Results/Conclusions We studied six tropical orchid species from Asia, Africa and the Caribbean islands, including several populations for each of them. They revealed contrasting features as compared to the ‘temperate rule’. Species from Asian Dipterocarpaceae forest shared diverse ectomycorrhizal species with the later trees; their isotopic content clearly indicated that, exactly as temperate models, they received carbon from this source. However, they were not specific, and had up to four different partner species per individual (and eight per population). The other models from Africa and the Caribbean islands, from forests devoid of the mycorrhizal fungal species usually colonizing MH orchids, associate with saprobic fungi. Together with the identity of the fungi, isotopic studies showed that the ultimate carbon source was, respectively, dead wood and dead leaves. These examples, obtained in the same phylogenetic context as the models studied in temperate regions, are unlikely to represent specific idiosyncrasies, but rather emphasize functional differences of tropical ecosystems, especially for fungi. We hypothesize that (1) a wetter climate allows saprophytic fungi to be sufficiently active over the rain season to provide carbon to MH plants and (2) a higher availability of photosynthates for tropical mycorrhizal fungi reduce arm race with exploiting MH orchids, and thus evolution toward specificity.