The fungus Villosiclava virens infects dominantly rice stamen filaments and some lodicules resulting in rice false smut. Here we examine the ultrastructures of the cell walls of various organs in rice spikelets around the anthesis to explore the specificity for infection. The inoculation was performed in rice cultivar, ‘Yongyou 12’, a high susceptible cultivar, and the infected spikelets were sampled at 5, 10, and 15 days after inoculation. The results showed that: (1) the stamen filament cells could elongate integrally for 4-6 folds, and the peripheral cells in top of lodicula could elongate significantly during flowering. (2) Microfibrils in those cell walls arranged loosely and could be clearly distinguished with transmission electronic microspcope. Conversely, the cell walls in ovaries, stigmas, and anthers were compact and the microfibrils could not be discerned. (3) The pathogen could grow in different orientations in both cell gaps and cell wall middle lamella in the stamen filaments, but its extension in the lodicula was limited mainly in cell gaps. This indicates that the structure and components of middle lamella in filaments and lodicula are different. (4) Cytochemical labeling revealed that there was less cellulose and no β1,3glucane in the cell walls of stamen filaments. These suggest that the ultrastructure and components in cell walls and middle lamella in various organs in rice spikelets are highly related to the specificity of infection by the pathogen