Wild rice is any of the four species of plants that make up the genus Zizania (common names: Canada rice, Indian rice, and water oats), a group of grasses that grow in shallow water in small lakes and slow-flowing streams; often, only the flowering head of wild rice rises above the water. The genus is closely related to true rice, genus Oryza, which is also a grass, and shares the tribe Oryzeae. Three species of wild rice are native to North America:
One species is native to Asia:
Texas wild rice is in danger of extinction due to loss of suitable habitat in its limited range and to pollution. The pollen of Texas wild rice can only travel about 30 inches away from a parent plant. If pollen does not land on a receptive female flower within that distance, no seeds are produced. Manchurian wild rice has almost disappeared from the wild in its native range, but has been accidentally introduced into the wild in New Zealand and is considered an invasive species there
The species most commonly harvested as grain is the annual species Zizania palustris. Native Americans harvest wild rice by canoeing into a stand of plants, and bending the ripe grain heads with wooden sticks called knockers, so as to thresh the seeds into the canoe.
The size of the knockers, as well as other details, are prescribed in state and tribal law. By Minnesota statute, knockers must be at most 1 inch in diameter, 30 inches long, and one pound in weight. The plants are not beaten with the knockers but require only a gentle brushing to dislodge the mature grain. The Ojibwa people call this plant manoomin meaning "good berry". Some seeds fall to the muddy bottom to overwinter and germinate in the spring. Wild rice and maize are the only cereal crops native to North America. It is a favorite food of dabbling ducks and other aquatic wildlife.
Almost always sold as a dried whole grain, wild rice is high in protein, the amino acid lysine and dietary fiber, and low in fat. Like true rice, it does not contain gluten. It is also a good source of the minerals potassium and phosphorus, and the vitamins thiamine, riboflavin and niacin. Because commercial, paddy-grown wild rice is harder and denser than naturally growing wild rice, it must be cooked longer to become soft enough to be eaten; it generally requires cooking for at least 45–60 minutes in a ratio of wild rice to water of approximately 1 to 3. Because of its comparatively high cost and chewy texture, it is often cooked together with true rice, often in a ratio of true rice to wild rice of 8 to 1 or 4 to 1. Manoomin, on the other hand, is not nearly as hard as paddy rice, allowing it to be cooked in 15–30 minutes. This is usually because of the lower temperatures and high degree of scarification used in smaller processing facilities where much of this wild rice is processed Manoomin often has a softer texture than cultivated wild rice and is preferred by the traditional wild rice users in wild-rice-growing regions of Minnesota and Canada.
Because of its nutritional value and taste, wild rice increased in popularity in the late 20th century, and commercial cultivation began in the US and Canada to supply the increased demand. In the US the main producers are California and Minnesota (where it is the official state grain) and it is mainly cultivated in paddy fields. In Canada, it is usually harvested from natural bodies of water; the largest producer is the province of Saskatchewan. Wild rice is also produced in Hungary and Australia. In Hungary, cultivation started in 1974 on the rice field of Szarvas. The Indian Rice Ltd. was founded in 1990. Now, the Hungarian wild rice growing and processing is managed only by this company. In Australia production is controlled by Ricewild Pty. Ltd. at Deniliquin in Southern New South Wales.
Manchurian wild rice gathered from the wild, was once an important grain in ancient China. Because of the difficulty of its domestication, it gradually lost importance with increasing population density, as its habitat was converted for use in raising rice. It is now very rare in the wild, and its use as a grain has completely disappeared in China, though it continues to be cultivated for its stems.
The vegetable is especially common in China, where it is known as gaosun or jiaobai (). Other names which may be used in English include coba, makomo (マコモ), and water bamboo.
In the Parable of the Tares told by Jesus in the New Testament of the Christian Bible, the plant otherwise known as darnel or tares is described as zizania. This is the plural form of the Greek word ζιζάνιον (zizanion).