An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life without causing apparent disease.[1][2] Endophytes are ubiquitous and have been found in all the species of plants studied to date; however, most of these endophyte/plant relationships are not well understood.[3][4] Many economically important grasses (e.g., Festuca spp., Lolium spp., Zea) carry fungal endophytes which enhance their growth,[5] may improve the plant's to tolerate abiotic stresses such as drought, as well as improve their resistance to insect and mammalian herbivores.[6][7][8]