text: geastrum quadrifidum 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 2 – 3 cm ( 0 . 8 – 1 . 2 in ) wide and up to about 3 cm ( 1 . 2 in ) 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. . ( for example , as in imai , 1936 ) ; within taxonomical terminology , this usage is an 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 of the section , 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 " . description as in all geastrum fungi , the internal spore - producing gleba is enclosed in the peridium , a protective structure composed of four layers of tissue : an inner endoperidium , and outer exoperidium that may further be divided into an external mycelial , a tough and membranous middle fibrillose layer , and an internal fleshy layer ( known as the pseudoparenchyma ) . the immature , unopened fruit body is roughly spherical to somewhat flattened or irregular in shape . it lies partly or wholly submerged , encrusted with debris . the expanded fruit body is usually taller than it is wide , about 10 – 40 mm ( 0 . 4 – 1 . 6 in ) high , with mycelial cup included about 15 – 55 mm ( 0 . 6 – 2 . 2 in ) . the exoperidium ( the outer tissue layer of the four - layered peridium ) splits in the middle into three to six , but usually four or five rays . the exoperidium is typically fornicate — a structural feature that arises when the separates from the exoperidium , adhering only at the edge . in this way , the endoperidium ( the internal tissue layer that encloses the spore sac ) is lifted upwards with the downward movement of the rays . in this species , the tips of the rays remain attached to the mycelial layer , which remain attached to the substrate as a cup in the ground . unlike those of some other geastrum species , the rays of g. quadrifidum are not hygroscopic : they do not open and close in response to changes in humidity . generally , the rays are broad , but they may seem narrow as their edges are often rolled inwards . the width of the exoperidium ( when still attached to the mycelial cup ) is 8 – 25 mm ( 0 . 3 – 1 . 0 in ) , when fully expanded about 15 – 90 mm ( 0 . 6 – 3 . 5 in ) . the pseudoparenchymatous layer when fresh is about 1 – 2 mm thick , initially whitish , later turning beige to brownish ( sometimes over reddish tints ) , and dark brown when old . in newly expanded specimens this layer is covered with a thin layer of crystals and hyphae , sometimes forming a pseudoparenchymatous cup or collar that often peels off in patches , when dry shrunken and hard . the fibrous layer is papery to leathery . the inner side , when free from pseudoparenchymatous remnants , is almost white , in age becoming dirty grayish - white and sometimes greenish due to algae ; the outer side is initially whitish , somewhat glossy , but in age becomes grayish - white and dull . the mycelial layer has a whitish inner side and is strongly attached to the litter on its outer side . it persists for a long time ( 1 – 2 - year - old fruit bodies with intact mycelial cups have been found ) . the spore sac is variable in shape , ranging from roughly spherical to egg - shaped or irregular , but it is usually taller than it is wide . its diameter ranges between 3 . 5 and 16 mm ( 0 . 14 and 0 . 63 in ) , although it is most commonly between 5 and 10 mm ( 0 . 2 and 0 . 4 in ) . an apophysis ( a swelling on the underside of the spore sac ) is often present . the stalk is visible when the pseudoparenchymatous layer has dried up , and is short but distinct , measuring 1 – 2 . 5 mm tall . the color is variable ; in dry specimens it is whitish , light beige , beige gray , smoky gray or brownish - gray . the endoperidium in newly expanded fruit bodies is pruinose : covered with a light beige to whitish powder of hyphae and crystalline matter . this powder gradually disappears as the fruit body ages . its color is highly variable , and both light and dark are present . the peristome ( a clearly demarcated region encircling the opening of the spore sac ) is distinctly delimited , with a disc - like to more or less conical shape . it is lighter in color than the spore sac , and up to 2 mm high . in old specimens , the hyphae around the peristome sometimes stick together to develop radial grooves . the color is variable , but often of grayish or grayish - brown tints , often lighter than the endoperidium . the columella ( sterile tissue , usually originating in the base of the gleba , extending into or through the gleba ) is rather weak , more or less columnar to club - shaped , emerging from a more or less bulge - like continuation of the stalk and intruding to about the half or more into the mature gleba . the mature gleba is dark brown . g. quadrifidum is inedible . microscopic characteristics the basidia of g. quadrifidum have a basal clamp connection , or they narrow into a hyphal part that ends at a clamp . when they are young , they are more or less ellipsoid to club - shaped , but in age they often become more or less bottle - shaped , ampullaceous or sometimes almost , among other shapes ; when mature they measure 14 – 21 x 4 . 5 – 7 µm ( excluding the hyphal part ) . the hyphal part is less than 1 – 6 x 1 – 2 µm . the sterigmata ( thin projections of the basidia that attach to the spore ) are 4 – 6 µm long and mostly 1 – 1 . 