Small, grass-like rush, very variable. Plants can be erect and tufted with creeping stems or semi-submerged, floating.
Stems are swollen at base, without rhizomes but rooting at nodes. Slender hollow leaves. Small reddish-brown flowers, pale-brown fruit. Plant is often viviparous, with leafy buds replacing the flowers.
Frequent, can be abundant in or by water and on seasonally wet ground. Usually on acidic to neutral soil but is also found in some calcareous turloughs in the Burren, Co.Clare.