Fr ovoid, flattened laterally, constricted at the commissure, smooth to tuberculate or bristly, with narrow, inconspicuous, rounded ribs; carpophore cleft at the top; oil-tubes 1-3 in the intervals, 2 on the commissure; umbels peduncled, terminal and from the upper axils, loose and open, few-rayed; invol wanting, or of 1 or 2 slender bracts; involucel of a few small linear bractlets; umbellets 2-6-fld; sep obsolete; pet white; stylopodium low-conic; annuals with glabrous, ternately decompound lvs, the ultimate segments linear or filiform. 4, New World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.