Introduction:
Red alder (Alnus rubra), also called Oregon alder, western alder, and Pacific coast alder, is the most common hardwood in the Pacific Northwest. It is a relatively short-lived, intolerant pioneer with rapid juvenile growth. The species is favored by disturbance and often increases after logging and burning.
Description:
Red alder is in the birch family (Betulaceae). Red alder is a deciduous tree native to the Pacific Northwest of North America. The trees are medium-sized, reaching various heights to 60 feet average tall when mature. These fast-growing trees often grow 2 to 3 feet per year until 20 years of age. A shrub form occurs when the trees grow in open exposed areas. The branches are slender and spreading.
Range:
Red alder is most often observed as a lowland species along the northern Pacific coast. Its range extends from southern California (lat. 34° N.) to southeastern Alaska (60° N.). Red alder is generally found within 125 miles of the ocean and at elevations below 2,400 ft. It seldom grows east of the Cascade Range in Oregon and Washington or the Sierra Nevada in California, although several isolated populations exist in northern Idaho.
Foliage:
The alternately arranged leaves of red alder are dark green, simple and broadly ovate. The leaves are 4.5" long on average with a pointed tip. The leaf edges are serrated or softly lobed and slightly rolled under, giving a dark-green edging effect from the underside of the leaf. The undersides of the leaves are rusty colored and covered with fine soft hairs.
Fruit:
Red alder trees are monoecious, bearing both female flowers and male catkins. The tassel-like catkins grow in cluster of two to four. The catkins are greenish-yellow and 10 to 16 cm long. The flowers appear in spring either before or with the leaves. The flowers develop into small-scaled cones (fruits) that are 2 to 2.5cm long and 1 to 1.5 cm across. Each cone contains from 50 to 100 seeds that are tiny flat nutlets. The abundant seeds are wind dispersed from May to winter months.
Wood Value:
Red alder wood is used in the production of wooden products such as food dishes, furniture, sashes, doors, millwork, cabinets, paneling and brush handles. It is also used in fiber-based products such as tissue and writing paper. In Washington and Oregon, it was largely used for smoking salmon.
In Depth:
Conservation and erosion control: Red alder is an excellent species for re-establishing woodlands. The trees are used in forested riparian buffers to help reduce stream bank erosion, protect water quality, and enhance aquatic environments.
Ethnobotanic: Native American tribes from Alaska to Southern California have long recognized the value of red alder and put its bark layers, roots, leaves, twigs, cones, and sap to use for a variety of purposes. The inner bark was often dried, grounded into a powder and then used as a thickener in soups or mixed with cereals when making bread.
Related Species: White alder (Alnus rhombifolia) was also widely used for the same purposes as red alder by Native American tribes. White alder occurs in inland areas while red alder generally grows in areas of maritime influence. Red alder and white alder can be difficult to distinguish from each other. White alder does not have red inner bark or rolled leaf margins.
