Description from Flora of China
Herbs annual or perennial, rarely shrubs or trees, sometimes with swollen stems. Leaves opposite, sometimes alternate on upper part of stem, densely covered with 4-merous mucilaginous glands; stipules absent. Flowers zygomorphic, solitary, axillary, rarely in few-flowered cymes. Pedicel with extrafloral nectaries. Calyx (4 or)5-parted. Corolla bilabiate or obscurely so; lobes 5, imbricate. Stamens 4 and didynamous, sometime 2; staminodes usually 1; anthers 2-locular, dehiscing longitudinally. Disc fleshy. Ovary superior or rarely inferior, 2- or 4-locular; placentation axile; ovules 2 to numerous, anatropous. Style filiform; stigma 2-lobed. Fruit dehiscent or indehiscent, winged or usually with horns or hooks. Seeds 1 to many in each locule.
About 13 or 14 genera and 62-85 species: primarily tropical and subtropical parts of the Old World, especially Africa; two genera and two species in China.
Tao Deding. 1990. Pedaliaceae. In: Wang Wentsai, ed., Fl. Reipubl. Popularis Sin. 69: 63-66.
(Authors: Zhang Zhi-yun; Heidrun E. K. Hartmann)