Raupo, Cats Tail, Bullrush
Bullrush is a wetland plant growing up to 4 m tall. The erect, slightly fleshy, strap-shaped leaves grow up to 2 m long and each is about 2 – 3 cm wide. They are clustered on unbranched upright stems. Leaf bases develop long sheaves, often 30 cm or more long, that encircle each stem. Distinctive flower spikes borne near the top of the stems provide a foolproof means of identification. Spikes are cylindrical clusters of tightly packed flowers encircling the stem, 2 – 5 cm in diameter. These are 10 – 30 cm long for female flowers. The much narrower and shorter cluster of male flowers forms further down the stem. These female and male clusters are often separated by a few centimetres. Copious quantities of mustard-yellow pollen are produced by the male spike in midsummer. The female spike develops tightly packed seeds with dense parachute hairs (pappus) facing outwards, to produce the distinctive velvety chocolate – brown seed head.
These beautiful reeds inhabiting swamp lands or water logged soils in and around sheltered lakes, ponds or seepages, throughout most of the country. It is absent from Stewart Island. Bullrush is found in other parts of the world being also native to Eastern Asia from Japan and China southwards to Australia.
Surface sow seed in a pot and stand this in a container of 3cm of water to germinate. Plant out at a depth of 15cm at the margins of water ways or in mud during summer and autumn. Dig up the rhizomes by dividing mature plants in spring. Taking young shoots with some root attached, plant these into their permanent locations. Plants invade deeper water by growth of their rhizomes. Planting of raupo has the potential to become a weed problem. This can be avoided by surrounding any planting with 2 metre deep trenches.
Natural and constructed raupo wetlands provide valuable habitat for wildlife, including eels, water fowl, spawning whitebait (inanga) and other native fish and rare native birds such as fern bird, marsh crakes and bittern. Its natural occurrence has decreased markedly due to draining about 80 percent of pre-European wetland in the last 150 years.
In New Zealand all parts of the raupo plant have being harvested and used in a variety of ways. Dry leaves are the traditional material for covering poi which was then filled with the fluffy down from the seed heads. It was an important food source for the Maoris and has been used as a survival food in many countries. The top of the yellow spike, hand shaken lets loose profuse amounts of edible pollen which was made into bread (punga punga). Adding water made an acceptable gruel. The starchy rhizome was eaten raw or boiled as a green vegetable. Traditionally stalks were used for thatching the walls and roofs of whare and storehouses and the down for stuffing bedding. The leaves were used for canoe sails and kites, while bundles of the stalks made temporary rafts.
Water Purification – rapid growth of raupo, stimulated by its fertile habitat and continual supply of moisture, results in annual biomass production that is among the highest of any habitat in the world. Along with other herbaceous aquatic species, raupo is being used in constructed wetlands, built specifically for water purification purposes. Storm water, sewage and effluent from mining sites and farm animals can be effectively treated this way. Where toxic residues build up, they can be dug out for further dryland treatment.
The pappus (hair) of the seeds is used as an application for sores, wounds and ulcers. The Indians utilise the rhizomes which are slightly astringent, anti dysenteric and diuretic. The Chinese use the pollen as a healant for wounds and as an astringent.
Landcare Research NZ, Medicine of the Maori-Christina Macdonald, Maori Herbal Remedies – Dr Raymond Stark.