Description from Flora of China
Herbs or shrubs, glabrous or pubescent, occasionally glandular, bristly, or thorny. Leaves alternate or opposite, occasionally in a basal rosette, simple or variously lobed or divided, without stipules. Inflorescences solitary flowers, cymose, or paniculate. Flowers bisexual, actinomorphic, usually 5-merous, often showy. Calyx ± gamosepalous, sinuses sometimes appendaged. Corolla gamopetalous, campanulate, tubular, or rotate; lobes overlapping in bud. Stamens usually 5; filaments attached to corolla, often alternating with scalelike appendages; anthers 2-locular, longitudinally dehiscent. Ovary superior, 1- or 2- (several) locular, with 2 parietal placentae; ovules few or numerous. Styles 1 or 2, usually lobed or divided; stigma capitate. Fruit a loculicidal capsule, rarely also septicidal or opening irregularly. Seeds usually with a sculptured or pitted coat; endosperm enclosing a small embryo.
Eighteen to 22 genera and ca. 300 species: mostly in North and South America, with a few in Africa, Asia, and Australia; one genus with one species in China.
Fang Rhui-cheng & Huang Shu-hua in Wu Cheng-yih, ed. 1979. Hydrophyllaceae. Fl. Reipubl. Popularis Sin. 64(1): 160-161.
(Authors: Fang Rhui-cheng; Lincoln Constance)