Perennial, biennial or annual herbs, pubescent and often glandular. Leaves mostly alternate, sometimes with some leaves opposite, petiolate or sessile. Inflorescences terminal, a simple or branched scorpioid cyme; bracts present. Flowers sessile or pedicellate; sepals 5, connate at base, often elongating with age; corolla regular, 5-lobed, tubular to rotate, deciduous or marscescent, violet to blue or white, often with a pair of scales near the base of each filament; stamens exserted from or included in corolla-tube, filaments shorter or longer than corolla, anthers elliptic to oblong or globose; ovary 2-celled, style cleft, shortly bifid to divided nearly to base; stigmas 2, capitate. Fruit a loculicidal capsule, globose to ovoid; seeds 2–more than 100.
c. 200 species, mostly western U.S.A and Mexico, with a few species elsewhere in the Americas; 1 species naturalised in Australia.
Sometimes treated in Hydrophyllaceae.