Sp. Pl. 1: 480. 1753.
Gen. Pl. ed. 5, 215. 1754.
Herbs, annual or perennial, usually short-lived, succulent, usually conspicuously papillate, glabrous. Roots fibrous. Stems prostrate to ascending. Leaves basal and cauline, alternate or opposite, sessile or petiolate; stipules absent; blade reddish with age, flat or terete, margins often undulate. Inflorescences terminal or axillary, flowers solitary or in cymes; bracts absent or 1–2, sessile or pedicellate. Flowers showy, 4–10[–20] mm diam., tubular; calyx lobes (4–) 5, 2 often leaflike; petals (including petaloid staminodia) 20–40[–150], distinct or connate into short tube, free, white, pink, or yellowish, linear; nectary glands 5; stamens 30[–120]; pistil (4–)5-carpellate; ovary half-inferior, (4–)5-loculed, convex; placentation axile; stigmas (4–)5, erect, filiform. Fruits capsules, persistent, valves (4–)5, with expanding interior keels when moistened, forming capsule lids when dried, dehiscence loculicidal. Seeds 100–200, black or dark [light] reddish brown [ochre or whitish], compressed [globose], often with 1 straight edge, 1 mm, smooth to rough with minute tubercles; arils absent.
Introduced; s, w Africa, also introduced in Mexico, South America, Europe (Mediterranean), Asia, Atlantic Islands, Australia.
Species 74 (2 in the flora).
As described here, Mesembryanthemum is the narrowly delineated genus sensu H. M. L. Bolus (1928–1958, part 3, p. 164, fig. 25).
The ability of Mesembryanthemum crystallinum and M. nodiflorum to accumulate and release salt into the surrounding soil is one mechanism by which these species dominate disturbed areas (N. J. Vivrette and C. H. Muller 1977; N. J. Vivrette 1980).