Leaves ovate, acute, full and rounded and often unsymmetrical and somewhat oblique or abruptly narrowed and cuneate at base, divided into numerous short acute lateral lobes, sharply and doubly serrate with straight glandular teeth, glandular-viscid as they unfold, at maturity membranaceous, yellow-green on the upper surface, pale and very lustrous on the lower surface, glabrous, or villose along the under side of the stout midrib with short brown hairs also forming tufts in the axils of the numerous slender primary veins, 3′—6′ long, 1½′—4′ wide; petioles stout, grooved, abruptly enlarged at the base, ½′—¾′ in length; stipules oblong to spatulate, rounded and apiculate at apex, puberulous, about ¼′ long. Flowers: staminate aments sessile, in pairs in the axils of the upper leaves sometimes reduced to small bracts, and single in the axil of the leaf next below, during the winter about ½′ long and ⅛′ thick, with dark red-brown shining puberulous apiculate scales, becoming when the flowers open from spring to midsummer 4′ or 5′ long, with a puberulous light red rachis and ovate acute apiculate 3-flowered scales; calyx-lobes rounded, shorter than the 4 stamens; pistillate aments in elongated panicles, inclosed during winter in buds formed the previous summer in the axils of the leaves of short lateral branchlets, long-pedunculate, ⅓′ long, ⅙′ thick. Fruit: strobiles on slender peduncles in elongated sometimes leafy panicles 4′—6′ in length, oblong, ½′—⅝′ long, about ⅓′ thick, their truncate scales thickened at the apex; nut oval, about as wide as its wings.
A tree, sometimes 40° high, with a trunk 7′—8′ in diameter, short small nearly horizontal branches forming a narrow crown, and slender slightly zigzag branchlets puberulous and very glandular when they first appear, bright orange-brown and lustrous and marked by numerous large pale lenticels during their first season, much roughened during their second year by the elevated crowded leaf-scars, becoming light gray. Winter-buds acuminate, dark purple, covered especially toward the apex with close fine pubescence, about ½′ long. Bark thin bluish gray, with bright red inner bark; often a shrub only a few feet tall spreading into broad thickets.
Distribution. Northwest coast from the borders of the Arctic Circle to the high mountains of northern California; common in the valley of the Yukon and eastward through British Columbia to Alberta, and through Washington and Oregon to the western slopes of the Rocky Mountains in Montana; at the north with dwarf Willows, forming great thickets; in southeastern Alaska often a tall tree on rich moist bottom-lands near the mouths of mountain streams, and at the upper limits of tree growth a low shrub; very abundant in the valley of the Yukon on the wet banks of streams and often arborescent in habit; in British Columbia and the United States generally smaller and a shrub, growing usually only at altitudes of more than 3000° above the sea, and often forming thickets on the banks of streams and lakes.
2. [Alnus rubra] Bong. Alder.
Alnus oregona Nutt.
Leaves ovate to elliptic, acute, abruptly or gradually narrowed and cuneate at base, crenately lobed, dentate with minute gland-tipped teeth, and slightly revolute on the margins, covered when they unfold with pale tomentum, at maturity thick dark green and glabrous or pilose with scattered white hairs above, clothed below with short rusty pubescence, 3′—5′ long, 1¾′—3′ wide, or on vigorous branchlets sometimes 8′—10′ long, with a broad midrib and primary veins green on the upper side and orange-colored on the lower, the primary veins running obliquely to the points of the lobes and connected by conspicuous slightly reticulate cross veinlets; petioles orange-colored, nearly terete, slightly grooved, ¼′—¾′ in length; stipules ovate, acute, pale green flushed with red, tomentose, ⅛′—¼′ long. Flowers: staminate aments in red-stemmed clusters, during the winter 1¼′ long, ⅛′ thick, with dark red-brown lustrous closely appressed scales, becoming 4′—6′ long and ¼′ thick, with ovate acute orange-colored glabrous scales; calyx yellow, with ovate rounded lobes rather shorter than the 4 stamens; pistillate aments in short racemes usually inclosed during the winter in buds formed during the early summer and opening in the early spring, ⅓′—½′ long, about 1/16′ thick, with dark red acute scales; styles bright red. Fruit: strobiles raised on stout orange-colored peduncles sometimes ½′ in length, ovoid or oblong, ½′—1′ long, ⅓′—½′ thick, with truncate scales much thickened toward the apex; nut orbicular to obovoid, surrounded by a membranaceous wing.
A tree, usually 40°—50°, occasionally 90° high, with a trunk sometimes 3° in diameter, slender somewhat pendulous branches forming a narrow pyramidal head, and slender branchlets marked by minute scattered pale lenticels, light green and coated at first with hoary tomentum sometimes persistent until their second year, becoming during the first winter bright red and lustrous and ultimately ashy gray. Winter-buds about ⅓′ long, dark red, covered with pale scurfy pubescence. Bark rarely more than ¾′ thick, close, roughened by minute wart-like excrescences, pale gray or nearly white, with a thin outer layer, and bright red-brown inner bark. Wood light, soft, brittle, not strong, close-grained, light brown tinged with red, with thick nearly white sapwood; in Washington and Oregon largely used in the manufacture of furniture and for smoking salmon; by the Indians of Alaska the trunks are hollowed into canoes.
Distribution. Shores of Yakutat Bay, southeastern Alaska, southward near the coast to the cañons of the Santa Inez Mountains, Santa Barbara County, California; common along the banks of streams, and of its largest size near the shores of Puget Sound; in California most abundant in Mendocino, Humboldt and Marin Counties, forming groves on bottom-lands near the coast; often ranging inland for 20 or 30 miles, and occasionally ascending to altitudes of 2000° above the sea.