Alnus maritima

Common Name: seaside alder 
Type: Tree
Family: Betulaceae
Native Range: Delaware, Georgia, Maryland, Oklahoma
Zone: 4 to 7
Height: 20.00 to 30.00 feet
Spread: 16.00 to 29.00 feet
Bloom Time: August to September
Bloom Description: Yellow
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Medium
Suggested Use: Hedge, Water Plant, Rain Garden
Flower: Showy
Leaf: Good Fall
Tolerate: Drought, Erosion, Clay Soil, Wet Soil


Best grown in medium to wet soils in full sun to part shade. Best in wet soils in full sun. Thrives in moist areas along streams and rivers and in swampy areas. Grows in standing water. Tolerates flooding. At the other end of the spectrum, this shrub/tree also has some tolerance for dry, infertile soils.

Noteworthy Characteristics

Alnus maritima, commonly called seaside alder, is a deciduous, multi-trunked, upright-rounded, fall-blooming large shrub or small tree that typically grows to 20-30' tall. It is usually found in wet soils at low elevations along ponds, streams and rivers, including some dense pure stands in swamp-like areas with standing water. It is an uncommon to rare species that is native to the U. S. where it occurs in three small disjunct populations, with each population now being classified as a separate subspecies: (1) Alnus maritima subsp. maritima (coastal plain of Delaware and Maryland - Delmarva Peninsula); (2) Alnus maritima subsp. georgiensis (Bartow county in NW Georgia); and (3) Alnus maritima subsp. oklahomensis (Johnson and Pontotoc Counties in south central Oklahoma near the upper Blue River). Notwithstanding the remote locations of these three subspecies, fossil records seem to suggest that this Alnus maritima once enjoyed a much larger geographic distribution many years ago.

Genus name is the Latin name for alder.

Specific epithet comes from Latin meaning growing by the sea.


No known serious insect or disease problems.


Good selection for difficult sites such as moist to wet low spots. Effective as a windbreak. Landscape specimen.