Abstract: The physioecology of Ranunculus bungei Steud.Was investigated from 1986 to 1991 in arapid-flowing stream in the Maoershan Mountain of North Temperate. Laboratory experiments were meanwhile designed to examine and to verify the results obtained from the fieldstudy. Changes of the conductivity in tissues of the plant were recorded at different temperature using an electrical conductivity gauge, and the ultrastructure of the plant eells observedun der electrical micro scope.It is considered that light was the factor detennining thephotosynthesis of the plant due to the microclimate in the forest studied, and nitrogen was thelimiting factor for the growth of the plant as the rivulet was oligotrophic. However,iee andsnow had roles in either protecting of stimulating the freezlng of the plant.Microclimate areawas put forward to explain the surviving of the plant over the winter and the peculiar distribution of some other aquatic plants.Regenerated niche was also raised to compare with realized niche from static to dynamic state so as to explain some particular phenomena in thegrowth and distribution of the plant.