Seaside alder Alnus maritima

Seaside alder is a deciduous small tree or large shrub in the Betulaceae (birch) family. Native only to three small disjunctive populations, with each classified as a separate subspecies (subspecies maritima in the coastal plains of Southern Delaware and the eastern shore of Maryland, subspecies georgiensis in northwest Georgia, and subspecies oklahomensis in south-central Oklahoma). In nature, it is often found growing beside streams and ponds near coastal areas and sometimes in standing water, making it well-suited to wet soils or areas with seasonal flooding. The genus name is Latin for alder and the species name comes from the Latin "growing by the sea".

Growing at a medium rate it reaches a mature height of 20 to 30 feet tall and 16 to 30 feet wide, Thriving in part shade as well as sun, seaside alder tolerates clay and alkaline soils, and is somewhat drought tolerant once established. It also tolerates saline soils, but will not do well in full shade.

Its dense deciduous foliage is attractive to nesting birds and makes it suitable as a windscreen, hedges, or specimen plant. It is also known for its ability to fix nitrogen in the soil. Other landscape uses include rain gardens, riparian, and naturalized areas, especially those with wet soils.

Insects, Diseases, and Other Plant Problems: No serious problems.

VIDEO created by Grant L. Thompson for “Trees, Shrubs, and Woody Vines for Landscaping” a plant identification course offered by the Department of Horticulture at Iowa State University.