Pileus (1) 2-3 cm broad, convex becoming broadly convex, some- times obtusely umbonate, disc glabrous and viscid, deep vinaceous- brown (“Natal Brown”) becoming paler to “Army Brown” or redder; margin white fibrillose from remains of the veil, edge often fringed with fibrils. Context watery grayish, fading to white; odor and taste raphanoid; FeS04 on base of stipe olivaceous.
Lamellae broad, close, adnate, whitish at first as seen across the gills, faces at first avellaneous becoming dull cinnamon; edges not beaded and not spotted.
Stipe 4-7 cm long, 3-5 mm thick, equal, solid, white and fibril- lose overall at first but veil white and not leaving an annulus; near base soon becoming brown and the change progressing upward (the FeS04 color change most pronounced on the discolored area).
Spores 7.5-10 × 5-6 j.Lm, smooth in KOH, minutely punctate in Melzer’s, not dextrinoid, in face view ovate to elliptic, in profile ovate to elliptic (not inequilateral to any degree).
Hymenium.-Basidia 4-spored, narrowly clavate, 7-9 /-lm broad, some with hyaline globules within as mounted in KOH. Pleurocystidia none. Cheilocystidia abundant, not agglutinated, cylindric down to a subventricose basal area, 38-56 × 6-9 × 4-6 f,Lm, neck straight, not branched or forked.
Lamellar and pilear tissues.-Lamellar trama typical for the genus (not red in Melzer’s). Cuticle of pileus an ixotrichodermium of long tubular elements, walls near hypoderm ± finely roughened, hyphae 2.5-3.5 f,Lm diam, walls gelatinizing, clamps present. Hypodermium hyphoid, the hyphae 5-11 (15) f,Lm wide, walls rusty brown in KOH and some incrustations present, no dextrinoid debris noted. Pileus trama of compactly interwoven hyaline to ochraceous, smooth-walled hyphae of various widths, lacking a red flush in Melzer’s.
Habit, habitat, and distribution.-More or less clustered under alder, Snowmass Village, Pitkin County, Colorado, August 25, 1979 (type, MICH).