Annual; stems spreading, often weak, usually branched from the base, 2-6 dm, glabrous or sparsely hairy; lf-segments oblong to ovate, glabrous beneath or with a few hairs; rays 1-3, the pedicels 2-6, very short at anthesis, later to 1 cm, filiform; fr narrowly elliptic or oblong, 5.5-10 mm, convexly narrowed to the summit, the ribs filiform, much narrower than the intervals. Moist woods and alluvial soil; N.Y. and s. Ont. to Mich., s. Wis., and e. Neb., s. to Ga., Ark., and Okla. Apr., May. Typical C. procumbens has glabrous fr. Occasional plants from Ind., O. and Ky. have pubescent fr and have been called var. shortii Torr. & A. Gray.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.