Erect or ascending, pubescent annual 2-7 dm; lvs 4-7 cm; lfls 9-18 pairs, 4-8 mm; peduncles 2-4 cm, from the upper axils; heads 2-6-fld, subtended by a pinnate leafy bract; fls white or pink, 5-9 mm; fr with 3-5 strongly nerved oval joints each 3-4 mm, the terminal one beaked; 2n=14. Native of the Mediterranean region, established on Long Island. June-Aug.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.