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.
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.
Leaves ovate, acute or acuminate with a short broad point, coarsely usually doubly and often very irregularly serrate except at the rounded abruptly cuneate or gradually narrowed base, bright green, glandular-resinous, pubescent and clothed below on the midrib and primary veins and on the petioles with long white hairs when they unfold, at maturity thick and firm, dull dark green and glandless or rarely glandular on the upper surface, light yellow-green and glabrous or puberulous, with small tufts of pale hairs in the axils of the primary veins and covered with many black glands on the lower surface, 2′—3′ long, 1½′—2′ wide, with a slender yellow midrib marked, like the remote primary veins, with minute black glands, turning light clear yellow in the autumn; petioles stout, yellow, glandular, glabrous or pubescent, ½′—¾′ long; stipules ovate, acute, ciliate on the margins with pale hairs, light green. Flowers: staminate aments clustered during the winter, ¾′—1¼′ long, about ⅛′ thick, with ovate, acute scales light brown below the middle, dark red-brown above it, becoming 3½′—4′ long, and about ⅓′ thick; pistillate aments 1′—1¼′ long, about 1/16′ thick, with light green lanceolate scales long-pointed and acute or rounded at apex; styles bright red. Fruit: strobiles cylindric, glabrous, about 1½′ long and ⅓′ thick, hanging on slender stalks, their scales very rarely entire (var. elobata Sarg.); nut ellipsoidal, about 1/16′ long, much narrower than its thin wing.
A tree, usually 60°—70° tall, with a trunk 2°—3° in diameter, becoming in old age, or when crowded by other trees, branchless below and supporting a narrow open head of short pendulous branches, and branchlets at first light green, slightly viscid, marked by scattered orange-colored oblong lenticels and covered with long pale hairs, dark orange color and glabrous or pubescent during the summer, becoming dull red in their first winter, gradually growing dark orange-brown, lustrous for four or five years and ultimately covered with the white papery bark of older branches. Winter-buds obovoid, acute, about ¼′ long, pubescent below the middle and coated with resinous gum at midsummer, dark chestnut-brown, glabrous and slightly resinous during the winter, their inner scales becoming strap-shaped, rounded at apex, about ½′ long and ⅛′ wide. Bark on young trunks and large limbs thin, creamy white or rarely bronze color or orange-brown and lustrous on the outer surface, bright orange color on the inner, marked by long narrow slightly darker colored raised lenticels, separating into thin papery layers, pale orange color when first exposed to the light, becoming on old trunks for a few feet above the ground sometimes ½′ thick, dull brown or nearly black, sharply and irregularly furrowed and broken on the surface into thick closely appressed scales. Wood light, strong, hard, tough, very close-grained, light brown tinged with red, with thick nearly white sapwood; largely used for spools, shoe-lasts, pegs, and in turnery, the manufacture of wood-pulp, and for fuel. The tough resinous durable bark impervious to water is used by all the northern Indians to cover their canoes and for baskets, bags, drinking-cups, and other small articles, and often to cover their wigwams in winter.
Distribution. Rich wooded slopes and the borders of streams, lakes, and swamps scattered through forests of other trees; Labrador to the southern shores of Hudson’s Bay, and southward to Long Island, New York, northern Pennsylvania, central Michigan, northern Wisconsin, northern-central Iowa, eastern Nebraska, North and South Dakota and Wyoming; common in the maritime provinces of Canada and North of the Great Lakes, and in northern New England and New York; small and comparatively rare in the coast region of southern New England and southward; on the highest mountains of New England and northward the var. minor S. Wats and Cov. is common as a small shrub.
Often planted in the northeastern states as an ornamental tree.
× Betula Sandbergii Britt. and its f. maxima Rosend. generally believed to be natural hybrids of B. papyrifera and B. pumila var. glandulifera Regl. occur in Tamarack swamps in Hennepin County, Minnesota.
Passing into the following varieties.
Betula papyrifera var. cordifolia Fern.
Leaves ovate, abruptly pointed and acuminate or acute at apex, cordate at base, coarsely doubly serrate, glabrous or pilose on the under side of the midrib and veins, often furnished below with axillary tufts of pale hairs, 1½′—3′ long, 1′—2½′ wide; petioles glabrous or rarely villose, ½′—¾′ in length. Fruit: strobiles ¾′—2′ long and ¼′—½′ thick, on villose peduncles up to ¾′ in length; scales glabrous or pubescent.
