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

G YROPOR US

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quite irregular in shape, hollow and easily broken in removing it from
the substratum, surface dry, tomentose to appressed-fibrillose, often
becoming glabrous toward the apex or with age, not reticulate, instantly
blue when injured.
Spore deposit pale yellow ("colonial-buff' to "straw-yellow");
spores 8-10 X 5-6 p, smooth, lacking an apical pore, elliptic in face view,
subelliptic in profile or slightly reniform (the dorsal line in an optical
section nearly straight), with an inconspicuous hyaline sheath, greenish
hyaline in KOH, pale tan in Melzer's.
Basidia 24-30 X 9-12 ut, clavate, 4-spored. Pleurocystidia absent as
far as observed. Cheilocystidia 33-56 X 7-10 p typically abundant, rarely
apparently absent, thin-walled, narrowly clavate to subcylindric, apex
somewhat tapered and thickened, walls sometimes appearing pale yellow
in KOH and nearly orange in Melzer's.
Tubetrama of hyphae divergent from a distinct central strand,
nonamyloid, often staining yellowish in KOH. Cuticle of pileus a thick
tangled trichodermium of filaments whicl become appressed in age and
resemble a cutis, the hyphae thin-walled, the walls picric yellow revived
in KOH, the cells 8-15 p or more in diameter and often sausage-shaped
or variously somewhat inflated, smooth, nonamyloid, and content not
distinctly colored in Melzer's. Context of floccose, interwoven hyphae,
nearly hyaline to faintly yellowish in KOH, the walls nonamyloid, in
Melzer's the content of many of the hyphae reddish orange and homogeneous. Surface of the stipe with hyphae similar to those of the pileus
cuticle. Clamp connections regularly present.
Habit, habitat, and distribution.-Solitary to scattered or cespitose
but also gregarious, along roads or railroad cuts on exposed soil or on
humus in open hardwood stands. It is not uncommon, and most likely
to be collected in quantity along sandy roads through hardwoods. It
fruits during the summer and early fall. We have seen it most abundantly in Luce County.
Observations.-This is rated as an exceptionally good edible species
in Europe, but in North America, where emphasis has been on avoiding
species which turn blue, it has not come into much prominence as an
esculent. Getting rid of the sand is a problem with us. It is one of the
species which can be accurately identified in the field. The overall buff
to olive-tinged coloration, the slight veil (observe buttons), hollow stipe,
and above all else the quick change to blue when any part is touched,
serve to characterize it. Var. cyanescens turns greenish yellow before
progressing to blue. We have not found this variety in Michigan.