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The families of flowering plants

L. Watson and M.J. Dallwitz

Aizoaceae Rudolphi

Alternatively Ficoideae (Ficoidaceae) Juss.

Including Glinoideae (Glinaceae) Link, Mesembryneae (Mesembryaceae) Dum., Mesembryanthemaceae Fenzl, Sesuviaceae Horan.; excluding Molluginaceae, Tetragoniaceae.

Habit and leaf form. Small shrubs, or herbs. ‘Normal’ plants, or plants of very peculiar vegetative form; commonly more or less neotenic (being often reduced to a single annual pair of leaves, some forms partly subterranean with only a clear window at each leaf tip exposed above-ground). Leaves well developed (usually), or much reduced. Plants succulent. The herbs annual, or perennial; with a basal aggregation of leaves, or without conspicuous aggregations of leaves. Xerophytic. Leaves minute to medium-sized; alternate, or opposite (or in false whorls); often terete; fleshy; imbricate to not imbricate; shortly petiolate to sessile; when opposite, connate, or not connate; sheathing, or non-sheathing; mostly simple; epulvinate. Lamina entire; one-veined, or pinnately veined, or palmately veined. Leaves stipulate, or exstipulate. Vegetative buds not scaly. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina mostly bifacial to centric. Abaxial epidermis papillose, or not papillose. Stomata anomocytic, or anomocytic and paracytic. Hairs present, or absent; eglandular, or glandular; unicellular, or multicellular. Unicellular hairs branched, or simple (sometimes 2-armed). Urticating hairs absent. Adaxial hypodermis absent. Lamina without secretory cavities. Main veins embedded. Minor leaf veins without phloem transfer cells (Mesembryanthemum).

Axial (stem, wood) anatomy. Secretory cavities absent. Cork cambium present, or absent; initially deep-seated. Nodes unilacunar. Primary vascular tissues comprising a ring of bundles, or comprising two or more rings of bundles; collateral. Internal phloem absent. Cortical bundles present (commonly, representing leaf trace bundles). Medullary bundles present, or absent (depending on interpretation?). Secondary thickening absent, or developing from a conventional cambial ring (rather rarely), or anomalous. The anomalous secondary thickening via concentric cambia (in the woodier genera), or from a single cambial ring. Primary medullary rays wide.

The vessel end-walls usually simple. The axial xylem with libriform fibres. ‘Included’ phloem present, or absent. The wood partially storied (VP), or not storied.

Reproductive type, pollination. Plants hermaphrodite (usually), or monoecious (rarely), or dioecious (rarely). Pollination entomophilous (diurnal).

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in heads. The ultimate inflorescence units cymose. Inflorescences cymes and heads. Flowers small, or medium-sized; regular; cyclic; pentacyclic to polycyclic. Free hypanthium present to absent. Hypogynous disk present, or absent.

Perianth sepaline, or with distinct calyx and corolla (generally considered apetalous, but often with colourful, conspicuous staminodal ‘petals’); (1–)4–5(–20), or 20–120 (if the staminodes are interpreted as petals). Calyx (1–)4–5(–8); 1 whorled; gamosepalous (nearly always), or polysepalous (sometimes in Gunniopsis, Galenia); regular, or unequal but not bilabiate (e.g. sometimes with two large members and three smaller); fleshy; persistent; imbricate, or valvate (rarely). Corolla if considered present, 5–120 (of staminodal origin); 1–6 whorled.

Androecium (3–)4–5, or 8–10, or 15–200 (i.e. to ‘many’, by branching). Androecial members commonly branched (by dédoublement), or unbranched; when branched/many, maturing centrifugally; free of one another, or coherent; when coherent 3–9 adelphous (?), or 1 adelphous (the filaments basally connate into bundles, or forming a short monadelphous sheath); 1–16 whorled (i.e to ‘many whorls’). Androecium including staminodes (nearly always), or exclusively of fertile stamens (i.e. occasionally no staminodal ‘petals’). Staminodes when present, 3–120 (usually numerous); external to the fertile stamens; petaloid. Stamens (1–)5, or 6–120 (i.e. to ‘many’); reduced in number relative to the adjacent perianth (rarely), or isomerous with the perianth, or diplostemonous to polystemonous; filantherous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer, or initially with more than one middle layer; of the ‘basic’ type, or of the ‘monocot’ type. Tapetum glandular. Pollen monosiphonous; shed as single grains. Pollen grains aperturate; 3 aperturate; colporate (colporoidate), or colpate; spinulose; 3-celled.

Gynoecium (1–)2–5(–20) carpelled. The pistil (1–)2–5(–20) celled. Gynoecium syncarpous (rarely pseudomonomerous); synovarious to synstylovarious; superior to inferior. Ovary (1–)2–5(–20) locular. Gynoecium non-stylate to stylate. Styles 1–20 (or absent); apical, or apical to lateral (excentric). Stigmas (1–)2–5(–20); wet type, or dry type; papillate; Group II type, or Group III type. Placentation when unilocular (i.e., rarely) parietal; when plurilocular, axile (typically), or basal (rarely), or axile to apical (e.g. Galenia), or parietal (Mesembryanthemum sensu lato). Ovules (1–)50 per locule; arillate, or non-arillate; anatropous, or campylotropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Endothelium not differentiated. Embryo-sac development Polygonum-type (or unspecified). Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped, or hooked (rarely). Endosperm formation nuclear. Embryogeny caryophyllad, or solanad.

