Out of the Himalaya-Hengduan Mountains: Phylogenomics, biogeography and diversification of Polygonatum Mill. (Asparagaceae) in the Northern Hemisphere

•This study provided a robust phylogenetic framework of Polygonatum, based on whole-plastome data.•Polygonatum originated in the HHM region during the early Miocene (c. 20.10 Ma), as well as began to radiate and disperse to other regions since the mid-Miocene.•Decreasing dysploidy accompanied by karyotype change and polyploidization in Polygonatum appears to be associated with its diversification and colonization.