The families of flowering plants

L. Watson and M.J. Dallwitz

Dichapetalaceae Baill.

Including Chailletiaceae R.Br., Hirtellaceae Horan. (p.p.)

Habit and leaf form. Small trees, shrubs, and lianas; non-laticiferous. Self supporting, or climbing. Mesophytic, or xerophytic. Leaves alternate; spiral; ‘herbaceous’, or leathery; petiolate; non-sheathing; simple. Lamina entire; pinnately veined; cross-venulate. Leaves stipulate. Stipules intrapetiolar; caducous. Lamina margins entire. Leaf development not ‘graminaceous’. Domatia occurring in the family; manifested as pits.

Leaf anatomy. The leaf lamina usually dorsiventral. Mucilaginous epidermis usually present. Stomata present; mainly confined to one surface (abaxial); paracytic (see illustration). Hairs present; exclusively eglandular; unicellular. Unicellular hairs simple (with wartlike papillae: see illustration). Adaxial hypodermis present (sometimes with mucilage cells), or absent. The mesophyll containing mucilage cells (often), or not containing mucilage cells; containing crystals. The crystals druses and solitary-prismatic.

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 mixed wide and narrow.

The wood diffuse porous. The vessels solitary and radially paired, or radially paired and in radial multiples, or clustered. The vessel end-walls simple, or scalariform and simple. The vessels with vestured pits; without spiral thickening. The axial xylem with tracheids, or without tracheids (depending on interpretation?); without vasicentric tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; without septate fibres. The fibres without spiral thickening. The parenchyma apotracheal, or paratracheal; wood not storied. Tyloses present, or absent.

Reproductive type, pollination. Plants hermaphrodite, or monoecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes and in fascicles. The ultimate inflorescence units cymose. Inflorescences axillary (to petiolar), or epiphyllous; dichotomous cymes or fascicles. Flowers small; regular, or somewhat irregular; cyclic. Free hypanthium absent. Hypogynous disk present; of separate members, or annular (when a corolla tube present).

Perianth with distinct calyx and corolla; 8, or 10; 2 whorled; isomerous. Calyx (4–)5; 1 whorled; polysepalous, or gamosepalous (sometimes basally connate); imbricate. Corolla (4–)5 (the petals usually two-lobed or bifid); 1 whorled; polypetalous (usually), or gamopetalous (rarely with a basal tube). Corolla lobes markedly longer than the tube. Corolla imbricate; regular, or unequal but not bilabiate. Petals broadly clawed, or sessile; deeply bifid, or bilobed, or entire (rarely).

Androecium (4–)5. Androecial members free of the perianth, or adnate (sometimes epipetalous); all equal; free of one another, or coherent; 1 whorled. Androecium exclusively of fertile stamens (usually), or including staminodes (rarely). Staminodes when present, 2 (then with three fertile stamens); in the same series as the fertile stamens. Stamens 3, or 5; reduced in number relative to the adjacent perianth, or isomerous with the perianth; oppositisepalous; filantherous, or with sessile anthers. Anthers dehiscing via longitudinal slits (the connective often dorsally thickened). Pollen grains aperturate; 3 aperturate; colporate.

Gynoecium 2 carpelled, or 3(–4) carpelled. The pistil 2 celled, or 3(–4) celled. Gynoecium syncarpous; synovarious, or synstylovarious; superior to inferior. Ovary 2 locular, or 3(–4) locular. Styles 1 (usually), or 2–3(–4) (rarely); free (rarely), or partially joined; apical. Placentation apical. Ovules 2 per locule; pendulous; epitropous (micropyle superior); with ventral raphe; arillate (often carunculate), or non-arillate; anatropous.

Fruit fleshy (rarely), or non-fleshy; indehiscent; a drupe. The drupes with one stone (1–3 locular). Seeds non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo straight.

Seedling. Germination cryptocotylar.

Physiology, phytochemistry. Sugars transported as oligosaccharides + sucrose (in Tapura). Alkaloids present, or absent. Saponins/sapogenins absent. Aluminium accumulation not found.

Geography, cytology. Sub-tropical to tropical. Pantropical. X = 20, 24.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Euphorbiales. Cronquist’s Subclass Rosidae; Celastrales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Malpighiales.

Species 200. Genera 3; Dichapetalum, Stephanopodium, Tapura, (Gonypetalum, Falya).

Economic uses, etc. The poisonous seeds of Dichapetalum toxicarium have been used in West Africa to kill rats.

Illustrations. • Dichapetalum leucosepalum: Thonner. • Dichapetalum pedunculatum, as Chailletia: Lindley. • Tapura amazonica, as T. ciliata: Hook. Ic. Pl. 5 (1842–3). • Abaxial leaf epidermis of Tapura amazonica, with stomata and a papillate hair: 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.’.