Solitary shrub 1-3(-5) m; young twigs loosely pubescent, later ±glabrate and becoming maroon, the pith dark brown; old bark fissuring; infl a flat to somewhat rounded cyme; sep 1-2 mm; distal 1 mm of style abruptly thickened to twice the diameter below; fr blue, 6-9 mm; stone strongly ridged; 2n=22. Moist or wet woods and along streams; Me. and Que. to Minn., s. to Ga., Ark., and Okla. May-July. Two well marked geographic vars.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.