Hispidulous to subglabrous, 1-4 dm, usually branched from the base; rays 1-3; involucel of 2-lobed bractlets; fr-body quadrangular, 6-15 mm, the flat, straight beak 2-7 cm; 2n=16. Native of the Mediterranean region, widely established as a weed in the U.S., n. to N.J. and S.D. May-July.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.