A tree, occasionally 50°—60° high, with a short trunk 2° in diameter, usually not more than 20°—30° tall, with a trunk 18′—20′ thick, long slender branches drooping at the ends and forming a round-topped or open head frequently 50° across, and slender, very tough branchlets, light green, coated with pale appressed hairs when they first appear, becoming light orange color and very lustrous by midsummer, glabrous, dark red-brown and lustrous during their first winter, and then growing gradually darker brown and losing their lustre; or covered like the petioles and peduncles with short erect glandular hairs (var. glandulosa Sarg.). Winter-buds ovoid, light chestnut-brown, slightly puberulous, ¼′ long. Bark about ¼′ thick, broken into thick narrow oblong closely appressed plate-like light brown scales slightly tinged with red on the surface. Wood strong, hard, tough, durable, light brown tinged with red or often nearly white, with thick pale sapwood of 40—50 layers of annual growth; used for fence-posts, handles of tools, mallets, and other small articles.
Distribution. Dry gravelly slopes and ridges often in the shade of oaks and other large trees; Island of Cape Breton and the shores of the Bay of Chaleur, through the valley of the St. Lawrence River, and along the northern shores of Lake Huron to western Ontario, Manitoba, Minnesota, eastern North Dakota, the foothills of the Black Hills of South Dakota, eastern, northern and northwestern Nebraska, eastern Kansas and Oklahoma, and southward to northern Florida and eastern Texas; most abundant and of its largest size in southern Arkansas and in Texas. From Quebec and Ontario to western New England, western New York, Ohio and in Central Michigan, the glandular form prevails: the two forms occur in New Jersey, Pennsylvania, Indiana, northern Illinois, southwestern Missouri, Oklahoma, and southward on the high Appalachian Mountains.
2. [Ostrya Knowltonii] Cov. Ironwood.
Leaves elliptic to obovate, acute or round at apex, gradually narrowed and often unequal at the rounded cuneate rarely cordate base, sharply serrate with small triangular callous teeth, covered with loose pale tomentum when they unfold, at maturity dark yellow-green and pilose above, pale and soft-pubescent below, 1′—2′ long, 1′—1½′ wide, with a slender yellow midrib slightly raised on the upper side, and slender primary veins connected by obscure reticulate veinlets; turning dull yellow in the autumn before falling; petioles ⅛′—¼′ long; stipules pale yellow-green, often tinged with red toward the apex, ½′ long, about ½′ wide. Flowers: staminate aments on stout stalks covered with rufous tomentum and sometimes ½′ long, rarely sessile, about ½′ long during their first season, with dark brown puberulous scales gradually contracted into a long slender subulate point, becoming when the flowers open 1′—1¼′ long, with broadly ovate concave scales abruptly narrowed into a nearly triangular point, yellow-green near the base, bright red above the middle; pistillate aments about ¼′ long, with ovate-lanceolate light yellow-green puberulous scales ciliate on the margins. Fruit: nuts ¼′ long, gradually narrowed at the apex, their involucres 1′ long, nearly glabrous at the apex, sometimes slightly stained with red toward the base, in clusters 1′—1½′ long and about ¾′ broad, on stems ½′ in length.
A tree 20°—30° high, with a trunk 12′—18′ in diameter, usually divided 1° or 2° above the ground into 3 or 4 stout upright stems 4′—5′ thick, slender pendulous often much contorted branches forming a narrow round-topped symmetrical head, and slender branchlets dark green and coated with hoary tomentum when they first appear, dark red-brown and pubescent during their first summer, becoming light cinnamon-brown, glabrous, and lustrous in the winter, and ultimately ashy gray. Winter-buds ovoid, dark brownish red, about ⅛′ long. Bark internally bright orange color, ⅛′ thick, separating into loose hanging plate-like scales light gray slightly tinged with red, and 1′—2′ long and wide. Wood light reddish brown, with thin sapwood.
Distribution. On the southern slope of the cañon of the Colorado River in Coconino County, Arizona, at altitudes of 6000°—7000° above the sea (Hance trail, seventy miles north of Flagstaff); in the cañon of Oak Creek, south of Flagstaff (P. Lowell); and on Grand River, Utah (Moab, Grant County, M. E. Jones).
3. BETULA L. Birch.
Trees, with smooth resinous bark marked by long longitudinal lenticels, often separating freely into thin papery plates, becoming thick, deeply furrowed, and scaly at the base of old trunks, short slender branches more or less erect and forming on young trees a narrow symmetrical pyramidal head, becoming horizontal and often pendulous on older trees, tough branchlets, short stout spur-like 2-leaved lateral branchlets much roughened by the crowded leaf-scars of many years, and elongated winter-buds covered by numerous ovate acute scales, and fully grown and bright green at midsummer. Leaves open and convex in the bud, often incisely lobed; stipules ovate and acute or oblong-obovate, scarious. Flowers in 3-flowered cymes, the lateral flowers of the cyme subtended by bractlets adnate to the base of the scale of the ament; staminate aments long, pendulous, solitary or clustered, appearing in summer or autumn in the axils of the last leaves of a branchlet or near the ends of short lateral branchlets, erect and naked during the winter, their scales in the spring broadly ovate, rounded, short-stalked, yellow or orange-color below the middle and dark chestnut-brown and lustrous above it; staminate flowers composed of a membranaceous 4-lobed calyx often 2-lobed by suppression, the anterior lobe obovate, rounded at apex, as long as the stamens, much longer than the minute posterior lobe, and of 2 stamens inserted on the base of the calyx, with short 2-branched filaments, each branch bearing an erect half-anther; pistillate aments oblong or cylindric, terminal on the short spur-like lateral branchlets, their scales closely imbricated, oblong-ovate, 3-lobed, light yellow, often tinged with red above the middle, accrescent, becoming brown and woody at maturity, and forming sessile or stalked erect or pendulous short or elongated strobiles usually ripening in the autumn, deciduous with the nuts from the slender rachis; calyx of the pistillate flower 0; ovary sessile, compressed, with styles stigmatic at apex. Nut minute, oval or obovoid, compressed, bearing at the apex the persistent stigmas, marked at the base by a small pale scar, the outer coat of the shell produced into a marginal wing interrupted at the apex.
Betula is widely distributed from the Arctic circle to Texas in the New World, and to southern Europe, the Himalayas, China, and Japan in the Old World, some species forming great forests at the north, or covering high mountain slopes. Of the twenty-eight or thirty species now recognized twelve are found in North America; of these nine are trees. Of exotic species the European and Asiatic Betula pendula Roth. in a number of forms is a common ornamental tree in the northern states, where several of the Birch-trees of eastern Asia also flourish. Many of the species produce wood valued by the cabinet-maker, or used in the manufacture of spools, shoe-lasts, and other small articles. The thin layers of the bark are impervious to water and are used to cover buildings, and for shoes, canoes, and boxes. The sweet sap provides an agreeable beverage.