TREES & plants

European black alder (Not recommended)

European black alder has invasive traits that enable it to spread aggressively. This tree is under observation and may be listed on official invasive species lists in the near future. Review of risks should be undertaken before selecting this tree for planting sites. Growing 40 to 60 feet tall, black alder is typically tall and narrow but sometimes pyramid-shaped. It can be identified by its large, glossy green, oval to round leaves with a toothed margin; dangling catkins in early spring; and cone-like fruits, in fall. Young leaves and shoots are often sticky from a resin. The seed are dispersed by wind and, if they fall on water, can be spread for long distances. Along stream beds and in other wet areas, it can form dense groves that displace native plants. Like members of the bean family, it can fix nitrogen from the air, allowing it to colonize very poor soils. It invades woodlands and wetlands such as forest preserves where it disrupts the forest ecosystem by preventing the growth of understory shrubs and other plants. The tree was brought from Europe to the East Coast by early colonists. 

Botanical name: 
Alnus glutinosa
All Common Names: 
European black alder, European alder, Common alder
Family (English): 
Family (Botanic): 
Tree or Plant Type: 
  • Tree
Native Locale: 
  • Non-native
Size Range: 
  • Large tree (more than 40 feet)
Mature Height: 
40-60 feet
Mature Width: 
20-40 feet
Light Exposure: 
  • Full sun (6 hrs direct light daily)
  • Partial sun/shade (4-6 hrs light daily)
Hardiness Zones: 
  • Zone 4
  • Zone 5
  • Zone 6
  • Zone 7
Soil Preference: 
  • Wet soil
Acid Soils: 
  • Tolerant
Alkaline Soils: 
  • Tolerant
Salt Spray: 
  • Intolerant
Soil Salt: 
  • Intolerant
Drought Conditions: 
  • Moderately Tolerant
Poor Drainage: 
  • Tolerant
Planting Considerations: 
  • Excessive sucker growth
  • Deciduous (seasonally loses leaves)
Ornamental Interest: 
  • Persistent fruit/seeds
  • Attractive bark
Flower Color & Fragrance: 
  • Inconspicuous
Shape or Form: 
  • Pyramidal
Growth Rate: 
  • Fast
Transplants Well: 
  • Yes
  • Nesting birds
  • Seed-eating birds
  • Small mammals
More Information: 

Native geographic location and habitat

Europe and central Asia

Bark color and texture 

Light to greenish gray

Leaf or needle arrangement, size, shape, and texture

Leaves oval to rounded, glossy green, with a toothed margin. Young leaves and shoots often sticky from a resin.

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.