Ar: allelic richness; H _O: observed heterozygosity; H _S: average heterozygosity;F _IS: inbreeding coefficient.

Among the four group of OLa, OLb, OTc and OTd, A_r showed OLb (1.528) > OTd (1.477) > OLa (1.456) > OTc (1.447), H _S was OLb (0.107) > OTd (0.099) > OLa (0.096) > OTc (0.090), and H o showed OLb (0.131) > OLa (0.126) > OTd (0.125) > OTc (0.121). The OLb group had highest genetic diversity among the four groups.

Between the two species, the values of A_r,H _O and H _S of O. longilobus were 1.678, 0.128 and 0.104 respectively, which were higher than 1.608, 0.123 and 0.096 of O. taihangensis . More, all the diversity index of Opisthopappus species showed that a trend of high in the middle and northern and southern end areas and low in other regions (Fig. 3).