Abstract: This paper deals with the characters of leaf epidermis of Zizania and its relative genera. We find that Zizania L. is similar to Gen. Oryza, Leersia etc. by the Oryza-type silica-bodies, triangular subsidiary-cells and filiform micro-hairs, but it is clearly distinguished from them by its silicabodies usually irregularely arranged on the veins (usually regularly arranged over the veins in Oryza, Leersia ctc.)and the stomata are sually overarched by papillae. Hence, this genus may be considered as an only genus of subtribe Zizaniinae in tribe Oryzeae by connected with its chromosome number 2n=2x=30, 34 different from everyone with basic chromosome number x=12. There are 4 species 2 subspecies(Z.aquatica subsp, aquatica, Z.aquatica subsp. brevis(Fass.)S. L. Chen, Z.palustris subsp. palustris, Z.palustris subsp. interior(Fass.) S. L. Chert, Z.tenana Hitchc. and Z.latifolia(Griseb.)Turcz. ex Stapf) in the world.