Stropharia riparia

[ Basidiomycetes > Agaricales > Strophariaceae > Stropharia . . . ]

by Michael Kuo

This small to medium-sized Stropharia is honey yellow when in the button stage, but soon becomes whitish, yellowish, or dingy olive. It usually has a ring zone of fibers darkened by falling spores, rather than a persistent ring--and its stem base develops reddish brown discolorations. It was originally described from aspen-based lowlands in Washington, but it is apparently cosmopolitan, appearing in a variety of West-Coast habitats, including woodchip beds (where it often fruits alongside Stropharia aurantiaca).

Whether or not Stropharia riparia is the same as Stropharia magnivelaris and/or Stropharia percevalii is up for debate. My collection, made in woodchips on an entrance ramp to California's Highway 101 as cars and trucks zoomed by and my wife Kate contemplated our untimely death, had substantially larger spores (15-18 x 5-8 µ) than what is described for Stropharia riparia and seemed a better match to the European species Stropharia percevalii, which is described as having large spores and a woodchip habitat. Perhaps there are several species going under the name Stropharia riparia--one in riparian ecosystems, and one in woodchips--or perhaps there is only one species, variable in its morphology.

Stropharia riparia is reported as edible by some California collectors, but I do not recommend experimenting until edibility is more thoroughly established.

Description:

Ecology: Saprobic; growing scattered or gregariously on woody debris in aspen-based lowlands--or in disturbed ground, grassy areas, and woodchips; summer, fall, and winter; West Coast.

Cap: 3-9 cm; convex, becoming broadly convex or broadly bell-shaped; sticky when fresh but soon dry; honey yellow when young, quickly becoming yellowish, whitish, or dingy olive; smooth or finely hairy in places; the margin adorned with hanging white partial veil remnants, especially when young.

Gills: Attached to the stem or beginning run down it; close; whitish at first, becoming purplish gray to purple-black.

Stem: 5-10 cm long; up to about 1 cm thick; equal; dry; with a ring zone that darkens with falling spores; finely hairy; whitish, developing reddish brown discolorations from the base upwards; base usually hairy, often with mycelial threads.

Flesh: White.

Odor and Taste: Not distinctive.

Spore Print: Dark purple-brown to blackish.

Chemical Reactions: KOH on cap surface yellow.

Microscopic Features: Spores 11-15 x 6-8 µ; smooth; elliptical to subfusoid. Chrysocystidia absent. Cheilocystidia abundant; clavate to cylindric; flexuous.

REFERENCES: Smith, 1979. (Smith, Smith & Weber, 1979; Wood & Stevens, 2007.) Herb. Kuo 01160601.

Further Online Information:

Stropharia riparia at MykoWeb
Stropharia riparia at Mushroom Observer

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Cite this page as:

Kuo, M. (2007, October). Stropharia riparia. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/stropharia_riparia.html