Slender annual 2-6 dm, ascending or erect, the stem glabrous or nearly so; lvs 2-7 cm, strigillose, the lower ones ±ovate, narrowed to a petiole, 1-2-pinnatifid or 3-5-cleft with the parts again incised, the upper ones smaller and less dissected; spikes elongate, very slender, paniculately disposed or in 3's or even solitary; bracts usually half as long as the cal; cal 2-2.5 mm, glandular-hairy, subtruncate, its teeth minute; cor blue, purple, or lilac, the tube to 3 mm, the limb 4 mm wide, with ±rounded lobes; nutlets 2 mm; 2n=14, 28. Native of Europe, naturalized along roadsides and in fields and waste places in se. U.S., n. to Mass. and possibly Me. June-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.