Manawa, commonly known as grey mangrove or white mangrove, is a species of mangrove tree classified in the plant family Acanthaceae. Grey mangroves grow as a shrub or tree to a height of 3 to 10 m (9.8 to 32.8 ft), or up to 14 m in tropical regions. The habit is a gnarled arrangement of multiple branches. It has smooth light-grey bark made up of thin, stiff, brittle flakes. This may be whitish, a characteristic described in the common name. The leaves are thick, 5 to 8 cm (2.0 to 3.1 in) long, a bright, glossy green on the upper surface, and silvery-white, or grey, with very small matted hairs on the surface below.