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

BOLETUS

255

Tubes 6-10 mm deep, dull yellow becoming dull olive-yellow,
readily splitting when pileus is broken downward; pores large (about 1
per mm), near stipe sublamellate, slowly staining cinnamon when
bruised.
Stipe 3-6 cm long, 5-10 mm thick, equal to a pinched off base,
solid, yellow within, with bright yellow mycelium around the base, surface yellowish with a thin overlay of cinnamon pruina, not reticulate.
Spore deposit olive when fresh; spores 9-12 (13) X 3.5-4.5,
smooth, lacking an apical pore, shape in face view suboblong or tapered
slightly to apex, in profile somewhat inequilateral, color in KOH yellowish hyaline to greenish yellow, duller in Melzer's; wall about 0.2 g thick.
Basidia 4-spored, 24-36 X 7-10 p, narrowly clavate, pale yellow in
KOH, a fleeting-amyloid reaction present and very strong. Pleurocystidia
32-50 X 7-12 /, narrowly fusoid, thin-walled, hyaline in KOH, content
homogeneous. Cheilocystidia similar to pleurocystidia but smaller and
neck shorter. Caulocystidia 30-50 X 10-16 u, short- to long-clavate,
thin-walled, smooth, in KOH content hyaline to yellowish, occurring in
fascicles from the subiculum.
Tube trama of wide (8-12 u) scarcely gelatinous and only obscurely divergent hyphae, with a strong fleeting-amyloid reaction (sections at first violet-black in Melzer's). Pileus cuticle a trichodermium, the
elements incrusted with dextrinoid patches of amorphous material, the
cells 20-60 X 9-12 u, tubular or nearly so and the apical cell merely
blunt. Hyphae below cuticle merely yellow in Melzer's. Clamp connections absent.
Habit, habitat, and distribution.-Scattered under oak-pine, Topinabee, Cheboygan County, August 10, 1968, W. Patrick and Smith 75911.
Observations.-This variety differs from var. spadiceus in the
slightly smaller spores, and narrower stipe as well as in the strong fleeting-amyloid reaction of the hymenophoral trama. The stipe was not
ridged near the apex. This is a taxon somewhat intermediate between
the B. illudens group and the B. subtomentosus group, in fact it is a
bridging variant.
133. Boletus subtomentosus Fries
Syst. Mycol. p. 389. 1821
Leccinum subtomentosum (Fries) S. F. Gray, Nat. Arr. Brit. Pls. 1:647. 1821.
Rostkovites subtomentosus (Fries) P. Karsten, Rev. Mycol. 3:16. 1881.
Versipellis subtomentosa (Fries) Quelet, Enchir. Fung. p. 158. 1886.