Aster vestitus Franch.,A.poliothamnus Diels and A.sikuensis W.W.Smith et Farr.comprise Aster Series Vestiti Ling (Asteraceae) whose monophyly was not supported by a new molecular phylogenetic investigation.Karyotypes of four populations of the three species were analyzed by conventional root tip squash method.The results showed that all the three species had a karyotypic formula of 2n=2x=18=14m+4sm(2SAT),while the two populations of A.vestitus belonged to the Stebbins’ 1A karyotype and the other two species to the Stebbins’ 2A.The karyotypic data of A.vestitus and A.sikuensis were reported for the first time and that of A.poliothamnus was quite different from that reported by the only previous related study.The results did not suggest maintaining Ser.Vestiti but support the comment of Li et al.on subgeneric classification.Satellite size of the three species belonged to “Asterinae type”,which supported the opinion that there is no close relationship between Eurasian Aster and North American asters.