Thinleaf Alder

Thinleaf alder is a thicket-forming shrub or small tree along streams in western mountains from Alaska to New Mexico. Its thin, smooth green-gray or reddish-brown bark and multiple stems signal its colonizing habit. The leaves are thinner than those of white alder, with more finely toothed margins. It rarely exceeds 40 feet and often remains shrubby, especially on harsh, exposed sites.

Thinleaf alder tolerates cold, harsh mountain sites with short growing seasons. It establishes readily on wet disturbed soils and eroding streambanks where its nitrogen-fixing roots stabilize soils and begin enrichment. Fast-growing (20 feet in 20 years on good sites) and moderate-lived. This species is primarily valuable for riparian and avalanche path restoration in mountain settings.