Abstract: By means of disc polyacrylamide gel electrophoresis, peroxidase isoenzymes of 9 species of Cupressus Linn, were analysed. The interspecific zymogramatic differences are obvious. Each species possesses its specific zymogram, distinguishable form the others. According to the zymogramatic similarity among these species calculated with the method of polar ordination, they may be grouped into 5 groups, which may be grouped in turn into two categories. C. gigantea Cheng et L. K. Fu, C. torulosa D. Don, C. duclouxiana Hichel, C. chengiana S. Y. Hu, and C. jiangeensis N. Chao. fall into one category. The second category contains C. sempervirens, C. arizonica Greene, C. lusitanica and C. funebris Endl. The experimental result about peroxidase comfirms the interspecific relationships of Cupressus suggested by the previous works. A positive relation is found between the peroxidases isoenzyme zymogramatic similar degree and the geographical vicarism of the related species, which has been used for analysing the regularity of phytogeographical vicarism. The mean zymogram distance of Cupressus Linn. among species is 0.75, from which it is inferred that the divergency took place the Jurassic. The advantage of polar ordination method in the study of iso-enzyme zymogram is discussed.

Key words: Cupressus Linn, Isoenzyme zymogram, consanguinity