A grass with improved environmental stress tolerance and low animal toxicity is disclosed where the grass is infected with an isolated endophyte selected from the groups consisting of USDA-PI no. 269850, Ijoukak, Morocco 92060, Boumalne-de-Dades, Morocco KBG 5921, USDA-PI no. 516560, Oujda, Morocco KBG 5892, and mixtures and combinations thereof. A method for stably infecting the grasses is also disclosed.