Largest phylum of fungi

The largest of the seven phyla (highest taxonomic groups) of fungi currently recognized by mycologists is Ascomycota. It contains more than 64,000 species already formally recognized by science, and many additional species still undiscovered and unnamed are believed to exist too. Commonly referred to as sac fungi and of global distribution, ascomycetes are characterized by a sac-like sexual structure called the ascus in which their non-motile spores known as ascospores are formed.

Some ascomycetes are asexual, and therefore lack an ascus and ascospore production. As a result, in earlier times these asexual ascomycetes were classified separately from the sexual species, but owing to advances in genetic analyses their DNA has revealed that asexual and sexual ascomycetes really are closely related to one another after all – despite their very different reproductive mechanisms.