The boletes of Michigan, by Alexander H. Smith and Harry D. Thiers.

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THE BOLETES OF MICHIGAN

the extent that the pedicels of the terminal cells often appear thickerwalled than the other parts of the cell or adjacent cells. B. sensibilis is
the most closely related species but has the stipe apex reticulate, smaller
spores, the terminal cells of the cuticular hyphae are tubular to only
slightly cystidioid.
144. Boletus subfraternus Coker & Beers
Bol. North Carol. p. 61. 1943
Illus. P1. 108.
Pileus 3-4.5 cm broad, broadly convex becoming nearly plane,
margin even; surface unpolished, dry and velvety, dull rose (red) in
buttons, becoming flame-scarlet and colors fading further to orange-buff
and in dried pilei more or less olive-buff with a reflection of red remaining along the margin, margin undulating in age at times. Context buffy
pallid and staining blue when cut, yellowish as dried, soft and fragile,
ammonia on cuticle no reaction.
Tubes up to 1 cm deep, adnate to nearly free from the stipe, dull
yellow but soon olive-yellow and stained greenish blue slightly where
injured; pores almost boletinoid-lamellate toward the stipe, poroid near
pileus margin, olive-yellow and staining blue slightly on bruising.
Stipe 2.5-4 cm long, 1-1.5 cm thick, solid, narrowed slightly toward base, yellow (flavous) in base, paler above, staining blue in apex
when cut; surface above ochraceous, downward pale scarlet over an
ocher ground color, the red pigment located mostly in a faint pruinosity.
Spores 9-13 (14) X 4-5 (6) p, smooth, apex lacking a pore, shape
in face view subfusiform, in profile obscurely inequilateral (the suprahilar depression broad and shallow); color in KOH bright ochraceous, in
Melzer's dull yellow-brown (as if with a gray shadow indicating a fleeting-amyloid reaction), wall about 0.5 g thick.
Basidia 4-spored, clavate, 8-11,1 broad, hyaline to pale yellow in
KOH. Pleurocystidia scattered, 28-42 X 9-14,, fusoid-ventricose with
subacute to obtuse apex, thin-walled, hyaline in KOH and Melzer's.
Cheilocystidia smaller than pleurocystidia and often with yellow content
revived in KOH. Caulocystidia clavate to fusoid-ventricose or some subcylindric, yellow in KOH but soon hyaline as color dissolves in the
mounting fluid, thin-walled, variable in size but not gigantic (18-40 X
8-15 p and clavate, 25-38 X 9-15 pS and fusoid-ventricose, and 40-56 X
8-12 p and subcylindric), thin-walled, smooth.