Populations of arbuscular mycorrhizal fungi in the Glomeromycota are thought to have occupied the same soil habitats for millions of years, slowly adapting to changes in site conditions (Trappe & Molina 1986, Brundrett 2002). Many of these fungi have worldwide distribution patterns, but soil factors such as pH restrict the distribution of other taxa (Abbott & Robson 1991). Consequently, habitat information is as important as knowledge of the taxonomic identity of fungi, for comparing the results of experiments, or the selection of isolates for practical use.
The classification of the Glomeromycota is based on the structure of their soil-borne spores and DNA sequences. Accurate identification of these fungi often requires them to be isolated in cultures with host plants, to observe developmental stages, avoid the loss of diagnostic features and obtain healthy spores for DNA extraction. There now are many DNA sequences of Glomeromycotan fungi in databases such as Genbank. Information on Glomeromycotan systematics is available via the links below.