Perennial or annual terrestrial herbs, sometimes suffruticose, often with underground parts as rhizomes or tubers. Stem erect or prostrate, simple or branched, sometimes as stolon or runners or assuming a cushion like habit. Leaves simple, radical, in basal rosettes or cauline, alternate, opposite or verticellate, exstipulate, entire or variously lobed, sessile to petiolate, sometimes farinose, revolute, involute or conduplicate in bud. Flowers bisexual, regular, 5(-7-9)-merous, axillary solitary or few or disposed in panicles, racemes or spikes, sometimes in verticels, umbellate or in few flowered or dense capitate heads, fairly large and showy or small and inconspicuous; scape well developed or obsolete. Bracts present, sometimes leafy, often prolonged downwards to form a spur. Bracteoles absent. Pedicels variable in length and may elongate after antheses. Calyx 1/3rd to 2/3rd cleft, persistent. Corolla campanulate, rotate or infundibuliform, 5-lobed, imbricate or convolute, sometimes absent or nodding; tube long or short. Throat may be constricted and sometimes obstructed with hairs. Stamens 5, epipetalous and opposite the corolla lobes. Slender or scale-like staminodes, alternating with corolla lobes present in Samolus. The anther dehiscence introrse and by longitudinal slits; filaments free or adnate at the base of the corolla. Carpels 5, syncarpous. Ovary superior or semi-inferior (Samolus), with one to many ovules on basal or free central placentae; ovules semi-erect or erect (Samolus), usually bitegmic. Style and stigma simple, the latter capitate. Fruit a capsule dehiscing by 5(-10) valves which are opposite the sepals, or irregularly or by a lid (Anagallis). Seeds few to many, testa smooth to vesiculose or papillose, often reticulate or faintly so.