The North American Species of Pholiota

197. Pholiota virescentifolia sp. nov.

Illustrations: Text figs. 445-446.

Pileus 4-5 cm latus, conicus, demum conico-umbonatus, sordide luteo-brunneus, viscidus. Contextus albus, lamellae adnato-decurrentes, albidae demum olivaceo-luteae, confertae, latae, fimbriatae. Stipes 3.5-4 cm longus, 8-12 mm crassus, subradicatus, sursum albidus, deorsum sordidus, siccus. Vellum luteum, copiosum. Sporae 5.5-6.5 (7) x 3.5-4 µ. Pleurocystidia (40) 50-75 (85) x 10-17 µ, fusoide ventricosa. Caulocystidia 36-80 x 7-15 µ, clavata. Specimen typicum in Herb. Univ. Tenn. conservatum est; legit prope Mt. LeConte G.S.M.N.P. 5 Sept. 1952. Hesler 20591.

Pileus 4-5 cm broad, conic, then more or less expanding, "tawny-olive," pellicle separable, viscid, rivulose under lens, margin even. Context white, thick on disc, thin on margin; odor and taste slight.

Lamellae adnate, short-decurrent, white at first, then pale greenish yellow, finally brownish yellow, close, broad, edges fimbriate.

Stipe 3.5-4 cm long, 8-12 mm thick, subradicate, apex white, dingy below, dry fibrillose, spongy-hollow. Veil copious, yellow, submembranous-webby.

Spores 5.5-6.5 (7) x 3.5-4 µ, smooth, apex with a very minute pore; shape in face view elliptic to ovate, in profile obscurely inequilateral to elliptic; color pale tawny in KOH, about the same color in Melzer's reagent; wall about 0.25 µ thick.

Basidia 4-spored, 20-25 x 5-6 µ, narrowly clavate, hyaline to yellowish in KOH. Pleurocystidia abundant, (40) 50-75 (83) x 10-17 µ, fusoid-ventricose with usually a long narrow pedicel (14-27 µ) and an obtuse apex, thin-walled, hyaline and smooth as revived in KOH, but often ochraceous when first revived; content of homogeneous colloidal material in the neck, only a few with some amorphous to crystalline material in the apical region, this material more or less dextrinoid. Cheilocystidia similar to pleurocystidia but smaller and more of them tending to remain ochraceous in KOH, many with somewhat stringy ochraceous content as seen in KOH. Caulocystidia 36-80 x 7-15 µ, clavate, in tufts.

Gill trama of short- to long-celled parallel hyphae with thin nongelatinous walls hyaline to yellowish in KOH and Melzer's sol.; subhymenium a gelatinous to subgelatinous zone of narrow (2-3.5 µ), interwoven hyaline filaments. Pileus cutis a thick gelatinous layer of appressed-interwoven hyphae 2-5 µ diam., with band-like to spiral incrustations, yellowish to hyaline in KOH, hyphae hyaline to yellowish individually; hypodermium of bright tawny floccose hyphae 4-12 µ diam. with more or less incrusted walls. Context hyphae hyaline to yellowish in KOH, cells variously inflated, thin-walled, hyphae interwoven. All hyphae inamyloid.

Habit, Habitat, and Distribution: On soil and humus, under hemlock, Tennessee, September; Hesler 20591, type.

Observations: The tawny olive pileus, white context, white young lamellae which become greenish yellow, subradicate stipe which is white above, and the large, clavate caulocystidia in tufts all characterize this species. When collected, it appeared to be a form of P. spumosa, but its microscopic characters separate it.