Psathyrella laevissima

Description

Psathyrella laevissima is a saprotrophic mushroom that lives on dead wood of Beech (Fagus spp.) and Oaks (Quercus spp.), and occasionally other dead hardwoods. Most often this undistinguished fungus is found on rotting stumps or fallen large branches in shaded locations.

Fairly widespread in Britain and Ireland, P. laevissima occurs also in many other countries of central and northern Europe.

Common names: Slender Stump Brittlestem.

Mushroom Identification

1. 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.

2. Gills

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

3. 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.

4. Pleurocystidia

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

5. Cheilocystidia

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

6. Spores

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

7. Spore Print

   Blackish purple

8. Odor and Taste

   Not distinctive.

9. Habitat

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

10. Season

    May to November.

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.

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.

Synonyms

1. Psathyrella subpapillata sensu Kits van Waveren (1985)

2. Psathyrella laevissima laevissima (Romagn.) Singer, 1969

3. Psathyrella laevissima nothofagi Singer, 1969

4. Drosophila laevissima

Photo sources:

Photo 1 - Author: Björn S... (CC BY-SA 2.0)

Photo 2 - Author: Strobilomyces (CC BY-SA 3.0)

Photo 3 - Author: Björn S... (CC BY-SA 2.0)

Photo 4 - Author: Holger Krisp (CC BY-SA 4.0)