12 Species Of Alder Trees For Your Yard

The most notable features of all varieties of alder trees are their catkins and strobiles. Both male and female flowers (catkins) appear on the trees. As a monoecious species, alders self-pollinate. Female flowers begin developing as small, round green growths in the summer or fall before the next spring’s bloom. Yellowish male flower clusters form into 1.2 to 3.9-inch slender, dropping cylinders, releasing their pollen in early spring (January-April). The plant is wind pollinated. When the female flowers are pollinated, they mature into small cones (called strobiles). Though the majority of alder tree species are deciduous, these trees resist the brilliant autumn color change of most other deciduous species. Green leaves simply turn brown and fall from the tree as it prepares for dormancy. Since these trees are able to fix nitrogen in the soil, they can grow in less than fertile areas. Plants with nitrogen fixation capabilities form symbiotic relationships with bacteria that allow them to improve the soil on recently cleared land, for example. In the case of ​alders, it is with the Frankia bacteria. This quality allows them to grow in landscaping areas where other plants may struggle. They typically grow well in moist areas, such as along riverbanks. Alders make excellent hosts for many moth and butterfly larvae, plus birds are attracted to the strobiles. The flowers attract pollinators, but the male flowers may cause allergy sufferers discomfort with the profuse pollen they produce.

Alder Tree Identification

Alder trees as a genus can be fairly easily distinguished from similar trees by inspecting various features:

Leaves: Young leaves are sticky to the touch and are very shiny. Mature leaves will have a rounded shape with notched edges, not the pointed tips found on birch trees. The leaves tend to turn brown rather than vibrant yellow or red in the fall.Flowers: These are elongated catkins rather than blossoms. They appear in early spring. Male catkins are long and turn yellow with pollen. Female catkins are much shorter, purple in color, and gradually transform into cones containing seeds.Bark: All species have grayish, rough bark that develops fissures as the tree trunk expands. These trees lack the papery bark found in birches.Habitat: Alders are naturally found in wetland areas and along rivers.

Spotting small differences within these features will help you identify specific species within the genus. Here are 12 common alder trees and shrubs for your landscaping needs.

Native Area: Europe, Northern Africa, and Western AsiaUSDA Growing Zones: 3 to 7Height: 40 to 60 feetSun Exposure: Full sun to part shade

There are several different subspecies of green alder found throughout the world, including: Alnus viridis subsp. crispa (sometimes seen as A. crispa), A. viridis subsp. fruticosa, A. viridis subsp. viridis, A. viridis subsp. maximowiczii (sometimes A. maximowiczii), A. viridis subsp. sinuata, (sometimes A. sinuata) and A. viridis subsp. suaveolens.

Native Area: North America, EuropeUSDA Growing Zones: 3 to 7Height: 6 to 14 feetSun Exposure: Full sun to part shade

Native Area: Europe and North AmericaUSDA Growing Zones: 2 to 6Height: 20 to 35 feetExposure: Full sun to part shade

Native Area: North AmericaUSDA zones: 4 to 9Height: 10 to 20 feetExposure: Full sun to part shade

Native Area: Corsica, Southern ItalyUSDA zones: 5 to 7Height: 30 to 50 feetExposure: Full sun

Interestingly, Fender has used red alder as the hardwood of choice for its electric guitars since the 1950s. The acoustic properties, plus the fact that it was abundantly available on the west coast near Fender headquarters, made it a natural choice.

Native Area: North America: Pacific coast, southeast Alaska, British Columbia, Washington, Oregon, Southern California, Northern IdahoUSDA Zones: 4 to 7Height: 40 to 80 feetExposure: Full sun

Native Area: North AmericaUSDA zones: 4 to 7Height: 20 to 30 feetExposure: Full sun

Native Area: North AmericaUSDA Zones: 8 to 11Height: 30 to 50 feetExposure: Full sun to part shade

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Native Area: AsiaUSDA Zones: 5 to 7Height: 40 to 60 feetExposure: Full sun

Native Area: Central America: Honduras, Guatemala, MexicoUSDA Zones: 7 to 12Height: 65 to 80 feetExposure: Full sun

Native Area: Cyprus, Iran, Lebanon-Syria, Palestine, TurkeyUSDA Zones: 7 to 9Height: 25 to 50 feetExposure: Full sun

Native Area: Pakistan, western Himalayas, NepalUSDA Zones: 7 to 10Height: 65 to 80 feetExposure: Full to part sun