Major Groups > Boletes > Tylopilus > Tylopilus ferrugineus


Tylopilus ferrugineus

[ Basidiomycota > Boletales > Boletaceae > Tylopilus . . . ]

by Michael Kuo

Separating Tylopilus ferrugineus from Tylopilus badiceps is no easy task. Both species are associated with oaks in eastern North America, both have pigmented stems and brown-bruising pore surfaces, and both feature a mild (rather than bitter) taste. However, Tylopilus ferrugineus is brown to reddish brown (rather than maroon) when young, often features uncharacteristically firm flesh for a bolete, often appears stocky and hard when young, and has spores that measure 10-14 µ long (the spores of Tylopilus badiceps, in contrast, are 8-11 µ long). An additional means of separating the two species may be suggested by my collecting experience; I only find Tylopilus ferrugineus in grassy areas in urban locations or in parks, while my collections of Tylopilus badiceps have all been woodland.

Tylopilus indecisus is also similar, but features a whitish-when-young stem and softer flesh.


Ecology: Mycorrhizal with oaks; growing alone, scattered, or gregariously; summer and fall; widely distributed east of the Rocky Mountains. The illustrated and described collections are from Illinois.

Cap: 3-10 cm; convex when young, becoming broadly convex or nearly flat in age; dry; very finely felty when young, becoming bald; brown to reddish brown, fading to tan.

Pore Surface: Creamy white, remaining so for quite a while but eventually becoming pinkish and eventually nearly brownish; bruising promptly brown; pores circular to angular, 2-3 per mm; tubes to 17 mm deep.

Stem: 2-10 cm long; 1-4 cm thick; club-shaped when young, becoming more or less equal; brown like the cap except for a pale apical zone; bald; not reticulate, or merely finely so near the apex; basal mycelium white.

Flesh: Notably firm when young and fresh; white; staining pinkish to brownish when sliced.

Odor and Taste: Odor not distinctive, or sweet and thick; taste mild, not distinctive.

Chemical Reactions: Ammonia negative to gray on cap surface and flesh. KOH dark red to black on cap surface; yellowish to orangish on flesh. Iron salts negative on cap surface; negative to bluish or slightly greenish on flesh.

Spore Print: Brownish pink to pinkish brown.

Microscopic Features: Spores 10-14 x 3-4.5 µ; subfusiform; smooth; yellowish in KOH. Hymenial cystidia up to 40-60 x 5-10 µ; fusiform to fusoid-ventricose; smooth; golden in KOH. Pileipellis a collapsing trichoderm; golden in KOH; terminal cells cylindric with rounded, subacute, or fusiform-cystidioid apices, 2.5-5 µ wide.

REFERENCES: (Frost, 1874) Singer, 1947. (Saccardo, 1891; Snell & Dick, 1970; Both, 1993; Bessette, Roody & Bessette, 2000.) Herb. Kuo 09020103, 07020701, 07130803, 06201001, 07231003, 06211508, 06211509.


Tylopilus ferrugineus

Tylopilus ferrugineus

Tylopilus ferrugineus

Tylopilus ferrugineus

Tylopilus ferrugineus

Tylopilus ferrugineus
Ammonia, KOH, iron salts

Tylopilus ferrugineus

Tylopilus ferrugineus
Hymenial cystidia

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Kuo, M. (2016, May). Tylopilus ferrugineus. Retrieved from the MushroomExpert.Com Web site: