Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Cal deeply bilabiate, the upper lip 2-toothed, the lower entire or 3-lobed; standard suborbicular with strongly reflexed sides; wings united toward the summit; keel-pet strongly convex on the lower side, prolonged into a beak-like apex; stamens 10, monadelphous into a closed tube for about half their length; anthers alternately linear or minute and subglobose; pods oblong, flattened, with 2–several seeds; herbs with palmately compound, 1–many-foliolate lvs and handsome white, yellow, pink, or blue fls in terminal racemes or spikes. 200, widespread.