29th Aug (Wed) 9:40 - 10:20

Plenary Talk 1

Chairperson: Leonardo Borges

Extrafloral nectaries, legumes, and ants: a complicated relationship

Brigitte Marazzi* (Natural History Museum of Canton Ticino, Lugano, Switzerland)

Leguminosae are well known for their diversity of mutualistic interactions with ants, such as the ecologically important protection mutualisms facilitated by extrafloral nectaries (EFNs). EFNs are secretory structures that produce a sugary reward to attract aggressive arthropods like ants and use them as bodyguards. In fact, the story is not that simple: the ecological function of EFNs has long been debated, and although they all secret nectar, EFNs are an outstandingly diverse plant character. They occur in over one hundred plant families from nearly all terrestrial ecosystems and display an impressive structural and ecological diversity in terms of morphology, location, phenology, and activity, just to mention a few aspects. EFNs are particularly common in legumes, but the large size of the family and the high morphological and ecological diversity of its EFNs have made the EFN-legume-ant relationship a complicated and passionate story to unravel. In this talk, I will first provide an overview on the history of EFNs studies in legumes and how they have contributed in shaping our current knowledge on protective mutualisms. Next, I will present our latest understanding of the systematic distribution and morphological diversity of EFNs in the family. This is the result of a collaborative effort that started almost ten years ago, during which we compiled from published reports and herbarium, greenhouse, and field observations a list of over 140 genera with EFNs. Finally, I will focus on our current knowledge of the role of legume EFNs at the plant community level, showing results from published and unpublished studies in different ecosystems. Some patterns can be observed in the evolutionary history of legume EFNs, but there are still many open questions, which I hope will inspire a lot of future research.