Orchids, one of the largest families of flowering plants, contain the highest abundance of mycoheterotrophs, or plants that obtain carbon and other nutrients through fungal parasitism. In addition to the presence of over 250 species of fully mycoheterotrophic, achlorophyllous species, a growing number of green orchids are known to combine fungal parasitism and photosynthesis in a strategy known as partial mycoheterotrophy. Our knowledge about the breadth and identity of fungal hosts of partial mycoheterotrophs is still developing, but recent findings have shown that partial mycoheterotrophs associate with broad functional groups of fungi including both mycorrhizal fungi and free-living saprotrophic fungi. Here, we investigate Triphora trianthophoros (Epidendroideae, Triphoreae), or three birds orchid, an enigmatic North American terrestrial orchid of conservation concern, for its fungal relationships, host preference, and trophic mode. Triphora trianthophoros has a suite of features that suggest it has a strong relationship with soil fungi including a long underground transit time, presence in shaded forest understories during the late summer when irradiance is the lowest, and the persistence of achlorophyllous mutant individuals. Using comparative stable isotope analysis and two-source mixing models, we determined that green T. trianthophoros plants derive approximately 50-100% of its C from fungal parasitism, indicating a strongly partially mycoheterotrophic strategy. Next, we extracted, amplified, and sequenced ITS loci from fungi within T. trianthophoros roots from sites across its North American range to uncover the identity of its fungal symbiont. Future steps, in progress, will further increase sampling across different forest types and ecological contexts that T. trianthophoros occurs in. We expect this study to contribute to our understanding of the particular fungal requirements of this rare orchid species, advance in-situ and ex-situ conservation efforts, and give further insight into partial mycoheterotrophs in the North American orchid flora.