Succulent, dwarf, perennial herbs, caespitose or creeping, rarely prostrate or pendent. Stems glabrous, mostly 4- or 5(6)-angled and prominently toothed along angles, rarely subcylindric. Leaves modified to form acute tips to tubercle teeth, without stipules, sometimes persisting and becoming hardened, acute points, rarely rudimentary, in a few species forming soft bristles at apex of teeth. Inflorescence glabrous, usually 1 per stem, a successively flowering, shortly pedunculate cyme in lower half of stem, rarely single-flowered; peduncle short, stout. Corolla tubular, campanulate, bicampanulate or subrotate, with or without an annulus; corolla 5-lobed with 5 intermediate lobes in sinuses, seldom exceeding 50 mm in diameter; outside smooth or sometimes scabrellous, rarely minutely asperate, glabrous; inside mostly papillate or tuberculate, rarely smooth, often provided with simple bristles or setae, clavate and/or much inflated hairs; lobes spreading to reflexed, flat or concave, sometimes canaliculate towards apex, very slightly convex but never replicate, margins without cilia. Corona 10-lobed in 2 alternating series, sessile outer lobes partially adnate to base of tube, velvety textured, united to form a flattish or somewhat conical, or convex disc merging into staminal column; inner lobes arising at top of staminal column, smooth-textured, simple, incumbent on anthers, ovate, triangular-oblong, obtuse or subacute, subulate, or variably clavate, apical portion often minutely tuberculate, usually with a transverse ridge or gibbosity at their base, and sometimes shortly decurrent below, the gibbosity is much enlarged and sometimes erect. Staminal column erect, anther wings erect, diverging at base, forming a 'gape' with +/- triangular nectarial orifice behind and a small fleshy tubercle in front. Anthers 2-locular, horizontal on top of style head. Pollinia compressed oblong-ellipsoid; caudicles short; corpuscle relatively short and broad, attached to edge of pentagonal style head by short lateral wings. Follicles erect, fusiform, glabrous. Seeds +/- ovate, much compressed, almost flat, with a tuft of hairs. x = 11 ( polyploidy).