Letters to the twenty-first century botanist: “What is a flower?” (3) The flower as an evolutionary arms race: was Linnaeus’s choice misleading?

摘要

In this series of ‘Letters to the twenty-first century botanist’ dedicated to the flower (Dodinet and Selosse 2016), Nadot and Dodinet (2016) established a first definition based on morphology and supported by evo-devo. Dodinet (2016) then challenged this view by proposing the ethnobotanist’s perspective, and evidencing the variability of perception of the flower depending on the ethnographical context. But even in the framework of western science, not every scientific community sees the flower in the same way. The current essay seeks to bring an evolutionist’s outlook to the multiple ways of approaching and defining the flower. I first describe the flower in co-evolution with animals, entailing an acceleration of evolution by an arms race; then I show that the diversity of flowers provided tools for classification, especially for Linnaeus’s scheme, fully based on flowers; finally, I describe how a phenomenon arising from fast co-evolution, namely convergence, makes flower shapes often irrelevant as criteria for families retrieved by modern, phylogenetic classifications.