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A diverse assemblage of fungi has been isolated from hair roots of genera within the Ericaceae and Epacridaceae. Isolates are generally slow growing, and many produce dark mycelium (dematiaceous mycelium) when grown on various media. For many years, only one fungal species, Pezizella ericae = Hymenoscyphus ericae = Rhizoscyphus ericae, identified originally by characteristics of the mycelium in culture and the production of asexual propagules (arthroconidia), had been shown by synthesis experiments to form ericoid mycorrhizas with members of the Ericaceae. The characteristic arthroconidia now place this fungus in the anamorph genus Scytalidium. Cultures of the fungus have also been shown to form sexual
reproductive structures (apothecia with asci and ascospores), and molecular evidence confirms that at least one isolate of Scytalidium (S. vaccinii) is identical to H. ericae (R. ericae). H. ericae is now described as the teleomorph stage of this fungus.
Several other isolates are known to form typical ericoid mycorrhizas with a variety of ericaceous hosts. Among these, anamorph species of Oidiodendron and their teleomorphic states, Myxotrichum and Byssoascus (Hyphomycetes), are especially important. Many unidentified isolates cultured from ericaceous hosts also form typical ericoid mycorrhizas; their taxonomic placement is beginning to be clarified with the help of molecular methods.
Many fungal isolates have also been obtained from hair roots in the Epacridaceae. The mycelium of many of them is, in culture, dematiaceous, but isolates can range in colour from white to pink to various dark shades. Molecular studies show genotype similarities between some of the Epacridaceae isolates and Hymenoscyphus and Oidiodendron from the Ericaceae, but none are identical at the species level. As more host species in both families, Ericaceae and Epacridaceae, are examined with respect to their fungal partners, there is no doubt that the number of identified fungal species will increase. There is some evidence that fungal species belonging to the basidiomycetes are involved in forming ericoid mycorrhizas. Dark septate endophytes are also frequently found within hair roots of members of the Ericales.
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