Small, usually delicate, annual or perennial herbs; stems often prostrate or nearly so. Lvs sessile or petiolate, very membranous, sometimes all radical. Fls solitary or in racemes, ☿, axillary or terminal. Calyx tube adnate to ovary; lobes nearly equal. Corolla tube cylindric or funnelform; limb somewhat 2-lipped to almost regular; lobes spreading, those of upper lip sometimes narrower, free. Stamens with filaments free; anthers connate, subequal, the 2 smaller setulose. Style simple; stigma surrounded by a hairy brush. Capsule dehiscing by 2 apical valves. Seeds numerous, minute.