The colourful life of flowers

ABSTRACT

Flowers are the flagship structure of angiosperms (flowering plants). This spectacular innovation has probably contributed in a significant way to the extraordinary success of angiosperms, which today make up 90% of land plant species. Flowering plants display a beautiful and spectacular diversity of floral forms that results largely from the diversification of reproductive strategies, including co-adaptation with pollinators. One of the most spectacular variations concerns flower colour, with an almost endless range of shades varying from pure white to near black. In many plants, floral colours contrast with the rest of the plant, and are generally produced by the presence of pigments other than chlorophyll, although in some cases colour is created by light-reflecting structures. The biosynthetic pathways of carotenoids, anthocyanins and betalains, the three main classes pigment, have been deciphered. In many species, flower colour plays a key role in pollination as a visual cue to attract biotic pollinators. Although petals are often the most colourful and showy part of the flower, there are many exceptions, including examples where bracts are showier than the flowers themselves. Colour is usually stable within a species, resulting from adaptive processes linked to plant-pollinator relationships. The evolutionary and genetic mechanisms involved in flower colour shifts have been described in several taxa, providing insights into some of the processes that have shaped the diversity of flowering plants.

KEYWORDS:

• Flower
• pigments
• structural colour
• pollination
• selection

Acknowledgments

We thank the Société Nationale d’Horticulture de France for inviting us to give a talk on this subject, which gave us the idea of writing this review. We are also grateful to the members of the EVA team at ESE for warmly encouraging us to write this review. The manuscript was greatly improved thanks to the critical comments of the editor Finn Kjellberg and two anonymous reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

Sophie Nadot and Laetitia Carrive wrote the manuscript and designed the figures.