Habit: fast-growing, multi-stemmed deciduous shrub usually forming dense thickets. The bark is thin, smooth, and reddish brown turning dark gray with age. Leaves are shiny green with a slightly sticky underside and edges with fine long pointed teeth. Male catkins form on the tips of branches drooping about 4 in (10 cm). On the same twig the female cone-like catkins bloom from late spring to mid-summer. The seeds are surrounded by papery wings. Sitka alder has a shallow root system.
Ecology: sitka alder can be found along streams, in damp woods, and on moist mountain slopes where the soil remains moist all year. It grows at middle elevations 1640 ft (500m) but prefers the moist cool sites of higher elevations 3000-7000 ft (914-2134 m). Establishes well in disturbed areas, such as avalanche chutes, and places recently glaciated.
Growing Conditions: full sun to partial shade, moist to wet soil. It is moderately shade tolerant.
Sitka alder has the ability to fix nitrogen, increasing fertility of soil and is valuable for slope stabilization and erosion control on steep slopes by slowing the snowmelt water flow. Wildlife habitat, deer browse leaves, and birds forage the seed.