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. [Illustration: Fig. 210] 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.