Plus ça change, plus c'est la même chose: The developmental evolution of flowers

The study of floral developmental evolution may be as old as the study of botany itself, but its history as a modern field largely dates to the characterization of the ABC model of floral organ identity. As we have come to understand more about the wide range of genetic programs that influence floral development, the potential for comparative studies has increased, leading to a steady expansion of research questions. This review attempts to take a broad view of these many questions, highlighting classic and recent findings that are shaping the way we think about floral evolution. Conservation of genetic pathways is a common theme, but there are often differences, whether due to drift or co-option, that have the potential to surprise. On the whole, the field of floral evo-devo is in transition, as we apply new approaches that allow us to move away from our reliance on candidate genes and, potentially, discover genuinely new developmental mechanisms.