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. [Illustration: Fig. 203] 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. [Illustration: Fig. 204]