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Seaside alder

Seaside alder in winter.

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.

Botanical name:

Alnus maritima

All common names:

seaside alder, brook alder

Family (English):


Family (Botanic):


Planting Site:

  • Residential and parks,
  • City parkway,
  • Wide median,
  • Under utility lines

Tree or Plant Type:

  • Tree


  • Deciduous (seasonally loses leaves)

Native Locale:

  • North America

Landscape Uses:

  • Utility,
  • Specimen,
  • Parkway/street

Size Range:

  • medium tree (25-40 feet),
  • Small tree (15-25 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 (Chicago),
  • Zone 6,
  • Zone 7

Soil Preference:

  • Moist, well-drained soil,
  • Wet soil


  • Wet sites,
  • Occasional flooding,
  • Alkaline soil,
  • Clay soil

Acid Soils:

  • Tolerant

Alkaline Soils:

  • Tolerant

Salt Spray:

  • Intolerant

Soil Salt:

  • Intolerant

Drought Conditions:

  • Moderately Tolerant

Poor Drainage:

  • Prefers

Planting Considerations:

  • Intolerant of pollution,
  • May be difficult to find in nurseries

Ornamental Interest:

  • Fall color,
  • Persistent fruit/seeds

Seasons of Interest:

  • early fall

Flower Color & Fragrance:

  • Yellow

Shape or Form:

  • Pyramidal

Growth Rate:

  • Fast


  • Nesting birds

More Information:

Tree & Plant Care

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

Disease, pests, and problems

Potential problems include cankers, alder aphids, and leaf miners.

Native geographic location and habitat

Native to the United States.  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.



Location of Alnus maritima (Seaside alder) at the Arboretum