The families of flowering plants
Including Millingtoniaceae Wight & Arn., Wellingtoniaceae Meissn.
Habit and leaf form. Trees and shrubs. Leaves evergreen; alternate; leathery; petiolate; simple (?), or compound; when simple, pinnate (imparipinnate, with opposite leaflets), or unifoliolate (when simple?). Lamina when compound, entire. Leaves exstipulate. Lamina margins of entire leaves or leaflets entire, or serrate.
Leaf anatomy. The leaf lamina dorsiventral. Stomata present; mainly confined to one surface (abaxial); anomocytic, or paracytic. The mesophyll containing crystals. The crystals druses.
Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays rather narrow (tending to be distally triangular in the phloem).
The wood diffuse porous. The vessels solitary, radially paired, and in radial multiples (i.e., both solitary and in radial multiples of 2 or three). The vessel end-walls simple, or scalariform and simple. The vessels without vestured pits; without spiral thickening. The axial xylem without fibre tracheids (the bordered pits very small); with libriform fibres; including septate fibres, or without septate fibres. The fibres with spiral thickening. The parenchyma scanty paratracheal. Included phloem absent. The wood not storied.
Reproductive type, pollination. Plants hermaphrodite, or polygamodioecious.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in inflorescences; in panicles. Inflorescences compound panicles. Flowers small; very irregular; zygomorphic; cyclic. Free hypanthium absent. Hypogynous disk present; annular (cupular, 38 dentate, the teeth sometimes bifid).
Perianth with distinct calyx and corolla; 8–10; 2 whorled; isomerous. Calyx 4, or 5; 1 whorled; polysepalous; imbricate, or open in bud. Corolla 4, or 5; 1 whorled; opposite the calyx; polypetalous (the petals rounded); imbricate (sometimes subvalvate); unequal but not bilabiate (the two inner members small, sometimes bifid, sometimes linear-acute and then subvalvate).
Androecium 5. Androecial members free of the perianth, or adnate (to the bases of the petals); markedly unequal; free of one another; 1 whorled. Androecium of male and hermaphrodite flowers including staminodes. Staminodes 3 (these smaller, opposite the larger petals); in the same series as the fertile stamens. Stamens 2; isomerous with the perianth; alternisepalous; opposite the corolla members (opposite the reduced petals); filantherous (the filaments flattened). Anthers with a much expanded connective; dehiscing by large openings; bilocular (didymous, large, globular). Endothecium developing fibrous thickenings. Anther wall initially with more than one middle layer (two). Pollen grains aperturate; 3 aperturate; colporate (or colporoidate); 2-celled (in Meliosma).
Gynoecium 2–3 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled, or 3 celled. Gynoecium syncarpous; synovarious to eu-syncarpous; superior. Ovary 2 locular, or 3 locular. Gynoecium stylate. Styles 1–3; if detectably 23, partially joined; apical. Stigmas 1–3; dry type; non-papillate; Group II type. Placentation axile. Ovules 2 per locule; pendulous, or horizontal; superposed; hemianatropous; unitegmic; crassinucellate. Outer integument not contributing to the micropyle (and no micropyle formed). Embryo-sac development Polygonum-type. Endosperm formation helobial.
Fruit fleshy; indehiscent; a drupe. The drupes with one stone (usually one locular, rarely bilocular). Fruit 1 seeded. Seeds non-endospermic. Embryo at least sometimes coiled (sometimes more or less spirally contorted).
Physiology, phytochemistry. Not cyanogenic. Proanthocyanidins present.
Geography, cytology. Paleotropical and Neotropical. Sub-tropical. Warm Asia, America. 2n = 32 (Meliosma).
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgrens Superorder Rosiflorae (tentatively re-assigned from Rutiflorae, cf. Chase et al 1993); near Hamamelidales (?). Cronquists Subclass Magnoliidae; Ranunculales. APG 3 core angiosperms; peripheral eudicot; cf. Superorder Proteanae; Order Sabiales (as a synonym of Sabiaceae).
Species 105. Genera 2; Meliosma, Ophiocaryon (Phoxanthus).
General remarks. Meliosmaceae are supposed to be readily distinguishable from Sabia (q.v.) by the zygomorphic flowers and the androecium comprising 3 staminodes and 2 fertile stamens.
Illustrations. • Meliosma cuneifolia: Bot. Mag. 1487 (1911). • Technical details: Meliosma (Hutchinson).
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: 13th March 2017. delta-intkey.com/angio’.