Abstract: A method for developing new varieties of plants which host an endophytic fungus, said fungus conferring enhanced performance on its plant host. The method comprises selecting a maternal parent which hosts an endophytic fungus capable of enhancing its host plant's performance. A paternal parent plant of the same or of a different variety as the maternal parent plant is selected. The selected maternal parent plant is then crossed with the selected paternal parent plant. The progeny of the cross which have the desired enhanced-performance characteristics are themselves selected. These progeny are then sexually or asexually propagated and the seed, vegetative propagules, or disseminules harvested.