Northern Prairie Wildlife Research Center
Aquatic and Wetland Vascular Plants of the Northern Great Plains
11. Betulaceae, the Birch Family
1. Alnus P. Mill. -- Alder
1. Alnus incana (L.) Moench -- Speckled alder
Shrub to 5 m tall; twigs reddish-brown, pruinose, mostly with conspicuous,
light-colored lenticels. Leaves dark green and glabrous above, paler
and pubescent on the veins beneath, ovate to elliptic, 5-14 cm long, 3-7 cm
wide, serrate and shallowly lobed; petioles 1-2.5 cm long; stipules caducous,
irregularly lanceolate, 6-15 mm long, 1.5-5 mm wide, variably pubescent. Catkins
in terminal clusters of 3-several; male catkins short-peduncled, elongate, 4-9
cm long, 7-9 mm thick; female catkins sessile, cylindric, in flower 5-6 mm long,
2-2.5 mm thick, the scales unlobed, in fruit becoming conelike, 13-18 mm long,
8-13 mm thick. Nutlets flat, slightly winged, obovate, 3 mm long, about
as wide. Flowering May, fruiting Aug--Sep. Swampy areas and stream banks; occasional
in e ND; (Newf. to AK, s to MD, OH, n IN, MN, e ND, NM, AZ and CA; also Eurasia).
A. rugosa (Du Roi) Spreng.
North American A. incana is designated subsp. rugosa (Du Roi)
R. T. Clausen.
Return to Family -- Betulaceae - The
Next Species -- Betula glandulosa Michx. --
Dwarf birch, swamp birch