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The families of flowering plants

L. Watson and M.J. Dallwitz

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 (including some mangroves). 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. Leaf development not ‘graminaceous’. Domatia occurring in the family (seen in 11 genera and numerous species); manifested as pits, or pockets, or hair tufts (mostly).

Leaf anatomy. The leaf lamina dorsiventral (usually), or centric (rarely). Hydathodes present (occasionally), or absent. Stomata mainly confined to one surface (usually, abaxial), or on both surfaces; anomocytic. Hairs present (of various kinds); eglandular, or glandular (commonly, of various forms); commonly unicellular. Unicellular hairs branched (commonly 2-armed), or simple. Adaxial hypodermis present, or absent. Lamina with secretory cavities, or without secretory cavities. Secretory cavities containing mucilage. The mesophyll with sclerenchymatous idioblasts (as fibres extending from the veins), or without sclerenchymatous idioblasts; containing crystals. The crystals almost exclusively druses. Minor leaf veins without phloem transfer cells (Combretum).

Axial (stem, wood) anatomy. Secretory cavities present (e.g., canals in Terminalia), or absent; with mucilage. Cork cambium present; initially deep-seated, or initially superficial. Nodes unilacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral, or bicollateral. Internal phloem present, or absent. Secondary thickening developing from a conventional cambial ring, or anomalous. The anomalous secondary thickening from a single cambial ring. Primary medullary rays narrow.

The wood ring porous to diffuse porous. The vessels small to large; solitary (sometimes exclusivey so), or solitary, radially paired, and in radial multiples. The vessel end-walls horizontal to oblique; simple. The vessels with vestured pits (usually), or without vestured pits; without spiral thickening. The axial xylem with tracheids; with vasicentric tracheids (rarely), or without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; at least sometimes including septate fibres, or without septate fibres (?). The fibres without spiral thickening. The parenchyma predominantly paratracheal (typically aliform to confluent, only occasionally scanty). ‘Included’ phloem present (commonly), or absent. The wood not storied.

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 units 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, phytochemistry. Anatomy non-C4 type (Lumnitzera, Terminalia). Sugars transported as oligosaccharides + sucrose. Cyanogenic (?), or not cyanogenic. Alkaloids present, or absent (mostly). Anthraquinones detected (Terminalia); polyacetate derived. Iridoids not detected. Saponins/sapogenins absent. 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). Aluminium accumulation not found.

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 III core angiosperms; core eudicot; Superorder Rosanae; malvid. APG IV 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. • Le Maout and Decaisne: Combretum, Quisqualis. • Combretum racemosa: Thonner. • Combretum coccineum, as C. purpureum: Lindley. • Quisqualis indica: as Q. sinensis, Bot. Reg. 1844, 15. • Terminalia fagifolia: Martius, Nova Gen. et Spec. Pl. Brasiliensium (1824). • Terminalia oliveri: Hook. Ic. Pl. 23 (1894). • Anogeissus bentii: Hook. Ic. Pl. 24 (1895). • Calycopteris, Combretum, Conocarpus, Laguncularia, Terminalia: leaf hairs (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.’.