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

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THE BOLETES OF MICHIGAN

Pileus 5-7 cm broad, convex becoming plane to broadly convex,
surface dry and unpolished but matted down like felt under a lens (not
velvety), surface very uneven; color dingy cinnamon to clay color and
retaining a strong ochraceous tone on drying. Context yellowish,
brighter yellow as dried, bright yellow near tubes when fresh, pallid near
cuticle, no color change when basidiocarp is sectioned, taste acid, odor
mild, KOH orange on tubes and flesh, FeSO4 olive on tubes; in age
reddish around larval tunnels.
Tubes dull olive, 1 cm long, depressed around the stipe, unchanging when injured; pores small (about 2 per mm), honey-yellow but often
stained orange or finally brownish but not staining blue anywhere.
Stipe 5-6 cm long, 1-1.5 cm thick at base, solid, lemon-chrome
within, red-brown around wormholes; surface somewhat pruinose,
lemon-chrome at apex, toned reddish in lower portion or variegated
yellow, red and brown, at apex subreticulate from decurrent tubes,
rather uneven downward.
Spores 14-18 X 5-6.5 i, smooth, with a thin spot at apex (appearing as a pore only in giant spores), smooth, wall thin (-0.2 pi thick), in
face view fusoid, in profile elongate-inequilateral, the suprahilar depression shallow to elongate, color yellowish to olive-ochraceous revived
in KOH, in Melzer's reddish tawny for the most part (moderately dextrinoid-often only in the distal half).
Basidia 4-spored, 23-31 X 7-10 u, yellowish to hyaline revived in
KOH, yellowish in Melzer's. Pleurocystidia and cheilocystidia-none found.
Tube trama of the bilateral Boletus type but hyphal divergence
not pronounced, all hyphae having thin hyaline walls. Pileus cuticle a
trichodermium with the elements in the form of chains of globose cells
10-55 Ju in diameter or a few terminal cells clavate, the content yellowish to hyaline in KOH and orange-brown in Melzer's, walls thin. Context
hyphae not distinctive in either KOH or Melzer's. Clamp connections
absent.
Habit, habitat, and distribution.-Scattered under oaks, on a golf
course near Ann Arbor, September 15, 1961, Smith 64279.
Observations.-This species is somewhat similar to B. illudens, but
has a true trichodermium of upright hyphal elements composed mostly
of globose to greatly inflated cells-the largest we have yet seen in a
bolete cuticle. The pores are small as compared to B. illudens, and the
spores are larger.