The phylogenetic diversification and ecological radiation of angiosperms (flowering plants) that took place in the Early Cretaceous, between about 135 and 65 million years ago, was one of the major biotic upheavals in the history of life. It had dramatic consequences for the composition and subsequent evolution of terrestrial ecosystems. Ancient Mesozoic vegetation, which was dominated by ferns, conifers, ginkgos and cycads, as well as Bennettitales and other groups of extinct seed plants, was eventually almost entirely replaced by more modern ecosystems dominated by angiosperms. Since the Early Cretaceous, high diversification rates have generated more than 350 000 extant angiosperm species. Today there are more living species of angiosperms than all other groups of land plants combined.

In their rise to ecological dominance angiosperms have exhibited extraordinary developmental and evolutionary plasticity. This has resulted in overwhelming morphological diversity and a great variety of adaptive types. Angiosperms are far more diverse in vegetative form and in the structure of their reproductive organs than any other group of land plants.