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

100

THE BOLETES OF MICHIGAN

when bruised turning deep blue-green then deep brownish red; not
stuffed when young.
Stipe 4-6 cm long, 7-10 mm thick near center, crooked, nearly
equal or tapering slightly upward, the base pinched to a point; surface
finely dotted, often somewhat streaked, about the color of the pileus
and tubes below, with a bluish to pea-green area near apex; context on
cut surface becoming pinkish.
Spores 10-13.5 X 4-5.5 i, smooth, lacking an apical pore, smoky
brown in KOH and in Melzer's slightly more rusty but in a few spores
amyloid particles may be present, in face view narrowly elliptic, in profile somewhat inequilateral.
Basidia 4-spored. Pleurocystidia fusoid-ventricose, 34-60 X 9-12,u,
neck often elongated, with dark yellow-brown content in Melzer's or
(rarely) with amyloid granules filling the cell. Caulocystidia numerous,
clavate, 28-56 X 9-16 j, hyaline in KOH, with a hyaline (in KOH)
refractive thickening in the apex.
Pileus cuticle a trichodermium, the cells of the elements with
smooth walls and the cells inflated somewhat in the lower 3-5 cells of
the filament (9-18 g broad), the upper 1-3 cells more or less cylindric
and 5-9 iu in diameter, the end-cell blunt and seldom inflated, content as
revived in KOH weakly ochraceous, more ochraceous in Melzer's but
remaining homogeneous. Hyphae of context next to the cuticle with an
orange content in Melzer's. Clamp connections absent.
Habit, habitat, and distribution.-Mostly solitary on barren hillsides and in open woods or on roadbanks, etc., during warm humid
summer weather, rare in Michigan and most likely to be found in the
southern counties.
Observations.-The yellowish tubes, the thickening in the wall of
the caulocystidia at the apex, and the narrow spores are distinctive. The
pinched off stipe apparently to some extent resembles that of T.
umbrosus.
Material examined.-Washtenaw: Kauffman 1915; Smith 1680,
18490, 64172, 64188, 64227, 64341.
43. Tylopilus sordidus (Frost) Smith & Thiers
Mycologia 60:950. 1968
Boletus sordidus Frost, Bull. Buff. Soc. Nat. Sci. 2:105. 1874.
Illus. Figs. 32-33, 35-36; P1. 50.
Pileus (3) 6-12 cm broad, convex, slowly expanding to broadly
convex and finally nearly plane, margin even and at times uplifted in