Fruit fleshy (rarely), or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry. Capsules loculicidal, or valvular, or septicidal, or circumscissile. Seeds non-endospermic. Perisperm present (mealy). Seeds with starch. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous (2/2); curved. The radicle dorsal.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C4, or CAM. C4 physiology recorded directly in Lithops, Sesuvium, Trianthema, Zaleya — but Lithops salicola and L. venteri are also listed as CAM. CAM recorded directly in Aizoanthemum, Amoebophyllum, Anisocalyx, Aptenia, Argyroderma, Aridaria, Aspazoma, Astridia, Bergeranthus, Brownanthus, Carpobrotus, Carruanthus, Cephalophyllum, Cheiridopsis, Conophytum, Disphyma, Drosanthemum, Eberlanzia, Faucaria, Fenestraria, Hereroa, Jacobsensis, Lampranthus, Lapidaria, Leipoldtia, Lithops, Malephora, Mesembryanthemum, Mestoklema, Meyerophytum, Mitrophyllum, Monilaria, Nananthus, Opophythum, Platythyra, Prenia, Psilocaulon, Rhombophyllum, Ruschia, Sceletium, Sphalmanthus, Stoeberia, Titanopsis, Trichodiadema, Vanheerdia. Anatomy C4 type (Lithops, Sesuvium, Trianthema, Zaleya), or non-C4 type (Aizoon, Carpobrotus, Disphyma, Galenia, Mesembryanthemum, Neogunnia, Sesuvium). Not cyanogenic. Alkaloids present (commonly), or absent. Iridoids not detected. Betalains present. Saponins/sapogenins absent. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present, or absent; when present, kaempferol, or kaempferol and quercetin. Ellagic acid absent (4 species, 4 genera). Aluminium accumulation not found. Plants commonly accumulating free oxalates. Sieve-tube plastids P-type; type III (a).

Geography, cytology. Chiefly southern Africa, but also tropical Africa and Asia, Australia, California, South America. X = 8, 9.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG III core angiosperms; core eudicot; Superorder Caryophyllanae. APG IV Order Caryophyllales.

Species 1100. Genera 126; Acrodon, Acrosanthes, Aethephyllum, Aizoanthemum, Aizoön, Aloinopsis, Amphibolia, Antigibbaeum, Antimema, Apatesia, Aptenia, Arenifera, Argyroderma, Aspazoma, Astridia, Bergeranthus, Berrisfordia, Bijlia, Braunsia, Brownanthus, Carpanthea, Carpobrotus, Carruanthus, Caryotophora, Cephalophyllum, Cerochlamys, Chasmatophyllum, Cheiridopsis, Circandra, Cleretum, Conicosia, Conophytum, Corpuscularia, Cylindrophyllum, Cypselea, Dactylopsis, Delosperma, Dicrocaulon, Didymaotus, Dinteranthus, Diplosoma, Disphyma, Dorotheanthus, Dracophilus, Drosanthemopsis, Drosanthemum, Eberlanzia, Ebracteola, Enarganthe, Erepsia, Esterhuysenia, Faucaria, Fenestraria, Frithia, Galenia, Gibbaeum, Glottiphyllum, Gunniopsis, Hallianthus, Hereroa, Herreanthus, Hymenogyne, Imitaria, Jacobsenia, Jensenobotrya, Jordaaniella, Juttadinteria, Khadia, Lampranthus, Lapidaria, Leipoldtia, Lithops, Machairophyllum, Malephora, Mesembryanthemum, Mestoklema, Meyerophytum, Mitrophyllum, Monilaria, Mossia, Muiria, Namaquanthus, Namibia, Nananthus, Nelia, Neohenricia, Octopoma, Odontophorus, Oophytum, Ophthalmophyllum, Orthopterum, Oscularia, Ottosonderia, Phyllobolus, Pleiospilos, Plinthus, Polymita, Psammophora, Pseudobrownanthus, Psilocaulon, Rabiea, Rhinephyllum, Rhombophyllum, Ruschia, Ruschianthemum, Ruschianthus, Saphesia, Schlechteranthus, Schwantesia, Scopelogena, Sesuvium, Skiatophytum, Smicrostigma, Stayneria, Stoeberia, Stomatium, Synaptophyllum, Tanquana, Titanopsis, Trianthema, Trichodiadema, Vanheerdea, Vanzijlia, Wooleya, Zaleya, Zeuktophyllum.

General remarks. Molluginaceae and Tetragoniaceae (q.v.) seem hardly defensible as separate families. Apart from absence of betalains and differences in photosynthetic pathways (with data for both reflecting limited sampling), Aizoaceae seem to differ from the more variable Molluginaceae sensu stricto (q.v.) only in being succulent. Floral morphological assignments of perianth members to calyx/corolla, stamen counts etc. in this circle of affinity (supposedly important in distinguishing APG-supported segregate families) are unconvincing: cf. Kewaceae, Gisekiaceae, Macarthuriaceae.

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

Illustrations. • Le Maout and Decaisne: Mesembryanthemum. • Trianthema pentandrum: Thonner. • Lampranthus bicolor: Bot. Mag. 2 (1788). • Aethephyllum pinnatifidum, as Mesembryanthemum: Bot. Mag. 2 (1788). • Mesembryanthemum rubrocinctum: Bot. Reg. 1732, 1835. • Mesembryanthemum barbatum: Bot. Mag. 2 (1788). • Semonvillea, fruit. • Acrosanthes humifusa and Zaleya decandra (as Trianthema) - floral diagrams: Engler, Bot. Jahrb 42 (1909). • Leaf anatomy of Aizoon and Mesembryanthemum, with a foliar hair of Glinus (Molluginaceae): Solereder, 1908..

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.