Sharply spinous shrubs. Lvs reduced to a spine-like tip or a small scale; stipules 0. Fls solitary or shortly racemose, axillary; bracts small; bracteoles small and broad, inserted below calyx, minute, or 0. Calyx membranous, usually yellowish, 2-partite with upper lip 2-toothed and lower lip 3-toothed. Corolla yellow; petals obtuse; keel hairy. Stamens monadelphous; tube entire; anthers alternately long and basifixed or short and versatile. Style somewhat curved; stigma capitate. Pod 2-valved and explosively dehiscent, 1-6-seeded; seeds strophiolate.