Glabrous, 2-4 dm, often branched from the base, the decumbent stems often emitting new shoots the next year; young stems and lvs commonly somewhat red-tinted; cauline lvs numerous; oblanceolate to obovate, or the upper oval to ovate, commonly sessile; lvs subtending the umbel broadly elliptic to ovate or subcordate, those of the umbel broadly triangular-reniform, tending to be connate; rays of the primary umbel usually 3; fr smooth, 3 mm; seeds pale gray, 1.5-2 mm, deeply and uniformly pitted on both faces; 2n=28. Moist woods and shaded hillsides; Pa. to s. Ont., Mich., and Minn., s. to Fla. and Tex. Apr.-June. (Tithymalus c.; Galarhoeus c.) Southern plants, extending n. to Va., Ky., and Mo., with all cauline lvs oblanceolate and long (5-12 mm)-petioled, have been segregated as var. erecta Norton.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.