Shrub to 1 m tall Leaves: alternate, stalked (5 - 12 mm), bright green, 4 - 10 cm long, oblong or elliptic to egg-shaped with a wedge-shaped base and rounded to pointed tip, irregularly round-toothed, with six to eight vein pairs, smooth or slightly hairy along veins beneath. Flowers: borne solitary or in clusters of two or three, greenish, with five sepals and five stamens but lacking petals. Fruit: fleshy with three center seeds (drupe), black, 6 - 8 mm wide, nearly spherical. Twigs: covered with wooly hairs when young.
Similar species: Rhamnus frangula, Rhamnus alnifolia, Rhamnus arguta var. velutina, and Rhamnus lanceolata all have alternate leaf arrangements and usually lack spines at the tips of the stems. Rhamnus frangula reaches 7 m tall, usually has non-toothed leaf margins, and has buds that lack scales (naked). Rhamnus arguta var. velutina reaches 3 m tall and has broad oval to egg-shaped leaves with sharply awl-shaped teeth and a hairy lower surface. Rhamnus lanceolata grows to 2 m tall and has lance-shaped leaves with finely toothed margins and a hairy lower leaf surface.
Habitat and ecology: Local in bogs, shaded calcareous springy fens and swamps. Habitat destruction has made this species much less common in recent years.
Occurence in the Chicago region: native
Etymology: Rhamnus is the ancient Greek name for buckthorn. Alnifolia means "with leaves like an alder."
Shrub to 1(1.5) m; lvs alternate, lance-oblong to elliptic or lance-ovate, obtuse to acuminate, crenate-serrate; petioles 5-15 mm; umbels sessile, 1-3-fld; fls appearing with the lvs, 5-merous; hypanthium saucer-shaped; sep 1.5-2 mm; pet none; styles 1 mm, connate a third their length; stamens very short in the pistillate fls; fr black, 6-8 mm; stones 3. Swamps and bogs; Nf. and Que. to B.C., s. to N.J., Pa., O., n. Ind., n. Ill., Io., and Calif.; also in Tenn.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.