Stout erect annual 5-20 dm with 4-angled stems and no tendrils; lfls 2 or 3 pairs, large, ovate or elliptic, 4-10 cm; fls 20-30 mm, mostly white, veined with violet, the wings with a large violet spot; fr 8-20 × 1-3 cm, with 2-4 large seeds; 2n=14. Long cult. in Europe, occasionally cult. in Amer. and rarely escaped.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.