Slender annual, 0.5-6(-9) dm, ±hirsute; ultimate lf-segments linear, to 1 mm wide; invol bracts not scarious-margined, with segments under 1 cm, closely appressed to the infl in fr; fls all white (seldom purplish), the umbellets mostly 5-12-fld; fr 3-5 mm, usually broadest below the middle; 2n=22. Dry, open places, somewhat weedy; widespread in s. U.S., n. to Mo. and N.C., and to be expected in s. Va. May-July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.