The veiled species of Hebeloma in the western United States / Alexander H. Smith, Vera Stucky Evenson, and Duane H. Mitchel.

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The Veiled Species of Hebeloma

luteobrunneus; gustus amarus, odor raphaninus. Lamellae latae, confertae, argillaceae. Stipes + 5 cm longus, circa 5 mm crassus, brunnescens, striatus. Velum ochraceum, fibrillosum evanescens. Sporae 7.5-9
x 4.5-5 Jim, subleves, ellipsoideae vel ovoideae, non dextrinoideae.
Cheilocystidia 34-60 x 5-7 jIm, filamentosa vel ad basin leviter ventricosa. Cuticula pileorum gelatinosa.
Specimen typicum in Herb. Denver Bot. Garden est, Shirley
Chapman (DBG 2473); legit prope Sacramento, Park County, Colorado, 13 Sep 1969.
Pileus + 3 cm broad, plano-convex but with a small umbo, glabrous (veil remnants buff colored and soon obliterated), surface
slightly viscid; colors tan over the disc and clay color to buff over the
margin. Context thin, tan, watery, odor raphanoid, taste bitterlingering and almost acrid.
Lamellae broad, close, sinuate, extending beyond the edge of the
pileus, buff colored, as dried almost clay color.
Stipe + 5 cm long, about 5 mm thick, slender, equal, darkening
below, longitudinally striate with tan polished striations; remnants of
the thin veil soon evanescent. Spores 7.5-9 (10) x 4.5-5 pxm, oblong
to a few ovoid, smooth (apparently) in KOH, + thin-walled and pale
orange-yellow (in KOH), not dextrinoid, some with a large (oil?) drop
within.
Hymenium.-Basidia 4-spored, 22-24 x 8-9 pim, clavate, yellowish in KOH. Pleurocystidia none. Cheilocystidia 34-60 x 5-7 Rxm,
filamentous with apex blunt to slightly enlarged, or ~ ventricose near
the base.
Lamellar and pilear tissues.-Lamellar trama typical for the genus. Cuticle of pileus an ixocutis, the hyphae 3-6 Vxm diam, yellowish
in KOH. Hypodermium "cellular" (from cut ends of hyphae), + hyphoid in radial sections, dark yellow-brown in KOH, cells up to 15 pLm
diam. Pileus trama typical of the genus (the hyphae of the pileus trama
+ radially disposed). Clamps present.
Habit, habitat, and distribution.-Caespitose in moss on shaded
black soil, collected at Sacramento (west of Fairplay), Park County,
Colorado, September 13, 1969, by Shirley Chapman (type, DBG); also
collected by Charles Barrows, no. 2021, in New Mexico.
Observations.-The color of the pileus closely resembles that of
H. pascuense but the striations on the stipe readily distinguish it in the
field. We have, to date, seen this feature on only one other species,
and it belongs in subgenus Denudata. The narrow spores, persistently
bitter to ~ acrid taste, thin veil, striate stipe, and pale pileus are
distinctive as a package.