SESUVIUM, in botany; a genus of plants belonging to the class of icofandria, and to the order of trigynia. The calyx is coloured and divided into five parts; there are no petals; the capsule is egg-shaped, three-celled, opening horizontally about the middle, and containing many seeds. There is only one species, the portulacastrum, purslane-leaved seuvium, which is a native of the West Indies.