The North American Species of Pholiota

102. Pholiota squarrosoides (Pk.) Saccardo Syll. Fung. 5: 750. 1887.

Agaricus (Pholiota) squarrosoides Peck., New York State Mus. Ann. Rept. 31: 33. 1879.
Hypodendrum squarrosoides (Peck.) Overholts, North Amer. Fl. 10: 278. 1932.

Illustrations: Text figs. 204-207; pls. 45-46. Atkinson, Stud. Amer. Fungi, 2nd ed., pl. 48. Harper, Wisconsin Acad. Sci. Arts 8c Letters 17, pls. 36, 37. Overholts, Annals Mo. Bot. Gard. 14, pl. 22. Peck, N. Y. State Mus. Ann. Rept. 54, pl. 73, figs. 6-15.

Pileus (2.5) 3-7 (11) cm broad, obtuse becoming broadly umbonate to convex, at times nearly plane, color white to whitish when fresh, becoming only slightly tinged with cinnamon in age, or remaining whitish, the margin often fringed with veil remnants, surface viscid beneath the scales, the scales dry, recurved to squarrose, pale tawny ("tawny" to "ochraceous-tawny"), scattered near the margin, often crowded over the disc. Context thick, whitish, rather pliant; odor and taste not distinctive.

Lamellae adnate but becoming sharply adnexed, close to crowded, moderately broad (more or less 5 mm), broadest at base and tapering toward the margin, whitish at first, slowly changing to dull rusty brown as the spores mature, sometimes with brighter rusty stains.

Stipe (4) 5-10 (14) cm long, 5-10 (15) mm thick, dry, fleshy-pliant, lower two-thirds covered by coarse, recurved, ochraceous tawny, persistent scales, tinged pale buff between the scales or with a tendency to stain rusty-brown near the base, ground color typically pallid, apical region whitish and silky, equal, stuffed or solid. Annulus superior, pallid, often more fibrillose than membranous, often evanescent.

Spores 4-5.5 (6) x (2.5) 3-3.5 µ, smooth, apical pore not evident; shape in face view ovate to broadly elliptic, in profile, subelliptic to obscurely inequilateral; in KOH pale dull cinnamon, in Melzer's reagent paler; wall less than 0.25 µ thick.

Basidia 17-22 (27) x 4-6 µ, 4-spored, narrowly clavate, hyaline in KOH and in Melzer's reagent scarcely colored. Pleurocystidia abundant, (25) 30-50 (65) x (6) 8-15 (18) µ, clavate, clavate-mucronate, fusoid-ventricose with an apical mucro or elongation, or wavy in outline and one of the above basic shapes; wall thin, smooth, hyaline in KOH; content homogeneous-opaque but hyaline or nearly so (no refractive inclusion), rarely secondarily septate, at times when poorly revived seen to have an ochraceous-brown content. Cheilocystidia 26-40 (50) x 5-11 (13) µ, clavate, fusoid-ventricose, or resembling the pleurocystidia in shape and then with similar content, none seen with a refractive-amorphous inclusion. Caulocystidia in scattered clusters, filamentose to narrowly clavate 26-55 x 5-8 µ, 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 µ) hyaline hyphae. Pileus cuticle with a gelatinous layer beneath the scales, the hyphae narrow and walls disintegrating 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 Ontario 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 (elongate-clavate) 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; Smith 16407, 16443, 16626, 17538 (dark colored), 19582, 31217, 31427, 31822, 47850, 49074; WYOMING: Kauffman 8-22-23, 8-24-23; CANADA: (Ontario): Beardslee 8-20-20; Cain 16024 (TENN); DAOM 33854 (MICH); Kelly 742, 1258, 1314, 1620; Smith 26380, 26467; NOVA SCOTIA: Wehmeyer 862.