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

FUSCOBOLETINUS

85

compound-several smaller ones in a slight depression bounded by a
raised border of dissepiment).
Stipe 4-6 cm long, 8-12 mm thick, equal or subequal and tapering
upward, sometimes attenuate below, solid, usually reticulate, pallid to
greenish white above the annulus, somewhat viscid lower down, smoky
gray, brownish gray or brownish below the annulus; context white at
times becoming slightly yellowish; veil submembranous, grayish to
yellowish, rarely bright yellow.
Spore deposit vinaceous-brown ("fawn-color") moist, nearer avel-.
laneous when air-dried; spores 8.5-12 X 3.5-5 u, smooth, lacking an
apical pore, in face view elliptic to subfusiform, in profile obscurely
inequilateral in a majority, nearly hyaline to dingy yellowish brown in
KOH, in Melzer's slightly dextrinoid, wall thickened slightly.
Basidia 4-spored, 20-30 X 6-8 u, short-clavate to elongate-clavate,
hyaline to yellowish in KOH. Pleurocystidia mostly in clusters with
yellow-brown incrustations concentrated around the base, with a hyaline
to yellow-brown coagulated content, thin-walled for the most part, subcylindric to subcapitate. Cheilocystidia similar to pleurocystidia or more
broadly clavate. Hymenophore with trama composed of a central strand
of floccose tissue, more or less interwoven floccose hyphae hyaline in
KOH, merely yellowish in Melzer's, without particles or incrustations.
Clamp connections absent.
Chemical reactions: KOH on pileus no reaction, on context and
stipe surface brown. NH40H on pileus no reaction, on context brown.
Habit, habitat, and distribution.-Scattered to gregarious during
late summer and fall; common throughout the state under larch.
Observations.-This well-known species, associated with larch
(Larix, also known as tamarack) is not exactly attractive, and for this
reason, perhaps, is seldom collected for the table. The degree of yellow
showing varies greatly from one region to another in the United States.
In Michigan the variation Peck described as Boletus elbensis is the one
usually found. It often occurs along with F. spectabilis, as one would
expect.
Material examined.-Emmet: Smith 1244. Livingston: Smith 6066.
Ogemaw: Smith 3190. Washtenaw: Smith 5085, 9-10-40, 10-?-50.
35. Fuscoboletinus serotinus (Frost) Smith & Thiers, comb. nov.
Boletus serotinus Frost, Bull. Buffalo Soc. Nat. Sc. 2:100. 1874.
Pileus 5-12 cm broad, obtuse to convex, expanding to plane with
a low umbo or broadly convex, slimy-viscid when fresh with the slime