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Psathyrella laevissima (Romagn.) Singer - Slender Stump Brittlestem

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Psathyrellaceae

Psathyrella laevissima, northern France

Slender Stump Brittlestems are saprotrophic on dead wood of Beech (Fagus spp.) and Oaks (Quercus spp.), and occasionally other dead hardwoods. Most often these undistinguished gregarious little mushrooms are found on rotting stumps or fallen large branches in shaded locations.

Psathyrella laevissima, Slender Stump Brittlestem, Wales

Distribution

Fairly common and widespread in Britain and Ireland, Psathyrella laevissima occurs also in many other countries of central and northern Europe including Denmark, where it is reported to be quite rare, Holland, France and Slovenia.

Psathyrella laevissima, Slander Stump Brittlestem

Taxonomic history

This brittlestem mushroom was described scientifically in 1952 by French mycologist Henri Charles Louis Romagnesi (1912 - 1999), who gave it the scientific name Drosophila laevissima. It was in 1969 that German-born American mycologist Rolf Singer transferred it to the genus Psathyrella, establishing the scientific name Psathyrella laevissima by which it is generally known today.

Synonyms of Psathyrella laevissima include Drosophila laevissima Romagn.

Etymology

Psathyrella, the genus name, is the diminutive form of Psathyra, which comes from the Greek word psathuros meaning friable; it is a reference to the crumbly nature of the caps, gills and stems of mushrooms in this genus. The specific epithet laevissima means completely smooth.

Identification guide

Psathyrella laevissima - Slender Stump Brittlestem  - view of gills and stems

Cap

1.5 to 35cm across; broadly convex or conical-convex, flattening often with a slight umbo; smooth; margin lined and becoming wrinkled with age; surface honey brown, becoming mid brown but paler in dry weather; turning dark brown and then blackening when very old.

Psathyrella laevissima - Slender Stump Brittlestem  - view of gills and stems

Gills

Broadly adnexed, very crowded; pale brown becoming reddish brown with paler edges.

Stem

Whitish above a fragile and often fleeting stem ring, yellowish below; hollow; usually curved due to tufted growing form; 2 to 4cm long; 2 to 4mm diameter; very brittle.

Psathyrella laevissima - Slender Stump Brittlestem - view of stem

Pleurocystidia

Pleurocystidia are few and can be hard to find: mainly fusoid (spindle shaped), 30-45 x 10-15µm, with slightly mucronate pointed tips.

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Cheilocystidia: subspherical to broadly clavate (club-shaped), 10-30 x 7.5-20µm.

Spores of Psathyrella laevissima

Spores

Broadly ellipsoidal, smooth, 5.5-6 x 3-3.5µm with a germ pore.

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Spore print

Blackish purple

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic, on decaying hardwoods, particularly Oak or Beech stumps.

Season

May to November in Britain and Ireland.

Culinary Notes

Insubstantial; easily confused with poisonous species such as the Funeral Bell Galerina marginata, and so of no culinary interest..

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

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