Abstract: Mosia hangchouensis Matsuda is an endangered species distributed along the coastal areas of Zhe-jiang Province. We studied the pollination intensity, pollinators' efficiency and nutlet set in a natural population in Hangzhou and an artificial population in Beijing Experimental Garden of our Institute to test the hypothesis that nutlet set is dependent on pollination intensity and pollinators' efficiency. Although this species is self- compat-ible, careful examination on stigmas of virgin flowers revealed that no stigma was pollinated before corolla open-ing due to the spatial isolation between stigmas and anthers. This indicated that nutlet set is dependent on polli-nators. Hand pollination experiment in the natural population showed close nutlet set between self- pollination, geitonogamy and cross - pollination. Significant effect of pollination intensity on nutlet set was found by the anal-ysis of variance of nutlet set( F = 71.606 * * * , P < 0.01).

Key words: Mosla hangchouensis, Nutlet set, Pollination