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''Paxillus involutus'', commonly known as the brown roll-rim, common roll-rim, or poison pax, is a basidiomycete fungus widely distributed across the Northern Hemisphere. It has been unintentionally introduced to Australia, New Zealand, and South America, where it has likely been transported in soil with European trees. Various shades of brown in colour, the fruit body grows up to 6 cm (2.4 in) high and has a funnel-shaped cap up to 12 cm (5 in) wide with a distinctive inrolled rim and decurrent gills that may be pore-like close to the stipe. Although it has gills, it is more closely related to the pored boletes than to typical gilled mushrooms. It was first described by Pierre Bulliard in 1785, and was given its current binomial name by Elias Magnus Fries in 1838. Genetic testing suggests that ''Paxillus involutus'' may be a species complex rather than a single species. A common mushroom of deciduous and coniferous woods and grassy areas in late summer and autumn, ''Paxillus involutus'' forms ectomycorrhizal relationships with a broad range of tree species. These benefit from the symbiosis as the fungus reduces their intake of heavy metals and increases resistance to pathogens such as ''Fusarium oxysporum''. Previously considered edible and eaten widely in Eastern and Central Europe, it has since been found to be dangerously poisonous, responsible for the death of German mycologist Julius Schäffer in 1944. It had been recognised as causing gastric upsets when eaten raw, but was more recently found to cause potentially fatal autoimmune hemolysis, even in those who had consumed the mushroom for years without any other ill effects. An antigen in the mushroom triggers the immune system to attack red blood cells. Serious and potentially fatal complications include acute renal failure, shock, acute respiratory failure, and disseminated intravascular coagulation. ==Taxonomy and naming== The brown roll-rim was described by French mycologist Pierre Bulliard in 1785 as ''Agaricus contiguus'',〔 although the 1786 combination ''Agaricus involutus'' of August Batsch〔 is taken as the first valid description.〔 James Bolton published a description of what he called ''Agaricus adscendibus'' in 1788;〔 the taxonomical authority Index Fungorum considers this to be synonymous with ''P. involutus''.〔 Additional synonyms include ''Omphalia involuta'' described by Samuel Frederick Gray in 1821,〔 and ''Rhymovis involuta'', published by Gottlob Ludwig Rabenhorst in 1844.〔 The species gained its current binomial name in 1838 when the 'father of mycology', Swedish naturalist Elias Magnus Fries erected the genus ''Paxillus'', and set it as the type species.〔 The starting date of fungal taxonomy had been set as January 1, 1821, to coincide with the date of Fries' works, which meant that names coined earlier than this date required sanction by Fries (indicated in the name by a colon) to be considered valid. It was thus written ''Paxillus involutus'' (Batsch:Fr.) Fr. However, a 1987 revision of the International Code of Botanical Nomenclature set the starting date at May 1, 1753, the date of publication of Linnaeus' seminal work, the ''Species Plantarum''. Hence the name no longer requires the ratification of Fries' authority. The genus was later placed in a new family, Paxillaceae, by French mycologist René Maire who held it to be related to both agarics and boletes.〔 Although it has gills rather than pores, it has long been recognised as belonging to the pored mushrooms of the order Boletales rather than the traditional agarics.〔 The generic name is derived from the Latin for 'peg' or 'plug', and the specific epithet ''involutus'', 'inrolled', refers to the cap margin.〔 Common names include the naked brimcap,〔 poison paxillus,〔 inrolled pax,〔 poison pax, common roll-rim, brown roll-rim,〔 and brown chanterelle.〔 Gray called it the "involved navel-stool" in his 1821 compendium of British flora.〔 Studies of the ecology and genetics of ''Paxillus involutus'' indicate that it may form a complex of multiple similar-looking species.〔〔 In a field study near Uppsala, Sweden, conducted from 1981 to 1983, mycologist Nils Fries found that there were three populations of ''P. involutus'' unable to breed with each other. One was found under conifers and mixed woodlands, while the other two were found in parklands, associated with nearby birch trees. He found that the first group tended to produce single isolated fruit bodies which had a thinner stipe and cap which was less inrolled at the margins, while the fruit bodies of the other two populations tended to appear in groups, and have thicker stipes, and caps with more inrolled and sometimes undulating margins. However, there were only general tendencies and he was unable to detect any consistent macroscopic or microscopic features that firmly differentiate them.〔 A molecular study comparing the DNA sequences of specimens of ''Paxillus involutus'' collected from various habitats in Bavaria found that those collected from parks and gardens showed a close relationship with the North American species ''P. vernalis'', while those from forests were allied with ''P. filamentosus''. The authors suggested the park populations may have been introduced from North America. A multi-gene analysis of European isolates showed that ''P. involutus'' ''sensu lato'' (in the loose sense) could be separated into four distinct, genetically isolated lineages corresponding to ''P. obscurosporus'', ''P. involutus'' ''sensu stricto'' (in the strict sense), ''P. validus'', and a fourth species that has not yet been identified.〔 Changes in host range have occurred frequently and independently among strains within this species complex.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paxillus involutus」の詳細全文を読む スポンサード リンク
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