STUDIES ON THE CYTOTAXONOMY OF POLYGONATUM Ⅰ.Karyotypes and evolution of eight species of Polygonatum in China

The present paper analyzed the karyotypes of 8 species of iPolygonatum in China. The results are as follows: P. macropodium Turcz. 2n=22=14m(4SAT)+2sm(SAT)+6st; P. cyrtonema Hua 2n=22=8m+8sm(2sc)+6st(2sc) ; P. odoratum(Mill.)Druce 2n=20=12m+8sm; P. humile Fisch. ex Maxim. 2n=20=8m(2sc)+8sm+4st; P. filipes Merr. 2n=16(18)=10m+4sm+2st; P. involucratum Maxim. 2n=18=8m+10sm; P. sibiricum Delar. ex Redoute 2n = 24 = 4m + 8sm (2sc) + 12st (2sc);P. cirrhifolium Royle 2n = 20 = 12m (2sc) + 8sm.From this paper and previous reports by other authors, it is presumed that the basic chromosome number of Polygonatum is X=10. In the trend of evolution of the chromosome number, as a rule, aneuploid variations are more predominant than the euploid variations, ascending variations is the main stream and descending variation is not so important. According to degree of asymmetry of the karyotypes, the 8 species might be divided into three gradations. The evolution of karyotype variation from symmetry to asymmetry is correlated with the trend of evolution of the chromosome number.