Mesembryanthemum \Me*sem`bry*an"the*mum\, n. [NL., fr. Gr. ? midday + ? flower.] (Bot.) A genus of herbaceous or suffruticose plants, chiefly natives of South Africa. The leaves are opposite, thick, and f?eshy. The flowers usually open about midday, whence the name.
Mesembryanthemum n : South African annual or biennial plants having flowers that open only in bright sunlight [syn: {genus Mesembryanthemum}]