A tree rarely more than 30° tall, with slender glabrous or pubescent branchlets, and at high altitudes on the New England mountains reduced to a low shrub. Bark separating in thin layers, white or dark reddish brown.
Distribution. Labrador and Newfoundland to northern New England, and westward to the shores of Green Bay, Wisconsin, and those of Lake Superior, Minnesota (Grand Marais, Cook County); on Mt. Mitchell, North Carolina, at an altitude of 5550° (W. W. Ashe).
Betula papyrifera var. subcordata Sarg.
Betula subcordata Rydb.
Leaves ovate, acute or acuminate at apex, slightly cordate or rounded at base, rarely slightly lobed above the middle, finely often doubly serrate with teeth pointing forward or spreading, glabrous, 2′—2½′ long, 1′—1½′ wide; petioles sparingly villose or glabrous, ½′—¾′ in length. Fruit: strobiles drooping on slender peduncles 1′—1½′ long, about ⅓′ thick, their scales puberulous, ciliate on the margins, the middle lobe acute, rather longer than the broad truncate lateral lobes; nut obovoid, cuneate at base, 1/12′ long, narrower than its wings.
A tree 25°—40° or occasionally 60° high, with a trunk 12′—18′ in diameter, and slightly glandular glabrous red-brown branchlets. Bark separating freely into thin layers, white or occasionally dark reddish brown or orange color.
Distribution. Alberta (Crow Nest Pass, neighborhood of Jasper and Cypress Hills), through northern Montana and Idaho to western Washington, northeastern Oregon (Minum River Valley) and British Columbia.
Betula papyrifera var. montanensis Sarg.
Betula montanensis Butler.
Leaves broadly ovate, acute at apex, truncate or rounded at base to oblong-ovate or lanceolate and long-pointed and acuminate at apex, narrowed and rounded at base, coarsely doubly serrate, thick, dark green above, paler, sparingly pubescent and furnished with conspicuous tufts of axillary hairs below, 3′—5′ long, 2′—2¼′ wide; petioles puberulous, ¾′—1′ in length. Flowers unknown. Fruit: strobiles cylindric, 1¾′—2′ long, ½′ thick, pendent on puberulous peduncles ½′—¾′ in length, their scales puberulous, finely ciliate on the margins, the slender base of those below the middle of the ament rather more than twice as long as the expanded upper portion of the scale.
A tree 40°—50° high, with a trunk 12′—18′ in diameter, and slender branchlets red-brown, lustrous, marked by small pale lenticels and puberulous during their first season. Winter-buds narrow-obovoid, acuminate, dark red-brown, resinous, ⅓′ long. Bark white, or dark gray or brown.
Distribution. Shore of Yellow Bay, Flathead Lake, Flathead County, Montana, and at Sandpoint, Bonner County, Idaho.
Betula papyrifera var. occidentalis Sarg.
Betula occidentalis Hook.
Leaves ovate, acute, or abruptly acuminate at apex, rounded or occasionally cordate or rarely cuneate at the broad base, coarsely and generally doubly serrate with straight or incurved glandular teeth, thin and firm in texture, dull dark green above, pale yellow-green below, and puberulous on both sides of the stout yellow midrib and slender primary veins, 3′—4′ long, 1½′—2′ wide; petioles stout, glandular, at first tomentose, ultimately pubescent or puberulous, about ¾′ long; stipules oblong-obovate, rounded and acute or apisculate at apex, ciliate on the margin, puberulous, glandular-viscid. Flowers: staminate aments during the winter about ¾′ long and ⅛′ thick, with ovate scales rounded or abruptly narrowed and acute at apex; puberulous on the outer surface, ciliate on the margins, becoming 3′—4′ long and about ¼′ thick; pistillate aments about 1′ long and 1/16′ thick, with acuminate bright green scales. Fruit: strobiles cylindric, puberulous, spreading, 1¼′—1½′ long, ¼′—½′ thick, on stout peduncles ¾′ in length, their scales ciliate on the margins; nut oval, about 1/16′ in length, and nearly as wide as its wings.
