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Coprinopsis strossmayeri

by Michael Kuo, 24 June 2024

Coprinopsis strossmayeri is a common urban coprinoid mushroom in the Midwestern United States, where it appears in spring, in dense clusters on stumps or, more often, in lawns on the dying root systems of recently removed trees. It is a medium-sized to large species (on the coprinoid scale) with prominent but small, fibrillose scales on its cap surface.

Similar species include Coprinus comatus (usually larger and less clustered, not associated with wood or roots, with a ring on the stem and a "string" in the hollow portion of the stem), Coprinopsis romagnesiana (with orangish brown cap scales that are not easily removed, and a scaly, booted lower stem), and Coprinopsis variegata (appearing in woods on well-rotted hardwood logs, with larger, patch-like scales and a stem base with a rimmed bulb).

Coprinopsis strossmayeri was originally described from Austria (Schulzer 1878) as appearing in "May and June when it is sunny and very warm in the orchards near the apple trees" (my translation), but the species is rare in Europe and may, there, be a transplant resulting from human landscaping activity. In North America its range is uncertain; the name strossmayeri is not often used on our continent, but this may be the result of confusion with other species.

A preliminary phylogeny by Douglas et al. (2020), using a single gene (ITS) to compare an English collection with GenBank sequences, found some separation between sequences from North America, Europe, and Asia representing collections identified as Coprinopsis strossmayeri and Coprinopsis variegata; the researchers' results "indicated the presence of a potential species complex that would need further DNA sequencing and morphological analysis to resolve."

Coprinus strossmayeri is a synonym.


Ecology: Saprobic, growing in dense clusters in woodchips, on stumps, or from senescent roots around stumps or locations where trees have been removed; usually appearing in spring and early summer; originally described from Austria (Schulzer 1878); widespread but uncommon in Europe; common in the Midwestern United States; reported from British Columbia, Armenia, and eastern Asia; overall distribution uncertain. The illustrated and described collections are from Illinois.

Cap: 2–7 cm across; egg-shaped when young, expanding to conic, broadly conic, or bell-shaped; whitish to gray and eventually blackish underneath small, whitish, fibrillose scales that often have yellow-brown tips and are easily removed from the cap surface; the margin becoming grooved and finally splitting apart.

Gills: Narrowly attached to the stem or free from it; crowded; short-gills frequent; white at first, becoming gray, then black; eventually liquefying.

Stem: 4–14 cm long; 0.5–1 cm thick; more or less equal, or tapered to apex; finely fibrillose or nearly bald; becoming hollow; base attached to reddish brown rhizomorphs.

Flesh: White; not changing when sliced.

Odor: Not distinctive, or sometimes a bit foul and reminiscent of creosote.

Chemical Reactions: KOH on cap surface negative.

Spore Print: Black.

Microscopic Features: Spores 7–10.5 x 4.5–6 µm; ellipsoid, with a pore about 1 µm across; smooth; brown in KOH. Basidia 24–26 x 6–7 µm; 4-sterigmate; surrounded by brachybasidioles. Pleurocystidia 35–150 x 10–40 µm; subclavate to lageniform, subutriform, or nearly cylindric; smooth; thin-walled; hyaline in KOH. Cheilocystidia similar to pleurocystidia. Veil elements more or less cylindric; up to about 15 µm wide; smooth or a little encrusted; hyaline in KOH; branching; occasionally diverticulate. Clamp connections present.

REFERENCES: (S. V. M. Schulzer, 1878) S. A. Redhead, R. J. Vilgalys & J. -M. Moncalvo, 2001. (Uljé & Noordeloos, 1997; Uljé, 2003; Uljé, 2005; Boccardo et al., 2008; Badalyan et al., 2011; Vesterholt, 2018; Læssøe & Petersen, 2019; Douglas et al., 2020; Kibby, 2021; Prydiuk & Lomberg, 2021.) Herb. Kuo 05260801, 08060803, 05281301, 05171401, 06081402, 05121601, 05301801, 05172401.

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


Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri

Coprinopsis strossmayeri
Veil elements

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Kuo, M. (2024, June). Coprinopsis strossmayeri. Retrieved from the MushroomExpert.Com Web site: