Summary:
Section Sinapizantia. The Arora(1) description is for Hebeloma sinapizans group recognized by a brown to reddish-brown cap, a thick stem adorned with small scales, dull brown usually notched gills, and absent veil. The scaly stem is according to Smith(15) the most important field character. Field characters of North American species differ from European according to Schalkwijk-Barendsen who reports it "sensu American authors" from AB. Smith(44)(1984) described from Michigan a North American variant that is said to differ from the European type in "slightly more vinaceous brown colors when fresh and the cheilocystidia were more frequently clavate than fusoid-ventricose". That taxon was redescribed (Grilli(1)) as Hebeloma megacarpum in 2005. Smith(15)(1949) earlier described Hebeloma sinapizans from Michigan and Oregon but does not mention Oregon material in Smith(44).

Cap:
4-13(20)cm across, convex with inrolled margin, becoming flat or with uplifted, often wavy margin; "brown to cinnamon, ochre-brown, pinkish-tan, or dark reddish-brown, but often shaded with gray or overlaid with a pallid sheen toward margin"; slightly viscid when moist, smooth, margin at first minutely cottony, (Arora), (4)7-12(15)cm across, broadly convex with inrolled margin, expanding to nearly flat "or finally the margin arched or uplifted"; "with a pallid sheen obscuring the cinnamon-tan or deeper vinaceous brown ground color"; viscid, margin cottony when still inrolled, but no veil present, (Smith(15))

Flesh:
thick; whitish, (Arora), "hard at first but soon soft, thick", (Smith(15))

Gills:
"close, usually adnexed or notched"; "pallid becoming pale brown, then dull brown or dull cinnamon"; "the edges minutely serrated and often beaded with droplets in wet weather and brownish-dotted when dry", (Arora), deeply adnexed to emarginate, close, broad; pallid but becoming pale clay or cinnamon-tinged; "edges soon serrulate and often beaded", (Smith(15)), the dots forming when spore-filled droplets dry up (Schalkwijk-Barendsen)

Stem:
4-13cm x 1-3cm, usually swollen at base, firm, solid; "whitish, with distinct pallid to brownish flakes or protruding scales", top usually powdered with small white granules, (Arora), 6-12cm x 1.5-3cm, "nearly equal above a somewhat bulbous base", rigid, stuffed but soon hollow; "white from the cuticle which is soon broken up into series of scales", finally sordid when old, (Smith(15))

Veil:
absent (Smith(15))

Odor:
usually distinctly radish-like (Arora), distinctly of radishes, (Smith(15)), very strongly of radish or of raw potatoes (Schalkwijk-Barendsen)

Taste:
distinctly of radishes (Smith(15))

Microscopic spores:
spores 10-13 x 6-8 microns, elliptic, slightly rough, (Arora); spores 10-12.5 x 6-7 microns, suboval [somewhat oval] in face view, almond-shaped in side view, distinctly roughened, pale cinnamon in KOH; basidia 4-spored, 26-28 x 8-9 microns; pleurocystidia absent, cheilocystidia very abundant, 48-70 x 10-11 microns, "subcapitate to clavate at apices, narrower and flexuous in the shank"; gill trama of parallel to subparallel, colorless hyphae as revived in KOH; cap trama of interwoven hyphae, pellicle thick and gelatinous, (Smith(15))

Spore deposit:
dull brown (Arora), medium to reddish brown (Schalkwijk-Barendsen), red-brown (Buczacki)

Notes:
The Smith(15) description for Hebeloma sinapizans indicates its presence in OR and MI (or at least the presence of a close species). Collections from BC, AB, and CA are at the University of British Columbia, and from BC at Pacific Forestry Centre. The University of Washington has collections from WA, AK, WY, and ON.

EDIBILITY

poisonous, causes vomiting and diarrhea, (Arora)