Shrubs , spreading or rather compact, to 3(--4) m. Bark grayish brown; lenticels pale. Leaf blade dark green, broadly to narrowly ovate or elliptic, 3.5--6(--10) × 3--5(--7) cm, leathery, base rounded, obtuse, or cuneate, sometimes nearly cordate, margins serrulate or finely serrate, apex obtuse to acute; surfaces abaxially glabrous to velutinous or occasionally tomentose, moderately to heavily resin-coated. Inflorescences: staminate catkins 2.5--9 cm. Infructescences 1.2--2 × 0.5--1.2 cm; peduncles 1--5 cm. 2 n = 28.

Flowering spring. Singly or in thickets along streams, lakeshores, coasts, and bog or muskeg margins, or on sandy or gravelly slopes or flats; 0--2000 m; St. Pierre and Miquelon; Greenland; Alta., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask.; Maine, Mass., Mich., Minn., N.H., N.Y., N.C., Pa., Tenn., Vt., Wis.

Alnus viridis subsp. crispa grows across much of the continent in the far North; widely disjunct populations occur in the Appalachians in Pennsylvania and on the summit of Roan Mountain on the North Carolina--Tennessee border (R. B. Clarkson 1960; E. T. Wherry 1960).

The Cree used Alnus viridis subsp. crispa medicinally for the astringent qualities of the bark and to treat dropsy (D. E. Moerman 1986).