text: mycena acicula mycena acicula , commonly known as the orange bonnet , or the coral spring mycena , is a species of fungus in the mycenaceae family . it is found in asia , the caribbean , north america and europe . the fruit bodies , or mushrooms , of the fungus grow on dead twigs and other woody debris of forest floors , especially along streams and other wet places . they have small orange - red caps , up to 1 cm ( 0 . 4 in ) in diameter , held by slender yellowish stems up to 6 cm ( 2 . 4 in ) long . the gills are pale yellow with a whitish edge . several other mycena species look similar , but may be distinguished by differences in size and / or microscopic characteristics . m. acicula is considered inedible because of its small size . taxonomy first named agaricus acicula by the german scientist jacob christian schäffer in 1774 , the species was also referred to as agaricus by another german , naturalist august batsch . it was given its current name in 1871 by paul kummer . rolf singer transferred the species to the genera hemimycena and marasmiellus , but the binomials resulting from these transfers are now considered synonyms . the fungus is classified in the section of the genus mycena . the specific epithet acicula is derived from the latin word meaning " small needle " . the mushroom is commonly known as the " orange bonnet " , or the " coral spring mycena " . description the cap is initially convex , but as it matures , it expands to a bell - shape , typically reaching 0 . 3 to 1 cm ( 0 . 1 to 0 . 4 in ) in diameter . the cap sometimes has a small abrupt umbo ( a central bump ) , and the cap margin is pressed closely against the stem when young , often flaring or curving slightly inward . as the cap expands , a narrow sterile ( i.e. , without any reproductive cells typical of the hymenium ) band which frequently becomes lobed or irregularly - jagged often forms at the extreme margin . the cap surface is smooth , faintly translucent - striate when moist , at first pruinose but soon naked . the color is red when young , soon becoming yellowish toward the margin , and slowly fading to bright orange - yellow . the flesh is thin , brittle , yellow , and has no distinctive odor or taste . the gills are adnate ( with gills broadly attached to the stem , slightly above the bottom of the gill , with most of the gill fused to the stem ) or slightly rounded next to the stem . the individual gills are close to subdistant , with between 10 – 14 reaching the stem , and two or three tiers of lamellulae ( short gills that do not reach the stem ) . the gills are moderately broad , pale orange to whitish , often yellowish at the base and whitish along the edges . the stem is 1 to 6 cm ( 0 . 4 to 2 . 4 in ) long , and up to 1 mm thick ; flexuous ( winding from side to side ) , brittle , with the base covered with sharp , straight , and stiff white hairs . the surface is densely white - pruinose initially , but soon becomes naked with a subsequent color shift to orange - yellow or lemon yellow . this species has been described as " a delight to behold " , but " one usually has to get down on hands and knees to find it ! " the fruit bodies of mycena acicula are considered inedible , as they are too small and insubstantial to be considered for consumption . microscopic characteristics the spores are roughly spindle - shaped ( i.e. , tapering at each end ) , with dimensions of 9 – 11 by 3 . 5 – 4 . 5 µm . they are nonamyloid , meaning they do not take up iodine when stained with melzer 's reagent . the spore - bearing cells , the basidia , are club - shaped , four - spored and measure 20 – 22 by 5 – 6 µm . the and pleurocystidia ( cystidia found on the edge and face , respectively , of a gill ) are similar , club - shaped to spindle - shaped or egg - shaped , and have apices that are often covered with a resinous secretion . the hyphae that comprise the cap cuticle are up to 3 . 5 µm wide , clamped , and covered with cylindrical excrescences that measure 2 – 9 by 1 – 3 µm . the hyphae of the cortical layer of the stem are up to 4 . 5 µm wide , clamped , and densely covered with simple to somewhat branched , cylindrical to inflated excrescences that are up to 20 by 5 µm . these latter excrescences are embedded in gelatinous matter . similar species mycena adonis , m. , and m. leptophylla are larger species belonging to the section of the genus mycena . in that section , among other differences , the hyphae of the cortical layer ( the outer layer of tissue ) of the stem are smooth . m. oregonensis is similar in appearance to m. acicula , but the cap is yellower , the gills are broadly adnate or decurrent with a short tooth , the gill edge is orange to bright yellow , and the stem is dry , not sticky . the hyphae of the cortical layer of the stem are smooth and not embedded in gelatinous matter , and in european collections the basidia are two - spored and do not have clamps . m. strobilinoides , a north american and european species , looks similar with its orange cap , but may be distinguished microscopically by the cheilocystidia which are densely covered by excrescences ; it also has a larger cap , up to 2 cm ( 0 . 8 in ) . m. aurantiidisca can be distinguished by the reddish - orange cap which tends to become paler at the margin . mycena specialist alexander h. smith further noted of m. acicula that it could readily be mistaken for a hygrophorus . habitat and distribution the fruit bodies of mycena acicula grow singly , in groups , or somewhat clustered on debris in wet places , especially along streams or the borders of swamps . the appearance of the fruit bodies is not significantly influenced by the effect of rainfall , perhaps because " such minute fungi are largely determined by the microenvironment prevailing under dense vegetation , etc . , which is no doubt less affected by recent rain than more exposed situations . " the fungus is widely distributed throughout the eastern united states and canada and occurs in washington , oregon , and california along the pacific coast . it has also been reported from trinidad , britain , norway , spain , korea , and the ussuri river valley in the northeast of china .