A tree, 100°—120° high, with a trunk 3°—4° in diameter, comparatively small branches often pendulous on old trees, and pale orange-brown branchlets more or less glandular and coated with long pale hairs when they first appear, becoming bright orange-brown and nearly destitute of glands during their first winter, and in their second year orange-brown, glabrous, and very lustrous. Winter-buds acute, bright orange-brown, ⅛′—¼′ long, their light brown inner scales sometimes becoming ¾′ in length. Bark thin, marked by long oblong horizontal raised lenticels, dark orange-brown or white, very lustrous, separating freely into thin papery layers displaying in falling the bright orange-yellow inner bark.
Distribution. Banks of streams and lakes; southwestern British Columbia and northwestern Washington and eastward through eastern Washington and northern Idaho to northern Montana west of the continental divide; nowhere common and probably of its largest size on the alluvial banks of the lower Fraser River, and on the islands of Puget Sound.
Betula papyrifera var. kenaica A. Henry. Red Birch. Black Birch.
Betula kenaica Evans.
Leaves ovate, acute or acuminate, broadly cuneate or somewhat rounded at the entire base, irregularly coarsely often doubly serrate, glabrous, dark dull green above, pale yellow-green below, 1½′—2′ long, 1′—1¾′ wide, with a slender yellow midrib and 5 pairs of thin primary veins; petioles slender, ¾′—1′ long. Flowers: staminate aments clustered, 1′ long, with ovate acute scales apiculate at apex, puberulous on the outer surface; pistillate aments, ⅓′—½′ long, about 1/16′ thick, on slender glandular pubescent peduncles ½′—¾′ in length; scales acuminate light green strongly reflexed; styles bright red. Fruit: strobiles cylindric, glabrous, 1′ long, their scales ciliate on the margins; nut oval, somewhat narrower than its thin wing.
A tree, 30°—40° high, with a trunk 12′—20′ in diameter, wide-spreading branches, stout branchlets marked by numerous small pale lenticels, bright red-brown during 2 or 3 years, gradually becoming darker. Bark thin, more or less furrowed, very dark brown or nearly black near the base of the trunk, grayish white or light reddish brown and separating into thin layers higher on the stem and on the branches.
Distribution. Coast of Alaska from Cook Inlet southward to the head of the Lynn Canal.
7. [Betula alaskana] Sarg. White Birch.
Leaves rhombic to deltoid-ovate, long-pointed, truncate, rounded or broadly cuneate, or on leading shoots occasionally cordate at the entire base, coarsely and often doubly glandular-serrate, thin, dark green above, pale and yellow-green below, 1½′—3′ long, 1′—1½′ wide, with a slender midrib and primary veins pubescent or ultimately glabrous below; petioles often bright red, somewhat hairy at first, finally glabrous, about 1′ long; Flowers: staminate aments clustered, sessile, 1′ long, ⅛′ thick, with ovate acuminate scales puberulous on the outer surface, and bright red, with yellow margins; pistillate aments slender, cylindric, glandular, 1′ long, ⅛′ thick, on stout peduncles nearly ½′ in length. Fruit: strobiles glabrous, pendulous or spreading, 1′—1¼′ long, ⅓′—½′ thick, their scales ciliate on the margins; nut oval, narrower than its broad wing.
A tree, usually 30°—40°, occasionally 80°, high, with a trunk 6′—12′ in diameter, slender erect and spreading or pendulous branches, and glabrous bright red-brown branchlets more or less thickly covered during their first year with resinous glands sometimes persistent until the second or third season. Winter-buds ovoid, obtuse at the gradually narrowed apex, about ¼′ long, with light red-brown shining outer scales sometimes ciliate on the margins, and oblong rounded scarious inner scales hardly more than ½′ long when fully grown. Bark thin, marked by numerous elongated dark slightly raised lenticels, dull reddish brown or sometimes nearly white on the outer surface, light red on the inner surface, close and firm, finally separable into thin plate-like scales.
Distribution. Valley of the Saskatchewan northwestward to the valley of the Yukon, growing sparingly near the banks of streams in forests of coniferous trees and in large numbers on sunny slopes and hillsides; the common Birch-tree of the Yukon basin.
× Betula commixta Sarg., a shrub, growing on the tundra near Dawson, Yukon Territory, is believed to be a hybrid between B. alaskana and B. glandulosa Michx.
8. [Betula fontinalis] Sarg. Black Birch.
