Webster’s Revised Unabridged Dictionary · 1913
Mesembryanthemum
Me·sem′bry·an′the·mum (mē·sĕm′brĭ·ăn′thē·mŭm), n. [NL., fr. Gr. μεσημβρία midday + ἄνθος flower.] (Bot.) A genus of herbaceous or suffruticose plants, chiefly natives of South Africa. The leaves are opposite, thick, and fleshy. The flowers usually open about midday, whence the name.