Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

Mesembryanthemum
     n : South African annual or biennial plants having flowers that
         open only in bright sunlight [syn: {genus
         Mesembryanthemum}]