<i>Mycena citrinomarginata</i> is associated with roots of the perennial grass <i>Festuca roemeri</i> in Pacific Northwest prairies

Prairies in the Pacific Northwest are dominated by perennial bunchgrasses. A <i>Mycena</i> in the <i>citrinomarginata</i> complex was observed to tightly co-occur with bunchgrasses at several prairie study sites. Mapping and spatial statistics showed that it was strongly and significantly associated with <i>Festuca roemeri</i> tussocks. We further found that this fungus is attached to <i>F. roemeri</i> roots (17/17 examined) and both specific primers and next-generation DNA sequencing established that the fungus is in the roots, suggesting that <i>M. citrinomarginata</i> may be endophytic or biotrophic in some contexts, and not simply saprotrophic. These results combined with a literature review indicate that <i>Mycena</i> species are often found as endophytes in grass roots. Given the importance of grasses and grasslands for humans, this ecological association deserves further study.