Annual or biennial with prostrate or ascending stems to 8 dm; stipules lanceolate, entire or toothed; lfls elliptic to obovate, 1-2 cm; peduncles much exceeding the subtending lvs; heads globose to short-cylindric, to 1 cm; fls yellow, 10-50 per head, 2-4 mm; pods nearly black, 2-3 mm, reniform, unarmed, 1-seeded, the conspicuous veins tending to be longitudinal; 2n=16. Native of Eurasia, common as a weed in our range and elsewhere. May-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.