Polygamous, heterostylous, annual or perennial herbs or more rarely shrubs. Ocreae with or without a terminal fringe of setae. Flowers borne in axillary, leafless, often triquetrous, rather slender and elongated spiciform racemes. Bracteoles 2, conjoined. Male flowers with a very short tube and 4–5 petaloid tepals. Hermaphrodite flowers tubular, the tepals marcescent, the tube very accrescent around the ovary. Stamens 8, in 2 series; 5 outer adnate to the tepals near their bases, 3 inner with flattened bases forming a contiguous ring around the base of the style. Styles 3, free or conjoined below; stigmas capitate. Fruiting perianth fusiform, conical, ampulliform or lanceolate-ampulliform, trigonous or not, unarmed, or with 3 (–9) spreading prickles of varying size and development at the centre or below, or at the base, rarely with 3 additional prickles or teeth on the angles of the lower half, sometimes winged.