Rhizophora mucronata is a small to medium size evergreen tree growing to a height of about 20 to 25 metres (66 to 82 ft) on the banks of rivers. On the fringes of the sea 10 or 15 metres (33 or 49 ft) is a more typical height. The tallest trees are closest to the water and shorter trees are further inland. The tree has a large number of aerial stilt roots buttressing the trunk. The leaves are elliptical and usually about 12 centimetres (4.7 in) long and 6 centimetres (2.4 in) wide. They have elongated tips but these often break off. There are corky warts on the pale undersides of the leaves. The flowers develop in axillary clusters on the twigs. Each has a hard cream-coloured calyx with four sepals and four white, hairy petals. The seeds are viviparous and start to develop whilst still attached to the tree. The root begins to elongate and may reach a length of a metre (yard) or more. The propagule then becomes detached from the branch when sufficiently well developed to root in the mud below.