Perennial forb to 50cm tall. Leaves basal and alternating up the stems, with a sheath at the base, 2-16cm long, 3-10mm wide,. linear to flat, hairless, with small lobes at the base, and pointed tips. Leaves subtending the flower clusters with wavy edges. Flowers with 6 'petals', in whorls of 12 or more at the bases of the leaves.
Resembles Rumex brownii but the leaves are narrower, and the fruiting bodies have 2 straight to curved teeth on each side.
Description (page 236) and line drawing of fruiting body (Fig. 43g page 235) in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales
PlantNET description: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Rumex~tenax