Leaves ovate, acute or acuminate, sharply and often doubly serrate, except at the rounded or abruptly cuneate often unequal base, and sometimes slightly laciniately lobed, pale green, pilose above, and covered by conspicuous resinous glands when they unfold, at maturity thin and firm, dark dull green above, pale yellow-green, rather lustrous and covered by minute glandular dots below, 1′—2′ long, ¾′—1′ wide, with a slender pale midrib, remote glandular veins, and rather conspicuous reticulate veinlets; turning dull yellow in the autumn; petioles stout, puberulous, light yellow, glandular-dotted, flattened on the upper side, often flushed with red, ⅓′—½′ long; stipules broadly ovate, acute or rounded at apex, slightly ciliate, bright green, soon becoming pale and scarious. Flowers: staminate aments clustered, ½′—¾′ long and 1/16′ thick during the winter, with ovate acute light chestnut-brown scales pale and slightly ciliate on the margins, becoming 2′—2½′ long, and about ⅛′ thick, with apiculate scales; pistillate aments short-stalked, about ¾′ long, with ovate acute green scales; styles bright red. Fruit: strobiles cylindric, rather obtuse, puberulous or nearly glabrous, 1′—1¼′ long, ½′ thick, erect or pendulous on slender glandular peduncles, ¼′ to nearly ¾′ in length; their scales ciliate, puberulous, the lateral lobes ascending, shorter than the middle lobe; nut ovoid or obovoid, puberulous at apex, nearly as wide as its wing.
A tree 20°—25° high with a short trunk, rarely more than 12′ or 14′ in diameter, ascending spreading and somewhat pendulous branches forming a broad open head, and slender branchlets, when they first appear light green glabrous or puberulous and covered with lustrous resinous glands persistent during their second season, and dark red-brown in their first winter; more commonly shrubby, with many thin spreading stems forming open clusters, 15°—20° high; often much lower, and frequently crowded in almost impenetrable thickets. Winter-buds ovoid, acute, very resinous, chestnut-brown, ¼′ long. Bark about ¼′ thick, dark bronze color, very lustrous, marked by pale brown longitudinal lenticels becoming on old trunks often 6′—8′ long and ¼′ wide. Wood soft and strong, light brown, with thick lighter-colored sapwood; sometimes used for fuel and fencing.
Distribution. Moist soil near the banks of streams usually in mountain cañons; generally distributed, although nowhere very common: valley of the Saskatchewan (Saskatoon), Saskatchewan, westward to the basin of the upper Fraser and Pease Rivers, British Columbia, southward along the Rocky Mountains to eastern Utah, northern New Mexico and Arizona, the valleys of the Shasta region and the eastern slope of the Sierra Nevada, northern California, and eastward in the United States to the eastern foothills of the Rocky Mountains of Colorado, the Black Hills of South Dakota, and northwestern Nebraska. Passing into
Betula fontinalis var. Piperi Sarg.
Betula Piperi Britt.
A tree occasionally 50°—60° high with a tall trunk 12′—18′ in diameter, short spreading branches, and usually longer and often narrower strobiles.
Distribution. Spokane, Spokane County, Almota and Pullman, Whitman County, eastern Washington.
9. [Betula Eastwoodæ] Sarg.
Leaves broad-ovate to elliptic, acute, rounded or abruptly short-pointed at apex, coarsely serrate except at the cuneate base, thick, glabrous, dark green above, pale below, reticulate-venulose, the veinlets more conspicuous on the lower surface, 1′—1½′ long, ¾′—1½′ wide; petioles slender, glabrous ⅕′—⅓′ in length; stipules scarious, ovate-oblong, rounded at apex. Flowers: staminate aments usually solitary or in pairs, sessile, 1′—1¼′ long, ⅕′ thick, with broadly ovate pubescent dark red scales acute and apiculate at apex; pistillate aments ½′ long, about 1/12′ thick, with acute light green scales. Fruit: strobiles pendulous on peduncles ⅓′—½′ long, cylindric, ¾′ in length, about ⅙′ thick, their scales glabrous longer than broad, the lobes narrowed at the rounded apex, ciliate, the lateral slightly spreading, one third shorter than the terminal lobe.
A tree 18°—20° high, with a trunk rarely more than 6′ in diameter, and slender red glabrous branchlets thickly covered with circular white glands. Bark close, chestnut-brown, marked by conspicuous horizontal white lenticels, about ⅕′ thick.
Distribution. Swamps near Dawson, Yukon Territory, forming jungles with Betula glandulosa Michx., B. alaskana Sarg., and various Willows; as a large shrub in Jasper Park near Jasper, Alberta.