Description from Flora of China
Shrubs, deciduous; branches hollow or with solid pith. Leaves simple, opposite, margin entire or serrate, occasionally sinuate; stipules present or absent. Inflorescence a spike or flowers in sessile whorls of 6, terminal or axillary, often with conspicuous leaflike involucral bracts. Sepals 5. Corolla 5-lobed, white, pink, purple-red, or orange-yellow, funnelform, regular; tube gibbous at base. Stamens 5; anthers dorsifixed. Ovary 5-, 7-, or 8-locular, with numerous ovules per locule; style long, slender; stigmas peltate or capitate. Fruit a berry, with persistent calyx; seeds minute, numerous.
Five species: Sino-Himalayan region; four species in China.