Part 30

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.

_Betula_ is the classical name of the Birch-tree.

CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT SPECIES.

Strobiles oblong-ovoid, nearly sessile, erect, the lateral lobes of their scales broad and slightly divergent; wing not broader than the nut; leaves with 9—11 pairs of veins; bark of young branches aromatic. Leaves heart-shaped or rounded at base; scales of the strobiles glabrous; bark dark brown, not separating into thin layers. 1. B. lenta (A, C). Leaves cuneate or slightly heart-shaped at base; scales of the strobiles pubescent; bark yellow, or silvery white, rarely dull yellowish brown; separating into thin layers. 2. B. lutea (A). Strobiles oblong or cylindric, erect, spreading or pendant, on slender peduncles; wing broader than the nut; leaves with 5—9 pairs of veins. Strobiles oblong, erect, ripening in May or June, their scales pubescent, deeply lobed, the lateral lobes erect; leaves rhombic-ovate, glaucescent and more or less silky-pubescent beneath; bark light reddish-brown, separating freely into thin persistent scales. 3. B. nigra (A, C). Strobiles cylindric, pendant or spreading. Scales of the strobiles pubescent, with recurved lateral lobes, the middle lobe triangular, nearly as broad as long; leaves long-pointed; petioles slender, elongated. Leaves triangular to rhombic, bright green and lustrous; bark chalky white, not separable into thin layers. 4. B. populifolia (A). Leaves ovate, cuneate to truncate or rounded at base, dull blue-green; bark white tinged with pink, lustrous, not easily separable into thin layers. 5. B. cœrulea (A). Scales of the strobiles with ascending or spreading lateral lobes, the middle lobe usually acuminate, longer than broad; leaves acute or acuminate. Bark separating freely into thin layers; scales of the strobiles glabrous. Bark creamy white, or in some forms orange-brown; leaves ovate. 6. B. papyrifera (A, B, C, F). Bark dull reddish brown or nearly white; leaves rhombic to deltoid-ovate. 7. B. alaskana (A, B). Bark not separable into thin layers, dark brown; scales of the strobiles glabrous or puberulous; branchlets glandular. Leaves ovate, acute or acuminate, truncate or rounded at the broad base. 8. B. fontinalis (B, F, G). Leaves broad-ovate to elliptic, acute, rounded or abruptly short-pointed, cuneate at base. 9. B. Eastwoodæ (F).

1. Betula lenta L. Cherry Birch. Black Birch.

Leaves ovate to oblong-ovate, acute or acuminate, gradually narrowed and often unequal at the cordate or rounded base, sharply serrate with slender incurved teeth, or very rarely laciniately lobed (f. _laciniata_ Rehdr.), when they unfold light green, coated on the lower surface with long white silky hairs, and slightly hairy on the upper surface, at maturity thin and membranaceous, dark dull green above, light yellow-green below, with small tufts of white hairs in the axils of the veins, 2½′—6′ long, 1½′—3′ wide, with a yellow midrib and primary veins prominent and hairy on the lower surface, and obscure reticulate cross veinlets; turning bright clear yellow late in the autumn; petioles stout, hairy, deeply grooved on the upper side, ¾′—1′ long; stipules ovate, acute, light green or nearly white, scarious and ciliate above the middle. Flowers: staminate aments during the winter about ¾′ long, nearly ¼′ thick, with ovate acute apiculate scales bright red-brown above the middle and light brown below it, becoming 3′—4′ long; pistillate aments ½′—¾′ long, about ⅛′ thick, with ovate pale green scales rounded at the apex; styles light pink. Fruit: strobiles oblong-ovoid, sessile, erect, glabrous, 1′—1½′ long, about ½′ thick; nut obovoid, pointed at base, rounded at apex, about as broad as its wing.

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 ¼′ long, with ovate acute light chestnut-brown loosely imbricated scales, those of the inner ranks becoming ½′—¾′ 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 ½′—¾′ thick, dull, deeply furrowed and broken into large thick irregular plates 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 boat-building. 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 altitudes of 4000° to northern Georgia; in Alabama, and in eastern Kentucky and Tennessee; a common forest tree at the north, and of its largest size on the western slopes of the southern Alleghany Mountains.

× _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, 3′—4½′ long, 1½′—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, ¾′—1′ long; stipules ovate, acute, light green tinged with pink above the middle, about ½′ long. Flowers: staminate aments during the winter ¾′—1′ long, about ⅛′ thick, with ovate rounded scales light chestnut-brown and lustrous above the middle, ciliate on the margins, becoming 3′—3½′ long and ⅓′ thick; pistillate aments about ⅔′ long, with acute scales, pale green below, light red and tipped with clusters of long white hair at apex, and pilose on the back. Fruit: strobiles erect, sessile, short-stalked, pubescent, 1′—1½′ long, about ¾′ thick; nut ellipsoidal to obovoid, about ⅛′ long, rather broader than its wing.

