Aster ageratoides polyploid complex has been reputed t o be a difficult taxonomical subject.However,taxonomical study and cytological data on the complex from China,its main distribution region,are extremely scanty.Therefore,9populations of Aster ageratoides var.scaberulus Ling were investigated cytologically.The result shows that A.ageratoides var.scaberulus is a tetraploid with 2n=4x=36,and the reports that it pos-sesses a hexaploid likely came from m isidentification.Based on the fact that the karyotype variation of 6pop-ulations of A.ageratoides var.scaberulus is correlated with longitude,...