E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Pseudosperma sororium is recognized by relatively large size, a sharply conical to umbonate, creamy to yellowish, radially fibrillose cap, and the odor of fresh green corn. The stem is white or tinged cap color, fibrillose, and often scurfy. The close or crowded gills are adnate to adnexed and whitish becoming yellowish then brown. According to Stuntz(1), Heim considered Inocybe sororia synonymous with Inocybe fastigiata (Fr.) Quel., perhaps partly due to Kauffman''s description of odor as "somewhat pungent or lacking". Stuntz says the odor difference is distinct and constant. It is common in the Pacific Northwest.

Kauffman notes Pseudosperma sororium for New England to VA and westward to OR and WA. It is also found in CA (Desjardin), There are collections from BC at the University of British Columbia. There are collections at the University of Washington from WA, OR, ID, AK, CA, LA, and MI.

Gills:
adnate to adnexed, often seceding to free, close or crowded; pallid becoming yellowish, then olive-yellow and finally brownish gold or brown; the edges paler usually, (Arora), adnexed to narrowly adnate, crowded, rounded at both ends, shallowly ventricose, rather narrow, 0.3cm broad, thin, "Isabella color" to "buffy citrine" or ''bistre green'', becoming ''golden bronze green'', finally "Dresden brown", (Stuntz), attenuate-adnate, close to crowded, rather narrow, varying 0.2-0.5cm broad; at first whitish or yellow-tinted, then "olive-buff" to "mustard yellow" or "old gold"; the edges white-fimbriate [fringed], (Kauffman)

Stem:
3-14cm x 0.2-0.5(1)cm, equal or with a slightly enlarged base, white or tinged cap color, fibrillose and often scurfy, (Arora), 5-13cm x 0.4-1cm, equal or widening slightly downward, cylindric, base incrassated [wider], rather abrupt, or rounded-bulbous in some, stem solid or stuffed, becoming hollow in some; white, becoming tinged with dingy yellow or straw color in lower part; "rather densely white silky-floccose, the fibrils aggregated in small irregular flocci", (Stuntz), 3-7cm x 0.2-0.4(0.5)cm, equal or widening downward toward rounded somewhat bulbous base, straight, solid; whitish becoming dingy with age; at first silky-cortinate, glabrescent [becoming bald], innately fibrillose, pruinose at top, (Kauffman)

Veil:
absent (Arora)

Odor:
"usually strongly pungent, like freshly husked or green corn", (Arora), very strong, of "green corn", not at all spermatic, very persistent, (Stuntz), somewhat pungent or lacking (Kauffman)

Microscopic spores:
spores 10-13(17) x 5-8 microns, elliptic or bean-shaped, smooth; cystidia on gills thin-walled, (Arora); spores 11-15.5(17) x 5.8-8(8.8) microns, ovoid to subreniform [somewhat kidney-shaped], "very variable in size and somewhat so in shape"; pleurocystidia and cheilocystidia lacking, sterile cells abundant and conspicuous, crowded in a broad band along the edge of the gill, 45.5-73.5(81.5) x 13-28(35) microns, "one-celled, saccate, or clavate to subcapitate, very variable in shape and size", (Stuntz), spores 9-13(16) x 5.5-6(8) microns, very variable in size, elliptic or elongate-elliptic, "not truly subreniform, subinequilateral, obtuse at both ends"; pleurocystidia and cheilocystidia none, sterile cells clavate, on the gill edges, (Kauffman)

Spore deposit:
brown (Arora)