Heterobasidion is a genus of basidiomycetes in the family of Bondarzewiaceae. Species in this genus include tree decay fungi that may be pathogenic and cause deterioration of tree health including mortality. Fungi in the genus produce shelf-like polyporous fruiting bodies that release spores from pores. Mating studies in the late twentieth century and genetic studies in the early twenty-first century have led to description of several new species and replacement of some of the original names. As a result, two former Heterobasidion species, H. annosum and H. insulare, are now recognized to each comprise multiple distinct species.

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