The North American Species of Pholiota
115. Pholiota adiposa (Fr.) Kummer, Der Führer in die Pilzkunde, p. 83. 1871.
Agaricus adiposus Fries, Syst. Myc. 1: 242. 1821.
Hypodendrum adiposum (Fr.) Overholts, North Amer. Fl. 10: 279. 1932.
Illustrations: Text figs. 245-247.
Pileus caespitose, 6-9 (16) cm broad, convex, then plane, yellow to dark-yellow, viscid or glutinous, with ferruginous-brown, more or less concentric scales, which dry down to resemble cherry-gum. Context yellow.
Lamellae adnate to sinuate, at first yellow or straw-yellow, becoming ferruginous, close, broad.
Stipe 5-12 cm long, 6-15 mm thick, viscid or glutinous, yellow above, becoming ferruginous brown downward, base enlarged, with numerous, glutinous, superficial squarrose or recurved scales up to the apical ring. Inner veil yellowish, subfloccose, forming an evanescent annulus.
Spores 5-6 x 3-4 µ, smooth, with a minute apical pore; shape in face view ovate to elliptic, in profile subelliptic to slightly bean-shaped; color in KOH pale tawny to clay-color, in Melzer's merely ochraceous; wall thin (-0.25 µ). Basidia 16-20 x 3.5-5 µ, 4-spored, narrowly clavate, hyaline in KOH, weakly yellowish in Melzer's reagent. Pleurocystidia of two types: 1) 25-40 x 5-10 µ, subfusoid, walls thin smooth and hyaline, content coagulated and shrunken away from the walls, wrinkled, dark brown in KOH and in Melzer's reagent: 2) chrysocystidia 18-28 (33) x 6-9 (13) µ, fusoid to somewhat fusoid-ventricose; walls thin, smooth and hyaline; inclusion small, hyaline in KOH and Melzer's reagent, usually well defined. Caulocystidia none except for those in the caulohymenium at very apex of the stipe and resembling hymenial cystidia.
Gill trama a floccose central area of somewhat interwoven hyphae hyaline in KOH, the cell walls thin and smooth; subhymenium a thin gelatinous layer of very narrow hyphae. Pileus cutis a very thick gelatinous pellicle of yellow to cinnamon-colored hyphae 2-5 µ diam., collapsing, walls mostly smooth. Clamp connections present. All hyphae inamyloid.
Habit, Habitat, and Distribution: On hardwood logs, British Columbia. September.
Observations: This species has been misinterpreted by some European mycologists, and even to a greater extent in North America. We are following the concepts of Lange, Ricken, Kuhner & Romagnesi, Moser and Reid, all of whom appear to agree that its distinctive characters are a viscid or slimy pileus yellow to dark yellow with brown scales which become cherry-gum-like, viscid or slimy scales on the stipe, and spores 5-6 x 3-4 µ. This species has obviously been confused with P. aurivella, which also has broad gills, but has a dry stipe, and larger spores than P. adiposa. Many of the North American collections, in various herbaria, are filed erroneously under one of these names. The true P. adiposa appears to be rare in North America. The microscopic data given in our description are taken from a collection by Derek Reid at Oldbury, Sept. 22, 1951. The reliable characters of distinction are the very small pale colored spores, glutinous scales on the stipe, and yellowish young gills. The macroscopic features even to the glutinous scales apply to more than one taxon here in this group in North America.
Material Examined: BRITISH COLUMBIA; SLOVAKIA: Kmet, Prencow, Aug. 6, 1891 (STOCKHOLM). ENGLAND: Reid.