncles about \' in length, 



Fig. 197 



with ovate acute pale green glandular scales. Fruit: strobiles cylindric, pubescent, ob- 

 tuse at apex, about f long and thick, pendant or spreading on slender stems; nut ellip- 

 soidal to obovoid, acute or rounded at base, a little narrower 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 clothing the stem to 

 the ground and forming a narrow pyramidal head, and branchlets roughened by small 

 raised lenticels, resinous-glandular when they first appear, gradually growing darker, bright 

 yellow and lustrous before autumn like the young stems, bright reddish brown during their 

 first winter, and ultimately white near thee trunk; often growing in clusters of spreading 

 stems springing from the stumps of old trees. Winter-buds ovoid, acute, pale chestnut- 

 brown, glabrous, about \' long. Bark about \' thick, dull chalky white on the outer sur- 

 face, bright orange on the inner, close and firm, with dark triangular markings at the 



