Shrubs or trees, maritime. Branches terete, sometimes 4-ridged when young. Leaves opposite. Inflorescences small spikes or capitula; bracts and bractlets ovate, shorter than calyx, persistent. Flowers small, opposite, sessile. Calyx cup-shaped, deeply 5-lobed; lobes overlapping, persistent. Corolla nearly actinomorphic, campanulate, shortly inserted on an inconspicuous disc; lobes 4 or 5, upper lobe often broader than others. Stamens 4, adnate to apical part of corolla tube. Ovary imperfectly 4-locular, with a free central winged placenta; ovules pendulous. Capsules subtended by persistent calyx, dehiscent into 2 leathery valves.

About 14 species: maritime in tropics and subtropics of both hemispheres, one species in China.

Avicennia is sometimes placed in the monogeneric family Avicenniaceae.