Encyclop. Mycol. 14: 123. 1949.
Common Name: none
Synonym: Psathyrella gracilis (Fries) Quëlet
Cap 1.0-4.0 cm broad, obtuse-conic, campanulate to convex-umbonate at maturity, margin striate at first, obscurely so in age; surface moist, hygrophanous, medium-brown fading to pale buff-brown, the disc usually dingy yellowish-brown; flesh very thin, colored like the cap, unchanging; odor indistinct, taste, mild.
Gills adnexed, moderately broad, close to crowded, pale dingy-buff, becoming brownish-grey in age.
Stipe 4-8 cm tall, 1.5-3.0 mm thick, slender, thin, fragile, stuffed at maturity; more or less equal, sometimes twisted, occasionally continuing as a pseudorhiza with sparse white mycelium and adhering substrate; surface pruinose at the apex, often colored purple-brown from adhering spores, smooth elsewhere and concolorous with the cap; veil absent.
Spores 11-13 x 5.5-7.0 µm, elliptical, smooth, with an apical pore; spore print purple-brown.
Gregarious or in large troops in disturbed habitats, e.g. wood chips, leaves, open grassy areas; fruiting year-round when moisture is available but especially abundant from late fall to mid-winter.
This slender Psathyrella, ubiquitous to our urban parks, often fruits in vast numbers in chip beds along with Hypholoma aurantiaca and Tubaria furfuracea. Although fragile and short-lived, it can be found throughout the mushroom season, fresh flushes appearing after rains. Psathyrella corrugis is recognized by a brown hygrophanous cap (striate when fresh) that soon fades to pale buff-brown, the disc usually dingy yellowish-brown, and a slender stipe with a pruinose apex. Panaeolus foenisecii is very similar but occurs in grass during the warm months of the year and has mottled gills at maturity. Psathryrella longipes is a larger cousin of P. corrugis with an appendiculate cap margin.
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Smith, A.H. (1972). The North American Species of Psathyrella (Mem. NY. Bot. Gard.: 24). New York Botanical Garden: Bronx, NY. 521 p.