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''Geastrum quadrifidum'', commonly known as the rayed earthstar or four-footed earthstar, is an inedible species of mushroom belonging to the genus ''Geastrum'', or earthstar fungi. First described scientifically by Christian Hendrik Persoon in 1794, ''G. quadrifidum'' is a cosmopolitan—but not common—species of Europe, the Americas, Africa, Asia, and Australasia. The fungus is a saprobe, feeding off decomposing organic matter present in the soil and litter of coniferous forests. The small, tough, fruit bodies are grayish-brown balls that are initially enclosed by a skin, or peridium, made up of four distinct layers of tissue. The outer tissue layer splits to form star-like rays and expose a circular spore case. Inside the spore case is the gleba—fertile spore-producing tissue that is white and firm when young, but becomes brown and powdery in age. The grayish-brown spore case is set on a short, slender stalk, and has a well-defined narrow pore at the top where mature spores may escape. Fully expanded, the fruit body reaches dimensions up to wide and up to about tall. The outer skin is purplish-brown, with four or five cream or yellowish-brown colored rays that have their tips stuck in the substrate. There is a flat mat of interwoven mycelia between ray tips. The spores are spherical, warty, and have a diameter of up to 6 µm. ''Geastrum quadrifidum'' is one of a number of earthstars whose rays arch downward as they mature, lifting the spore sac upward, high enough to catch air currents that disseminate the spores into new habitats. The species is easily confused with ''Geastrum fornicatum'', a larger earthstar without a well-defined pore mouth. ==Taxonomy and naming== The Dutch mycologist Christian Hendrik Persoon published the first official description of ''Geastrum quadrifidum'' in 1794,〔 and later sanctioned this name in his 1801 ''Synopsis Methodica Fungorum'' (as ''Geastrum quadrifidum'' var. ''minus'', a variety now considered synonymous with ''G. quadrifidum'').〔 Although the species had been previously described as ''Lycoperdon coronatum'' by Jacob Christian Schaeffer (1763) and Giovanni Antonio Scopoli (1772),〔 then afterward as ''Geaster coronatus'' by Joseph Schröter (1889),〔 the epithet ''coronatus'' is not to be used because of the existence of the sanctioned name.〔 In Japan, ''G. quadrifidum'' has occasionally been called "''Geastrum minus''" (Pers.) G. Cunn. (for example, as in Imai, 1936);〔 within taxonomical terminology, this usage is an ''auctorum non''—a misapplication or misinterpretation of the species name.〔 According to Stanek's classification of the genus ''Geastrum'',〔 (a classification later endorsed in Sunhede's 1989 monograph of European ''Geastrum'' species), ''G. quadrifidum'' belongs in the subsection ''Glabrostoma'' of the section ''Perimyceliata'', a grouping of similar ''Geastrum'' species that incorporate and encrust debris in the mycelial layer, and have an even peristome (opening) that is fibrillose (made of more or less parallel thin thread-like filaments). Several common names for ''G. quadrifidum'' have been suggested, including "rayed earthstar",〔 "four-pointed earthstar"〔 and "four-footed earthstar".〔 Samuel Frederick Gray called it the "four-cut shell-puff" in his 1821 ''The Natural Arrangement of British Plants'',〔 but the name was not adopted by subsequent authors. The specific epithet ''quadrifidum'' is derived from Latin, and means "four-forks".〔 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「Geastrum quadrifidum」の詳細全文を読む スポンサード リンク
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