Red alder is a deciduous tree in the Betulaceae (birch) family. It is native to the western coast of North America from Alaska down to California. This is one of the larger alders and grows 65-98 feet tall. It gets its name from the orange/red underbark that was used to make dye by Native Americans. This tree can be distinguished from other alders by the rolled under margins of the leaves, the stalked buds and impressed veins on the underside of the leaves. Red Alder is able to grow in poor soils due to its association with the soil bacterium, Frankia , which allows it to fix nitrogen. Because of this, they are often used in land reclamation projects. This tree grows fairly fast and will spread by seed. It tolerates soils ranging from well-drained gravels and sands to poorly drained clay or organic soils. It will grow in full sun to partial shade and prefers cool wet winters and warm dry summers. Insects, Diseases, and Other Plant Problems: Red alder is fairly free from most insect and disease problems, especially when young (age 40 or 50) and uninjured. Phellinus igniarius, a white heart rot, is probably the major cause of cull in older trees. The forest tent caterpillar (Malacosoma disstria), western tent caterpillar (M. californicum), alder woolly sawfly (Eriocampa ovata), striped alder sawfly (Hemichroa crocea), the alder flea beetle (Altica ambiens), and a leaf beetle (Pyrrhalta punctipennis) have caused substantial damage but rarely kill the tree. VIDEO created by Ryan Contreras for “Landscape Plant Materials I: Deciduous Hardwoods and Conifers or Landscape Plant Materials II: Spring Flowering Trees and Shrubs” a plant identification course offered by the Department of Horticulture at Oregon State University
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand; Shallow Rocky
Soil drainage
Good Drainage
Available space
24-60 feet
Mature size
Height: 66 ft. 0 in. - 98 ft. 0 in. | Width: 35 ft. 0 in. - 50 ft. 0 in.
Growth rate
Rapid
Maintenance
Medium
Canopy layer
1 - Canopy (>40 ft)
Form & Appearance
Habit / form
Conical; Erect
Texture
Medium
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Ovate; Rhomboidal
Leaf margin
Serrate
Leaf size
3-6 inches long, 1-3 inches wide
Hairs present
Yes
Leaf detail
2.5-6 inch long green leaves are ovate with a pointed apex. The serrated margins are revolute or curled under and the veins are impressed especially on the undersides. Hairs are present on the undersides. They turn yellow in the fall.
Fall color
Gold/Yellow
Flower color
Red/Burgundy
Flower form
Insignificant
Flower detail
Male catkins are reddish and 4-6 inches long. Female catkins are cone-like and woody, oval
Bloom time
Spring
Fruit color
Brown/Copper
Fruit type
Samara
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
Produces small brown cone-like strobiles less than an inch long that stay on the tree throughout winter. Seeds are winged samaras.
Bark color
Light Gray
Bark detail
The bark is mottled, ash-gray and smooth, often colonized by white lichen and moss. When bruised or scaped it has a rusty red color.
Stem color
Brown/Copper; Green
Stem detail
Olive to reddish-brown twigs are triangular in cross-section, the buds are distinctly stalked and have 2-3 pubescent scales, lenticels are prominent.
Wildlife & Ecology
Native status
Native
Origin
Western North America
Distribution
Alaska, Yukon, British Columbia, Washington, Oregon, California, Idaho and Montana
Wildlife value
Deer and elk will browse the twigs and finches will eat the seeds
Attracts
Small Mammals; Songbirds
Play value
Wildlife Cover/Habitat; Wildlife Food Source
Food & Medicine
Fruit type
Samara
Uses (ethnobotany)
A russet dye was made from the bark. Native Americans also used the bark to treat various illnesses. The wood is used for furniture and cabinets.