The anatomical development of the abscission zone in grains of Z. aquatica was correlated with development of the embryo. The abscission zone was well developed when the embryo sac was mature. Soon after pollination, the 1st anatomical evidence of abscission appeared as plasmolysis of the separation layer parenchyma cells. This was followed by separation of the layers by dissolution of the middle lamella and fragmentation of cell walls. It is suggested that persistence of intact vascular tissue and the presence of a surrounding cone-shaped mass of lignified cells may be involved in abscission of wild rice grains.