Family Combretaceae
Combretaceae R. Br.Including Myrobalanaceae Juss. ex Martinov, Shaeae (Shaeaceae) Bertol. f., Strephonemataceae (Benth. & Hook. f.) Venkat. & Prak. Rao, Terminaliaceae Jaume St.-Hil. Habit and leaf form. Trees, or shrubs, or lianas. Plants non-succulent. Self supporting, or climbing (commonly); when climbing, stem twiners, or scrambling (via hooks representing persistent petiole bases); Combretum twining anticlockwise. Mesophytic to xerophytic (often in savanna), or helophytic. Leaves alternate, or opposite, or whorled (rarely); spiral, or distichous, or four-ranked; non-sheathing; gland-dotted, or not gland-dotted; without marked odour; simple. Lamina entire; pinnately veined; cross-venulate. Leaves minutely stipulate, or exstipulate. Lamina margins entire. Leaves without a persistent basal meristem. Domatia occurring in the family (from 11 genera and numerous species); manifested as pits, or pockets, or hair tufts (mostly). Leaf anatomy. Hydathodes present (occasionally), or absent. Lamina dorsiventral (usually), or centric (rarely); with secretory cavities, or without secretory cavities. Secretory cavities containing mucilage. Minor leaf veins without phloem transfer cells (Combretum). Stem anatomy. Secretory cavities present, or absent; with mucilage. Cork cambium present; initially deep-seated, or superficial. Nodes unilacunar. Internal phloem present, or absent. Secondary thickening developing from a conventional cambial ring, or anomalous; from a single cambial ring. ‘Included’ phloem present (commonly), or absent. Xylem with fibre tracheids; with libriform fibres, or without libriform fibres. Vessel end-walls horizontal to oblique; simple. Vessels with vestured pits (usually), or without vestured pits. Wood parenchyma predominantly paratracheal. Reproductive type, pollination. Plants hermaphrodite, or andromonoecious; viviparous (in the mangroves), or not viviparous. Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, in spikes, and in heads. The ultimate inflorescence unit usually racemose. Inflorescences usually racemose. Flowers usually small; regular; 3–8 merous; cyclic; tetracyclic, or pentacyclic. Free hypanthium present. Perianth with distinct calyx and corolla, or sepaline (the corolla sometimes absent); 4–5, or 9–10(–16); 1 whorled, or 2 whorled; isomerous. Calyx 4–5(–8); 1 whorled; gamosepalous (as lobes from the hypanthium); regular; persistent; imbricate, or valvate (or very small). Corolla when present, 4–5(–8); 1 whorled; polypetalous; when present, imbricate, or valvate; regular. Androecium often 10 (commonly twice K), or 5 (sometimes outer whorl missing), or 10–100 (rarely ‘many). Androecial members free of the perianth; all equal; free of one another (usually), or coherent (rarely grouped); 2 whorled (usually), or 1 whorled (sometimes the outer missing), or 3 whorled (rarely). Androecium exclusively of fertile stamens. Stamens 5, or 10, or 11–30; isomerous with the perianth, or diplostemonous (commonly), or polystemonous; oppositisepalous. Anthers dorsifixed; versatile; dehiscing via longitudinal slits; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer (Guiera), or initially with more than one middle layer (usually); usually of the ‘basic’ type (Guiera). Tapetum glandular. Pollen grains aperturate; 3 aperturate; colporate; 2-celled. Gynoecium 2–5 carpelled. The pistil 1 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; inferior. Ovary 1 locular. Epigynous disk present. Gynoecium stylate (mainly), or non-stylate (e.g. sometimes in male flowers of Terminalia). Styles 1. Stigmas wet type; non-papillate; Group IV type. Placentation apical. Ovules in the single cavity 2–5(–6); pendulous; non-arillate; anatropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type, or Penaea-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (somewhat, in Guiera), or not proliferating. Synergids hooked (sometimes with filiform apparatus). Endosperm formation nuclear. Embryogeny asterad. Fruit fleshy, or non-fleshy; indehiscent (usually), or dehiscent; a drupe (usually, often samaroid), or a capsule (rarely), or a samara, or capsular-indehiscent (?). The drupes with separable pyrenes (sometimes with the endocarp split longitudinally into unequal halves, e.g. Terminalia), or with one stone (usually). Dispersal often by water, by animals or by wind (the wind-dispersed forms winged). Fruit usually 1 seeded (by abortion). Seeds non-endospermic. Embryo well differentiated (the cotyledons usually convolute, sometimes folded, sometimes massive and hemispherical). Cotyledons 1 (by concrescence), or 2, or 3; folded, or rolled, or twisted (rarely planoconvex). Embryo chlorophyllous (2/2), or achlorophyllous (1/1). Seedling. Germination phanerocotylar, or cryptocotylar. Physiology, biochemistry. Cyanogenic (?), or not cyanogenic. Alkaloids present, or absent (mostly). Iridoids not detected. Arthroquinones detected (Terminalia); polyacetate derived. Proanthocyanidins present, or absent; when present, cyanidin. Flavonols present, or absent; kaempferol, or kaempferol and quercetin, or kaempferol, quercetin, and myricetin. Ellagic acid present (3 genera, 4 species). Saponins/sapogenins absent. Aluminium accumulation not found. Sugars transported as oligosaccharides + sucrose. Anatomy non-C4 type (Lumnitzera, Terminalia). Geography, cytology. Sub-tropical and tropical. Widespread. X = 7, 11–13. 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. Species 600. Genera about 20; Anogeissus, Buchenavia, Bucida, Calopyxis, Calycopteris, Combretum, Conocarpus, Dansiea, Guiera, Laguncularia, Lumnitzera, Macropteranthes, Melostemon, Pteleopsis, Quisqualis, Strephonema, Terminalia, Terminaliopsis, Thiloa. Illustrations. |
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