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

Summary:
Features include 1) a red-brown to yellow brown cap that is dry and velvety to smooth, 2) white unchanging flesh that is firm and brittle, 3) white to pale yellow pores and tubes neither of which turn blue, 4) a hollow stem colored like cap or slightly paler, 5) growth under hardwoods, 6) yellow spore deposit, and 7) microscopic characters including clamp connections.

Gyroporus castaneus is found in CA, WA, and OR, (Thiers), from eastern Canada south to FL, west to CA, and Mexico, (Bessette), NS (Grund), and Europe (Arora). Collections from BC are deposited at the Pacific Forestry Centre.

Cap:
2.5-7(10)cm, convex to flat or shallowly depressed; "chestnut-brown to brown, cinnamon-brown, orange-brown, or rusty-tawny"; "dry, minutely hairy to smooth, sometimes with a delicate whitish bloom when young", (Arora), 3-10cm, rounded to broadly convex becoming nearly flat, sometimes slightly depressed, margin often split and flaring when old; chestnut to yellow-brown or orange-brown; dry, velvety-tomentose to nearly bald, (Bessette), 3-7cm, obtuse to convex, becoming broadly convex to flat-convex, flat, or depressed; brown to tan to pinkish brown; dry, bald to finely tomentose to pulverulent [powdery], often cracked or areolate-cracked [cracked like dried mud] when old; margin becoming cracked or split, (Thiers), sometimes appearing granulose-reticulate when old, (Smith)

Flesh:
thick, firm; white, not turning blue when bruised, (Arora), brittle; white, not staining blue, (Bessette), thick; white, unchanging when exposed, (Thiers)

Pores:
white, becoming pale yellow when old, not turning blue; tubes the same color, (Arora), 1-3 per mm, round; whitish to buff or yellowish, never pinkish or colored like the flesh; tube layer 0.5-0.8cm thick, (Bessette), 1-2 per mm, angular, radially elongate near top of stem, white becoming yellow at maturity, unchanging or darkening slightly when bruised; tube layer 0.3-0.5cm thick, shallow to deeply and broadly depressed around stem, colored as pores, (Thiers), 1-2 per mm, round to angular; tubes free and deeply sunken around stem, (Phillips), tubes free and always shorter towards stem (Lincoff(1)), tubes free or deeply depressed around stem, rarely adnate or subdecurrent, whitish becoming yellowish, unchanging when bruised or merely changing to brownish, pores not staining when bruised, (Smith)

Stem:
3-9cm x 0.5-1(3)cm, more or less equal, sometimes wider in lower part, hollow or partially hollow at least when mature; "brown to tawny (colored more or less like cap or slightly paler)"; dry, uneven, (Arora), 3-9cm x 0.6-1.6cm, equal or often swollen in middle or lower part, often narrowed at top and base, "brittle, stuffed with a soft pith, developing several cavities" or becoming hollow when old; colored like cap or slightly paler toward top; surface uneven, not reticulate; partial veil and annulus absent, (Bessette), 2-4 x 0.5-1.5cm, equal or widening downward from top, hollow in lower part; tan to brown to pinkish brown, similar to cap; dry, unpolished, bald to tomentose to velvety, (Thiers)

Chemical Reactions:
cap cuticle stains yellow then bleaches to white with application of KOH and is negative with FeSO4, flesh stains very pale brownish or is negative with application of KOH or FeSO4, (Bessette)

Odor:
not distinctive (Bessette)

Taste:
not distinctive (Bessette), hazelnut (Lincoff(1)), mild, slightly acidic (Miller)

Microscopic:
spores 8-12 x 4.5-6 microns, elliptic-oblong, smooth, (Arora), spores 8-13 x 5-6 microns, elliptic to oval, smooth, colorless, (Bessette), spores 10-12.5(14) x 5-6 microns, elliptic, smooth, ochraceous in Melzer''s reagent, colorless to pale yellow in KOH, thin-walled; basidia 4-spored, 30-35 x 8-14 microns, clavate, colorless to pale yellow in KOH; hymenial cystidia abundant, 30-45 x 7-11 microns, fusoid to obscurely fusoid-ventricose, colorless, thin-walled; cap cuticle a layer of cystidioid cells forming a tangled trichodermium; stem cuticle similar to cap cuticle; clamp connections present, (Thiers), spores lacking germ pore; clamp connections present, but many pseudoclamps also present, (Smith)

Spore Deposit:
pale yellow to yellow, (Arora), pale yellow to buff (Bessette)