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TREES & plants

Speckled alder

Leaves of speckled alder.

Speckled alder is a smaller tree that is appropriate for planting under power lines. Early spring flowers are interesting, but not really showy. This tree may be difficult to find in local nurseries.

This species is native to the Chicago region according to Swink and Wilhelm's Plants of the Chicago Region, with updates made according to current research.  

Botanical name: 
Alnus incana subsp. rugosa
All Common Names: 
speckled alder
Family (English): 
Birch
Family (Botanic): 
Betulaceae
Tree or Plant Type: 
  • Shrub, 
  • Tree
Foliage: 
  • Deciduous (seasonally loses leaves)
Native Locale: 
  • Chicago area, 
  • Illinois, 
  • North America
Planting Site: 
  • Residential and parks, 
  • Under utility lines
Landscape Uses: 
  • Hedge, 
  • Massing, 
  • Screen, 
  • Utility
Size Range: 
  • Small tree (15-25 feet), 
  • Compact tree (10-15 feet), 
  • Large shrub (more than 8 feet)
Mature Height: 
15-25 feet
Mature Width: 
15-25 feet
Light Exposure: 
  • Full sun (6 hrs direct light daily), 
  • Partial sun/shade (4-6 hrs light daily)
Hardiness Zones: 
  • Zone 3, 
  • Zone 4, 
  • Zone 5 (Chicago), 
  • Zone 6
Soil Preference: 
  • Moist, well-drained soil, 
  • Wet soil
Acid Soils: 
  • Tolerant
Alkaline Soils: 
  • Intolerant
Salt Spray: 
  • Moderately Tolerant
Soil Salt: 
  • Intolerant
Drought Conditions: 
  • Moderately Tolerant
Poor Drainage: 
  • Tolerant
Planting Considerations: 
  • May be difficult to find in nurseries
Ornamental Interest: 
  • Spring blossoms, 
  • Persistent fruit/seeds, 
  • Attractive bark
Season of Interest: 
  • Early winter, 
  • Mid winter, 
  • Late winter
Flower Color & Fragrance: 
  • Inconspicuous
Shape or Form: 
  • Multi-stemmed
Growth Rate: 
  • Moderate, 
  • Fast
Transplants Well: 
  • Yes
Wildlife: 
  • Browsers, 
  • Small mammals, 
  • Songbirds
More Information: 

Tree & Plant Care

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

Disease, pests, and problems

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

Native geographic location and habitat

C-Value: 8

Bark color and texture 

Bark is smooth, dotted with warty lenticels.

Leaf or needle arrangement, size, shape, and texture

The oval leaves are 2 to 4 inches long and alternately arranged.  The edges of the leaves are doubly-toothed.  The upper leaf surface is dull green and the lower surface is grayish.  Little color change in fall.

Flower arrangement, shape, and size

Male flowers in dangling catkins, yellow-red, in early spring before leaves appear.  Female flowers small, pink, egg-shaped.

Fruit, cone, nut, and seed descriptions

Fruit are cone-like structures.

Alnus incana subsp. rugosa or Speckled alder