The purpose of my study was to identify mosses which influences the establishment and growth of Aster kantoensis. It is an endangered species in Japan, located along the banks of the rivers around Tokyo. This flower is known that its establishment and growth are likely to be affected by mosses. However, the mechanism is still unveiled. To find the way of mosses to disturb the growth of Aster kantoensis can be helpful to conserve the species and save diversity.