Bolboschoenus fluviatilis, commonly known as ririwaka or kukuraho, is a bull rush like swamp plant that grows from bulbous rhizomes of about 25mm in diameter. The double folded leaves grow to a height of 1.5-2m forming 3 angled flower spikelets of a dullish red brown colour. The leaves are summer green, dying down over the winter. This plant is distributed throughout most of the North Island in fresh water and brackish swamps. It is used widely for waste water treatment of polluted waterways.