A long-lived grass-like plant usually growing 20-50 cm tall. It produces a network of creeping underground stems with small tubers (10-25 mm long). Its upright flowering stems are smooth and three-angled in cross-section its very narrow leaves (7.5-20 cm long and 2-6 mm wide) are borne in a tuft at the base of the stems. Its seed-heads have 3-8 branches of varying in length (up to 10 cm long) and are subtended by two to four green leafy bracts. These branches bear several elongated reddish-brown or purplish-brown flower spikelets (10-25 mm long and 2-2.5 mm wide).