Erect or creeping, annual or perennial herbs, glabrous except for corolla and stamens, not heterostylous. Lvs opposite, alternate or verticillate, entire. Fls axillary, mostly solitary; pedicels often slender, rarely almost 0. Calyx deeply 5-lobed; lobes narrow. Corolla deeply 5-lobed, rotate or funnelform; tube very short. Stamens inserted at or near base of corolla tube, free or connate at base, reticulate or papillose. Capsule globose, circumscissile. Seeds numerous.

Perennial, heterostylous herbs or occasionally subshrubs, usually erect, sometimes prostrate. Lvs mostly opposite or whorled, entire. Fls 5-(7)-merous, in axillary or terminal racemes or panicles, or solitary and axillary; pedicels of varying lengths. Calyx divided almost or completely to base; lobe width very variable. Corolla rotate or campanulate; tube very short. Stamens inserted on corolla tube, sometimes unequal, sometimes partly monadelphous; filaments often scaly. Capsule globose or ovoid, 5-(7)-valved. Seeds few to many, rugose.