August 3, 1805, along the Jefferson River, Montana.
Shrub or small tree with rounded crown of spreading and drooping branches, usually forming clumps and often in thickets. Flowers tiny, yellowish or greenish. Height: 25 ft (7.6 m). Diameter: 6-12 in (15-30 cm).
Moist soil along streams in mountain canyons, usually in coniferous forests and with cottonwoods and willows.
Northeastern British Columbia, east to southern Manitoba, and south to northern New Mexico and California; at 2,000-8,000 ft (610-2,438 m).
This uncommon but widespread species is the only native birch in the Southwest and the southern Rocky Mountains. Sheep and goats browse the foliage.