Including Mouririaceae G. Gardner
Habit and leaf form. Trees and shrubs. Mesophytic. Leaves opposite; petiolate; simple. Lamina entire; lanceolate, or oblong, or ovate; pinnately veined (with a single midrib); cross-venulate. Leaves exstipulate. Lamina margins entire, or serrate (?). Leaves without a persistent basal meristem.
Leaf anatomy. Stomata paracytic.
Lamina without secretory cavities. The mesophyll with sclerencymatous idioblasts, or without sclerenchymatous idioblasts.
Stem anatomy. Young stems cylindrical, or oval in section. Cork cambium present; initially deep-seated, or superficial. Nodes unilacunar. Primary vascular tissue often bicollateral. Cortical bundles absent (always? — 2 genera listed by Metacalfe and Chalk 1950). Medullary bundles absent (at least from the 2 genera listed by Metacalfe and Chalk 1950). Internal phloem present. Secondary thickening developing from a conventional cambial ring, or anomalous; from a single cambial ring. ‘Included’ phloem present. Xylem without fibre tracheids; with vessels. Wood parenchyma paratracheal (only, mostly?), or apotracheal and paratracheal (sometimes?).
Reproductive type, pollination. Plants hermaphrodite (mostly), or androdioecious (Lijndenia). Pollination entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence unit cymose. Inflorescences axillary. Flowers regular to somewhat irregular. The floral irregularity involving the androecium. Flowers 4 merous, or 5 merous; cyclic. Free hypanthium present (tubular or campanulate above the ovary).
Perianth with distinct calyx and corolla; 8–10; 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; gamosepalous; regular; valvate, or open in bud. Corolla 4, or 5; 1 whorled; polypetalous; contorted; regular.
Androecium 4–5, or 8, or 10. Androecial members free of the perianth; all equal, or markedly unequal; free of one another; 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens, or including staminodes. Stamens 4–5, or 8, or 10; isomerous with the perianth, or diplostemonous. Anthers versatile; dehiscing via pores (apically), or dehiscing via short slits, or dehiscing via longitudinal slits; bilocular; initially tetrasporangiate (bisporangiate when mature); appendaged (from the connective, which has a dorsal, concave gland). Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. Tapetum glandular. Pollen grains aperturate; 3 aperturate, or 6 aperturate; colporate, or colpate and colporate (cf. Melastomaceae); 3-celled.
Gynoecium (3–)4–5(–14) carpelled. The pistil 1–5 celled. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary 1(–5) locular. Styles 1; apical. Stigmas 1. Placentation when unilocular, free central; when multilocular, axile to basal. Ovules in the single cavity when unilocular, 3–10; when multilocular, 2–3 per locule; ascending; collateral (in the locules, or whorled when unilocular); anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Endosperm formation nuclear.
Fruit fleshy; indehiscent; a berry; 1–5 seeded. Seeds non-endospermic. Embryo well differentiated (large). Cotyledons 2 (equal). Embryo chlorophyllous (1/2).
Seedling. Germination cryptocotylar.
Physiology, biochemistry. Cyanogenic, or not cyanogenic. Iridoids not detected. Saponins/sapogenins absent. Aluminium accumulation demonstrated (very commonly).
Geography, cytology. Tropical. Pantropical.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Myrtiflorae; Myrtales. Cronquist’s Subclass Rosidae; Myrtales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; malvid; Order Myrtales (as a synonym of Melastomataceae).
Species 430. Genera 7; Klaineastrum (= Warneckea), Lijndenia, Memecylon, Mouriri, Pternandra, Spathandra, Votomita, Warneckea.
Description corrected by S.S. Renner (1992).