Description from Flora of China
Herbs (perennial or rarely annual), or rarely shrubs, sometimes lianous. Stems usually branched. Petiole base slightly expanded or auriculate, clasping or nearly clasping. Inflorescences spicate-racemose; spikelets 1-flowered; bracts and bractlets herbaceous, greenish. Flowers conspicuous. Pedicel very short, persistent. Calyx tubular, ribs herbaceous and with stalked glands, membranous between ribs; limb not expanded but enlarging after anthesis; lobes minute, usually triangular. Corolla salverform, tube much longer than calyx, limb rotate, lobes apically rounded or acuminate. Stamens hypogynous, as long as corolla tube; filaments basally expanded; anthers linear. Ovary ellipsoid, ovoid, or pyriform. Styles connate, terminally 5-branched; stigma on inner surface of style branches, covered with stalked or sessile glands.
About 17 species: mainly in tropics; two species in China.