Nomenclature and taxon sampling

Names of Salvia subgenera and major clades follow Drew et al. (2017). A total of 91 taxa, representing 78 species, ten varieties and three forms from China, Japan and the Korean Peninsula, were sampled for this study. Except for the monotypic sect. Aethiopis and ser. Piasezkianae, our sampling represents all subgenera, sections and series sensuWu (1977) and Murata and Yamazaki (1993). In addition, 33 species of Salvia from other major lineages of Salvia (subg. Calosphace, Audibertia, Dorystaechas, Meriandra, Perovskia, Rosmarinus, Zhumeria, the ‘S. aegyptiaca clade’ and the ‘S. officinalis clade’) were sampled. Melissa and Lepechinia from subtribe Salviinae were also sampled. Horminum and Hedeoma were selected as outgroups based on Drew and Sytsma (2012). In total, our data set included 172 accessions, of which 145 were newly generated for this study (see Supplementary Data Appendix). Although sequences of many Chinese taxa are available from GenBank, we sampled and identified all Chinese taxa used in this study, and all sequences of Chinese taxa used here were independently produced to ensure independent results and accuracy.