Habit and leaf form. Low shrubs, or herbs. Leaves alternate; spiral; petiolate; simple. Leaf blades dorsiventral, or isobilateral; entire; pinnately veined; cross-venulate. Leaves without stipules (but with glands or floral nectaries at the base of the blade). Leaf blade margins dentate. Leaf anatomy. Hairs present. Stem anatomy. Secondary thickening developing from a conventional cambial ring.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants heterostylous. Selfing or entomophilous.
Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; when solitary, axillary; when aggregated, in racemes. Inflorescences epiphyllous (10 species). Flowers (bi-) bracteolate; regular; 5 merous; cyclic; tetracyclic. Free hypanthium present; short to tubular. Perianth with distinct calyx and corolla (without corona); 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; lobed; toothed; imbricate; regular; not persistent. Corolla present; 5; 1 -whorled; polypetalous; contorted; regular; yellow; deciduous. Petals clawed. Androecial members definite in number. Androecium 5. Androecial sequence not determinable. Androecial members free of the perianth (but inserted low on the hypanthium); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; attached inside the hypanthium; isomerous with the perianth; oppositisepalous; all alternating with the corolla members. Anthers dehiscing via longitudinal slits; introrse. Gynoecium 3 carpelled. The pistil 1 celled (placentae 3). Carpels reduced in number relative to the perianth. Gynoecium syncarpous; synovarious; superior. Ovary unilocular; 1 locular; sessile. Gynoecium stylate. Styles 3 (opposite the placentas); free; simple. Stigmas 3 (fringed); commissural (i.e. aligned with the placentas); dry type; non-papillate; Group II type. Placentation parietal. Ovules in the single cavity 25–100 (i.e. ‘many’); funicled; ascending; arillate (with an ostensibly funicular aril); anatropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules valvular (each of the three valves with a median placenta). Fruit mostly many-seeded. Seeds oblong or cylindric, curved; copiously endospermic. Endosperm oily. Seeds arillate. Embryo well differentiated. Cotyledons 2 (planoconvex). Embryo straight. Seedling. Germination phanerocotylar.