Trees and shrubs , to 25 m; crowns open. Bark light to dark gray, reddish, or brown, smooth, or in age broken into irregular plates; lenticels present or absent, conspicuous, enlarged or unexpanded. Winter buds stipitate, ellipsoid, 4--7 mm, apex rounded to nearly acute; stalk 1--3 mm; scales 2--3, equal, valvate, resin-coated. Leaf blade narrowly ovate to elliptic, base cuneate to narrowly rounded, margins doubly serrate, with distinctly larger secondary teeth, apex acute or short-acuminate to obtuse. Inflorescences formed season before flowering and exposed during winter. Flowering before new growth in spring. Infructescences ovoid to nearly cylindric; peduncles relatively short and stout. Samaras elliptic to obovate, wings narrower than body, irregular in shape.
"Tall colonial shrub or small tree; winter buds evidently stalked, with 2–3 equal scales; lvs oval, elliptic, or ovate, broadest near or below the middle, obtuse to short- acuminate, sharply and irregularly double-serrate or almost lobulate, broadly obtuse to rounded at base, with mostly 8–14 principal veins on a side, soon becoming pale and glaucous beneath, ± pubescent, especially on the veins, not glutinous; staminate catkins mature before the lvs begin to open; anthers virtually sessile; fruiting catkins mostly sessile or only short-pedunculate, crowded in small, naked infls, 1–1.5(2) cm, seldom much over 1 cm thick; frs 2–3.5 mm, narrowly coriaceous-winged or merely thin-margined; 2n=28. Wet soil; circumboreal, s. to Md., W.Va., Ill., and the w. cordillera. E. Amer. pls, as here described, are var. americana Regel (A. rugosa; A. incana ssp. rugosa)"
