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

LECCINUM

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3. Cut context not staining appreciably on exposure to air..... Stirps Vulpinum
3. Cut context in immature basidiocarps staining red to reddish cinnamon
before coming gray to blackish................... Stirps Aurantiacum
3. Cut context in immature basidiocarps at first staining lilaceous to violaceous or "avellaneous" (grayish) before darkening further (lacking a
preliminary red stage in the color change)............... Stirps Insigne
Stirps POTTERI
57. Leccinum potteri Smith, Thiers, & Waiting
Mich. Bot. 5:138. 1966
Illus. Pls. 62-63.
Pileus 4-12 cm broad, convex, becoming broadly convex; surface
at first coated with a thin submembranous pallid veil which soon breaks
up into small areolate patches that gradually disappear, margin with
sterile segments of the cuticle as in L. aurantiacum and some veil material adhering to outer surface of these segments at times, the surface
beneath the veil more or less matted-fibrillose and dull brick-orange to
dingy pale orange-tawny, evenly colored. Context pallid, when cut turning vinaceous then lavender and then gray, staining blue in the stipe
base; odor slight, taste not distinctive, FeSO4 bluish on context, KOH
yellow on the tubes.
Tubes white when young, becoming wood-brown at maturity, yellowish then brownish when pores are bruised; pores pallid where undamaged (when young), small, round.
Stipe 5-10 cm long, 1-2.5 cm thick at apex, equal or enlarged
downward, solid, white and scabrous when fresh, base slowly bluish and
scabrosity becoming finally near blackish brown ("mummy-brown") but
usually more nearly dark yellowish brown, when dried the surface over
basal part lime-green to sulphur-yellow, not so yellow in the interior,
upper parts drying pallid to grayish except for the dark ornamentation.
Spore deposit tawny-brown (Potter), olive-brown (Smith 72506);
spores 13-16 X 4-5 u, smooth, narrowly fusoid in face view, in profile
narrowly subinequilateral, suprahilar depression broad but shallow, when
revived in KOH dingy ochraceous and in Melzer's pale tawny to tawny,
no "fleeting-amyloid" reaction present.
Basidia 4-spored, 18-22 X 8-11 AI, hyaline in KOH, clavate. Pleurocystidia-none observed. Cheilocystidia 18-36 X 4-9,, clavate to elongate-fusoid or fusoid-ventricose, mostly ochraceous in KOH, soon gelatinizing. Caulocystidia in fascicles, clavate to ellipsoid or balloon-shaped,