5 µm thick . the hyphae located immediately underneath the basidia are thin - walled , 1 – 2 µm wide , provided with clamps and densely branched . the hyphae of the tramal plates are roughly parallel , thin - walled , 1 – 2 µm wide , and provided with clamps which may be dilated . the spores in mass are dark brown when mature . they are spherical , covered with " warts " or verrucae , and measure 5 – 6 µm in diameter ( including ornamentation ) . the spores often contain a drop of oil . scanning electron microscopy reveals the verrucae to be up to 0 . 8 µm long , conical to columnar processes with rounded to almost flattened tips . the apiculus ( the part of a spore which attaches to the sterigmata at the end of a basidium ) is distinct with radiating ridge - like processes . the young spore is first broadly egg - shaped before becoming roughly spherical in maturity . the capillitium refers to coarse , late - maturing , thick - walled cells in the gleba that develop pores or slits in their thick secondary walls . the capillitial hyphae are 1 . 5 – 9 . 5 µm wide , thick - walled , often with a narrow lumen , and with or without surface ornamentation . the columella hyphae are 1 . 5 – 14 µm wide ( occasionally wider , up to 34 µm ) , thick - walled , often with narrow lumen . single thin - walled , about 1 . 5 µm wide hyphae with clamps can be observed . the endoperidial hyphae are densely interwoven , thick - walled , and about 2 – 6 µm wide . the whitish powder on newly expanded specimens consists of crystalline matter and thin - walled , 1 . 5 – 4 µm wide , branched hyphae with clamps . the peristome hyphae are thick - walled , 2 – 11 µm wide . the pseudoparenchymatous layer is built up by bladder - like , thin - walled hyphae of varying size . on the surface of newly expanded specimens crystals and thin - walled hyphae of the same kind as on the endoperidium are present . the crystals are calcium oxalate dihydrate that have the crystalline structure of a pyramid , and are arranged singly or in loose aggregates , 11 to 30 µm in size . the fibrous layer has thick - walled hyphae 1 . 5 – 4 µm wide . the mycelial layer in the inner , very thin part ( seen as a glossy lining on the fibrous layer of newly expanded fruit bodies ) consists of a dense web of thin - walled , 1 . 5 – 4 µm wide , clamped hyphae . thick - walled hyphae are also present , measuring 2 – 11 ( sometimes up to 19 ) µm wide . the outer part ( the mycelial cup ) consists of thick - walled , branched and densely interwoven hyphae ( often with a narrow lumen ) that measure 1 . 5 – 4 µm wide . similar species geastrum quadrifidum is readily confused with g. fornicatum , which is larger — up to 15 cm ( 5 . 9 in ) — and has smaller spores ( 4 – 5 μm in diameter ) . geastrum minimum , although small like g. quadrifidum , is distinguished by having more rays ( usually more than seven ) , and it is not fornicate . also , its mycelial layer is attached to the fibrous layer for a long time , without forming a mycelial cup like g. quadrifidum . the chilean species g. does not have a clearly demarcated peristome . geastrum quadrifidum is also similar to g. , g. , and g. welwitschii in its fruit body morphology , especially the exoperidial rays , endoperidial body , and peristome . geastrum differs from g. quadrifidum by its often sulcate or silky fimbriate , smooth peristome , and slightly smaller spores ( 4 – 5 μm in diameter ) . geastrum can be distinguished from g. quadrifidum by its smaller spores ( 2 – 3 μm in diameter ) , and by its preference for growing in mosses on tree trunks . g. welwitschii differs from g. quadrifidum by its epigeal mycelial cup with a felted or tufted outer surface , and indistinctly delimited peristome . distribution , ecology , and habitat although geastrum quadrifidum has a wide distribution , it is not a common species . european countries from which the fungus has been reported include belgium , denmark , france , germany , montenegro , norway , poland , and sweden . in asia , it has been collected in china and japan . the north american distribution extends from canada south to mexico , and includes hawaii . it is also found in australia and new zealand , south africa , and south america . because of its rarity , it has been placed on the regional red lists of several european countries , including montenegro , denmark , norway , and poland . like most earthstars , g. quadrifidum is a saprobic fungus , and spends most of its life cycle as thin strands of mycelium , deriving nutrients by decomposing leaf litter and similar detritus , converting it to humus and mineralizing organic matter in the soil . the fungal fruit bodies are generally found in coniferous woodland , where they appear in summer and autumn . in mexico , it was found in tropical thorn forest and pine - oak forest in the summer . in britain , all collections have been made in beech forest on calcareous soil . cited books sunhede s. ( 1989 ) . geastraceae ( ) : morphology , ecology , and systematics with special emphasis on the north european species . synopsis fungorum , 1 . oslo , norway : . isbn 82 - - 05 - 5 .