Perennial aquatic forb, stems to 4m long. Leaves alternating up the stems, with a sheath at the base, flat, hairless. Submerged leaves 5-23cm long, 2-10mm wide, often with wavy edges. Floating leaves 1.5-10cm long, to 70mm wide. Upper submerged leaves may be intermediate between these two forms. Flowers small (less than 3mm across), with 4 'petals', brownish, in dense spikes to 5cm long, the stalks arising from the bases of leaf-like bracts.
Description and photo in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales page 40