Abstract: Plants exhibiting different growth forms possess different capabilities in adapting to their respective environments, consequently displaying distinct geographical patterns of phylogenetic relatedness across a broad environmental gradient. Here, we compare the geographical patterns of phylogenetic relatedness between woody and herbaceous angiosperms in China, based on three phylogenetic relatedness metrics, namely, the standardized effect sizes of phylogenetic diversity (PD_ses), mean pairwise distance (MPD_ses), and mean nearest taxon distance (MNTD_ses). Additionally, we explore the effects of three categories of environmental variables (current climate, historical climate change, and environmental heterogeneity) on the geographical patterns of phylogenetic relatedness of both plant groups. Our results indicate that the geographical patterns of phylogenetic relatedness of herbaceous and woody plants are inconsistent, and the deviations of phylogenetic relatedness between woody and herbaceous angiosperms have geographical patterns and vary along environmental gradients. Our study found that environmental variables have a greater influence on the phylogenetic relatedness of herbaceous plants than on that of woody plants, emphasizing that environmental variables, especially current climatic variables, are the primary drivers of the deviations of phylogenetic relatedness between woody and herbaceous angiosperms. In summary, we illustrate the distinct differences in phylogenetic relatedness among plants of different growth forms, providing valuable insights into the driving factors of species coexistence at various spatial scales.

Key words: angiosperms, China, deviation, environmental variables, growth forms, phylogenetic relatedness.