page_title: Ganoderma sessile
section_title: Taxonomy and history
hierarchical_section_title: Ganoderma sessile / Taxonomy and history
caption_attribution_description: English: Chlamydospores stained in lactophenol blue
context_page_description: Ganoderma sessile is a species of polypore fungus in the Ganodermataceae family. This wood decay fungus is found commonly in Eastern North America, and is associated with declining or dead hardwoods. There is taxonomic uncertainty with this fungus since its circumscription in 1902.
context_section_description: Murrill described 17 new Ganoderma species in his treatises of North American polypores, including for example, G. oregonense, G. sessile, G. tsugae, G. tuberculosum and G. zonatum. Most notably and controversial was the typification of Ganoderma sessile, which was described from various hardwoods only in the United States. The specific epithet "sessile" comes from the sessile, or without typical stem, nature of this species when found growing in a natural setting.  Ganoderma sessile was distinguished based on a sessile fruiting habit, common on hardwood substrates and occasionally having a reduced, eccentric or “wanting” stipe. In 1908, Atkinson considered G. tsugae and G. sessile as synonyms of G. lucidum, but erected the species G. subperforatum from a single collection in Ohio on the basis of having “smooth” spores. Although he did not recognize the genus Ganoderma, but rather kept taxa in the genus Polyporus, Overholts agreed with Atkinson, and considered G. sessile as a synonym of the European G. lucidum .
  In a 1920 report on Polyporaceae of North America, Murrill conceded that G. sessile was closely related to the European G. lucidum . It is difficult to determine if this concession was the result of political scrutiny or from a scientific foundation, due to the retention of the name by Murrill in a later publication  and a single herbarium collection in 1926 (www.mycoportal.org).
  Approximately a decade later, Haddow considered G. sessile a unique taxon, but suggested Atkinson’s G. subperforatum was a synonym of G. sessile, on the basis of the “smooth” spores, which was the original basis of G. subperforatum when earlier erected by Atkinson in 1931. Until this point, all identifications of Ganoderma taxa were based on fruiting body morphology, geography, host, and spore characters.
  In 1948 and then amended in 1965, Nobles characterized the cultural characteristics of numerous wood-inhabiting hymenomycetes including Ganoderma taxa. Her work laid the foundation for culture-based identifications in this group of fungi. Nobles recognized that there were differences in cultural characteristics between G. oregonense, G. sessile, and G. tsugae . Although Nobles recognized G. lucidum in her 1948 publication as a correct name for the taxon from North American isolates that produce numerous broadly ovoid to elongate chlamydospores (12.0-21.0 x 7.5-10.5 μm), she corrected this misnomer in 1968 by amending the name to G. sessile . Clarifying further, Bazallo & Wright and Steyaert agree with Haddow’s distinction between G. lucidum and G. sessile on the basis of “smooth” spores, but they synonymize G. sessile with G. resinaceum, a previously described European taxon. Later Adaskaveg and Gilbertson demonstrated the similarity in culture morphology and that vegetative compatibility was successful between the North American taxon recognized as ‘G. lucidum’ and the European G. resinaceum .
  In the monograph of North American Polypores written in 1986, which is still the only comprehensive treatise on this group of fungi unique for North America, the authors Gilbertson and Ryvarden do not recognize G. sessile, but rather recognize the five following laccate species being present in the U.S.: G. colossum (Fr.) C.F. Baker (current name: Tomophagus colossus (Fr.) Murrill), G. curtisii, G. lucidum, G. oregonense, and G. tsugae . They considered G. sessile along with other laccate species synonyms with G. lucidum, and in the comments under G. lucidum they discuss the taxonomic chaos of this particular species complex, and leave it somewhat unresolved.
caption: G. sessile chlamydospores stained in lactophenol cotton blue
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