Plants herbaceous, succulent, some species rhizomatous. Stems succulent, decumbent or ascending, 5-20-angled; angles with hexagonal or conicle tubercles; sap clear. Leaves usually scalelike, sometimes awl-shaped, scale-like leaves persistent or deciduous when dry, awl-shaped leaves persistent as stiff bristles. Infloresences usually with 2-3 flowers, located near the tips of the stems; pedicels usually short. Corolla shallowly cup-shaped to deeply urn-shaped; lobes variously shaped, glabrous or shortly hairy, smooth or papillose. Corona gynostegial, outer lobes joined in a cup or horn-shaped to linear; inner lobes incumbent on anthers, often connivent above gynostegium. Follicles terete, slender, slightly diverging. seeds with a tuft of hairs at one end.
A genus of about 30 species that grow in eastern and northeastern Africa, the Arabian Peninsula, and Socotra.