The estimation of divergence time and diversification rate analysis of Bupleurum A, B ITS C, D ITS + matK + psbA - trnH + rbcL A, C estimation of divergence time of Bupleurum, the 95% highest posterior density (HPD) estimates for each well-supported clade are represented by bars, historical carbon dioxide levels data from TimeTree B, D diversification rate analysis of Bupleurum.