It was, Charles Darwin wrote in 1879, “an abominable mystery”. Elsewhere he described it as “a most perplexing phenomenon”. Twenty years after the publication of his seminal work The Origin of Species, there were still aspects of evolution that bothered the father of evolutionary biology. Chief among these was the flower problem. … Today’s plant scientists understandably have a better handle on the origins of flowering plants than Darwin did, but they are still struggling to explain the group’s diversity, and why despite this it has failed to become dominant in some parts of the world.