White alder, scientifically known as Alnus rhombifolia, is a deciduous tree native to western North America. It belongs to the family Betulaceae and is commonly found in riparian areas, canyons, and foothills.
The white alder can reach heights of up to 65 feet (20 meters) and has a broad, rounded crown. It is known for its smooth, grayish bark that becomes furrowed with age. The leaves are alternate, simple, and shaped like a diamond, hence the species name "rhombifolia." They are dark green on the upper surface and paler beneath, with toothed edges. In the fall, the leaves turn yellow before dropping off.
The tree produces small, inconspicuous flowers that appear in late winter or early spring. These flowers are clustered in catkins, which are elongated, drooping spikes. The female catkins develop into cone-like structures that contain the tree's seeds.
White alders have an important ecological role as they are nitrogen-fixing trees, able to take nitrogen from the atmosphere and convert it into a usable form for other plants. They also provide habitat and food sources for various wildlife species, including birds and mammals.
In addition to its ecological value, white alder has been utilized by humans for various purposes. The lightweight wood is commonly used for making furniture, cabinetry, and veneer. The bark has been traditionally used by Indigenous communities for medicinal purposes, including treating skin conditions and as a diuretic.
Overall, white alder is an iconic tree of Western North America, valued for its ecological significance and practical uses.
