Partially mycoheterotrophic nutrition is a widespread trophic strategy in green-leaved Orchidaceae species in forest habitats. Owing to the light limitation of their habitats, many forest orchids meet carbon demands though autotrophy, and by tapping into the nutritional reserves provided by mycorrhizal fungi.
Schiebold et al. analysed the food webs of 12 taxa in the orchid genus Epipactis, obtaining stable isotope natural abundance measurements of Epipactis leaf tissue and fungal sporocarps, and molecular identification of mycorrhizal fungi. The pronounced gradient in 15N enrichment observed in Epipactis species is strongly driven by type and by the 15N abundance of the orchids’ mycorrhizal fungi.