The growth of vesicular-arbuscular mycorrhizal (VAM) fungi in pure culture in the absence of living host roots is an important objective. Currently their taxonomic classification is based almost entirely on the morphology of the chlamydospores and azygospores and their method of germination. If these fungi could be grown in culture, many more characteristics might be considered and classification on biochemical bases used as it is with other microorganisms. Other fundamental studies on VAM fungi would also be greatly facilitated, in particular, their genetic modification and selection to obtain superior strains.