E-Flora BC: Electronic Atlas of the Flora of British Columbia

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.

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).

Cap:
1.6-9cm, convex becoming nearly flat when old; "buff to yellow-brown, orange-brown or reddish brown"; bald or slightly fibrillose, dry or somewhat viscid, sometimes cracked when old, (Bessette), 3-7cm, convex becoming flat-convex to flat or occasionally subumbonate [somewhat umbonate] when old; reddish brown to brown when young, when old fading to pale reddish brown; moist to dry, often subviscid when old or when wet, dull, bald to obscurely appressed-fibrillose, when old sometimes appearing obscurely rimose or slightly fibrillose-scaly, (Thiers), (1.5)2-5(9)cm, obtuse to convex, becoming flat to flat-convex to occasionally subumbonate or margin slightly turned up; clay color to yellow-brown or orange-cinnamon, often darker on disc to rusty cinnamon; dry becoming subviscid, mostly unpolished, bald to somewhat fibrillose-streaked or appressed-squamulose, always bald when old, at times areolate [cracked like dried mud], (Smith), dull when dry, somewhat lubricous when wet, (Breitenbach), 2-8cm but usually less than 5cm, (Arora), reddish brown to rust brown or vinaceous brown, often with a mix of yellowish brown, and sometimes becoming more ochraceous brown when old, (Trudell)

Flesh:
"pale yellow or tinged reddish", becoming dingy purplish brown when old, not turning blue when cut or bruised; in stem lemon-yellow, not turning blue, (Bessette), 0.5-1.5cm thick, yellow, changing to pale vinaceous to pink near the cap surface, "unchanging or darkly pigmented areas changing to grayish vinaceous when exposed", not turning blue; in stem yellow, unchanging or darkening slightly when exposed, (Thiers), up to 1cm thick, firm; pale yellow, when old often with slight rose tint or distinctly vinaceous above tubes, becoming dingy-vinaceous-buff when old; in stem lemon-yellow and unchanging, (Smith), in stem brownish buff in upper part and bright yellow in base (Trudell), in cap 0.5-1.5cm thick, "pale yellow with a vinaceous line below the cap cuticle, darkening to cinnamon-brown when bruised, not bluing" (Desjardin)

Pores:
0.5-2mm wide, angular, sometimes radiating; "dull cinnamon, reddish cinnamon, or cinnamon-brown", becoming darker reddish brown when old, not turning blue when cut or bruised but sometimes staining brown; tube layer 0.3-1cm thick, (Bessette), 1-2mm, angular; red to reddish brown; tube layer 0.5-1cm thick, adnate to arcuate-decurrent when young, becoming depressed around stem when old, yellow to reddish yellow, unchanging or darkening slightly when bruised, (Thiers), 2 per mm average, angular, unequal, thin-walled; dull yellow when young, soon cinnamon and when old red to brick-red, not staining appreciably when injured (merely dark brown), tube layer 0.3-1cm thick, adnate to subdecurrent or faintly depressed, dingy ochraceous but slowly reddish when old, (Smith)

Stem:
4-9.5cm x 0.6-1.2cm, equal or narrowing downward, solid; colored as cap or paler, base with bright yellow mycelium; partial veil and annulus absent, (Bessette), 2-4cm x 0.5-1cm at top, equal or narrowing downward, solid; reddish brown, usually more or less colored as cap, with copious bright yellow mycelium at base; dry, bald to slightly appressed-fibrillose, (Thiers), (2)4-10(12)cm x (0.3)0.4-1(1.5)cm, solid, reddish cinnamon from pruina, with yellow ground color, base bright yellow from mycelium, (Smith), more or less colored as cap or more yellowish in upper part (Courtecuisse)

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)