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Browse Trees and Plants

Seaside alder

Alnus maritima

Common names:
seaside alder, brook alder

Content Detail

Seaside alder is a fast-growing native tree. It stays short enough to be used under utility lines, but may be difficult to locate in local nurseries.

  • Family (English) Birch
  • Family (botanic) Betulaceae
  • Planting site City parkway, Residential and parks, Under utility lines, Wide median
  • Tree or plant type Tree
  • Foliage Deciduous (seasonally loses leaves)
  • Native locale North America
  • Size range Small tree (15-25 feet), Medium tree (25-40 feet)
  • Mature height 20-30 feet
  • Mature width 16-20 feet
  • Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily)
  • Hardiness zones Zone 4, Zone 5 (Northern Illinois), Zone 6 (City of Chicago), Zone 7
  • Soil preference Moist, well-drained soil, Wet soil
  • Tolerances Alkaline soil, clay soil, Occasional flooding, Wet sites
  • Season of interest early fall
  • Flower color and fragrance Yellow
  • Shape or form Pyramidal
  • Growth rate Fast
  • Planting considerations Intolerant of pollution, May be difficult to find in nurseries
  • Wildlife Nesting birds
  • Has cultivars Yes

Native geographic location and habitat: 

Native to the United States, seaside buckthorn is generally found in wet locations.

Bark color and texture: 

Bark is light brown to reddish brown and may be mottled.

Leaf or needle arrangement, size, shape, and texture:

Simple, alternate leaves are oblong to egg-shaped with finely toothed margins.  Leaves are dark green in summer, changing to yellow-brown in fall.

Flower arrangement, shape, and size:

Male and female flowers on the same tree but in separate structures (monoecious). Male catkins flower in fall.

Fruit, cone, nut, and seed descriptions: 

Fruit are cone-like structures.

Plant care:

This species is best in moist to wet sites and is able to tolerate short-term flooding.

List of pests, diseases, and tolerances: 

Potential problems include canker diseases, alder aphids, and leaf miners.

Photo Gallery (4)

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