any fungus of the phylum Ascomycota (formerly class Ascomycetes) in which the spores (ascospores) are formed inside a club-shaped cell (ascus). The group includes yeast, penicillium, aspergillus, truffles, and certain mildews
a symbiotic association of the mycelium of a fungus, especially a basidiomycete, with the roots of certain plants, in which the hyphae form a closely woven mass around the rootlets or penetrate the cells of the root.
