Erect annual 1-5 dm, the angled stems retrorsely scabrous at least below; lvs in whorls of 4-8, 1-3 cm, the upper linear to lanceolate, blunt; fls subsessile in a terminal head subtended by an involucre of separate hairy lvs; cor blue-purple, 5-6.5 mm, salverform, the slender tube much longer than the lobes; fr smooth, 2-3 mm thick; 2n=22. Fields and waste places; native of Europe, adventive in s. 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.