Myrmecophytism is a common mutualism in tropical rainforests wherein plants provide ants with a nesting site and/or food resources in exchange for protection from herbivores and competitors. Yet, recent observations suggest that some myrmecophytic plants also benefit from recycling nutrient-rich ant waste. Moreover, some evidence indicates that microorganisms may mediate this nutritional interaction. Although these findings may completely modify our vision of the outcomes that drive the evolution of myrmecophytism, our knowledge of plant nutrition by ants is still too weak to draw broad conclusions. The aim of the present project is to reconsider myrmecophytism from a nutritional perspective. We propose to analyze nutrient flows between seven broadly distributed species of myrmecophytes in French Guiana, 11 ant partners and the associated microbiome using both correlational and experimental approaches. Moreover, we will conduct fine scale morphological and ultrastructural analyses of the plants to search for the specific structures that permit nutrient uptake. Using this information, we expect to be able to reconsider the evolution of myrmecophytism in response to both protective and nutritional selection pressures.