Cal slightly irregular, the tube short-cylindric, the lobes 4 through fusion of the upper 2; standard obovate, narrowed to the base, sometimes auricled below the middle; wings and keel slightly shorter, with elongate slender claws exceeding the blade, the wings oblong, auricled at the base of the blade, the keel-pet narrowly obovate, nearly straight, not auricled; stamens 10, diadelphous; anthers all alike; style glabrous; fr flat, oblong, pointed at both ends, mostly 3-seeded; plants producing, in addition to the typical fls and frs as described above, some nearly or wholly apetalous fls on long, filiform branches at the base of the stem, these developing small, 1-seeded, often subterranean frs; twining herbs with pinnately compound lvs of 3 stipellate lfls and small purplish to white fls in axillary racemes or panicles, each pedicel subtended by a striate bract; bractlets none. (Falcata) 3, Afr., Asia, N. Amer.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.