Summary:
Features include the white to grayish cap, decurrent gills, strong mealy odor, and pinkish spores. The few sequenced samples of Clitopilus prunulus sequenced in BC, OR and WA have turned out to match Clitopilus cystidiatus Hauskn. & Noordel., Ost. Z. Pilzk. 8: 200 (1999), (D. Miller, pers. comm.). It is unclear whether both species are present in the Pacific Northwest. Clitopilus prunulus is said to have a cap that is white or with a pale gray center, and no cheilocystidia, whereas Clitopilus cystidiatus is said to have a gray to gray brown cap with a paler gray margin, and filiform cystidia. The cucumber odor is caused by trans-2-nonenal, one of the chemicals causing the odor in the cucumber vegetable (Wood).

Cap:
3-10cm across, convex becoming flat or centrally depressed, margin often lobed or wavy; white to gray; "dry and slightly felty or in one form slightly viscid when moist, smooth", (Arora), typically flat or umbonate, margin typically inrolled; whitish with beige, grayish, or pinkish tones; dry, (Trudell)

Flesh:
rather thin; white, (Arora)

Gills:
decurrent or sometimes adnate, fairly close, narrow; whitish to gray, becoming pinkish, (Arora)

Stem:
2-8cm x 0.4-1.2cm, "central or off-center, solid", equal or narrowing downward; white or grayish, (Arora), hairless (Lincoff(2)), pruinous or pubescent [downy], villose [finely hairy] at base, (Lincoff(1)), similar in color to cap (Trudell)

Odor:
"strongly but pleasantly farinaceous (like sweetbread)", (Arora), "strongly mealy, of bread dough or cucumber", (Phillips)

Taste:
similar to odor (Phillips)

Microscopic spores:
spores 9-12 x 5-7 microns, elliptic, longitudinally ridged, angular only in end view, (Arora), spores 8.7-10.6(12) x 5.3-6.5 microns, fusiform-elliptic [spindle-shaped - elliptic], smooth, with 6-7(8) longitudinal ribs, colorless; basidia 4-spored, 32-47 x 11-14 microns, clavate, without basal clamp connection; pleurocystidia and cheilocystidia not seen; cap cuticle an ixocutis composed of irregular hyphae 3-6 microns wide, all slightly gelatinized, septa without clamp connections, (Breitenbach)

Spore deposit:
flesh-colored or salmon (Arora), brown-pink (Breitenbach)

Notes:
The following distributions have been reported for Clitocybe prunulus but some of them may be Clitopilus cystidiatus. Collections from BC are deposited at University of British Columbia. Collections from WA, OR, ID, AK, MA, MI, NM, NY, Sweden, and United Kingdom (Scotland) are deposited at the University of Washington. It is not uncommon on foray lists from BC and WA, and is found in CA (Arora, Wood). Breitenbach(4) give the distribution North America, Europe, Asia and North Africa.

EDIBILITY

yes, but not recommended: too easy to confuse with poisonous species, (Arora)