text: lactifluus deceptivus lactifluus deceptivus ( synonym lactarius deceptivus ) , commonly known as the deceiving milkcap , is a common species of fungus in the russulaceae family . it is found throughout eastern north america on the ground in coniferous forests near hemlock or deciduous forests near oak , and in oak - dominated forests of costa rica . it produces large mushrooms with funnel - shaped caps reaching up to 25 cm ( 9 . 8 in ) in diameter , on top of hard white stems that may reach 4 – 10 cm ( 1 . 6 – 3 . 9 in ) long and up to 3 cm ( 1 . 2 in ) thick . the gills are closely spaced together and yellowish - cream in color . when young , the cap is white in all parts , but the depressed center becomes dull brownish in age and breaks up into scales . the edge of the cap has a roll of cottony tissue that collapses as the cap expands . the surface of the stem — especially near the base — has a velvety texture . the mushroom " bleeds " a milky white acrid latex when it is cut or injured . the fruit bodies are edible , but have a bitter taste that can be removed with cooking . similar milk - cap species with which l. deceptivus might be confused include lactifluus piperatus , l. , l. caeruleitinctus , l. subvellereus , lactarius and lactarius . taxonomy the species was first described in the scientific literature by american mycologist charles horton peck in 1885 . the specific epithet deceptivus is derived from the latin word for " deceptive " . the name may allude to the contrasting appearance of young and old fruit bodies . it is commonly known as the " deceptive lactarius " , the " deceiving lactarius " , or the " deceptive milkcap " . in the state of puebla , mexico , it is known as de chivo , or " kid ear " . following the split - off of the phylogenetically distinct genus lactifluus from the other milk - caps in the genus lactarius , the correct combination for the species is the one made by otto kuntze in 1891 , lactifluus deceptivus . within the genus lactifluus , l. deceptivus is classified in the subgenus lactifluus , section . characteristics of species in this section include a white or whitish immature cap that may later turn yellow - brown to cinnamon - color ; white to cream - colored latex that typically has an acrid taste ; a velvet - textured stem due to a cuticle made of long narrow , thick - walled hairs . other species in this section include l. vellereus ( the type species ) , l. subvellereus , and l. caeruleitinctus . based on a morphological study published in 2005 , lactarius is considered synonymous with lactifluus deceptivus . l. , described by hesler and smith in their 1979 monograph of north american milk - caps , was considered by them to be a " satellite species " , differing from l. deceptivus on the basis of smaller spores , smaller ornamentations on the surface of the spores , crowded and forked narrow gills , and differences in the micro - structure of the cap cuticle . description the cap is 7 . 5 – 25 . 5 cm ( 3 . 0 – 10 . 0 in ) in diameter , initially convex , but becomes funnel - shaped in age . the margin ( cap edge ) is rolled inwards and cottony when young , concealing the immature gills . the cap surface is dry , smooth and whitish when young , often with yellowish or brownish stains , but becomes coarsely scaly and darkens to dull brownish - ochre with age . the gills have an adnate to decurrent attachment to the stem , close to subdistant , white at first then cream to pale ochre . they are 5 – 65 mm ( 0 . 2 – 2 . 6 in ) long and 1 – 7 mm ( 0 . 04 – 0 . 3 in ) deep . the stem is 4 – 10 cm ( 1 . 6 – 3 . 9 in ) long , up to 3 cm ( 1 . 2 in ) thick , nearly equal in width throughout or tapered downward . it is dry , scurfy to nearly smooth and white , staining brown with age . it is initially stuffed ( as if filled with cotton ) , but later becomes hollow . the flesh is thick and white , and between 3 and 15 mm ( 0 . 1 and 0 . 6 in ) thick . the latex produced by the mushroom is white , and does not change color upon exposure to air , although it stains the mushroom flesh a yellowish - brown color . the odor of the flesh and latex may range from indistinct to pungent or turnip - like in age ; the taste is strongly acrid — so much that it may have an effect in the throat . in his original description of the species , peck reported " an experiment of its edible qualities was made without any evil consequences . " thorough cooking removes the bitter taste , but the mushroom is not highly regarded as an edible , and as hesler and smith have noted " ... but even with this compensating feature some of our acquaintances have found it rather undesirable ( and indigestible ) . " the mushroom is sold at traditional markets in puebla , mexico . microscopic characteristics the spore print , freshly made , is white to whitish ; after drying out the spores in mass are pale yellowish . the spores are broadly ellipsoid , hyaline ( translucent ) and measure 9 – 13 by 7 – 9 µm . an apiculus is prominent . the spores are ornamented with warts and spines that do not form a reticulum ( a system of raised , net - like ridges ) on the surface . the prominences are up to 1 . 5 µm high , and amyloid , meaning they absorb iodine when stained with melzer 's reagent . the basidia ( spore - bearing cells ) are four - spored , and measure 46 – 58 by 7 – 9 µm . the pleurocystidia ( cystidia found on the face of a gill ) are very abundant , roughly club - shaped to ventricose ( swollen in the middle ) , with apices often tapering ; their dimensions are 48 – 96 x 6 – 10 µm . the cheilocystidia ( cystidia on the edge of the gills ) are 40 – 58 x 5 – 7 µm , and more or less similar in appearance to the pleurocystidia . the cap cuticle is made of a layer of somewhat uplifted hyphae . the stem cuticle is a layer of bent - over hyphae bearing thick - walled , filamentous caulocystidia ( cystidia on the stem ) , and it lacks a gelatinous layer . similar species the fungus lactifluus is very similar to l. deceptivus in its external appearance , but it has spore ornamentation that forms a reticulum , and its stem is an ixocutis ( a gelatinous layer of hyphae lying parallel to the surface ) . l. caeruleitinctus is also similar in appearance , but it has a milky - white stem with blue tints that develops more intense blue coloration after handling , and it lacks a cottony , inrolled margin . other lookalike species include lactarius , which has a much smaller cap and smaller spores , and lactarius , which has a small , zonate cap . russula brevipes and r. are also somewhat similar in appearance , but they do not produce latex when cut or injured . lactifluus subvellereus var. has more widely spaced gills , and an even cap margin . lactifluus piperatus has densely crowded gills , a firm rather than soft and cottony cap margin , and exceedingly acrid latex . habitat and distribution like all milk - caps ( lactarius and lactifluus ) , l. deceptivus is mycorrhizal , meaning the fungus forms a mutualistic association with certain trees and shrubs . the subterranean mycelium of the fungus forms an intimate association with tree roots , enveloping them in a sheath of tissue that allows both organisms to exchange nutrients they would otherwise be unable to obtain . the fruit bodies of the fungus grow solitarily , scattered , or in groups on the ground in conifer or hardwood forests , often under oak ( quercus ) or hemlock ( tsuga ) . smith has noted a preference for bogs and the edges of woodland pools in hardwood forests , and in oak stands that have an understory of blueberry bushes ( vaccinium species ) . it is widely distributed in eastern north america , and has also been reported from southern and western canada . it is a fairly common species , and fruits from june to october . the mushroom has also been reported from mexico ( in puebla and in veracruz ) from oak and pine forests , at altitudes slightly over 2 , 000 meters ( 1 . 2 mi ) , and from costa rica , where it is abundant in oak forests .