Decumbent to erect, virtually glabrous, annual or perennial herbs. Leaves alternate, sessile, terete to clavate. Flowers bisexual, solitary in axils, glabrous except for margins of the 5 membranous lobes; tube fleshy; stamens 5. Body (tube) of fruiting perianth subglobular, woody; apex with 0–4 tubercles or vertical wings developing between the immersed perianth lobes; style base hardened, pericarp otherwise membranous; seed horizontal.
Endemic Australian genus of 5 species, barely distinct from Threlkeldia in which it was included by Bentham (1870).