Phylogeny tree construction
A phylogenetic tree including all the 9370 species was obtained following Liu et al. (2017), which used the same species matrix. The phylogeny was constructed with the R package “S.PhyloMaker” (Qian & Jin 2016), with a species list as primary input data. An updated version of the supertree in Zanne et al. (2014), including 30,771 species of all families of extant seed plants based on the available genes in GenBank, was used as the backbone in the package “S.PhyloMaker”. Genera and species that were not included in the backbone tree were added as polytomies within their families or genera.