Abstract: "Male" tillers and smutted tillers of Zizania caduciflora can often be discovered in the process of normal cultivation. According to the morphological observations of Z. caduciflora, we have realized that the generation of "male" tillers is caused by the fact that mycelia of Ustilago esculenta in the main stem can not invade new tillers at tillering period. By the fact that the potential reproductive period of mycelia in the smutted tillers is shorter than that of normal one, clusters of different sizes of chlamydospores transformed from vegetative hyphae are generated in the hypertrophied part of the smutted tillers during process of hypertrophy.