Summary:
Cystoderma fallax is identified by its rusty-orange to cinnamon color, a granulose coating on the cap and stem, whitish gills that are attached to the stem, a prominent ring, a white spore deposit and amyloid spores. Vellinga(16) mentions that molecular work reported by Saar, Poldmaa, and Koljalg in 2008 supports considering Cystoderma fallax a variety of Cystoderma carcharias. This is Cystoderma carcharias var. fallax (A.H. Sm. & Singer) I. Saar, in Saar, Poldmaa & Koljalg, Mycol. Progr. 8(1): 68. 2009.

Cap:
2-5cm across, convex to flat or frequently with an umbo; cinnamon brown to rusty orange to tawny-ocher; dry, "with conspicuous mealy granules which are erect at first but flattened and more powdery in age (or often wear away completely)", margin often hung with veil remnants, (Arora), 2-5cm across, obtuse to somewhat convex with incurved margin, becoming bell-shaped or expanded umbonate, margin at first decorated with membranous flaps of veil remnants; almost ferruginous ("Sanford's brown", "cinnamon rufous", or "amber-brown"), duller rusty brown dried; dry, at first covered by erect granulose scales, finally evenly granulose or powdery or scales persisting around disc, (Smith(15))

Flesh:
thin; "whitish or tinged cap color", (Arora), thick in disc, thin toward margin; whitish to tinged cap color, in stem pallid to yellowish, (Smith(15))

Gills:
"adnexed to adnate, close"; white to pale pinkish buff or tinged yellow, (Arora), adnate to rounded adnexed, close, 2-3 tiers of subgills, narrow to moderately broad; "pinkish buff" or paler; edges even, (Smith(15))

Stem:
3-7cm x 0.3-0.5(0.7)cm, equal or widened in lower part, "smooth and pallid above the ring", sheathed with cinnamon brown to rusty ocher granules or flaky scales below, (Arora), 3-6cm x 0.3-0.7cm, usually widening downward or base narrowly club-shaped, sometimes equal, solid; cap-colored up to ring, pallid to pale buff above ring; sheathed up to flaring membranous ring with granulose covering similar in texture to cap, scales smaller and more poorly formed in lower part, bald and somewhat silky above the ring, base often conspicuously mycelioid, (Smith(15))

Veil:
ring large, delicate but persistent, often flaring, median to superior, smooth and pallid on upper side, colored like cap underneath, (Arora), ring persistent, upper surface silky and pallid to pale buff, (Smith(15))

Odor:
not distinctive or at times somewhat nauseous, (Smith), pleasant (Phillips) pleasant or unpleasant, one variant has green corn odor, (Laycock)

Taste:
not distinctive or at times somewhat nauseous, (Smith(15)), mild (Phillips)

Microscopic spores:
spores 3.5-5.5 x 3-4 microns, broadly elliptic to nearly round, smooth, amyloid, (Arora), spores 3.6-4.5 x 2.8-3.5 microns, broadly elliptic to nearly drop-shaped, smooth, amyloid; basidia 4-spored, 18-23 x 4-5.5 microns, colorless in KOH, yellowish in iodine; pleurocystidia and cheilocystidia not differentiated; cap cuticle of chains of spherical to ellipsoid cells 10-40 microns in diameter or 20-40 x 10-25 microns, "some pear-shaped or a few cylindric to subcylindric, the cells very dark rusty cinnamon in KOH"; clamp connections in cap trama, (Smith(15)), spores 3.5-5(5.5) x 2.8-3.6(4) microns, broadly elliptic to nearly drop-shaped, (Smith(46))

Spore deposit:
white (Arora, Smith(15))

Notes:
Smith(46) give the distribution as WA, OR, ID, CA, and CO. C. fallax is found also in BC (Lowe(1)) and is frequent on foray lists. There are collections from BC at the University of British Columbia.

EDIBILITY

unknown (Arora)

Synonyms and Alternate Names:
Cystoderma carcharias var. fallax (A.H. Sm. & Singer) I.