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

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THE BOLETES OF MICHIGAN

Basidia 4-spored, 27-36 X 7-9 u, narrowly to abruptly clavate, ochraceous in Melzer's, in KOH yellow fading to hyaline. Pleurocystidia 33-50
X 9-15 /, mostly fusoid-ventricose, thin-walled and with ochraceous to
rusty ochraceous content as revived in KOH, none seen with incrustations.
Tube trama of long-cylindric yellow to hyaline (revived in KOH)
filaments 5-8 I in diameter, subparallel in arrangement with diverging
elements to the subhymenium. Cuticle of pileus of interwoven hyphae
dull orange-ochraceous in Melzer's, lacking incrustations in KOH and
yellow fading to hyaline, the epicuticular zone compactly interwoven,
hyphal' end-cells with blunt to narrowed apex and some inflated to
8-12 / in the midportion. Clamp connections absent.
Habit, habitat, and distribution.-Cespitose on sawdust, near Betsy
Lake, Luce County, August 9, 1963, H. D. Thiers; rare in Michigan.
Observations.-The name Boletus sulphureus is not available for
this species (Watling, in press). No veil was present in our collection.
Barla's original plate shows an extension of the margin of the pileus
somewhat like that found in Section Leccinum of Leccinum The
habitat on wood, the colors, and the short, ellipsoid to oblong spores
form a distinctive combination of features.
Subsection MIRABILES (Singer), stat. et comb. nov.
Boletellus section Mirabiles, Singer
Farlowia 2:128. 1945
KEY TO SPECIES
1. Growing on or beside decaying conifer wood; pileus granulose-roughened
to coarsely rough-tomentose........................ B. mirabilis
1. Terrestrial; surface of young pileus subtomentose...........B. projectellus
115. Boletus mirabilis Murrill
Mycologia 4:217. 1912
Ceriomyces mirabilis Murrill, Mycologia 4:98. 1912.
Xerocomus mirabilis (Murrill) Singer, Rev. de Mycol. 5:6. 1940.
Boletellus mirabilis (Murrill) Singer, Farlowia 2:129. 1945.
Illus. Pls. 93-94.
Pileus 5-16 cm broad, convex when young, the margin inrolled,
becoming broadly convex in age, sterile margin distinct and either continuous or broken segments, hence somewhat crenate, surface of the