Perianth-segments 5, feebly to strongly 1–3(–5)-nerved, lanceolate to narrowly oblong, usually hairy (rarely glabrous), ± mucronate to aristate with the excurrent nerve
Stamens 5; filaments filiform, monadelphous below, alternating with mostly quadrate pseudostaminodes, these glabrous to pilose, simple or with a highly developed, fimbriate dorsal scale; anthers bilocular
Annual or perennial herbs with opposite, petiolate or sessile, entire leaves; rootstock slender to tuberous
Inflorescence spicate to capitate, elongating later or not, flowers spreading or in one species becoming deflexed after flowering
Flowers solitary in the bracts, hermaphrodite
Bracteoles 2, the midrib excurrent in a short, glabrous and pungent or longer, flexuose and pilose arista, lamina firm, chartaceous or horny, ± half the length of the perianth or more
Perianth falling with the ripe capsule, accompanied by the bracteoles or not; bracts persistent, spreading or rarely deflexed.
Ovary with a solitary pendulous ovule, fruiting wall very thin; apex at maturity firm, with a transverse crest passing through the base of the style, often forming a hump at each end where it meets the periphery, rarely without such a crest but with a circumferential rim or almost flat; style slender; stigma small, truncate-capitate