Mesembryanthemum L.

Scientific Description

Common name. Iceplants. Family Aizoaceae.

Habit and leaf form. Small, erect or prostrate shrubs (or subshrubs), or herbs. Plants succulent. The herbs annual, or biennial, or perennial. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Stem internodes solid. Xerophytic. Leaves minute to medium-sized; alternate (on lower branches), or opposite (sometimes, on flowering branches); fleshy; imbricate to not imbricate; subsessile, or sessile; connate, or not connate; sheathing, or non-sheathing; simple; epulvinate. Leaf blades entire; flat, or solid; semi-terete; ovate, or obovate (to spathulate); one-veined, or pinnately veined, or palmately veined. Leaves without stipules. Leaf blade margins entire (rigidly ciliate). Vegetative buds not scaly. Leaves without a persistent basal meristem. Leaf anatomy. Urticating hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring, or anomalous; via concentric cambia (in the woodier genera,), or from a single cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous (diurnal).

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; (when aggregated) in cymes, or in heads. The terminal inflorescence unit (when flowers aggregated) cymose. Inflorescences terminal, or axillary, or leaf-opposed (or in forks of branches (unclear which applies to the solitary or inflorescence condition)); cymes and heads. Flowers pedicellate, or sessile (shortly pedicellate); ebracteate; ebracteolate; small, or medium-sized; regular; cyclic; pentacyclic to polycyclic. Free hypanthium present; incorporating calyx, staminodes and stamens. Hypogynous disk present, or absent. Perianth sepaline (considered apetalous, but with colourful, conspicuous staminodal ‘petals’); 4–5. Calyx present; 4–5; 1 -whorled; gamosepalous; imbricate; unequal but not bilabiate (with 2 large and 3 smaller members, the former often leaf-like, the smaller ones with membranous margins); fleshy; persistent. Corolla absent (as usually interpreted). Androecial members indefinite in number. Androecium 25–200 (i.e. to ‘many’ branching). Androecial members branched (by dédoublement). Androecial sequence determinable. Androecial members maturing centrifugally; all equal; coherent; 1 - adelphous (the filaments basally forming a short monadelphous sheath); 3–16 -whorled (i.e in several or many series). Androecium including staminodes. Staminodes 20–50 (many, outside the stamens); petaloid (white). Stamens 20–100 (many); polystemonous; filantherous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed as single grains. Gynoecium 4–5 carpelled. The pistil (4–)5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior to inferior. Ovary plurilocular; (4–)5 locular; sessile. Gynoecium stylate. Styles (4–)5. Stigmas (4–)5. Placentation parietal. Ovules 20–50 per locule (numerous); arillate, or non-arillate; anatropous, or campylotropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Fruit (4–)5 celled; 20–100 seeded (many). Seeds non-endospermic. Perisperm present (mealy). Embryo well differentiated. Cotyledons 2. Embryo curved.

Economic uses, etc. Edible fruit from Mesembryanthemum edule (Hottentot fig).

Etymology. The earliest name Mesembrianthemum referred to flowering at mid-day, but when night-flowering species were discovered the name was changed to the present spelling with a y: a change in meaning without a change of sound.