The remarkable diversity of angiosperm species has prompted a search for universal drivers that modulate rates of speciation and extinction across this clade. To date, attempts to explain differences in species diversity have focused on the potential correlation of diversification rates with particular key traits.However, an often-overlooked explanation is that evolutionary lability, here defined as the rates of trait change, is a better predictor of the diversification dynamics than the observed traits themselves. This hypothesis, first proposed in the context of biome shifts 50 years ago, is based on the idea that the capacity to adapt to environmental changes is the key element defining angiosperm diversification dynamics. Using a phylogenetic dataset of 49 angiosperm clades including 18,617 species we demonstrate that the propensity of change between open and closed-canopy biomes is significantly correlated with lineage speciation and extinction rates across clades. Additionally, we find that transition rates tend to be faster from open to closed-canopy biomes. This results in ancestral state estimates that favor several deep time origins of open-canopy biomes, contrary to prevailing ideas that lineages occurring in open-canopy biomes tend to emerge from closed-canopy ones in angiosperms. We propose that a shift in focus from static traits to dynamic evolutionary processes may provide a more comprehensive understanding into how biodiversity is generated and maintained, in angiosperms and other organisms.