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''Psilocybe semilanceata'', commonly known as the liberty cap, is a psychedelic (or "magic") mushroom that contains the psychoactive compounds psilocybin, baeocystin and phenylethylamine. Of the world's psilocybin mushrooms, it is both one of the most widely distributed in nature, and one of the most potent. The mushrooms have a distinctive conical to bell-shaped cap, up to in diameter, with a small nipple-like protrusion on the top. They are yellow to brown, covered with radial grooves when moist, and fade to a lighter color as they mature. Their stipes tend to be slender and long, and the same color or slightly lighter than the cap. The gill attachment to the stipe is adnexed (narrowly attached), and they are initially cream-colored before tinting purple as the spores mature. The spores are dark purplish-brown in mass, ellipsoid in shape, and measure 10.5–15 by 6.5–8.5 micrometres. The mushroom grows in grassland habitats, especially wetter areas. But unlike ''P. cubensis'', the fungus does not grow directly on dung; rather, it is a saprobic species that feeds off decaying grass roots. It is widely distributed in temperate climate of the Northern Hemisphere, particularly in Europe. However, it has also been reported occasionally in temperate climate of the Southern Hemisphere as well. The earliest reliable history of ''P. semilanceata'' intoxication dates back to 1799 in London, and in the 1960s the mushroom was the first European species confirmed to contain psilocybin. The possession or sale of psilocybin mushrooms is illegal in many countries. ==Taxonomy and naming== The species was first described by Elias Magnus Fries as ''Agaricus semilanceatus'' in his 1838 ''Epicrisis Systematis Mycologici''.〔 Paul Kummer transferred it to ''Psilocybe'' in 1871 when he raised many of Fries's sub-groupings of ''Agaricus'' to the level of genus.〔 ''Panaeolus semilanceatus'', named by Jakob Emanuel Lange in both 1936 and 1939 publications, is a synonym.〔〔 According to the taxonomical database MycoBank, several taxa once considered varieties of ''P. semilanceata'' are synonymous with the species now known as ''Psilocybe strictipes'':〔 the ''caerulescens'' variety described by Pier Andrea Saccardo in 1887 (originally named ''Agaricus semilanceatus'' var. ''coerulescens'' by Mordecai Cubitt Cooke in 1881),〔 the ''microspora'' variety described by Rolf Singer in 1969,〔 and the ''obtusata'' variety described by Marcel Bon in 1985.〔 Several molecular studies published in the 2000s demonstrated that ''Psilocybe'', as it was defined then, was polyphyletic.〔〔〔 The studies supported the idea of dividing the genus into two clades, one consisting of the bluing, hallucinogenic species in the family Hymenogastraceae, and the other the non-bluing, non-hallucinogenic species in the family Strophariaceae. However, the generally accepted lectotype (a specimen later selected when the original author of a taxon name did not designate a type) of the genus as a whole was ''Psilocybe montana'', which is a non-bluing, non-hallucinogenic species. If the non-bluing, non-hallucinogenic species in the study were to be segregated, it would have left the hallucinogenic clade without a valid name. To resolve this dilemma, several mycologists proposed in a 2005 publication to conserve the name ''Psilocybe'', with ''P. semilanceata'' as the type. As they explained, conserving the name ''Psilocybe'' in this way would prevent nomenclatural changes to a well-known group of fungi, many species of which are "linked to archaeology, anthropology, religion, alternate life styles, forensic science, law enforcement, laws and regulation".〔 Further, the name ''P. semilanceata'' had historically been accepted as the lectotype by many authors in the period 1938–68. The proposal to conserve the name ''Psilocybe'', with ''P. semilanceata'' as the type was accepted unanimously by the Nomenclature Committee for Fungi in 2009.〔 The mushroom takes its common name from the Phrygian cap, also known as the "liberty cap", which it resembles;〔 ''P. semilanceata'' shares its common name with ''P. pelliculosa'',〔 a species from which it is more or less indistinguishable in appearance.〔 The Latin word for Phrygian cap is ''pileus'', nowadays the technical name for what is commonly known as the "cap" of a fungal fruit body. In the 18th century Phrygian caps were placed on Liberty poles, which resemble the stipe of the mushroom. The generic name is derived from the Ancient Greek ''psilos'' (ψιλός) ("smooth" or "bare") and the Byzantine Greek ''kubê'' (κύβη) ("head").〔〔 The specific epithet comes from the Latin ''semi'' ("half") and ''lanceata'', from ''lanceolatus'', meaning "spear-shaped".〔 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「Psilocybe semilanceata」の詳細全文を読む スポンサード リンク
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