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.