Alnus serrulata Willd.

Shrubs , open to rather densely ascending, to 10 m. Bark light gray, smooth; lenticels small, inconspicuous. Winter buds stipitate, ellipsoid to obovoid, 3--6 mm, apex mostly rounded; stalks 2--4 mm; scales 2, equal, valvate, moderately to heavily resin-coated. Leaf blade broadly elliptic to obovate, 5--14 × 3.5--8 cm, leathery, base broadly to narrowly cuneate, margins flat, serrulate, without noticeably larger secondary teeth, apex obtuse to rounded; surfaces abaxially glabrous to moderately villous, slightly to moderately resin-coated. Inflorescences formed season before flowering and exposed during winter; staminate catkins in 1 or more clusters of 2--5, 3--8.5 cm, stamens 4; pistillate catkins in 1 or more clusters of 3--5. Flowering before new growth in spring. Infructescences ovoid-ellipsoid, 1--2.2 × 0.6--1.2 cm; peduncles 1--3(--5) mm. Samaras obovate, wings narrower than body, irregularly elliptic or obovate, leathery. 2 n = 28.

Moist lowlands, such as swamps, and along ponds and streams where it forms thickets. Along streambanks, shorelines, swamps, bogs, fens, edges of sloughs, successional swampy fields, low wet woods alluvial and tidal swamps, ditches.

Can be grown by cuttings, graftings or seedlings.