This description is based on the annotations of collections sent to RET from the western coastal states of the U.S.
The cap of A. farinosa sensu Thiers is 50 - 67 mm wide, usually uniformly gray, occasionally uniformly tan, and never darker over disk. Its margin is barely striate in young material. The length of the striations becomes up to half the cap's radius in overmature material. The volva is present as a somewhat uneven, powdery layer covering the entire cap surface; it is uniformly gray and is bound to the cap's skin by hyphae.
The gills are narrowly adnate to adnate, close, white to whitish, and sometimes have brownish stains. The short gills are truncate, of many different lengths, and plentiful.
The stem is 55 - 60 × 10 - 18 mm and whitish; its bulb is subglobose to subclavate and sometimes vertically flattened. The stem's flesh is white and hollow to stuffed. There is never a ring on the stem. The volva is present at the stem's base in broken rows of small, pallid, powdery, warts and patches.
The odor is indistinct.
The spores of this species measure (6.5-) 7.5–9.5 (-10.6) × (5.0–) 5.5–7.2 (–7.6) µm, the are broadly ellipsoid to ellipsoid (very infrequently subglobose or elongate) and inamyloid. Whether there are clamps at the bases of basidia and how plentiful they are requires further observations.
The basidiome of this western entity is two to three times the size of the true A. farinosa of eastern North America and Central America; and the length of the marginal striations on the pileus is relatively short in the western "farinosa." The spores are proportionately narrower in the western entity (but a larger sample should be checked). Further distinctions between the taxa require (at least) microscopic observation of gill anatomy.
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47 - 69 mm wide, usually uniformly gray, occasionally uniformly tan, never darker over disk, convex to broadly convex to planar, ??; context white, ??; margin barely striate in young material, becoming striate (ca. 0.1R, up to 0.5R in overmature material); universal veil as somewhat uneven powdery layer over entire pileus surface, uniformly gray, bound to pileipellis (??and context) by hyphal connections.
narrowly adnate to adnate, close, white to whitish, sometimes with brownish stains, ??; lamellulae truncate, of diverse lengths, plentiful.
55 - 70 × 10 - 18 mm (with length probably including bulb length), whitish, narrowing upward, minutely scaly; bulb usually clavate, only slightly wider than adjacent lower stipe (15 - 19 mm wide), subglobose to subclavate, sometimes compressed horizontally (slightly flattened); context white, hollow to stuffed; exannulate; universal veil as broken rings of friable, pallid, warts and patches on bulb.
Odor indistinct; taste not recorded.
Odor "not strong." Taste not recorded.
45 - 65 µm wide, a branching structure of short uninflated hyphal segments, partially inflated cells, and plentiful inflated cells (up to ?? × ?? μm), with basidia arising from cells of all types.
[120/5/4] (6.5-) 7.5–9.2 (-10.6) × (5.0–) 5.5–7.2 (–7.6) µm, (L = 8.1 - 8.7 µm; L’ = 8.4 µm; W = 6.1 - 6.5 µm; W’ = 6.3 µm; Q = (1.14–) 1.20–1.48 (–1.70); Q = 1.28 - 1.40; Q’ = 1.33), hyaline, colorless, smooth, thin-walled, inamyloid, broadly ellipsoid to ellipsoid, infrequently subglobose or elongate, usually adaxially flattened; apiculus sublateral, cylindric, proportionately rather robust; contents monoguttulate, sometimes with additional small granules; white in deposit.
In small groups. California: At 120± m. In forests with Picea sitchensis. Oregon: At 440± m elev. In small open area ca. Acer, Tsuga, & Pseudotsuga menziesii with dense ground cover including Oxalis. Washington: ??.
U.S.A.: CALIFORNIA—Del Norte Co. - Jedediah Smith Redwoods St. Pk., Howland Hill Rd. [41°45.304' N/ 124°07.808' W, ca. 120 m], 18.xi.2008 Ronald L. Pastorino 11-18-08B (RET 426-9), 11-18-08F (RET 426-5), 20.x.2011 R. L. Pastorino 10-20-11A [mushroomobserver.org 80882] (RET 493-3); Rellin Ridge Tr., E of Crescent City, 2.xi.2005 R. Pastorino s.n. (RET ??).
OREGON—Clatson Co. - US Rte. 26, milepost 28.6, 50 m from Sunset Rest Area [45.7959° N/123.4593° W, 438], 21.vii.2012 Sava Krstic s.n. [mushroomobserver.org #102406] (RET 508-2). Lincoln Co. - Lincoln City, 25.x.1987 coll. unkn. s.n. [J. E. Lindgren 101] (in herb. J. E. Lindgren; RET 077-7); unkn. loc., "along coast," 14.ix.1987 Maggie Rogers s.n. [J. E. Lindgren 87-111] (RET 258-7).
WASHINGTON—Skamania Co. - GPNF, Pacific Crest Tr., Trout Crk., 22.ix.1990 J. E. Lindgren 90-44 (in herb. J. E. Lindgren; RET 077-8); Trout Crk. N., 9.ix.1989 J. E. Lindgren 89-173 (RET 258-8); Trout Crk. S., 30.ix.1992 J. E. Lindgren 92-50 (RET 258-9).
[Note: See Thiers 38416 (SFSU).]
The basidiome of this western entity is two to three times the size of the true A. farinosa of eastern North America and Central America; and the length of the marginal striations on the pileus is relatively short in the western "farinosa"—indicating proportionately thicker flesh.
As seen in the above comparison of sporographs, the spores are proportionately narrower in the western entity (but a larger sample should be checked). The western species has a lamella trama about 50% broader and a subhymenium three to four times broader than in the true A. farinosa.
—R. E. Tulloss
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Amanita farinosa sensu Thiers
"Western American Floury Amanita"
1. Amanita farinosa sensu Thiers, Jedediah Smith Redwoods St. Pk., Del Norte Co., California, U.S.A.
2. Amanita farinosa sensu Thiers, Jedediah Smith Redwoods St. Pk., Del Norte Co., California, U.S.A.
3. Amanita farinosa sensu Thiers, Jedediah Smith Redwoods St. Pk., Del Norte Co., California, U.S.A.
4. Amanita farinosa sensu Thiers, Jedediah Smith Redwoods St. Pk., Del Norte Co., California, U.S.A.
5. Amanita farinosa sensu Thiers, Jedediah Smith Redwoods St. Pk., Del Norte Co., California, U.S.A.
Ron Pastorino - (1-3) Jedediah Smith Redwoods State Park, Del Norte County, California, U.S.A. (RET 426-9).
(4-5) same location (RET 493-3) [mushroomobserver.org 80882].
Sava Krstic - (6-9) Clatson County, Oregon, U.S.A. (RET 508-2) [mushroomobserver.org 102406].
Each spore data set is intended to comprise a set of measurements from a single specimen made by a single observer;
and explanations prepared for this site talk about specimen-observer pairs associated with each data set.
Combining more data into a single data set is non-optimal because it obscures observer differences
(which may be valuable for instructional purposes, for example) and may obscure instances in which
a single collection inadvertently contains a mixture of taxa.