The integration of developmental genetics and evolution is providing a powerful synthesis towards understanding the mechanisms underlying the generation of biodiversity. Functional studies across the phylogenetic landscape are facilitating a comparative, integrative view highlighting that genes are mostly repurposed into new roles. I will present micro- and macro-evolutionary approaches on the evolutionary consequences of the emergence of novel traits in three distinct plant systems: an angiosperm, a gymnosperm and a fern. The flowering plant illustrates the effect of transitions to polyploidy, wind pollination and separate sexes on diversification rates, and on the underlying floral traits. The fern enables the reconstruction of the ancestral function of a master regulator of flowering, and the gymnosperm allows an exploration of the eco-evo-devo context of the emergence of fruit-like structures in seed plants.