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

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THE BOLETES OF MICHIGAN

Tubes 6-9 mm long, yellow turning blue instantly when cut, depressed around the stipe to nearly free; pores 2-3 per mm, round,
carmine or darker red, instantly blue when bruised.
Stipe 4-9 cm long, 1.5-2.3 cm thick, solid, equal, pale lemonyellow, changing to greenish blue when cut, red in the base especially in
the cortex, surface coated over the base with a thin coating of appressed
sulphur-colored hyphae, pruinose-furfuraceous overall, not at all reticulate.
Spore deposit olive; spores 11-15 X 4-5.5 j, smooth, apical pore
minute, color in KOH olive-yellowish (from a deposit) ochraceous-tan
from the tube tissue, in Melzer's dingy yellow-brown, shape in face view
subfusoid, in profile obscurely to somewhat inequilateral, wall about
0.2 g thick.
Basidia 4-spored, clavate, 8-12 u wide. Pleurocystidia clavaterostrate to fusoid-ventricose, 28-42 X 6-11 p/, neck about 3 p. wide and
often flexuous, apex obtuse, hyaline or with yellow to yellow-brown
content in KOH, brownish to hyaline in Melzer's, scarcely projecting
beyond sporulating basidia. Cheilocystidia narrowly clavate to fusoidventricose, 26-38 X 4-8 g, in mass ochraceous-tan in KOH. Caulocystidia versiform: (a) broadly ovate pointed and without a neck, 34-46
X 12-16 g,. often with adhering tawny debris as revived in KOH; (b)
elongate fusoid-ventricose to setiform but with thin walls (26) 40-180+
X 4-12 u, hyaline, broader cells with some adhering debris around the
ventricose part. Caulobasidioles often with tawny to ochraceous content.
Cuticle of pileus a thick (150+ u) layer of narrow interwoven
(3-5 M) hyphae with red content in Melzer's and yellow in KOH, at
surface arranged in fascicles of parallel hyphae indicating a tendency
toward a trichodermial structure, end-cells tubular. Hyphae of subcutis
and below them having dark red content in Melzer's, no dextrinoid
incrustations noted. Clamp connections absent.
Habit, habitat, and distribution. -Gregarious in grassy oak woods,
September, Washtenaw County, Smith 64046.
Observations.-The red cuticular hyphae and a similar pigment in
those of the context near the cutis as sections are revived in Melzer's,
the presence of long, setiform caulocystidia, the resinous feel of the
young pileus when it is touched, the instant color change to dark violet
of the cut context, and the numerous small pleurocystidia which scarcely project beyond sporulating basidia are a very distinctive combination
of features. When the neck of the pleurocystidium is ochraceous to
brown in the mounting medium one is likely to mistake it for a filamentous pseudocystidium.