as endophyte and pathogen.

is a common species of fungus frequently isolated from plants as both an endophyte and a pathogen. Although the current definition of rests on a foundation of morphological, genetic and genomic analyses, doubts persist regarding the scope of within the genus due to the varied symbiotic interactions and wide host range observed in these fungi. These doubts may be due in large part to the history of unstable taxonomy in , based on limited morphological characters for species delimitation and host specificity associated with toxins encoded by genes carried on conditionally dispensable chromosomes. This review explores the history of taxonomy, focusing in particular on the use of nutritional mode and host associations in species delimitation, with the goal of evaluating as it currently stands based on taxonomic best practice. Given the recombination detected among isolates of , different symbiotic associations in this species should not be considered phylogenetically informative.