Alder, Red - Alnus rubra

A rapidly growing tree up to 25 m (80 feet) tall; bark is thin, smooth and often appearing white mottled due to crutose lichens; pith and cambium in stems turns rusty color when freshly cut; roots nitrogen fixing; leaves alternate, deciduous, shiny dark green above, lighter below with rusty pubescence along veins on underside, double serrated; flowers catkins; fruit winged nutlet in semi-woody small cone. Habitat is slightly moist to wet soils at lower elevations. Harvest ripe seed in September and October; air dry to prevent molding; short term storage by refrigeration, long term storage at less than 10 percent moisture content and freezer-stored in moisture-proof containers at -12° to -13°C (10.4 to 8.6°F) for up to 5 years without loss of viability. Fresh seed sown in the fall readily germinates, do not cover the seed, adequate water and a low nitrogen, high phosphorus fertilizer enhances germination and growth. Transplant seedlings at one to two years old.

Greenhouse asexual propagation by softwood cuttings from young trees (< 7 years old), 6 to 12 cm (2.4 to 4.7 inches) long, 2 to 4 mm (0.08 to 0.16 inch) in diameter, treat with approximately 3,000 ppm indole-3-butyric acid (IBA), media of 1:1, perlite:vermiculite at 25°C (77°F); transplant to a 1:1:1, vermiculite:perlite:sandy loam soil; leave in greenhouse for five weeks at 21°C (70°F) days and 15°C (59°F) nights; Outplant the following year.

Field propagation by dormant unrooted hardwood cuttings is rare. Small seedlings can be collected from under mature trees and potted in containers for eventual reestablishment in riparian zones.

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Last Modified: 07/05/2007