Alnus incana subsp. tenuifolia (Nutt.) Breitung

Shrubs or trees, to 12 m; shrubs ascending, open, spreading, trees small, shrubby. Bark light gray to dark brown, smooth; lenticels pale, orbiculate to elliptic. Winter buds nearly divergent, ellipsoid, 4--7 mm, apex obtuse; stalks 1--3 mm; scales 2, equal, valvate. Leaf blade ovate to elliptic, 4--10 × 2.5--8 cm, thin, base broadly cuneate to rounded, margins distinctly doubly serrate to nearly crenate or lobulate, teeth relatively blunt or rounded, apex acute to obtuse; surfaces abaxially glabrous to sparsely pubescent, slightly to not noticeably resin-coated. Inflorescences: staminate catkins in 1 or more clusters of 3--5, 4--10 cm; pistillate catkins in 1 or more clusters of 2--5. Infructescences ovoid, 1--2 × 0.8--1.3 cm; peduncles 1--5 mm. 2 n = 28.

Can be grown by seedlings.