Epichloë festucae is a systemic and seed-transmissible endophytic fungus of cool season grasses.

First described in 1994, Epichloë festucae is a sister lineage to Epichloë amarillans, Epichloë baconii, Epichloë mollis and Epichloë stromatolonga. Epichloë festucae is found across North America, where it lives in the grass species Bromus kalmii and Elymus spp. (including Elymus patula).

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