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

288 THE BOLETES OF MICHIGAN
150. Boletus truncatus (Singer, Snell, & Dick) Pouzar
Ceska Mycol. 20:2. 1966
Xerocomus truncatus, Singer, Snell, & Dick, in Snell, Singer, & Dick, Mycologia
51:573. 1959.
Illus. Figs. 67-69; P1. 113.
Pileus 3-8 (11) cm broad, convex becoming broadly convex to
nearly plane; the margin finally often crenulated; surface velvety and
evenly dark olive to olive-brown, very soon red to reddish along the
margin or overall and the cutis becoming areolate with red usually showing in the cracks. Context whitish but rose-red under the cutis, slowly
becoming pale yellowish, usually red around the larval tunnels, staining
blue when cut; odor slight, taste mild; FeSO4 greenish gray on cut
surface.
Tubes yellowish olive ("Isabella color") when mature, pale yellow
young, becoming depressed around the stipe, 7-15 mm deep; pores pale
yellow young, when mature 1-2 per mm or in age up to 2 mm wide,
irregular in outline but not boletinoid, staining greenish when injured;
some splitting and some separating as the pileus is broken downward.
Stipe 4-8 cm long, 4-12 mm thick, equal or nearly so, solid, pallid
yellowish within above, soon rose-red from base up (dark brown within
with KOH); surface inconspicuously pruinose to naked, with dingy
ochraceous mycelium around the base.
Spore deposit olive-brown; spores 10-15 X 4.5-6.5 (7) g, smooth,
many with a truncate apex or apex in many appearing slightly notched,
with a small apical pore, shape in profile with a broad shallow suprahilar
depression, ovate to oblong in face view or some slightly ventricose, wall
slightly thickened, many with a weak fleeting-amyloid stage, in KOH
dingy ochraceous to pale yellowish brown.
Basidia 4-spored, clavate, 28-36 X 9-12 p, mostly yellow in KOH.
Pleurocystidia 50-70 X 10-16 u, ventricose with a long neck and acute
apex, smooth, thin-walled, readily collapsing, scattered to rare, content
not distinctive.
Pileus cuticle a trichodermium of hyphae 8-14 p wide, with dull
rusty brown (in KOH) patches or plates of pigment adhering, the terminal
cells tapered to an obtuse apex at times. Context hyphae hyaline in
Melzer's next to the cuticle. Clamp connections none.
Habit, habitat, and distribution.-Gregarious to scattered or solitary around old stumps on sandy soil, in hardwood slashings where soil
has been disturbed, along woods, borders of roads, etc. Common