A native rush with dark green, cylindrical stems that are tough and flexible. It forms dense clumps in wetlands and damp grassland. The stems are wiry and twisted, with a distinctive texture. The seed heads are reddish-brown, appearing in summer. The stems have no leaves, only a basal sheath. The photosynthesis happens in the green stems. The plant is wind-pollinated, with the seeds dispersed by wind and water. Wīwī is common in wetlands, damp grassland, and coastal areas throughout New Zealand. It is often found in the same habitats as pukio and oioi, forming mixed communities of rushes and sedges. The plant provides important habitat for wetland birds. The dense clumps offer shelter and nesting sites. The stems are used by birds as perches and as material for nest building. To find wīwī is to walk the edges of wetlands and streams. Look for the dense clumps of dark green, wiry stems. The stems are tough and springy underfoot. It is a plant of the damp places, a survivor of the wet ground. The wiry stems twist in the wind, a sign that the wetlands are healthy.