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

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THE BOLETES OF MICHIGAN

40-90 X 12-20 p, with smoky brown content in KOH, walls smooth and
thin.
Tube trama very soon gelatinizing in KOH, hyphal arrangement
obscurely bilateral. Pileus cuticle of appressed hyphae, the elements with
clavate end-cells 7-12 p wide when young, in age many of them show a
tapered neck, some hyphae with roughened and some with smooth
walls; with a tendency for cells to disarticulate at the septa, cell content
in KOH lemon-yellow to dingy brownish ochraceous, in Melzer's the
content merely yellowish and homogeneous or in a few hyphae red
pigment globules present in small numbers. Context hyphae hyaline in
KOH, thin-walled, interwoven, 9-12 (15) p wide, as revived in Melzer's
with masses of pinkish red granular material in some of the cells of
some hyphae, remaining cells hyaline to yellowish. Veil material lemonyellow in KOH from dissolved pigment, the hyphae interwoven, thinwalled and 4-10 p wide. Clamp connections absent. All hyphae with
inamyloid content.
Habit, habitat, and distribution.-Scattered on the ground in mixed
woods especially with large-toothed aspen, but also with scrub oak, common at times.
Observations.-This fungus has passed as a variant of L. aurantiacum for years in Michigan, but is constant in the KOH reactions, in the
veil features, and in the greenish yellow stipe base which is often quite
intensively colored when dried. Specimens of L. aurantiacum attacked
by the common white bolete mold may at times have some of the white
mold on the pileus as patches or along the pileus margin, but basidiocarps so infected seldom mature properly and do not have the abovementioned features. The white fragments of mycelium from the parasite
of L. aurantiacum can be cultured readily whereas the veil remnants on
L. potteri cannot, a further indication that the two are in no way
homologous. The KOH reaction of the cuticular hyphae will separate L.
potteri from L. aurantiacum if veil material is lacking.
Material examined.-Cheboygan: Smith 63856. Chippewa: Smith
72435. Gratiot: Potter 12480. Oakland: Smith 72575. Ogemaw: Smith
64492, 67445. Washtenaw: Smith 72504, 72506, 72529, 72657; Thiers
4584. Wayne: Smith 72656.
Stirps OBSCURUM
KEY
1. Cut context in stipe apex staining pinkish but not darkening to gray or
fuscous; spores 16-21 x 5-7 p...................... L. L.subatratum
1. Not as above....................................... 2