C. cedri has been shown to host three symbionts: a S symbiont, Buchnera aphidicola and bacteria in the genus Wolbachia.
Epichloë species and their close relatives, the Neotyphodium species, are systemic and constitutive symbionts of cool-season grasses (Poaceae subfamily Pooideae), and belong to the fungal family Clavicipitaceae.
This and other species in the genus contain a green algae in the genus Coccomyxa and also cyanobacteria in the genus Nostoc as symbionts.