Tetragoniaceae Link.
~ Aizoaceae
Habit and leaf form. Sub- shrubs and herbs. Plants succulent; autotrophic. Self supporting, or climbing; some scrambling. Mesophytic, or xerophytic. Leaves alternate; spiral; leathery; petiolate; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves exstipulate. Lamina margins entire.
Leaf anatomy. Stomata present; anomocytic.
Minor leaf veins without phloem transfer cells (Tetragonia).
Stem anatomy. Sieve-tube plastids P-type; type III (a).
Reproductive type, pollination. Plants hermaphrodite, or monoecious, or polygamomonoecious (?).
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes and in racemes. The terminal inflorescence unit cymose. Inflorescences not scapiflorous; few flowered, or racemiform cymes. Flowers small; regular; 3–5 merous. Free hypanthium present (continuous with and textured like the calyx).
Perianth sepaline (but coloured inside); 3–5(–7); joined; 1 whorled; persistent; accrescent. Calyx (the perianth being so interpreted) 3–5(–7); 1 whorled; gamosepalous; regular; fleshy (at least when young, coloured within); persistent; accrescent; induplicate valvate.
Androecium 1–100 (to ‘many’). Androecial members branched, or unbranched; adnate (to the perianth tube); free of one another, or coherent (sometimes fasciculate); 1 adelphous, or 2–5 adelphous (?). Androecium exclusively of fertile stamens. Stamens 1–35; reduced in number relative to the adjacent perianth to polystemonous; oppositisepalous (or at least, the staminal groups antesepalous). Anthers dehiscing via longitudinal slits; bilocular.
Gynoecium (1–)3–8(–10) carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth, or increased in number relative to the perianth. The pistil 1–10 celled. Gynoecium syncarpous; synovarious; partly inferior, or inferior. Ovary (1–)3–8(–10) locular. Styles (1–)3–8(–10); free. Placentation axile, or apical. Ovules 1 per locule; shortly funicled; pendulous; with dorsal raphe; hemianatropous.
Fruit fleshy to non-fleshy; indehiscent; a drupe, or a drupe and a samara (sometimes winged, horned or spiny, crowned by the accrescent perianth). Seeds endospermic. Embryo achlorophyllous (1/1); curved.
Physiology, biochemistry. Plants accumulating free oxalates. C3 and CAM. C3 physiology recorded directly in Tetragonia reduplicata. CAM recorded directly in Tetragonia reduplicata.
Geography, cytology. Mostly Southern hemisphere.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Caryophylliflorae; Caryophyllales. Cronquist’s Subclass Caryophyllidae; Caryophyllales. APG (1998) Eudicot; core Eudicot; neither Rosid nor Asterid; Caryophyllales (as a synonym of Aizoaceae). Species 60. Genera 2; Tetragonia, Tribulocarpus.
Economic uses, etc. Tetragonia expansa is used as table greens (New Zealand spinach).
Illustrations. • Technical details (Tetragonia).
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
