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

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THE BOLETES OF MICHIGAN

Tubes weakly yellow at first, then finally dark wood-brown, 2 cm
deep, depressed around the stipe; cut surface staining gray then fuscous;
pores small, staining olive when slightly bruised.
Stipe 9 cm long, 11 mm thick, equal, cut surface soon fuscous but
also stained blue around the base; surface ornamented with fine to
coarse lines and squamules on a pallid ground, the elements blackish
both fresh and as dried.
Spores 13-16 X 4-5 j, smooth, wall -0.5 p thick, lacking an apical
pore; shape in profile narrowly subfusoid, with scarcely any depression
in the suprahilar area, in face view subfusoid, with scarcely any apical
differentiation, color in KOH pale brownish ochraceous, in Melzer's many
soon become deep tawny to bay-brown.
Basidia 4-spored, about 25-30 p long, clavate, hyaline. Pleurocystidia
38-60 X 8-12 g, fusoid-ventricose with greatly elongated narrow neck
ending in an acute apex, smooth, thin-walled, content hyaline to
brownish in KOH and in Melzer's often reddish brown from granular
material (but the same pigment also present in the pedicels of some of
the basidia). Cheilocystidia 28-36 X 6-11, more or less fusoid and
ochraceous-brown as revived in KOH. Caulocystidia variable in size and
shape but mostly fusoid, fusoid-ventricose with or without a greatly
elongated neck, or (rarely) clavate, 38-60 X 8-12 p and 60-100 X
10-18 t, walls smooth and thin, content brownish and often aggregated
into denser areas (in KOH).
Tube trama typical of the genus; laticiferous elements present,
their content ochraceous to darker brown in KOH or Melzer's. Pileus
cutis of 2 types of appressed hyphae: (1) flexuous, smooth, tubular, and
with smoky ochraceous content homogeneous in KOH, 3-6 u wide, the
end-cells tubular, blunt at apex; septa sparse (cells elongate and wall not
or scarcely constricted at septa), cells not readily disarticulating, in
Melzer's some cells showing pigment globules 3-6 p in diameter but usually only 1-4 per cell if present at all; (2) hyaline smooth hyphae 5-9 p,
wide also with tubular, blunt end-cells and in Melzer's "empty" or with
finely granular material dispersed in the central part; the first type often
occurring as single cells or series of cells somewhere in an otherwise
hyaline hypha. No inflated cells evident in the layer. Hyphae of the
subcutis yellowish hyaline in Melzer's and gelatinized somewhat but
lacking pronounced warts and blisters (but with a slight amount of
adhering slime). Clamp connections none.
Habit, habitat, and distribution.-Solitary along the Yellow Dog
River, near Marquette, August 21, 1967, Mrs. Ingrid Bartelli.