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

gustus mitis. Lamellae adnatae, confertae, angustae demum latae, pallide cinnamomeae. Stipes 2-3 cm longus, 2-4 mm crassus, cavus, deorsum triste alutaceus, sursum pallidior. Velum fibrillosum, pallidum.
Sporae 9.5-12.5 (13) x 6-7.5 pxm, pallide ochraceae in "KOH," non
dextrinoideae, ellipsoideae. Basidia tetraspora, 7-9 tIm lata. Cheilocystidia 46-67 x 5-10 x 4-5 x 6-7 ptm, plerumque cylindraceosubcapitata ad apicem subcapitata vel deorsum subinflata vel flexuosa
filamentosa, saepe agglutinata.
Specimen typicum in Herb. Univ. Mich. conservatum est, Smith
23737; legit prope Ollalie Lake, Mt. Hood National Forest, Oregon,
25 Sep 1946, Gruber and Smith.
Pileus 2-3 cm broad, obtuse with an incurved margin, expanding
to broadly convex, plane or plano-umbonate, margin at first with scattered remains of a thin fibrillose veil, soon glabrous, ground color
about cinnamon-buff or more argillaceous, only slightly darker when
dried, rather evenly colored; odor and taste not distinctive.
Lamellae narrow to finally rather broad, close, adnate, pallid
becoming pale cinnamon, either beaded or spotted.
Stipe 2-3 cm long, 2-4 mm thick, equal, hollow, about concolorous with pileus when fresh but base somewhat darker, thinly fibrillous.
Veil pallid, not leaving an annular zone on the stipe.
Spores 9.5-12.5 (13) x 6-7.5 Jm, appearing smooth but faintly
marbled under high magnifications as seen in Melzer's, not dextrinoid
(pale ochraceous in either KOH or Melzer's), ellipsoid to ovoid, or
some obscurely bean-shaped in profile view.
Hymenium.-Basidia 4-spored, 7-9 [xm broad; hymenium dull
ochraceous in KOH. Pleurocystidia none. Cheilocystidia abundant,
45-67 x 5-10 x 4-5 x 6-7 pxm, cylindric-subcapitate mostly but
some slightly enlarged near the base, some flexuous-filamentous, only
slightly agglutinated at maturity.
Lamellar and pilear tissues.-Lamellar trama typical for the genus. Cuticle of pileus a collapsing ixotrichodermium of clamped hyphae 1.5-3,um diam, the hyphal walls refractive. Hypodermium hyphoid, delimited as a rusty ochraceous zone in KOH or in Melzer's,
hyphal walls not conspicuously encrusted. Tramal hyphae typical of the
genus but compactly interwoven.
Habit, habitat, and distribution.-Gregarious under conifers
(mostly Abies lasiocarpa), Skyline Road near Ollalie Lake, Mt. Hood
National Forest, September 25, 1946, Wm. B. Gruber and A. H.
Smith 23737 (type, MICH).
Observations.-This species resembles H. pascuense rather
closely but is distinguished by having the cuticle of the pileus at first