The North American Species of Pholiota

74a. Pholiota lutescens var. robusta var. nov.

Illustrations: Text figs. 88-89.

Pileus 3-7 cm latus, convexus, rare subumbonatus, viscidus, subsquamulosus, pallidus, demum avellaneus, lutescens. Lamellae pallidae, latae, subdistantes, subdecurrentes. Stipe 3-6 cm long, 4-8 mm crassus, pallidus, deorsum fulvescens. Sporae 5.5-6.5 (7.5) x 3.3-4 µ. Chrysopleurocystidia 25-38 (46) x 6-11 (13) µ. Specimen typicum in Herb. Univ. Mich. conservatum est; legit prope Milford, Mich., 30 Sept. 1951, Smith 38863.

Pileus 3-7 cm broad, broadly convex to plane or rarely with a slight umbo, surface viscid but soon dry, typically with minute slightly darker spot-like squamules around and over disc, pallid when young becoming avellaneous (grayish) and finally near snuff brown (dull yellow-brown), yellow tones dominant in dried material. Context pallid, thin, finally yellowish, odor and taste mild.

Lamellae pallid young, becoming near buckthorn brown and drying more ochraceous, more or less decurrent, broad, more or less subdistant, edges slightly fimbriate.

Stipe 3-6 cm long, 4-8 mm at apex, typically narrowed downward, pallid but soon dingy brown from base up though nearly evenly dingy buff as dried, with scattered minute scales below the veil-line, silky above.

Spores 5.5-6.5 (7) x 3.3-3.8 (4) µ, smooth, apical pore present, small but causing apex to appear obscurely truncate in many; shape in face view oblong to narrowly elliptic, in profile slightly bean-shaped to obscurely inequilateral; pale brownish revived in KOH, paler in Melzer's reagent; wall less than 0.25 µ thick.

Basidia 4-spored, 26-30 x 6-7.5 µ, clavate, hyaline in KOH, yellowish pallid in Melzer's reagent. Pleurocystidia abundant, 25-38 (46) x 6-11 (13) µ, clavate, mucronate to fusoid-ventricose, walls thin smooth and hyaline, content showing a highly refractive amorphous inclusion as revived in KOH, and merely yellowish in Melzer's reagent, or refractive material in more or less of a strand. Cheilocystidia abundant, 30-45 x 4-6 x 5-9 µ, filamentous-subcapitate, to capitate, varying to obtusely fusoid-ventricose, walls thin smooth and hyaline, content hyaline and homogeneous. Caulocystidia rare, as clavate hyaline end-cells of cortex hyphae projecting slightly and in width up to 16 µ thin-walled.

Gill trama a somewhat interwoven strand of floccose hyphae with cells inflated to 12 µ or more and with "colloidal" content, bright red in Melzer's reagent fading slowly to ochraceous; subhymenium a well-defined gelatinous layer of narrow hyaline hyphae. Pileus cutis a gelatinous layer of hyphae 4-7.5 µ broad, hyaline to yellowish, smooth to asperulate, many with hyaline "granular" protoplasm as seen revived in KOH; hypodermial region not sharply distinct from context, the hyphae of both floccose and of inflated cells to 15 µ or more wide, yellowish smooth walls in KOH and content reddish in Melzer's reagent when first mounted, near the subhymenium the hyphal walls slightly thickened (appearing layered). Clamp connections present.

Habit, Habitat, and Distribution: Subcaespitose on soil at Proud Lake Recreation Area, Sept. 30, 1951, Oakland County, Mich. Smith 38863 type, and 21380.

Observations: The squamules over and around the disc are grayish and the pileus soon develops darker coloration overall than in var. lutescens.