Lady Bird Johnson Wildflower Center - The University of Texas at Austin information

 Native Plant Database

Alnus viridis


Green alder


Betulaceae (Birch Family)



Alnus viridis (Green alder)
Weyand, Phyllis
Thicket-forming shrub or small tree, often with several trunks, and with shiny yellow-green leaves, gummy when young.

In Alaska, Green Alder is a pioneer in disturbed areas, following landslides, logging, and glacial retreat. Adapted to soils too barren for other trees, this species improves soil conditions by adding organic matter and nitrogen from bacteria in its roots. Alder roots have clusters of nodules containing nitrogen-fixing bacteria, which convert atmospheric nitrogen into a form usable by plants. Alders therefore thrive on nutrient-poor sites, and when these shrubs die and decompose, they release stored nitrogen and enrich the soil for other plants. (Kershaw) It acts as a short-lived nurse tree for Sitka Spruce (Picea sitchensis), later dying when shaded by the larger conifer.

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Plant Characteristics

Duration: Perennial
Habit: Tree
Leaf Retention: Deciduous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Venation: Pinnate
Breeding System: Flowers Unisexual , Monoecious
Fruit: Black, Brown
Size Class: 12-36 ft.

Bloom Information

Bloom Color: Yellow , Green , Brown
Bloom Time: May , Jun

Distribution

USA: AK , CA , ID , ME , MA , MI , MN , MT , NH , NY , NC , OR , PA , TN , VT , WA , WI , WY
Canada: NB , NL , ON , PE
Native Distribution: SW. and central Alaska and Yukon southeast to NW. California and central Montana; in Alaska to alpine zone above timberline; in NW. California to 7000 (2134 m).
Native Habitat: Along streams and lakes and in valleys.

Growing Conditions

Light Requirement: Part Shade , Shade
Soil Moisture: Wet
Soil Description: Sandy
Conditions Comments: Alder roots have clusters of nodules containing nitrogen-fixing bacteria, which convert atmospheric nitrogen into a form usable by plants. Alders therefore thrive on nutrient-poor sites, and when these shrubs die and decompose, they release stored nitrogen.

Benefit

Use Wildlife: Birds, Other Showy Insects
Attracts: Birds

Last Update: 2012-07-03