A tree, with slightly aromatic bark and leaves, occasionally 100° high, with a trunk 3°—4° in diameter, spreading and more or less pendulous branches forming a broad round-topped head, and branchlets at first green and covered with long pale hairs, light orange-brown and pilose during their first summer, becoming glabrous and light brown slightly tinged with orange, and ultimately dull and darker. Winter-buds about ¼′ long, somewhat viscid and covered with loose pale hairs during the summer, becoming light chestnut-brown, acute, and slightly puberulous in winter. Bark of young stems and of the branches bright silvery gray or light orange color, very lustrous, separating into thin loose persistent scales more or less rolled on the margins, becoming on old trees ½′ thick, reddish brown, and divided by narrow irregular fissures into large thin plates covered with minute closely appressed scales, or sometimes dull yellowish brown (_B. alleghaniensis_ Britt.). Wood heavy, very strong, hard, close-grained, light brown tinged with red, with thin nearly white sapwood; largely used for floors, in the manufacture of furniture, button and tassel moulds, boxes, the hubs of wheels, and for fuel.

Distribution. Moist uplands, and southward often in swamps; one of the largest deciduous-leaved trees of northeastern America; Newfoundland and along the northern shores of the Gulf of St. Lawrence to the valley of Rainy River, and southward to Long Island (Cold Spring Harbor) and western New York, Pennsylvania, northern Delaware, southeastern Ohio, northern Indiana, southwestern Wisconsin, northern, northeastern and central Iowa, and from the mountains of Virginia and West Virginia to the highest peaks of North Carolina and Tennessee at altitudes between 3000° and 5000°; very abundant and of its largest size in the eastern provinces of Canada and in northern New York and New England; small and rare in southern New England and southward.

× _Betula Purpusii_ Schn. believed to be a natural hybrid of _B. lutea_ with _B. pumila_ var. _glandulifera_ Regel has been found in Michigan and in Tamarack Swamps in Hennepin, Pine and Anoka Counties, Minnesota.

3. Betula nigra L. Red Birch. River Birch.

Leaves rhombic-ovate, acute, abruptly or gradually narrowed and cuneate at base, doubly serrate, and on vigorous young branches often more or less laciniately cut into acute doubly serrate lobes, when they unfold light yellow-green and pilose above and coated below, especially on the midrib and petioles, with thick white tomentum, at maturity thin and tough, 1½′—3′ long, 1′—2′ wide, deep green and lustrous above, glabrescent, pubescent or ultimately glabrous below, except on the stout midrib and remote primary veins; turning dull yellow in the autumn; petioles slender, slightly flattened, tomentose, about ½′ long; stipules ovate, rounded or acute at apex, pale green, covered below with white hairs. Flowers: staminate aments clustered, during the winter about ⅞ long and 1/16′ thick, with ovate rounded dull chestnut-brown lustrous scales, becoming 2′—3′ long and ⅛′ thick; pistillate aments about ⅓′ long, with bright green ovate scales pubescent on the back, rounded or acute at apex, and ciliate with long white hairs. Fruit ripening in May and June; strobiles cylindric, pubescent, 1′—1½′ long, ½′ thick, erect on stout tomentose peduncles ½′ long; nut ovoid to ellipsoidal, ⅛′ in length, pubescent or puberulous at apex, about as broad as its thin puberulous wing, ciliate on the margin.

A tree, 80°—90° high, with a trunk often divided 15°—20° above the ground into 2 or 3 slightly diverging limbs, and sometimes 5° in diameter, slender branches forming in old age a narrow irregular picturesque crown, and branchlets coated at first with thick pale or slightly rufous tomentum gradually disappearing before winter, becoming dark red and lustrous, dull red-brown in their second year, and then gradually growing slightly darker until the bark separates into the thin flakes of the older branches; or often sending up from the ground a clump of several small spreading stems forming a low bushy tree. Winter-buds ovoid, acute, about ¼′ long, covered in summer with thick pale tomentum, glabrous or slightly puberulous, lustrous and bright chestnut-brown in winter, the inner scales strap-shaped, light brown tinged with red, and coated with pale hairs. Bark on young stems and large branches thin, lustrous, light reddish brown or silvery gray, marked by narrow slightly darker longitudinal lenticels, separating freely into large thin papery scales persistent for several years, and turning back and showing the light pink-brown tints of the freshly exposed inner layers, becoming at the base of old trunks from ¾′—1′ thick, dark red-brown, deeply furrowed and broken on the surface into thick closely appressed scales. Wood light, rather hard, strong, close-grained, light brown, with pale sapwood of 40—50 layers of annual growth; used in the manufacture of furniture, wooden ware, wooden shoes, and in turnery.

