Habit and leaf form. Small shrubs. Plants succulent. Leaves cauline. Plants with neither basal nor terminal concentrations of leaves. Young stems cylindrical. Stem internodes stems to 1m long, nodes distant. Xerophytic. Leaves minute to medium-sized; opposite; fleshy; imbricate to not imbricate; petiolate (B), or sessile (scarious dilations of the petiole); connate; simple; epulvinate. Leaf blades entire; obovate (to narrowly obovate to oblanceolate), or ovate, or linear. Leaves with stipules (K), or without stipules (B). Leaf blade margins entire. Vegetative buds not scaly. Leaves without a persistent basal meristem. Leaf anatomy. Hairs absent. Urticating hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening anomalous.
Reproductive type, pollination. Fertile flowers hermaphrodite, or hermaphrodite and functionally male. Unisexual flowers present, or absent. Plants hermaphrodite, or andromonoecious. Male flowers with pistillodes. Entomophilous (diurnal).
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in cymes, or in heads, or in fascicles. The terminal inflorescence unit cymose. Inflorescences axillary. Flowers pedicellate (the pedicels thickening upwards); ebracteate; ebracteolate; small, or medium-sized; regular; cyclic; polycyclic. Free hypanthium present; obconic; incorporating calyx and stamens. Perianth sepaline (considered apetalous, but with colourful, conspicuous staminodal ‘petals’); 5; 1 -whorled. Calyx present; 5; 1 -whorled; gamosepalous; deeply blunt-lobed; green and pink, or green and purple (green outside, pink to purple inside); fleshy; persistent. Calyx lobes triangular (with scarious margins). Corolla absent. Androecial members indefinite in number. Androecium 50–200 (i.e. ‘many’). Androecial members branched. Androecial sequence determinable. Androecial members maturing centrifugally; free of the perianth; markedly unequal; free of one another, or coherent; when coherent, 1 - adelphous (then the filaments shortly adherent at the base); 3–16 -whorled (i.e to ‘many whorls’). Androecium including staminodes. Staminodes 30–100 (‘many’); petaloid. Stamens 5–100 (to ‘many’); attached on the rim of the hypanthium; all more or less similar in shape; isomerous with the perianth to polystemonous; alternisepalous (when 5 stamens); filantherous. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Pollen shed as single grains. Fertile gynoecium present, or absent (from male flowers). Gynoecium 2–5 carpelled. The pistil 2–5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary plurilocular; 2–5 locular; sessile. Gynoecium stylate. Styles 2–5; apical. Stigmas 2–5. Placentation axile. Ovules 5–50 per locule (several to many); anatropous, or campylotropous.
Fruit and seed features. Fruit non-fleshy; dehiscent (transversely circumciss about middle); a capsule. Capsules circumscissile. Fruit 2–5 celled; several-seeded. Seeds non-endospermic. Perisperm present (mealy). Embryo well differentiated. Cotyledons 2. Embryo curved.
Etymology. A Linnean name, derivation not known; the Sesuvii were a tribe in Gaul living west of the Seine, but the plant is tropical.