1) Stamens of Portulaca grandiflora flower are situated apart from pistils in early morning, but they gradually approach each other and self-pollination takes place. During the day time almost all the flowers, which remain not self-pollinated, are pollinated by the aid of insects or wind. 2) Although Portulaca flowers begin to burst almost at the same time, each of flowers has different closing time in the afternoon. 3) In early morning opening and closing movements of Portulaca flower are susceptible to temperature, but in the daytime they gradually lose their susceptibility. 4) By artificial pollination flowers of Portulaca close without fail. When the stigma was artificially kept against the pollination, the flower remained open still in the afternoon. 5) Closing movement of the flower usually occurred after 3-4 hours from the pollination, but in early morning it occurred after 4-5 hours. 6) The maximum speed of the closing of petals is about 4 degrees per minute. 7) The effect of the pollination on the closing movement by pollens of “Jewel” (Portulaca sp.) was less active than that of the pollen of Portulaca grandiflora. Both the pollen of Pharbitis nil and mineral particles did not affect closing movement of Portulaca flower. 8) Closing movement of Portulaca flowers takes place certain time after cutting of stigma or pistil.