Distribution. Banks of streams, ponds, and swamps, in deep rich soil often inundated for several weeks at a time; near Manchester, Hillsboro County, New Hampshire, northeastern Massachusetts, Long Island, New York, southward to northern Florida through the region east of the Alleghany Mountains except in the immediate neighborhood of the 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, 2½′—3′ long, 1½′—2½′ 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, ¾′—1′ long; stipules broadly ovate, acute, membranaceous, light green slightly tinged with red. Flowers: staminate aments usually solitary or rarely in pairs, 1¼′—1½′ long, about ⅛′ thick during the winter, becoming 2½′—4′ long, with ovate acute apiculate scales; pistillate aments slender, as long as their glandular peduncles about ½′ in length, with ovate acute pale green glandular scales. Fruit: strobiles cylindric, pubescent, obtuse at apex, about ¾′ long and ⅓′ thick, pendant or spreading on slender stems; nut ellipsoidal 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 the trunk; often growing in clusters of spreading stems springing from the stumps of old trees. Winter-buds ovoid, acute, pale chestnut-brown, glabrous, about ¼′ long. Bark about ⅓′ thick, dull chalky white on the outer surface, bright orange on the inner, close and firm, with dark triangular markings at the insertion of the branches, becoming at the base of old trees thicker, nearly black, and irregularly broken by shallow fissures. Wood light, soft, not strong, close-grained, not durable, light brown, with thick nearly white sapwood; used in the manufacture of spools, shoe-pegs and wood pulp, for the hoops of barrels, and largely for fuel.

Distribution. Dry gravelly barren soil or on the margins of swamps and ponds; Prince Edward Island, Nova Scotia, New Brunswick, and the valley of the lower St. Lawrence River southward to northeastern, central and on South Mountain, Franklin County, Pennsylvania, and northern Delaware, and westward through northern New England and New York, ascending sometimes to altitudes of 1800°, to the southern shores of Lake Ontario, and at the foot of Lake Michigan, Indiana; rare and local in the interior, very abundant in the coast region of New England and the middle states; springing up in great numbers on abandoned farm-lands or on lands stripped by fire of their original forest covering; most valuable in its ability to grow rapidly in sterile soil and to afford protection to the seedlings of more valuable and less rapid-growing trees.

A form with deeply divided leaves (var. _laciniata_ Loud.) and one with purple leaves (var. _purpurea_ E & B) are occasionally cultivated.

A shrub believed to be a natural hybrid of _B. populifolia_ with _B. pumila_ Michx. has been found near Mt. Mansfield, Vermont.

5. Betula cœrulea Blanch. Blue Birch.

Leaves ovate, long-pointed, broadly or narrowly concave-cuneate at the entire often unequal base, sharply mostly doubly serrate above with straight or incurved glandular often apiculate teeth, covered above when they unfold with pale deciduous glands, at maturity dull bluish green above, pale yellow-green below, and sparingly villose along the under side of the slender yellow midrib and primary veins, 2′—2½′ long, 1′—1½′ wide; petioles slender, ¾′—1¼′ long, yellow more or less deeply tinged with red. Flowers: staminate aments usually in pairs, or singly or in 3’s, 1¼′—2′ long, about 3/16′ thick, with ovate rounded short-pointed scales; pistillate aments slender, about ⅓′ long, with acuminate pale green much reflexed scales. Fruit: strobiles cylindric, pubescent, slightly narrowed at the obtuse apex, about 1′ long and ¼′ thick, pendant on slender peduncles ¼′—½′ in length; nut ellipsoidal, much narrower than its broad wing.

A tree, rarely more than 30° high, with a trunk 8′—10′ in diameter, small ascending finally spreading branches, and slender branchlets marked by numerous small raised pale lenticels, purplish and sparingly villose when they first appear, soon glabrous, becoming bright red-brown; often forming clumps of several stems. Bark thin, white tinged with rose, lustrous, not readily separable into layers, the inner bark light orange color.

Distribution. Moist slopes, Stratton and Windham, Windham County, Vermont, at altitudes of about 1800° (_W. H. Blanchard_), Haystack Mountain, Aroostook County, Maine (_M. L. Fernald_); the American representative of the European _Betula pendula_ Roth., and probably widely distributed over the hills of northern New England and eastern Canada. Perhaps with its variety best considered a natural hybrid between _B. papyrifera_ and _B. populifolia_.

Apparently passing into a form with larger leaves often rounded and truncate at the broad base, 3′—3½′ long and 2′ wide, stouter staminate aments, and strobiles frequently 1½′ long and ½′ thick (var. _Blanchardii_ Sarg. fig. 198 A). This under favorable conditions is a tree 60°—70° high, with a trunk 18′ in diameter; common with _Betula cœrulea_ at Windham and Stratton, Vermont (_W. H. Blanchard_), and on a hill near the coast in Washington County, Maine (_M. L. Fernald_).

6. Betula papyrifera Marsh. Canoe Birch. Paper Birch.