Description: Erect herbs or shrubs, with cystoliths; branches angular, constricted above each node.
Inflorescences axillary, flowers sessile, solitary or in few-flowered cymes; bracts [small] or conspicuous and obcordate; bracteoles small or absent. Calyx segments 5. Corolla tube wider above, 2-lipped; upper lip triangular, notched, lower lip 3-lobed and slightly longer than upper one. Stamens 2. Ovary with 2 ovules per loculus.
Capsule ellipsoid; seeds usually 4, discoid, smoothly tuberculate all over.
Distribution and occurrence: World: 5–10 species, India, China, Malesia & Australia. Australia: 1 species ( probably endemic).
Text by J. Everett