Compound spikes with clusters of unbranched greenish-yellow or pale-brown spikelets. Bracts of varying lengths. Smooth ribbed fruit, tapering to beak, very spiky appearance. Sharply 3-angled stems with erect bright-green leaves, can form dense tufts. 30-100cm.
Usually found on heavy, wet soils. Marshes, ditches, wet meadows. Scattered distribution in Ireland, usually coastal, occasionally inland.