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

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THE BOLETES OF MICHIGAN

maroon-red ("Dragon's blood-red") but duller by maturity, at edge of
pileus sometimes yellowish red.
Stipe 3-6 cm long, 1-2 cm thick solid, yellowish within, but
quickly staining bluish; surface evenly furfuraceous, base not hairy, apex
pale yellow, toward base reddish to reddish brown, not at all reticulate.
Spores 10-13 (14) X 4-5.5 (6.5) yu when mature, smooth, apical
pore lacking, shape in face view subelliptic, to subfusoid, in profile
somewhat inequilateral, color in KOH yellow-brown when mature, in
Melzer's weakly amyloid at first but soon dextrinoid, wall about 0.3 /
thick.
Basidia 4-spored, 7-10 u broad, clavate. Pleurocystidia 33-45 X
8-12 2, fusoid-ventricose with neck more or less elongated and apex
subacute, content "empty" in KOH or Melzer's. Cheilocystidia smaller
than pleurocystidia and with a red content fresh, as revived dingy ochraceous. Caulocystidia fusoid-ventricose, 30-50 X 8-14/., neck elongated
and apex obtuse to subacute, with thin hyaline smooth walls in KOH.
Tube trama of the Boletus subtype, not amyloid in any way under
the microscope but with a distinct fleeting-amyloid reaction when first
mounted in Melzer's. Pileus cuticle a tangled layer of interwoven hyphae
giving rise to fascicles of 2-3 cells long ascending or forming a loose
trichodermium, their content homogeneous and ochraceous in KOH (but
fading), in Melzer's more brownish ochraceous to buffy orange-brown,
walls thin, smooth (in both KOH and Melzer's) and hyphae tubular,
end-cells tubular to weakly cystidioid. Hyphae of subcutis and adjacent
context orange-buff in Melzer's but fading. Clamp connections absent.
Observations.-In Smith 9613 the pilei became redder as they
aged-a feature of the type-and as dried are dull red to reddish brown,
strikingly different from the yellow of B. subvelutipes. The tubes are
dark maroon as described by Frost. Frost described the context as
white, whereas in Smith 9613 it was yellow. This is a serious discrepancy. The immature spores in Smith 9613 are like those of the
Frost specimen and the mature spores are larger but still slightly shorter
than in B. subvelutipes. We believe that these differences are sufficient
to justify recognizing Frost's species as distinct from B. subvelutipes, at
least for the present, and we place Smith 9613 in Frost's species at least
until a truly critical study of Subsection Luridi can be completed on a
broader basis than the present flora. B. hypocarycinus Singer is obviously closely related. It is southern in distribution, and according to
Singer the terminal cells of the cuticular hyphae are clavate to fusoid
and have obtuse tips.