Alnus alnobetula subsp. sinuata, commonly known as Sitka Alder, Green Alder, or Mountain Alder, is a deciduous shrub or small tree native to the mountainous regions and forest margins of Northern North America, extending from Alaska through western Canada to California and New Mexico. It is particularly adapted to subalpine environments and disturbed areas such as avalanche tracks and riverbanks. Typically, it reaches a height of 9-20 feet (2.7-6 meters) and a width of 6-12 feet (1.8-3.7 meters). This species features catkins with green or yellow flowers that are not particularly showy, blooming in the spring. The bark is smooth and gray, and it produces small, woody cones that persist into winter.

Sitka Alder is valued for its ability to fix nitrogen in the soil, which enhances soil fertility, making it beneficial for reclamation projects and naturalized plantings. It is also used for erosion control due to its fast-growing root system. In cultivation, it is suitable for naturalistic settings, such as wildlife gardens and riparian plantings. This alder prefers full sun to part shade and thrives in medium or fast-draining clay, loam, or sandy soils with consistent moisture. It is relatively low-maintenance but can be susceptible to alder blight and phytophthora root diseases.CC BY-SA 4.0