The North American species of Pholiota, by Alexander H. Smith and L. R. Hesler.

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The North American Species of Pholiota

inclusion. Caulocystidia in scattered clusters, filamentose to narrowly
clavate 26-55 x 5-8 u,, thin-walled, smooth, hyaline in KOH, content
homogeneous.
Gill trama of a floccose central strand of more or less interwoven
hyphae with inflated cells, walls smooth, thin, hyaline to ochraceous in
KOH (hyaline in water mounts fresh); subhymenium a well defined
gelatinous layer of narrow (1.5-3 /u) hyaline hyphae. Pileus cuticle with
a gelatinous layer beneath the scales, the hyphae narrow and walls disintergrating to some extent; scales of more or less rusty brown encrusted
to smooth hyphal cells often about as long as broad; hypodermial region
of floccose ochraceous, brown, smooth to slightly encrusted hyphae. Context hyphae interwoven, inflated, thin-walled or wall thickened in the area
near the subhymenium and then the wall "laminate." Clamp connections
present. All hyphae inamyloid on standing but showing a tendency in
sections to be reddish when first revived.
HABIT, HABITAT, AND DISTRIBUTION: Singly or caespitose, on trunks
and stumps of hardwood trees, especially maple, birch, beech, basswood,
and in the northwestern United States on alder. Known from Oontario
and Nova Scotia in Canada and Maine, Vermont, Connecticut, New York,
Pennsylvania, North Carolina, Tennessee, Michigan, Colorado, Oregon,
and Washington in the United States. August to September.
OBSERVATIONS: The pleurocystidia of this species are not true chrysocystidia in that as revived in KOH the cell content is homogeneous instead of containing a highly refractive clearly delimited body. The shape
and size of the cystidia varies greatly even in a single pileus. The caulocystidia are unusual in that they are simple as to morphology (elongateclavate) and not like any of the lamellar cystidia.
The species differs from P. squarrosa in the gelatinous layer beneath
the scales on the pileus. We have not been able to recognize var. faginea
Pk. (1901: 183) on beech with smaller scales. The size of the clusters of
basidiocarps is directly related to the amount of food available. This is
a common species on the wood of red alder in the Pacific Northwest, and
in the hardwood slashings of northern Michigan.
MATERIAL EXAMINED: COLORADO: Barrows 816 (MICH); IDAHO:
Smith 70679, 70684; KENTUCKY: Kauffman 9-1-16; MAINE: Bigelow
4666; MARYLAND: Kelly 1700; MASSACHUSETTS: Harvard Forest
(MICH); MICHIGAN: Bartelli 127, 128 (MICH); Harding 300, 344,
345, 364, Ex-70 (basidiocarp produced in culture); Harper 2251; Imshaug
3945, 4028; Kauffman 9-1905, 8-21-06, 8-29-06, 9-14-27, 10-5-27, 9-19-29;
Povah 721, 7-30-14; Shaffer 201, 3746; Smith 32-597, 61, 25066, 37198,
37819, 38195, 39533, 64034, 67046, 67193, 68770; Thiers 1061; NEW
HAMPSHIRE: Mains 4164; NEW YORK: Kauffman 9-8-03, 7-31-03,
8-31-03; Marsden 514 (MICH); Peck (type); NORTH CAROLINA:
Hesler 15884; Smith 10185; OREGON: Smith 23832; 24369, 68771; TENNESSEE: Hesler 8324, 9388; Kauffman 9-11-16; Smith 10563; VERMONT: Shaffer 3394 (MICH); WASHINGTON: Kauffman 9-12-15;