Annual, strongly taprooted, prostrate to weakly erect monoecious herbs. Leaves alternate, petiolate, not articulate, entire; ochreas short, tubular, truncate, brown, membranous, glabrous, soon disintegrating. Male flowers clustered, shortly pedicellate, in short, loose axillary and/or terminal panicles; perianth segments sepaloid, 5 or 6, free, virtually equal; stamens 4–6; female flowers sessile or subsessile in axillary clusters; perianth segments 6, fused in lower part, the outer 3 spinescent, becoming hard, thickened and recurved in fruit, the inner 3 remaining erect, closing over the nut; stigmas 3, flattened, fringed. Nut trigonous to triquetrous, remaining within the enlarged fruiting perianth.
2 species, from the Mediterranean region and southern Africa, both naturalised in Australia.
Sometimes included in an expanded Rumex (e.g. Schuster et al. 2015).
Schuster, T.M.; Reveal, J.L.; Bayly, M.J. & Kron, K.A. (2015). An updated molecular phylogeny of Polygonoideae (Polygonaceae): Relationships of Oxygonum, Pteroxygonum, and Rumex, and a new circumscription of Koenigia., Taxon 64(6): 1188-1208.