In Canada, it is usually harvested from natural bodies of water; the largest producer is Saskatchewan. Wild rice is also produced in Hungary and Australia. In Hungary, cultivation started in 1974 on the rice field of Szarvas. Manchurian wild rice (), gathered from the wild, was once an important grain in ancient China. 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 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, when the stem will begin to turn black and eventually disintegrate into fungal spores. The vegetable is especially common in China, where it is known as gāosǔn (高筍) or jiāobái (茭白). Other names which may be used in English include coba and water bamboo. Importation of the vegetable to the United States is prohibited in order to protect North American species from the smut fungus. Typically sold as a dried whole grain, wild rice is relatively high in protein, the amino acid lysine and dietary fiber, and low in fat. Nutritional analysis shows wild rice to be the grain second only to oats in protein content per 100 calories. Like true rice, it does not contain gluten. It is also a good source of certain minerals and B vitamins. One cup of cooked wild rice provides 5% or more of the daily value of thiamin, riboflavin, iron, and potassium; 10% or more of the daily value of niacin, Vitamin b6, folate, magnesium, phosphorus; 15% of zinc; and over 20% of manganese. Wild rice seeds can be infected by the highly toxic fungus ergot, which is dangerous if eaten. Infected grains have pink or purplish blotches or growths of the fungus, from the size of a seed to several times larger. Anthropologists since the early 1900s have focused on wild rice as a food source, often with an emphasis on the harvesting of the aquatic plant in the Lake Superior region by the Anishinaabe people, also known as the Chippewa, Ojibwa and Ojibwe (Densmore 1929: 128).