Summary:
Features include 1) small yellowish brown to reddish brown cap, 2) yellowish flesh that does not turn blue, 3) angular pores that are cinnamon becoming reddish brown and not turning blue, 4) rather slender stem colored like cap except bright yellow at base, and 5) peppery taste. Some evidence suggests it is a mycoparasite on mycelium of Amanita muscaria (Desjardin(6)). Chalciporus piperatus is common in the Pacific Northwest, especially in the northern part.

Chemical Reactions:
cap stains dark reddish brown with application of KOH, and pale grayish green with FeSO4, flesh stains violet-gray with application of KOH and pale grayish green with FeSO4, (Bessette), with FeSO4 the line above the tubes is grayish, in KOH no reaction but on the cap surface staining dark red-brown, (Smith)

Odor:
not distinctive (Bessette, Smith)

Taste:
distinctly hot and peppery (Bessette), very sharply and distinctly acrid [peppery] (Smith)

Microscopic:
spores 9-12 x 4-5 microns, narrowly fusiform, smooth, pale brown, (Bessette), spores 8.5-12 x 3-4 microns, subfusoid to subelliptic, colorless to pale ochraceous in KOH, rust brown in Melzer''s reagent; basidia 4-spored, 24-29 x 8-10 microns, clavate, colorless in KOH; hymenial cystidia abundant, conspicuous, 45-70 x 10-15 microns, "fusoid-ventricose to subclavate to fusoid with obtuse apices", colorless; cap cuticle a tangled trichodermium staining dark brown in KOH and rust brown in Melzer''s reagent; stem cuticle a layer of fertile basidia and caulocystidia similar to the hymenium, with occasional areas lacking these and appearing as a layer of interwoven hyphae; clamp connections absent, (Thiers), spores (8.5)9-12 x 4-5 microns, narrowly fusiform, olivaceous-colorless to dingy ochraceous in KOH, rusty brown in Melzer''s reagent; cap cuticle a tangled trichodermium of broad (10-17 microns) hyphae with fusoid to elliptic or cylindric end-cells; tube trama inamyloid, (Smith)

Spore Deposit:
brown to cinnamon brown (Bessette), cinnamon brown (Thiers, Desjardin), dull cinnamon (Smith)

Notes:
It is fairly common and widely distributed through North America, (Bessette). There are collections from WA, OR, AK and ID at the University of Washington and from BC at the University of British Columbia. Material was studied from CA (Thiers), and reported from AB (Schalkwijk-Barendsen), as well as Europe and Asia (Breitenbach).

EDIBILITY

unknown (Bessette), McIlvaine reports that peppery taste is lost in cooking and then edible, but Murrill warns that it is poisonous, (Thiers)

Synonyms and Alternate Names:
Boletus piperatus Bull.
Sarcosphaera crassa (Santi) Pouzar
Sarcosphaera eximia (Durieu & Lev.) Maire