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

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THE BOLETES OF MICHIGAN

long to narrowly subfusoid in face view, inequilateral in profile, smooth,
dingy pale ochraceous in KOH, pale tawny in Melzer's (not truly dextrinoid).
Basidia 24-30 X 8-9 L, clavate, 4-spored, hyaline in KOH, yellowish in Melzer's. Pleurocystidia and cheilocystidia similar and scattered to
abundant, 38-50 X 8-13 p, fusoid-ventricose, thin-walled, the ventricose
portion in KOH filled with a smoky yellow content, hyaline in the neck
and apex, apices subacute to acute, in Melzer's the content of the ventricose part bister.
Tube trama divergent and hyaline (gelatinous?) in KOH, nonamyloid. Cuticle of pileus a well-formed trichodermium of hyphae
5-10 l or more wide and at first with smoky yellow content in KOH,
some hyaline incrustations present but not a conspicuous feature, cells
slightly broader and shorter in upper part of the trichodermial element.
Hyphae of context floccose, interwoven, nonamyloid, 6-12 u wide.
Clamp connections absent.
Habit, habitat, and distribution.-Solitary to scattered in grassy
open oak woods or in open hardwoods with no grasses present, frequent
during wet summers in the oak belt of Michigan.
Observations.-The color of the cystidia in KOH and in Melzer's is
a valuable aid in the identification of herbarium specimens, but the same
is true also for B. ornatipes. At times a strong ochraceous tone pervades
the whole basidiocarp, and then the resemblance to B. ornatipes is very
striking. Since a gradual progression from species with a white hymenophore when young to those with a strongly yellow one has been clearly
demonstrated in Leccinum it will hardly do to argue that the white
hymenophore in B. griseus precludes close relationship with B. ornatipes.
In the summer of 1966 B. griseus was found by Smith in abundance at
Highlands in Oakland County, and it was noted that the species actually
intergrade in the disposition of the yellow pigment.
Subsection LURIDI (Fries) Smith & Thiers, comb. nov.
Section Luridi Fries, Epicr. Syst. Myc. p. 417. 1838.
For the features of this group see the key to subsections. The
important point to keep in mind in the recognition of this group is that
the pores are colored before the basidiocarp reaches maturity. In a number of species throughout the genus, especially in those involved with
red pigments, the pores may become somwhat colored by old age.
Type species: Boletus luridus.