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

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THE BOLETES OF MICHIGAN

Xerocomus subtomentosus (Fries) Quelet, Flor. Myc. Fr. p. 418. 1888.
Ceriomyces subtomentosus (Fries) Murrill, Mycologia 1:153. 1909.
var. subtomentosus
Illus. P1. 104.
Pileus 5-18 (20) cm broad, convex becoming broadly convex,
rarely plane, margin at first incurved against the tubes; surface dry and
subtomentose to velvety, gradually rimose and in age often conspicuously areolate; color dull olivaceous to olive-yellowish or finally yellowbrown, with a dull reddish line under the cuticle which finally may give
a reddish tone to the pileus after the collapse of the epicutis (dull
"olive" to "Isabella color," "argus-brown," "antique brown," or in age
redder). Context thick and firm, whitish slowly becoming pale yellow,
not changing color when cut or bruised, odor and taste not distinctive.
Pileus surface mahogany-red with ammonia (NH40H).
Tubes 1-2.5 cm long, adnate becoming depressed or decurrent on
stipe by lines, yellow, when cut slowly very slightly greenish blue; pores
1-2.5 mm broad at maturity, somewhat angular or more rarely sublamellate near stipe, yellow, staining slightly greenish and finally brownish where injured.
Stipe 4-10 cm long, 1-2 (3) cm thick, equal downward to a narrowed base, solid, whitish in center, yellow in cortex, yellow around
larval tunnels; surface pruinose to scabrous, obscurely reticulate to
widely ridged-reticulate over upper part, around the base sulphur-yellow,
pallid to ocher-yellow above or overall but in age with brown areas or
near "orange-cinnamon" finally, at times reddish brown from handling.
Spore deposit olive to olive-brown; spores 10-13 (15) X 3.5-5 Ax, in
face view subfusoid to oblong, in profile narrowly inequilateral, smooth,
walls slightly thickened, in KOH pale lemon-yellow, in Melzer's dingy
pale olive yellowish (as if with a weak fleeting-amyloid reaction).
Basidia clavate, 4-spored, 25-34 X 6.5-9 I, hyaline to yellow in
KOH and Melzer's. Pleurocystidia scattered, lanceolate, 47-72 X 8-12 u,
hyaline in KOH, yellowish in Melzer's, thin-walled, smooth.
Tube trama of gelatinous hyaline hyphae in KOH, some divergence
to the subhymenium but central strand subparallel. Cuticle of pileus a
trichodermium of smooth thin-walled hyphae 8-14 p wide and with the
terminal cell merely obtuse, rarely slightly inflated at the midportion.
Clamp connections absent.
Habit, habitat, and distribution.-Common in the summer and fall
especially on road banks, but seldom do large numbers of basidiocarps
occur in one small area.