ABSTRACT
Certain specialized members of the Zygomycetes, Ascomycetes, and Basidiomycetes form symbioses with species in most plant families, including many angiosperms, gymnosperms, Pteridophytes, and Thallophytes (Harley and Smith, 1983; Harley and Harley, 1987; Morton, 1988). In 1885, A. B. Frank (1885), while investigating the possibility of introducing truffle cultivation to Russia, first described in detail these associations, which are characterized by recognizable structures, in beech, oak, and conifer roots. Frank coined the term "mykorrhizen," or ''fungus root'' for these structures, and later characterized them as ''ectoptropisch'' (Frank, 1885) when characterized by a conspicuous sheath of fungal tissue around the host root, or "endotropisch" where the external sheath was lacking (Harley and Smith, 1983; Harley, 1985; Morton, 1988; Schenck, 1982). Even earlier, the Polish botanist Kamienski (1882) described a mutualistic relationship between an unknown fungus and an achlorophyllous plant, Monotropa hypopitys L. Kamienski commented on the similarity between the "deformed" roots of Monotropa and those of nearby trees. Unlike Frank, however, who specifically pointed out the ubiquity and necessity of the mutualism between fungus and tree (Frank, 1885), Kamienski assumed that the relationship was a parasitic one.
