Patchy stomatal closure occurs in plants with heterobaric leaves, in which vertical extensions of bundle sheath cells delimit the mesophyll and restrict the diffusion of CO₂. The scale of patchy stomatal behavior was investigated in this study. The distribution of PSII quantum yield (Φ_II) obtained by chlorophyll fluorescence images were used to evaluate the scale of stomatal patchiness and its relationship with leaf photosynthesis of Quercus crispula Blume. Fluorescence patches were observed only during the day with low stomatal conductance. Comparison of numerical simulation of leaf gas exchange and chlorophyll fluorescence images showed that heterogeneous distribution of electric transport rate through PSII (ETR) was observed following stomatal closure with a bimodal manner in both leaves illuminated natural and saturated photosynthetic photon flux density (PPFD). Thus, fluorescence patterns can be interpreted in terms of patchy stomatal closure. The mapping of ETR obtained by chlorophyll fluorescence images showed that patches of ETR came from several (2*2-3*3) compartments bounded by vertical extensions of bundle sheath cells within a leaf. Our results suggest the spatial scale of stomatal patches in Q. crispula leaves.