Acer glabrum is a deciduous, tall, multi-stemmed shrub or small tree to 6 m. It has a wide, spreading root system with deep lateral roots. Plants begin producing seed before 10 years of age. The winged samaras contain large seeds dispersed by wind and animals. Large seed crops occur every 1 to 3 years, and seeds remain viable for a short time. Seedlings establish in partial shade on mineral soil. Plants readily sprout and grow vigorously from the root crown when disturbed. The species is a common understory plant and conspicuous in areas with recurring disturbances such as avalanche chutes (Anderson 2001a, Nesom 2000).

Acer glabrum grows throughout the mountains of the western cordillera. The typical variety, var. glabrum, occurs in the Rocky Mountains where the NVCS (NatureServe 2007a) recognizes an alliance. The alliance occurs in mesic, rocky settings, along streambanks, and moist seepage areas at mid- to high elevations where snowpack conditions are unstable or in drainage bottoms. Stands develop rapidly following disturbances from fire and avalanche in the Rocky Mountains (Nesom 2000, NatureServe 2007a). Further refinement of the alliance name is preferred with other diagnostic species, since the current alliance name in the NVC includes Abies lasiocarpa, yet most stands including all California stands do not.

California has three varieties of Acer glabrum var. torreyi is most common and occurs in the Klamath Mountains (M261A), Southern Cascades (M261D), and Sierra Nevada (M261). We know of local stands in avalanches chutes in the Trinity Alps, in the Marble Mountains, in the Siskiyou Mountains (Kagan et al. 2000), and in similar settings along the eastern escarpment of the Sierra Nevada between Yosemite National Park and Lone Pine in Inyo Co. Stands of var. diffusum appear to occur in the Inyo, Panamint, and White mountains, and stands of var. greenei may occur in the southern Sierra Nevada.