1. A classification is made on seven species of the genus Dysosma, of which four are proposed as new combinations, and one as new species. 2. The pollens of six species in the genus Dysosma and two species of Podophyl- lum are examined. Morphologically, the Asiatic. P. emodi is radically distinct from the North American P. peltatum and can be separated from Podophyllum as an indepen- dent genus-Sinopodophyllum. 3. The trend of evolution in Dysosma (fig. 2)and its relationships with the genera Sinopodophyllum and podophyllum are discussed. 4. Based on the evidence from an analysis of the ecology and geographical distribution of the component species (fig. 3), the problem of the centre of develop- ment of the genus Dysosma has been discussed.