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.