Washington Native Plant Society: Starflower Image Herbarium

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Alnus rubra

Red Alder

At a Glance: A fast-growing deciduous tree well suited to disturbed sites.

Height: Up to 80 feet (25 meters).
Growth Form: Tree.
Stems: Bark is thin and gray with smooth white patches of lichens.
Leaves: Leaves are alternate, broadly elliptic, sharply pointed at the base and tip, smooth above and slightly rust-colored below. Leaf margins are wavy and folded-over with coarse, blunt teeth. Size: 5-15 cm (2-6 in) long. Leaves remain green until dropping in the fall.
Flowers: Male flowers appear as hanging, cylindrical spikes (catkins) and emerge before leaves while female flowers are borne in small stubby cones. the catkins are reddish-orange with yellow highlights, 5-12 cm (2-4.5 in) long. The femal cones are green when young, then turning brown, 2 cm long.
Flowering Period: March.
Fruits: Clusters of brown cones 2 cm long containing oval-shaped, winged seeds remain on the tree over winter months.


Photo © 2004, Starflower Foundation

Sun/Shade Tolerance	Hydrology	Elevation Range
Shade intolerant. full sun > 80% mostly sunny 60%-80% partial sun and shade 40%- 60% mostly shady 60%-80% full shade > 80%	Grows taller in drier conditions. wet moist dry Wetland Indicator Status:	Below about 300 meters elevation. low elevation mid elevation sub-alpine high elevation

Soil Preferences
Fixes nitrogen, can flourish in poor soils.
sandy soils gravelly soils clay soils muddy soils peaty soils	well drained soils shallow soils deep soils acidic soils basic soils	humic soils nutrient rich soils nutrient poor soils mineral soils organic soils

Habitat Preferences
Aquatic and Wetland: Ponds or lakes Shallow pools Sloughs Swales or wet ditches Seasonally inundated areas Marshes or swamps Aquatic bed wetlands Emergent wetlands Scrub-shrub wetlands Forested wetlands Bogs, fens Seeps, springs Shorelines and Riparian: Lake shores Bog margins Streams or rivers Stream or river banks Riparian corridors River bars Floodplains Bottomlands Alluvial areas	Saltwater Areas: In or near saltwater Mud flats Tidal areas Estuaries Saltmarshes Brackish water Seashores Coastal dunes or beaches Rocky or Gravelly Areas: Coastal bluffs Cliffs Rocky slopes Outcrops Crevices Glacial outwash Gullies Slide areas Sub-alpine and Alpine: Heaths Snow beds Tundra Avalanche tracks	Forests and Thickets: Forests and woods Open forests Coniferous forests Old growth forests Deciduous forests Mixed forests Nurse logs Forest edges, openings, or clearings Thickets Meadows and Fields: Pastures or fields Meadows or grassy areas Mossy areas Disturbed Areas: Roadsides Trailsides Logged sites Burned areas Disturbed sites

Wildlife Value

Berries

Seeds

Nectar for hummingbirds

Nectar for butterflies

Host for insect larvae

Thickets and shelter

Thorny or protective cover

Birds: Birds that eat the seeds, buds, and insects associated with red alder include mallards, widgeons, grouse, bushtits, kinglets, siskins, vireos, warblers, and chickadees. Birds that use red alder for cover and nesting include warblers, bushtits, and sparrows. Cavity-nesting birds nest and roost in the red alder tree cavities.
Insects: The leaves are eaten by swallowtail butterfly larvae and tent caterpillars.
Mammals: Mammals that eat the twigs, leaves, or wood include snowshoe hares, beavers, porcupines, deer, and elk.
Other Wildlife: Alders create organic debris for soil organisms. Additionally, alders create good riparian cover for fish.

Ethnobotanical Uses and Other Facts

(data not available)

Suggested References

Cooke, S.S. A Field Guide to the Common Wetland Plants of Western Washington and Northwetern Oregon. Seattle Audubon Society and Washington Native Plant Society. Page 2.
Guard, B.J. 1995. Wetland Plants of Oregon & Washington. Lone Pine Publishing. Page 214.
Jacobson A.L. 2001. Wild Plants of Greater Seattle. Published by author. Page 72.
Link, R. 1999. Landscaping for Wildlife in the Pacific Northwest. University of Washington Press. Page 246.
Lyons, C., W. Merilees. Trees and Shrubs to Know in Washington and British Columbia. Lone Pine Publishing. Page 84.
Pojar, J., A. Mackinnon. 1994. Plants of the Pacific Northwest Coast. Lone Pine Publishing. Page 44.

The landscaping and restoration information provided on this page is taken from Starflower Foundation Image Herbarium. All photographs © Starflower Foundation unless otherwise noted.