Annual or biennial, much-branched, mostly erect, 2-5 dm, the stem appressed-hairy; petioles 5-12 mm, about equaling the lance-oblong stipules; lfls all sessile or nearly so, oblanceolate to obovate-oblong, 1-2 cm; heads short-cylindric, 1-2 cm, on peduncles 1-4 cm from the upper axils; pedicels 0.5 mm; fls 5-7 mm; cal strongly 2-lipped, glabrous, the tube 5-nerved, 1 mm, the lobes lance-linear, the lower 1.2-1.8 mm, the upper half as long; cor yellow, the standard obovate, conspicuously striate-sulcate in age, usually serrulate, the wings dilated, concave and somewhat spreading at the summit; 2n=16. Native of Eurasia, established as a weed along roadsides and in waste places from Nf. to B.C., to S.C. and Ark. May-Sept. (T. agrarium, a rejected name)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.