Trembling Aspen

Trembling aspen (Populus tremuloides) is the most widespread deciduous tree in North America and a characteristic species of the montane zone in Banff National Park. Its golden fall colour defines “Larch Season” rival displays in lower valleys.

Identification: Smooth, white to greenish bark; rounded leaves with flattened petioles that tremble in the slightest breeze; small, cottony seeds in spring. Clonal; stands often arise from a single root system; fall colour varies by clone (yellow to orange).

Habitat: Montane (1,350–1,650 m); valley floors, forest edges, burned or disturbed sites. Often mixed with lodgepole pine and Douglas-fir. Requires fire or disturbance to regenerate; shaded out by conifers over time.

Ecology: Critical for biodiversity; aspen stands support more understory plants and wildlife than conifer monocultures. Elk and deer browse buds and twigs; beavers prefer aspen. Leaves turn gold in September.