A first global phylogeny of Ajuga (Lamiaceae, Ajugoideae): Implications for taxonomy and evolutionary insights
Fei Zhao, Ferhat Celep, Taner Özcan, Trevor C. Wilson, Shu‐Han Li, Ya‐Ping Chen, Turan Arabaci, Orzimat T. Turginov, Bryan T. Drew, Tuncay Dirmenci, Chun‐Lei XiangAbstract
Ajuga (Lamiaceae, Ajugoideae) consists of ca. 69 species, most of which are herbaceous perennials. The genus is widely distributed across Eurasia, with extensions into Africa and Australasia. Although medicinally important, the phylogenetic relationships within Ajuga remain poorly understood. In this study, we present the first global phylogenetic analysis of the genus, based on 697 DNA sequences generated from seven chloroplast markers ( matK , ndhF , psbA‐trnH , rbcL , rpl32‐trnL , rps16 intron, trnL‐trnF region) and two nuclear regions (nrITS, nrETS). Sampling represented 51 species, accounting for all previously recognized infrageneric taxonomic categories. Although some topological incongruences were observed between the nuclear and plastid phylogenies, analyses using both maximum likelihood and Bayesian inference methods strongly support the monophyly of Ajuga and reveal two highly supported major clades. This split is further supported by geographical distribution and several morphological characteristics, including the shape of the upper corolla lip, the number of flowers per verticillaster, and corolla color. Additionally, none of the previously proposed infrageneric classifications are supported, indicating the need for a comprehensive taxonomic revision of the genus.