The four species of wild rice comprise the genus Zizania, a group of grasses that grow in shallow water in small lakes and slow-flowing streams. Often, only the flowering head rises above the water. Three of the four species are native to North America:
- Manchurian wild rice (Z. latifolia; incorrect synonym: Z. caduciflora), is a perennial native to China.
Texas wild rice is in danger of extinction due to loss of suitable habitat in its limited range as well as increasing pollution. 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.
Use as a grain
The seeds of the two annual species are the ones most commonly harvested as grain. Native Americans harvested wild rice by canoeing into a stand of plants, and bending and beating the ripe grain heads with the canoe paddles, so as to thresh the seeds into the canoe. The Ojibwa called this plant “manomin” or “good berry”. Some seeds fell to the muddy bottom to overwinter and germinate in the spring. Wild rice is the only cereal food native to North America. It is a favorite food of dabbling ducks and other aquatic wildlife.
Wild rice is high in protein, the amino acid lysine and fiber, and low in fat. It is also a good source of the minerals potassium and phosphorus, and the vitamins thiamine, riboflavin and niacin. 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 United States, California and Minnesota are the main producers; plants are mainly cultivated in paddies. Wild rice is the official state grain of Minnesota. Canadian wild rice is usually harvested from natural bodies of water; the province of Saskatchewan is the largest producer in Canada.
Manchurian wild rice, gathered from the wild, was once an important grain in ancient China, considered one of the “Six Grains”. Because it is difficult to domesticate, 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.
Use as a vegetable
The swollen, crisp white stems of Manchurian wild rice are grown as a vegetable, popular in East and Southeast Asia. The swelling occurs because of infection with the smut fungus Ustilago esculenta. The fungus prevents the plant from flowering, so the crop is propagated asexually, the infection being passed from mother plant to daughter plant. Harvest must be made between about 120 days and 170 days after planting, after the stem begins to swell but before the infection reaches its reproductive stage and the stem begins to turn black and eventually disintegrates.
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, and water bamboo.
Importation of the vegetable to the United States is prohibited in order to protect the North American species from the parasitic fungus.
Wild rice is also grown as an ornamental plant in garden ponds.