Slender aquatic or terrestrial perennial. Aquatic plants with stems floating at the surface or submerged and creeping, elongated, branching at the nodes, to over 1 m long; terrestrial plants creeping or forming more or less compact tufts, to 10 cm high. Spikelets solitary,ellipsoid to elliptic-ovoid, 5–10(–15)-flowered, 3–5 mm long; lowest involucral bract shorter than to far exceeding spikelet, glume-like to leaf-like; glumes obtuse, conspicuously numerous-nerved, straw-coloured, sometimes with red-brown patches, 1.7–2.8 mm long; stamens 2 or rarely 3; anthers 0.5–1.0 mm long; style 2-fid. Nut plano-convex, with angles not well-defined, broad-obovoid to ellipsoid, smooth, minutely reticulate, shining, grey-brown to dark brown, from one-half to three-quarters as long as glume, 1.4–1.8 mm long, c. 1 mm diam. Flowers spring–summer.
LoM, Wim, GleP, VVP, VRiv, MuF, GipP, OtP, WaP, Gold, CVU, GGr, DunT, NIS, EGL, EGU, WPro, HSF, HNF, OtR, Strz, MonT, HFE, VAlp. Widespread in swamps and streams, mostly in the cooler, southern parts of the State, but extending north near St Arnaud, Nagambie, Wangaratta areas.
