Spadix sessile, unbranched, permanently enclosed in the sheath of the uppermost If; axis flattened to a thin, membr. strap bearing ∞ fls on its concave outer face; stamens alternating with carpels in 2 longitudinal, often crowded series. Stamen of 2 pollen sacs joined by a curved connective adnate to the axis, each sac simulating a single, ovate, sessile, 1-celled anther. Carpel flask-shaped, rounded at base, attached above the middle by a cushion of tissue. Rhizome ± compressed, creeping, rooting at nodes and there producing either vegetative shoots with short internodes and long lvs or erect, short-lived, sympodial reproductive shoots with longer internodes and us. shorter lvs. Lvs ± translucent; sheath long, open or closed, ± auriculate above; lamina entire, top bluntly truncate or emarginate by erosion; primary nerves parallel, at least 3 (1 median and 2 sub-marginal), sts more; interstitial nerves more delicate, intersected at intervals by ± horizontal cross veins. Plants forming grass-like, mud-collecting swards. Cosmopolitan genus of c. 12 spp. N.Z. representatives are referred to 2 Australian spp., but the descriptions are drawn up from N.Z. plants.