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Stropharia rugosoannulata: white form

[ Basidiomycota > Agaricales > Strophariaceae > Stropharia . . . ]

by Michael Kuo

Like the "normal" form of Stropharia rugosoannulata, this form features purple-gray gills and a ring that is radially split or "cogwheeled" on the underside. However, the wine red to brown cap colors are completely absent, even in buttons, and the caps are uniformly creamy white. Additional differences include the foul, creosote-like odor, the pale orange reaction of the cap to KOH, and notably narrower spores. To my knowledge contemporary DNA-based comparison of the two forms has not been recorded; I suspect the possibility that separate species are involved.

Description:

Ecology: Saprobic; growing gregariously on woodchips, in gardens, and in other cultivated areas; spring through fall; North American distribution uncertain. The illustrated and described collection is from Illinois.

Cap: 5-9 cm; convex at first, becoming broadly convex to flat; dry; bald; creamy white; the margin hung with a few inconspicuous, white partial veil remnants.

Gills: Attached to the stem; close; short-gills frequent; pale gray at first, becoming purplish gray to purple-black, with paler edges.

Stem: 5-7 cm long; 1-2 cm thick; slightly enlarged toward the base; dry; bald or finely hairy; white, discoloring yellowish to orangish in age; with a high, thick, white ring that is finely grooved on its upper surface and radially split or "cogwheeled" on its underside; base with white mycelial threads.

Flesh: White; firm; unchanging when sliced.

Odor: Foul; reminiscent of creosote.

Spore Print: Dark purple-brown to blackish.

Chemical Reactions: KOH on cap surface pale orange.

Microscopic Features: Spores 12-14 x 5-7 µ; ellipsoid, with one end slightly truncated for a large pore measuring 1-1.5 µ across; smooth; thick-walled; brown in KOH. Cheilocystidia 25-50 µ long; fusoid-ventricose, often becoming rostrate; thin-walled; smooth; hyaline in KOH; developing globular, refractive inclusions and becoming chrysocystidia. Pleurocystidia similar to cheilocystidia. Pileipellis a gelatinized trichoderm of elements 2.5-10 µ wide; elements smooth, hyaline in KOH; terminal cells cylindric with rounded apices or occasionally fusiform-cystidioid.

REFERENCES: Farlow ex Murrill, 1922. (Phillips, 1991/2005; Kuo & Methven, 2014.) Herb. Kuo 06300701.


Further Online Information:

Stropharia rugosoannulata at Roger's Mushrooms


This site contains no information about the edibility or toxicity of mushrooms.

 

Stropharia rugosoannulata: white form

Stropharia rugosoannulata: white form
KOH

Stropharia rugosoannulata: white form
Spores



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Kuo, M. (2016, October). Stropharia rugosoannulata: white form. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/stropharia_rugosoannulata_white.html