information:classification, structural:expansion
Phylogenetic analyses

Through DNA sequencing, Salvia was shown to not be monophyletic but to consist of three separate clades (Salvia clades I–III) each with different sister groups. They also found that the staminal lever mechanism evolved at least two separate times, through convergent evolution. Walker and Sytsma (2007) clarified this parallel evolution in a later paper combining molecular and morphological data to prove three independent lineages of the Salvia lever mechanism, each corresponding to a clade within the genus. It is surprising to see how similar the staminal lever mechanism structures are between the three lineages, so Salvia proves to be an interesting but excellent example of convergent evolution.

Walker and Sytsma (2007) also addressed the question of whether Salvia is truly polyphyletic or just paraphyletic within the tribe Mentheae. To make Salvia monophyletic would require the inclusion of 15 species from Rosmarinus, Perovskia, Dorystaechas, Meriandra, and Zhumeria genera. The information attained by Walker and Sytsma (2007) supporting the three independent origins of the staminal lever indicate that Salvia is not the case where 15 species (currently not members of the genus) are actually members of Salvia but underwent character reversals—in other words, Salvia is paraphyletic as previously circumscribed. In 2017 Drew et al. recircumscribed Salvia, proposing that the five small embedded genera (Dorystaechas, Meriandra, Perovskia, Rosmarinus, and Zhumeria) be subsumed into a broadly defined Salvia. This approach would require only 15 name changes whereas maintaining the five small genera and renaming various Salvia taxa would require over 700 name changes.

The circumscription of individual species within Salvia has undergone constant revision. Many species are similar to each other, and many species have varieties that have been given different specific names. There have been as many as 2,000 named species and subspecies. Over time, the number has been reduced to less than a thousand. A modern and comprehensive study of Salvia species was done by Gabriel Alziar, in his Catalogue Synonymique des Salvia du Monde (1989) (World Catalog of Salvia Synonyms). He found that the number of distinct species and subspecies could be reduced to less than 700.