Alnus incana subsp. rugosa Speckled Alder
General
A Nitrogen-fixing, multiple-stem, small tree or large shrub that prefers wet to moist soils. Provides excellent wildlife cover. Will grow in a wide variety of locations, including stream edges and swamps, and is fairly adaptable. Good for bank stabilization.
Plant Description
Separate male and female flowers are produced on the same plant (monoecious), starting in early spring. Drooping male catkins are slender, cylindrical, to 2 inches long, female flowers are round catkins (1/2 inch) and develop by the fall into small seed-bearing cones. Cones may persist through the winter. Leaves are toothed and pointed at the tip, (as opposed to European alder/Alnus glutinosa which is notched at the leaf tip). “Speckled” refers to the lenticels on the bark.
Height (ft)
15-25
Spread (ft)
10-20
Soil moisture
Moist to Wet
Soil types
Fine to Medium
Wetland indicator
FACW
Shade tolerance
Tolerant, Full Sun to Part Shade
Bloom color
Yellow
Bloom period
Early Spring
Fall conspicuous
No
Anaerobic tolerance
High
Drought tolerance
Low
Salinity tolerance
Low
Mono/dioecious
Monoecious
Distribution
Frequently found along the edges of water bodies from mid-Canada south to Virginia and west along the Great Lakes.
Additional information
Kartesz, J.T., The Biota of North America Program (BONAP). 2015. North American Plant Atlas. (http://bonap.net/napa). Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press) LINK
USDA, NRCS. 2021. PLANTS Database (https://plants.sc.egov.usda.gov/, 10/06/2021). National Plant Data Team, Greensboro, NC 27401-4901 USA. LINK