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.

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Charles Deam "Flora of Indiana

Frequent on the alluvial flood plains of streams throughout the state except in the northern counties where it is rare. Where it is found it is usually abundant and sometimes an annoying weed. 

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Indiana Coefficient of Conservatism: C = 2

Wetland Indicator Status: FAC

Diagnostic Traits: glabrous, decumbant annual or biennial; leaves ternately decompound; umbel simple or 2-4 primary rays, ebracteate; umbellets 2-6 flowered, bractlets present; petals white; fruits oblong-elliptic, to 10 mm long.

Variety shortii (aka C. shortii) has finely pubsecent fruits.