Family Uapacaceae

Uapacaceae (Muell. Arg.) Airy Shaw

~ Euphorbiaceae

Habit and leaf form. Trees, or shrubs; non-laticiferous and without coloured juice; more or less pachycaul (the leaves crowded towards the branch tips). Leaves alternate; simple. Lamina entire; more or less cuneate obovate. Leaves stipulate.

Stem anatomy. Secondary thickening developing from a conventional cambial ring. Vessel end-walls simple. Vessels without vestured pits. Wood parenchyma paratracheal (and some scattered cells).

Reproductive type, pollination. Plants dioecious. Gynoecium of male flowers pistillodial (large, obconical, funnel- or mushroom-shaped, sometimes lobed).

Inflorescence, floral, fruit and seed morphology. Flowers solitary (female), or aggregated in ‘inflorescences’ (male); those of the male inflorescences in heads (these globular, capitate, pedunculate). Inflorescences and the solitary female flowers with involucral bracts (those of the male inflorescences 5–10, large, much imbricate); of male flowers pseudanthial (the involucre calycine). Free hypanthium absent. Hypogynous disk absent.

Perianth sepaline (male flowers), or vestigial (female flowers); of male flowers, 5–6; 1 whorled. Calyx of male flowers 5–6 (in female flowers, more or less sinuous or truncate); 1 whorled; gamosepalous; entire to lobulate (female flowers), or lobulate, or blunt-lobed, or toothed (male flowers); in male flowers, more or less campanulate (or turbinate).

Androecium of male flowers 4–6, or 8–12. Androecial members free of the perianth; free of one another; 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 4–6 (pilose, alternating with the stamens). Stamens 4–6; isomerous with the perianth; oppositisepalous; erect in bud. Anthers introrse. Pollen grains aperturate; 3(–4) aperturate; colporate.

Gynoecium (2–)3(–4) carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. The pistil (2–)3(–4) celled. Gynoecium syncarpous; synovarious; superior. Ovary (2–)3(–4) locular. Gynoecium stylate. Styles (2–)3(–4); free (thick, laciniate, recurved); apical. Placentation apical. Ovules 2 per locule; pendulous.

Fruit fleshy; indehiscent; a drupe. The drupes with separable pyrenes (these usually three, dorsally bisulcate). Seeds endospermic (the endosperm fleshy). Micropyle not zigzag.

Physiology, biochemistry. Inulin not found.

Geography, cytology. Paleotropical. Tropical. Tropical Africa, Madagascar.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Euphorbiales. Cronquist’s Subclass Rosidae; Euphorbiales. APG 3 core angiosperms; core eudicot; Superorder Rosanae; fabid; Order Malpighiales (as a synonym of Euphorbiaceae).

Species 50. Genera 1; only genus, Uapaca.