Hooked s. Low and often spreading, to 4 dm, branched from the base or only above; rays 5-14, ascending or suberect, unequal, to 1.5 cm; pedicels 2-6, to 7 mm, the central umbellets 1-fld, sessile; fr 1.5-2 mm, covered with short uncinate bristles; 2n=16. Dry prairies and barrens, and a weed in waste places; Ariz. and n. Mex. to Okla., La., Mo., and w. Ky., and rarely intr. e. to N.Y. May, June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.