Herbs, annual or perennial, subshrubs, or shrubs, succulent. Stems erect or prostrate. Leaves simple, rarely pinnate, mostly opposite, sometimes alternate, in many species fleshy, margin entire, rarely with teeth; true stipules absent, sometimes a stipule-like sheath present at base of petiole. Inflorescences terminal or seemingly axillary cymes, or solitary flowers. Flowers bisexual, rarely unisexual, actinomorphic, perigynous or epigynous. Nectaries separate or in a ring around ovary. Tepals (4 or)5(–8), connate below into a tube. Petals absent or present. Stamens 3 to many, free or connate at base, outermost often as filamentous staminodes; anthers dehiscing by longitudinal slits. Ovary inferior, syncarpous; carpels 2 to many; ovules 1 to many, on long funicles, mostly campylotropous; placentation axile or parietal, sometimes basal-parietal. Stigmas as many as carpels. Fruit a hygroscopic or circumscissile capsule, more rarely a berry or nut. Seeds with slender embryo curved around perisperm, rarely with an aril; endosperm scanty or absent.
Herbs, shrubs, or subshrubs, annual or perennial, often succulent, papillate, glabrous, hairy, or scaly. Roots usually fibrous, sometimes tuberous. Stems underground, or prostrate and mat-forming to erect. Leaves cauline or basal, alternate or opposite, sessile or petiolate; stipules usually absent, or free from or adnate to petiole; blade flat, terete, or triquetrous (3-angled), occasionally scalelike. Inflorescences axillary or terminal, flowers solitary or in cymes; bracts present or absent; bracteoles usually absent (present in Trianthema, Cypselea); pedicel present or absent. Flowers bisexual (sometimes unisexual in Tetragonia), inconspicuous to showy, tubular or campanulate; hypanthium present; calyx lobes (3-)4-5(-8), sometimes colored and petaloid, occasionally hooded and/or appendaged, equal or unequal; nectary absent, a ring, or separate glands; petals (including petaloid staminodia) 0-250[-300], distinct or connate proximally, often 2-4-seriate, linear; stamens 1-500(-700), distinct or connate in groups; pistil 1, 1-25-carpellate; ovary superior, inferior, or half-inferior, 1-25-loculed; placentation usually parietal, infrequently axile, apical, free-central, or basal; styles absent or 1-25, distinct or partly connate; stigmas 2-25. Fruits usually capsules, dehiscence loculicidal or septicidal, usually with multiple valves, with or without membranes covering seeds, or dehiscence circumscissile, or indehiscent berries, or nutlike. Seeds 1-500(-1000), often arillate, usually papillose; embryo coiled around perisperm.
Fruit capsular, loculicidal or circumscissile
Seeds usually subreniform, not strophiolate; embryo usually curved
Stamens 5–?, hypogynous, sometimes in pairs or in fascicles, when definite alternate with the perianth segments
Ovary superior, of 1–5 united carpels; loculi as many as carpels; ovules 1–? per loculus; placentation parietal, axile or apical
Perianth segments 5, united below into a tube or almost free, ± herbaceous, imbricate or valvate, persistent
Annual or perennial herbs or subshrubs, mostly succulent or subsucculent, glabrous or pubescent
Leaves simple, opposite, alternate or sometimes crowded, exstipulate, sometimes with small stipuliform lobes at base
Inflorescences solitary or in groups, axillary
Succulent or subsucculent annual or perennial herbs or subshrubs, less often shrubs
Leaves simple, alternate, opposite or verticillate, sometimes crowded, often with an expanded membranous base, exstipulate or with membranous stipules
Inflorescences cymose, loosely dichasial to umbelliform or glomerulate (flowers sometimes solitary), axillary or terminal
Flowers regular, hermaphrodite, rarely unisexual
Calyx of 5, less often 4 or 3, members, polysepalous or gamosepalous, usually herbaceous and persistent
Staminodes sometimes present, then often petaloid
Stamens 5-many, hypogynous or episepalous, sometimes fascicled, when definite alternate with the calyx-lobes
Ovary superior or inferior, of 2–5-many united (rarely free) carpels, or of 1 carpel; loculi as many as carpels; ovules one, few, or many per loculus; placentation basal, axile, apical or parietal but not free-central
Fruits usually capsular, loculicidal or circumscissile, sometimes indehiscent, rarely mericarpic
Adamson, R. S. and H. M. L. Bolus. 1950. Aizoaceae. In: R. S. Adamson and T. M. Salter. 1950. Flora of the Cape Peninsula. Cape Town. Pp. 363-365. Boetsch, J. R. 2002. The Aizoaceae and Molluginaceae of the southeastern United States. Castanea 67: 42-53. Brown, N. E., A. Tischer, and M. C. Karsten. 1931. Mesembryanthema. Ashford. Herre, H. 1971. The Genera of the Mesembryanthemaceae. Cape Town. Jacobsen, H. 1976. A Handbook of Succulent Plants.... 3 vols. Poole. Vol. 3. Jacobsen, H. 1977. Lexicon of Succulent Plants..., ed. 2. Poole. Pp. 395-583. Pax, F. A. and K. Hoffmann. 1934. Aizoaceae. In: H. G. A. Engler et al., eds. 1924+. Die natürlichen Pflanzenfamilien..., ed. 2. 26+ vols. Leipzig and Berlin. Vol. 16c, pp. 179-233, 587. Schwantes, G. 1957. Flowering Stones and Mid-day Flowers. London. Smith, G. F. et al. 1998. Mesembs of the World. Pretoria.