Deciduous broad leaf, one of the largest Alders reaching 30m.The name derives from the bright rusty red color that develops in bruised or scraped bark. The bark is mottled, ashy-gray and smooth, often draped with moss.The leaves turn yellow in the autumn before falling. The male flowers are dangling reddish catkins.Alnus rubra is an important forestry tree. Its rapid growth makes it useful in covering disturbed land, such as mine spoils. Alder leaves, shed in the fall, decay readily to form a nitrogen-enriched humus.
Alnus rubra are planted as ornamental trees and will do well in wet swales, riparian areas, or on stream banks.
If used domestically they should be planted well away from drainpipes, sewage pipes, and water lines, as the roots may invade and clog the lines. Alnus rubra are known for growing easily in burned or destroyed land, and are used as “pioneering” or “reclamation” trees.