Abstract: This paper deals with the cladistic taxonomy of Zizania L. and its related species (Oryza sativa L., Leersia japonica Makino, Chikusichloa aquatica Koidz.etc.) were selected as OTUs. By the results of Kexue compatibility analysis the character 5, 17, 24 and 27 which possess higher incompatible coefficients were deleted from the original data. The OTU13 which loads a higher incompatibility for the character 10 was revised. we finally rearranged the original data for cladistic analysis in Table 3. and by the quantitative method we inferred the evolutionary tree of Zizania being shown in Fig. 1. All quantitative analysis were carried out by KEXUE Quantitative Analysis System on microcomputer.The cladogram (Fig. 1) Was suggested that Pharus L. should be transferred to tribe Phareae. Genus Zizania should belong to tribe Oryzeae and may be considered as an isolated subtribe Zizaniinae. There are 4 species, 2 subspecies in the whole world. i. e. Z. latifolia, Z. texana, Z. aquatica subsp. aquatica, Z. aquatica subsp. brevis, Z. palustris subsp. palustris and Z. Palustris subsp. interior. The evolutionary tread of every species in this genus may be suggested that Z. latifolia is the most primitive species than others, Z. texana and Z. aquatica may be derived from Z. latifolia separately, and then Z. palustris may be derived from Z.aquatica.

Key words: Cladistic taxonomy, Zizauia L., Systematic evolution