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

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THE BOLETES OF MICHIGAN

Tubes 1-1.5 cm deep, depressed around the stipe, pallid to olivaceous-pallid at first, slowly becoming grayish as they mature, staining
yellowish where lightly bruised and the yellow darkening to dingy
brown.
Stipe 9-16 cm long, 1-2.5 cm thick, equal or tapered downward,
solid, when cut staining as in pileus but in addition at the base staining
blue and/or yellow but the yellow soon fading; surface with charcoalgray to (finally) black ornamentation as punctae but these soon
stretched into lines forming ridges and in some the latter fused to form
an obscure reticulum, ground color pallid or lower down blackish to
yellowish.
Spore deposit a dark dingy cinnamon-brown; spores 14-17 (18) X
3.5-5 p, smooth, apex lacking a distinct pore, in face view narrowly
fusoid, in profile narrowly and somewhat inequilateral, in KOH dull
tawny-brown, slightly yellower in Melzer's, walls less than 0.3 p thick.
Basidia 4-spored, 9-11 pL broad, variable in length, hyaline in KOH
and yellowish in Melzer's, as revived in KOH showing a large hyaline
globule in the central part. Pleurocystidia rare and inconspicuous, content hyaline to dingy ochraceous revived in KOH. Cheilocystidia numerous, similar to pleurocystidia or smaller. Caulocystidia (28) 36-55 (80)
X (8) 10-15 (22) p, mostly fusoid-ventricose and with narrow often proliferated necks, the apex subacute, content dingy yellow-brown in KOH,
walls thin and smooth.
Tube trama of hyaline, tubular, smooth hyphae 4-7 p wide, weakly
divergent in mounts of fresh material in water, gelatinization of walls
not pronounced. Pileus cutis of appressed hyphae 5-11 p wide, mostly
nearly tubular but end-cells often clavate and up to 15 p wide in broadest part, walls thin and smooth to minutely roughened (as in L. insigne),
the cells mostly 4 times longer than broad and often disarticulating,
content yellow-brown in KOH and in this medium often rounding into
more or less globose concentrations (but boundaries not sharp), in
Melzer's forming beads 2-6 p in diameter in many hyphae as well as in
some less distinct larger bodies. Hyphae of subcutis and adjacent context
not highly colored as revived in Melzer's. Clamp connections absent.
Habit, habitat, and distribution.-Gregarious under aspen and
willow in a marshy area at Wycamp Lake, Emmet County August 3,
1968, H. D. Thiers collector, Smith 75837.
Observations.-The outstanding features of this species are the
change to reddish and then fuscous when the flesh is cut, the narrow
spores, proliferated caulocystidia, pigment globules in the cuticular
hyphae as mounted in Melzer's, the lack of color in the subcuticular