The present invention is directed to methods and compositions of endophytic fungi that confer stress tolerance in inoculated plants, including both monocots and dicots. In particular, Curvularia species, isolated from a host grass Dichanthelium languinosum growing in the geothermal zones of Lassen Volcanic and Yellowstone National Parks, confers such stress tolerance. Upon inoculating a target plant or plant part with endophytic fungi, the resulting plant shows stress tolerance, particularly drought and thermal tolerance.