Zizania latifolia andUstilago esculenta, a Grass-Fungus Association

Zizania latifolia (Manchurian wild rice), native to eastern Asia, is often infected by the smut fungus, Ustilago esculenta, causing culm enlargement and failure to produce flowers. The enlarged infected culms have been used as a vegetable (gau sun) in China since the 10th century. The occasionally-used nameZ. Caduciflora is shown to be only a synonym. To facilitate identification of the host, a taxonomic key shows thatZ. Latifolia differs from and is fully distinct from the American species ofZizania. The nature and structure of the fungus and the history and cultivation of the vegetable are described. As a precaution we propose quarantine of the host and fungus to prevent possible disastrous widespread infection of American wild rices by the fungus.