Rhizome tough, long; shoots distant. Culms erect, triquetrous, smooth below, scabrous above, 20–100 cm long, to c. 2 mm diam. Leaves shorter than culms, 2–4 mm wide; sheath pale brown, leaf sheath front (inner face) not cross-rugulose; ligule obtuse to rounded. Inflorescence erect, dense, 2–7 cm long, with up to c. 20 short spikes solitary at nodes; lowest involucral bract shorter than (rarely exceeding) inflorescence. Spikes sessile, densely contiguous, somewhat spreading at maturity, 0.5–1 cm long; upper spikes with male flowers above female flowers or wholly female; glumes long-acute, pale red-brown with broad whitish margins; female glumes 3.5–4.5 mm long; utricles 4–5 mm long, 1.6–1.8 mm diam., ovoid, ± strongly many-nerved, minutely scabrous or hispid on narrowly winged margins, pale red-brown; beak c. 1 mm long, with apex split; style 2-fid. Nut ovoid, lenticular, dark brown. Flowers spring–summer.
VVP, EGL, VAlp. Also naturalised in ACT. Native to Eurasia. Apparently very uncommon in Victoria, recorded in recent times only from boggy flats near Lake Condah, and two 1943 collections from boggy flats at Marlo.
The distribution of male and female flowers in the inflorescence is very variable. In Australian specimens, generally the spikes have male flowers above female, or the middle spikes are wholly male, whereas in Europe the common condition is for the upper and lower spikes to be female and the middle spikes male. Very similar to Carex arenaria, a species which has not yet been found in Victoria, but which is naturalised on sand dunes at Hawks Nest, in north coastal New South Wales, and may turn up in far eastern coastal Victoria. C. arenaria differs in having longer female glumes which are 5–6 mm long, and the uppermost spike is entirely male. Also, the utricles in C. arenaria are broadly winged, and pale green brown. In C. disticha the utricles are very narrowly winged, and red brown. May also be confused with C. divisa, which has shorter inflorescences, fewer spikes, and smaller utricles. It could also possibly be confused with forms of C. appressa with a reduced inflorescence, but C. appressa is shortly rhizomatous, leaves are often septate-nodulose, has numerous spikes, the inflorescence is usually longer than 12 cm, all spikes have male flowers above female flowers, the female glumes are smaller, and the utricles are smaller.
