Much branched annual 1-3 dm; stems glandular-villosulous; lvs 1-2 cm, deeply and ±ternately divided into short, obtuse, oblong segments; petioles 5-10 mm; bracts not much smaller than the lvs; fls usually 4-6 at each node, on pedicels 4-8 mm; cal strongly saccate at base, especially in age, eventually to 1 cm, its lobes shorter than the tube, broadly triangular, the 2 lower somewhat the smaller; cor 15-20 mm; 2n=32. Native of Europe, occasionally intr. in waste places from N. Engl. to O. and W.Va. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.