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Moist thickets and other wet areas.
New England, south to VA and west to IA, MN, and SD and well north into Canada. Circumboreal if included with A. incana.
Deciduous shrub. Twigs dark gray with prominent lenticels. Leaves acute to short-acuminate, broadest near the middle, doubly serrate with irregular teeth. Staminate catkins mature before leaves emerge; fruiting catkins short, mostly sessile or on short peduncles.
Flowers March to April
Wetland Indicator: Obligate
Associates with a nitrogen fixing bacterium in the genus Frankia, which is part of a larger group of bacteria called the actinomycetes. The symbiosis results in the formation of nodules on the roots of the alder. Some botanists consider this species to be a subspecies of the European A. incana and would refer to this plant as Alnus incana (L.) Moench ssp. rugosa (Du Roi) R.T. Clausen.
Gleason, Henry A.
and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States
and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY
Swink, F. and G.
Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.
© Michael Hough 2004