Tetramelaceae (Warb.) Airy Shaw
~ Datiscaceae
Habit and leaf form. Large, often buttressed trees. Mesophytic. Leaves alternate; petiolate; non-sheathing; simple. Lamina entire; ovate; palmately veined; cross-venulate; cordate. Leaves exstipulate. Lamina margins entire, or dentate. Leaves without a persistent basal meristem.
Leaf anatomy. Stomata present; anomocytic.
Lamina dorsiventral. The mesophyll with sclerencymatous idioblasts (at least in Octomeles). Minor leaf veins without phloem transfer cells (Tetrameles).
Stem anatomy. Cork cambium present; initially superficial. Secondary thickening developing from a conventional cambial ring. Vessel end-walls simple. Wood partially storied (VPI); parenchyma paratracheal.
Reproductive type, pollination. Plants dioecious. Female flowers without staminodes.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in spikes and in panicles. Inflorescences terminal, or axillary; terminal panicles or axillary, solitary spikes. Flowers regular to somewhat irregular; cyclic. Free hypanthium present (the corolla inserted on the calyx).
Perianth with distinct calyx and corolla, or sepaline; 4, or 1216; 1 whorled, or 2 whorled; isomerous. Calyx 4, or 68; 1 whorled; gamosepalous; unequal but not bilabiate, or regular; valvate. Corolla when present, 68; 1 whorled; polypetalous; valvate.
Androecium 4, or 68. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens (in the male flowers). Stamens 4, or 68; isomerous with the perianth. Anthers dorsifixed; dehiscing via longitudinal slits; extrorse; bilocular. Pollen grains aperturate; 3 aperturate; colporate.
Gynoecium 4 carpelled, or 68 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synovarious; inferior. Ovary 1 locular. Gynoecium stylate. Styles 4, or 68; free; apical. Placentation parietal. Ovules in the single cavity 20100 (many); pendulous to horizontal; anatropous; bitegmic.
Fruit non-fleshy; dehiscent; a capsule. Capsules valvular. Fruit 20100 seeded (many). Seeds scantily endospermic, or non-endospermic (?); minute. Embryo straight.
Peculiar feature. The young, syncarpous unilocular gynoecium and later the capsule open.
Geography, cytology. Tropical. Southeast Asia, Malaysia, Australia. X = 11, 23 (or more).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Myrtiflorae (?); Myrtales (? - cf. Lythraceae). Cronquists Subclass Dilleniidae; Violales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid I; Cucurbitales. Species 2. Genera 2; Tetrameles, Octomeles.
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).