Mountain alder

Mountain alder (Alnus incana tenuifolia), also known as thinleaf alder is a subspecies of multi-stemmed, shrubby trees in the birch family, with a wide range across the cooler parts of the Northern Hemisphere. Tolerant of wetter soils, it can slowly spread with runners and is a common sight in swamps and wetlands.

It is a small- to medium-sized tree 15–20 metres tall with smooth grey bark even in old age.

Mountain alder is found in Western North America. The roots of this subspecies have nitrogen-fixing nodules.

Main Photo Credit: "Mountain alder (Alnus incana tenuifolia), Colorado, USA" by Greenkava, 2026. CC BY-NC 2.0.

Description: Wikipedia