text: stropharia caerulea stropharia caerulea , commonly known as the blue roundhead , is an inedible species of agaric fungus in the family strophariaceae . it is a common species found in europe and north america , where it grows as a in meadows , roadsides , hedgerows , gardens , and woodchip mulch . s. caerulea was officially described to science in 1979 , although it was known to be a distinct species for about two centuries before that . the taxon stropharia cyanea , as defined by risto tuomikoski in 1953 , and used by several later authors , is a synonym of s. caerulea . the fruit bodies ( mushrooms ) of stropharia caerulea feature a greenish - blue cap sparsely covered in white flecks of veil at the margin , and a sticky , glutinous surface texture . gills on the cap underside have an adnate or sinuate attachment to the stipe . they are initially pale purplish - brown , becoming darker brown in age as the spores mature . the greenish stipe is covered in white scales up to a thin , transient ring . it is similar in appearance to its less common relative stropharia aeruginosa , but that species has a more robust ring on its stipe , more scales on the cap , and darker gills with white edges . taxonomy in 1953 , the finnish scientist risto tuomikoski observed that the well - known stropharia aeruginosa had a lookalike species that was characterized by a brown spore print , an indistinct , temporary ring on the stipe , and lining the gill edges . tuomikoski called this lookalike stropharia cyanea , a name he based on james bolton 's 1820 taxon agaricus cyaneus . later researchers confirmed the existence and widespread european distribution of this taxon . tuomikoski 's use of the name s. cyanea , however , was incorrect as bolton 's type refers to the purple - brown spored species s. aeruginosa . despite this , the misapplied name s. cyanea has persisted in some contemporary field guides . stropharia caerulea was first mentioned in the scientific literature by james bolton in 1788 , under the name agaricus . this usage is not considered valid according to nomenclatural rules , because it was used by christian hendrik persoon to refer to another species in his 1801 synopsis methodica fungorum , which is a sanctioned work . stropharia caerulea was officially described by mycologist hanns kreisel in 1979 from collections made near , germany . machiel noordeloos transferred the species to psilocybe in 1995 , but today this genus is mostly reserved for species that contain the psychoactive compounds psilocybin and psilocin . although psilocybin had once been reported from s. caerulea , subsequent analyses have not revealed any traces of the substance in the fruit bodies . the specific epithet caerulea is latin for " blue " . the mushroom is commonly known as the blue roundhead . french mycologist régis courtecuisse has called the mushroom " verdigris agaric " , but numerous other authors use this name to refer instead to stropharia aeruginosa . description fruitbodies have conical to flattened caps measuring 2 – 7 . 5 cm ( 0 . 8 – 3 . 0 in ) in diameter . they usually have a low , broad umbo . the colour of the cap depends on its age , ranging from pale blue - green to yellowish - bluish green . there is often a whitish zone around the margin , which invariably has bluish - green tints . when moist , the cap is sticky with a cuticle that may be readily peeled ; dry caps are smooth and shiny . gills are initially pale purplish - brown , becoming darker brown in age as the spores mature . they have an adnate or sinuate attachment to the stipe . the stipe has a short - lived annular ( ring ) zone ; above this zone the stipe is smooth , while below it is fibrous and scaly . the flesh is colourless , although it may have tinges of blue in the cap and stipe , and lacks any distinctive odour or flavour . stropharia cyanea fruit bodies are not edible . the spore print is brown . spores typically measure 8 . 0 – 9 . 0 by 4 . 0 – 5 . 5 µm , and have an ellipsoid to oblong to ovoid shape , depending on the viewing angle . basidia ( spore - bearing cells ) are narrowly club - shaped , four - spored , and have dimensions of 24 – 40 by 7 – 12 µm . the ( found on the gill edge ) are club - shaped , measuring 30 – 55 by 4 – 40 µm , with a neck that is 2 – 5 µm wide . ( on the gill face ) are 40 – 60 by 5 – 18 µm with a 2 – 4 µm - wide neck . clamp connections are abundant in all tissues of s. caerulea . the fungus produces acanthocytes , which are spiny cells produced on short branches on the mycelium . similar species there are a few greenish stropharia with which s. caerulea might be confused . stropharia is an uncommon species that grows in meadows . it has a more slender form than s. caerulea , a soft , spongy stipe , and flesh with an odour similar to fresh pepper . microscopically , it has a dense palisade of slender , capitate ( with a spherical tip ) non - staining cheilocystidia on the gill edge . this gives the gills of young , fresh fruit bodies a whitish edge , a feature that is absent from s. caerulea . another lookalike , s. aeruginosa , is less common than s. caerulea . it is distinguished from the latter by the well - developed ring zone on its stipe , darker gills with white edges , and more numerous whitish scales around the cap margin . additionally , s. aeruginosa has more stable colours than s. caerulea , the colouration of which tends to quickly wash out . however , collections of stropharia often show characteristics that are intermediate between two or more species , making them difficult to identify accurately . habitat , distribution , and ecology stropharia caerulea is a saprophytic fungus that fruits singly or in groups . it grows in or on meadows , roadsides , hedgerows , gardens , and woodchip mulch . in europe it is often found in beech woods in alkaline soil . it is a common species found throughout europe , where it fruits from july to november . although also found in north america , generally fruiting from august to october , the full extent of its distribution there is unknown . fruitbodies of stropharia caerulea form mycelial cords – rootlike structures consisting of a dense mass of hyphae – which create extensive underground networks that move nutrients and allow the fungus to " forage " for resources . these cords are often associated with stems and rhizomes of the common nettle ( dioica ) . these mycelial systems ' development and the species 's interactions with other cord - forming wood decomposer basidiomycetes have been investigated . the mycelia of stropharia caerulea form a fractal structure characterized by a dense , relatively slowly extending front , a formation associated with finding relatively homogeneously distributed nutrients – equivalent to short - range foraging . an increase in the supply of soil nitrogen or phosphorus increases the fractal branching of the mycelia , allowing increased uptake of nutrients .