Sep 5, distinct or nearly so, elongate, usually unequal; cor tubular or narrowly campanulate, bilabiate, the lobes of the upper lip united nearly to the tip, hairy at the base within, those of the lower lip rounded; stamens 2, inserted near the middle of the cor-tube; second pair of stamens represented by minute sterile filaments, or none; connective of anthers in most spp. expanded and saucer-shaped, longer and wider than the transverse pollen-sacs, or in G. pilosa not expanded, shorter and narrower than the longitudinal pollen-sacs; stigmas 2, plate-like; fr septicidal or also loculicidal; small annual or perennial herbs with opposite lvs and small yellow or white fls on solitary axillary pedicels, usually subtended by a pair of sep-like bractlets just beneath the cal. 20, widespread.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.