Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Cal eventually deciduous, the tube campanulate, the lobes subequal, subulate to lanceolate, acute or acuminate; pet separate; standard oblong to obovate, usually longer than the others; wings and keel coherent, but the wings not spurred on the surface and with only a short basilateral lobe; stamens 10, diadelphous; ovary short, sessile or somewhat stipitate, but the style ± elongate; pod ovate or rotund, slightly compressed to subglobose, 1–4-seeded, usually indehiscent; annual or biennial (seldom short-lived perennial) herbs with 3-foliolate, serrulate lvs, the terminal lfl stalked; fls white or yellow, small, numerous in elongate peduncled racemes from the upper axils, with a repeating trip-mechanism; stipules partly adnate to the petiole. 20, Old World.