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Eleocharis dulcis (Burm.f.) Trin. ex Hensch. 1833
(Cyperaceae – the sedge family)
common names: Chinese Water Chestnut, Water Chestnut, Spike-rush
This is a grass-like sedge grown for its edible corms. It is found in India, south-east Asia, New Guinea, Polynesia, and in Australia right across the north of the country, and down into NSW as far as the Murwillumbah area. The water chestnut is actually not a nut at all, but an aquatic vegetable that grows in marshes, underwater in the mud. It has tube-shaped, leafless green culms that grow to about 150 cm tall.
The culms are terete, flattening easily when they are dried, and transversely septate, 3 – 10 mm in diameter. The spikelet is cylindrical, 25–50 mm long; the glumes are very obtuse, striate, with a distinct midrib and hyaline margins, about 6 mm long, and straw-coloured. There are 6–8 bristles, rather stout, flattened and united near the base, irregularly retrorsely toothed; there are 3 stamens; the anthers are about 3 mm long, and the style trifid.
The corms are turgidly biconvex, obovoid, up to 2 mm long, a little less in diameter, golden brown in colour. They have a crisp white flesh and can be eaten raw, slightly boiled, or grilled, and are often pickled or canned. They are a popular ingredient in Chinese dishes. In China, they are most often eaten raw, sometimes sweetened. They can also be ground into a flour, used for making water chestnut cake, which is common as part of dim sim cuisine. They remain crisp after being cooked or canned, because their cell walls are strengthened by phenolic compounds. They are rich in carbohydrates, and are a good source of dietary fibre, riboflavin, vitamin B6, potassium, copper and manganese. If eaten raw, the surface of the plants can transmit Fasciolopsiasis.
The plant spreads by creeping rhizomes that produce additional sucker plants throughout the summer months. In autumn the leaves start to yellow, and the chestnuts form at the terminal ends of the rhizomes. Over the next few weeks the culms die back entirely, and the chestnuts can be harvested. Some varieties are not sweet, and are grown for starch and pig food. The native Australian variety is small but quite sweet, and it is one of the main food sources for the six and a half million magpie geese of the Northern Territory. Most commercial growers cultivate Chinese varieties rather than the native one.
The explorer Leichhardt noted in his log that the water chestnut was the tastiest native food offered to him by the aborigines.
Photographs taken in marshy ground by the side of the West Point road, 2012
Page last updated 19th November 2016