The chromosome-number of six species in Oryzoidcae was studied. The results can be summarized as follows: Tribe Oryzeae n 2n Leersia hexandra Sw. 48 Leersia oryzoides Sw. var. japonica Hack. 60 Leersia japonica Makino. 96 Hygroryza aristata Nees 24 Chikusichloa aquatica Koidz. 24 Tribe Zizanieae Zizania latifolia Turcz. 17 34
