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

FUSCOBOLETINUS

83

Spore deposit purplish brown ("Vandyke-brown" to "warm
sepia"); spores 9-13 (15.2) X 4-5.6 (6.5) g, smooth, lacking an apical
pore, in face view elliptic, in profile inequilateral with a pronounced
suprahilar depression and beyond this narrowed to apex, revived in KOH
pale yellow to ochraceous-tawny, in Melzer's strongly dextrinoid.
Basidia 4-spored, 30-36 X 5-7 /, yellowish in KOH and in Melzer's
reagent. Pleurocystidia in numerous clusters, surrounded at the base by
material bister in KOH and reddish brown in Melzer's, individual cystidia
40-80 X 6-9 p, cylindric and narrowed toward the apex, thin-walled.
Cheilocystidia similar to pleurocystidia or the tube-edge often covered
with amorphous bister material.
Tube trama hyaline and divergent from a yellowish (in KOH) central strand. Pileus cuticle a thick layer of gelatinous hyphae, with smoky
yellow content in KOH, becoming hyaline, representing a matted trichodermium, hyphae of short cells 4-8 p in diameter with no appreciable
incrustation. Context of loosely interwoven floccose hyphae with colorless incrustations (sections bister in KOH if rather thick), nonamyloid.
Stipe surface similar to pileus cuticle but not appearing gelatinous.
Clamp connections absent.
Chemical reactions: KOH on pileus surface bleaching the color
that is present, on the context dark green; NH4OH no reaction on pileus
and context; Melzer's deep greenish brown on pileus and stipe context.
Habit, habitat, and distribution.-Solitary to scattered under larch
(Larix laricina), not uncommon in larch bogs during September in
Michigan.
Observations.-This very characteristic species can hardly be mistaken for any other. The duplex veil which in button stages is broken
into coarse squamules gives the pilei the appearance of a Strobilomyces.
The spores are large for the genus, and the KOH reaction of the pileus
context is most unusual in this genus or in Suillus, in fact we do not
recall a species which shows it other than this one. The color of the
spore deposit as it air dries is more of a vinaceous-brown, but still
within the "spectrum" generally treated under the term purple-brown in
the taxonomy of fleshy fungi, certain authors to the contrary notwithstanding.
Material examined.-Cheboygan: Smith 1094, 50589. Emmet:
Kauffman 8-27-05; Smith 43820. Gratiot: Potter 6443. Oakland: Smith
38851, 67760. Ogemaw: Smith 67589. Washtenaw: Hintikka 10-6-61;
Kauffman 186, 1594, 9-22-24; Smith 11016, 15313, 18795, 62208,
64655.