What You Should Know
Tylopilus ferrugineus is a bolete fungus in the family Boletaceae native to North America. It is brown to reddish-brown (rather than maroon) when young, often features uncharacteristically firm flesh for a bolete, and often appears stocky and hard when young.
Originally described by Charles Christopher Frost in 1874 as Boletus ferrugineus, it was placed in the genus Tylopilus by Rolf Singer in 1947.
Boletus ferrugineus Frost (1874) is a synonym.
Other names: Rusty Bolete.
Tylopilus ferrugineus Mushroom Identification
Mycorrhizal with oaks; growing alone, scattered, or gregariously; summer and fall; widely distributed east of the Rocky Mountains.
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.
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.
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.
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.
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.
Brownish pink to pinkish brown.
Spores 10–14 x 3–4.5 µm; subfusiform; smooth; yellowish in KOH. Hymenial cystidia up to 40–60 x 5–10 µm; fusiform to fusoid-ventricose; smooth; golden in KOH. Pileipellis is a collapsing trichoderm; golden in KOH; terminal cells cylindric with rounded, subacute, or fusiform-cystidioid apices, 2.5–5 µm wide.
Tylopilus badiceps (Peck) A. H. Smith & Thiers, with paler brown colors in pileus and stipe, and usually beveled margin. The taste is also mild.
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