A comprehensive dated phylogeny of China's vascular plants reveals a hidden global biodiversity hotspot

Identifying centres of neo- and palaeo-endemism is crucial for defining global conservation priorities, yet data gaps hinder prioritization in megadiverse regions. Using a dated phylogeny of 16,585 native vascular plant species, we unravel spatio-temporal dynamics of China's extant flora. Temporally, most genera originated in the Oligocene-Miocene, whereas the Pleistocene was key for speciation, tying floristic assembly to Pleistocene climatic oscillations. Spatially, mismatched phylogenetic and taxonomic endemism centres highlight complementary conservation priorities. We identify three major taxonomic endemism centres across China, with Central China, embedded within the East Asian subtropical evergreen broad-leaved forest ecoregion, emerging as a critical and overlooked conservation gap. This region harbours over 14,431 vascular plant species, including at least 2,024 endemics, but has experienced severe loss of its original natural vegetation. We therefore advocate its designation as a global biodiversity hotspot. Our multi-dimensional assessment challenges frameworks that neglect evolutionary history and underscores the global conservation importance of Central China.