Mycoheterotrophic plants parasitize fungi for most to all their nutritional needs, and often have reduced genomic and morphological features. The relationship between the plants and their fungal hosts provides a compelling system to address questions of how host specificity may limit plant distribution, abundance, and diversity across multiple populations. However, the evolutionary consequences of mycoheterotrophy across a broad geographic region and fungal-host specificity remain poorly understood. We are using the widespread Corallorhiza maculata complex to address questions of fungal host specificity across the broad geographic range. The complex contains C. mertensiana, C. maculata var. maculata, C. maculata var. occidentalis, C. bulbosa, C. maculata var. mexicana, and C. macrantha. Members of the C. maculata species complex vary in flowering time, floral morphology, geographic distribution, and fungal associations, with the predominant hosts belonging to the family Russulaceae (Basidiomycota). Previous work identified a pattern of high orchid-fungal host specificity based on orchid-fungal ITS genotypes and geography, but the reliance on Sanger sequencing of fungal hosts and ITS-RFLP in the orchids may not reveal the full extent of orchid-fungal associations. Our goal is to determine fungal host diversity and specificity of the C. maculata complex from populations across North America. To address host diversity, we are using fungal metabarcoding, targeting the ITS2 region to quantify the range of fungal hosts used by the C. maculata complex. We sequenced 229 rhizome samples comprising all North American members of the complex, with deeper sampling from C. maculata vars. maculata and occidentalis in Oregon, California, and Colorado. We found evidence of associations with multiple fungal families within the complex, with the predominant family being Russulaceae, followed by Thelephoraceae and Ceratobasidiaceae. We also identified that the primary trophic mode of fungi associated with the C. maculata complex to be ‘symbiotrophic,’ comprising fungi that receive nutrients in a mutualistic relationship with another plant host (e.g. ectomycorrhizal). Previous work has identified the C. maculata complex to be exclusive to Russulaceae; however this study may have implications for conservation research due to the identification of other potential hosts, including some that may be able to be cultured easily (e.g. Ceratobasidium). Our finding that there are additional fungal families targeted by the C. maculata complex suggests that fungal host identification via Sanger sequencing does not give a complete picture of fungal host diversity and may be biased towards the most abundant taxa. Further, alternative sequencing approaches are being explored such as PacBio long-read sequencing to provide species-level resolution of fungal host identity, as ITS2 Illumina sequencing appears to lack this level of resolution. The outcomes of this study will allow for the identification of host diversity and plant-fungal associations across a broad geographic range, and greatly expand what is currently known for fully mycoheterotrophic orchids and their fungal hosts.