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

LECCINUM

195

Spores 12-16.5 X 4.5-6 u, smooth, with a minute apical hyaline
spot, wall about 0.2 u thick, in face view fusoid to subfusoid, in profile
somewhat narrowly inequilateral, the suprahilar depression rather deep
but not sharply defined at the edges, in KOH dingy ochraceous, slightly
darker in Melzer's or finally some weakly dextrinoid.
Basidia 4-spored, 25-30 X 9-11 u, clavate, hyaline in KOH,
scarcely yellow in Melzer's. Pleurocystidia 36-52 X 8-12 ji, mostly near
the tube edges, thin-walled, smooth, content ochraceous-brown. Cheilocystidia similar to pleurocystidia. Caulocystidia small and large (25-36 X
7-10 g and 40-60 X 12-20/ ), both types intermixed, walls thin and
smooth, content smoky ochraceous.
Tube trama obscurely bilateral, the Boletus subtype. Pileus cuticle
a tangled layer of hyphae 6-10 g wide, the terminal cells 6-10 Ag wide,
tapered to a subacute apex, with yellow-brown pigment in KOH, walls
smooth or slightly roughened, rarely some end-cells bullet-shaped (on
the broader hyphae), no inflated or sphaerocyst-like cells observed in
the elements-most of the cells elongate and tubular, but these cells
readily disarticulating (fig. 18). Context hyphae with content not distinctively colored in Melzer's. Clamp connections absent.
Habit, habitat, and distribution.-Scattered under birch and aspen,
Carp Lake Bog, Carp Lake, Cheboygan County, July 13, 1961, Smith
63555.
Observations.-In revived material the hyphae adjacent to the subcutis are not orange to red as revived in Melzer's. This distinguishes
dried specimens from L. proximum. Both stain gray when the context is
cut. Although the cuticle is composed of narrow hyphae the cells disarticulate readily. This is a rare feature in this genus. The broad hyphae
are usually the ones in which the cells separate.
Subsection SCABRA
In this subsection are grouped the species with yellow-brown to
fuscous-brown or blackish pilei in which the sectioned context in the
stipe apex does not stain gray to any appreciable extent. However,
nearly all species show a change to blue or greenish in some part of the
stipe and some will in addition show a change to pink or red or yellow
or various combinations of these.
Type species: Leccinum scabrum.