Crepidotus variabilis

Description

Crepidotus variabilis is a tiny, kidney-shaped fungus that appears on dead twigs of broad-leaved trees in autumn and winter. Common in woodlands, this mushroom occurs across mainland Europe and is also recorded in many other parts of the world including North America.

Common names: Variable Oysterling.

Mushroom Identification

1. Cap

   The cap is initially white, turning creamy-ochre with age. The fruitbody is nearly always laterally attached to its substrate - usually small twigs - via its cap, rather than with a stem. Typically 0.5 to 2cm in diameter and often slightly lobed.

2. Gills

   The gills, which radiate from the point of attachment, are moderately crowded. White at first, they gradually turn yellow-brown or buff.

3. Stem

   Almost invariably this little woodland mushroom has no stipe (stem) at all.

4. Spores

   Ellipsoidal, ornamented with minute spiny warts, 5-7 x 3-3.5um.

5. Spore Print

   Pinkish buff.

6. Cheilocystidia

   Clavate, sometimes branched, 20-25 x 5-12μm.

7. Odor and Taste

   Not distinctive.

8. Habitat

   Saprobic, on twigs in deciduous and mixed woodland and at the bases of hedgerows.

9. Season

   August to December in Britain and Ireland.

Look-Alikes

1. Crepidotus cesatti

   Has a scalloped margin and its spores are sub-globose rather than ellipsoidal.

2. Crepidotus mollis

   Is larger and its cap has small scales on an ochre background.

History

The variable oysterling was described in 1799 by Christiaan Hendrik Persoon, who established its basionym when he gave it the binomial scientific name Agaricus variabilis. It was German mycologist Paul Kummer who, in 1871, transferred this species to the genus Crepidotus, whereupon it acquired its currently accepted scientific name Crepidotus variabilis.

The generic name Crepidotus comes from crepid- meaning a base, such as a shoe or a slipper (although some sources state that it means ;cracked'), and otus, meaning an ear - hence it suggests a 'slipper-like ear'. In the past mushrooms in this genus were sometimes referred to as slipper mushrooms. The specific epithet variabilis means, as you might expect, variable. These little mushrooms are indeed very variable in shape, depending on where they are attached to their substrate; for example, they can form neat semicircular brackets on the sides of twigs and branches or almost perfectly circular fans when growing underneath a dead branch.

Synonyms

1. Crepidotus variabilis trichocystis Hesler & A. H. Sm., 1965

2. Crepidotus variabilis stercorarius Reichert & Aviz.-Hersh., 1959

3. Crepidotus variabilis subsphaerosporus J. E. Lange, 1938

4. Crepidotus multiformis Murrill, 1917

5. Crepidotus variabilis duriusculus Sacc., 1880

6. Crepidotus variabilis variabilis (Pers.) Gillet, 1876

7. Crepidotus variabilis variabilis (Pers.) P. Kumm., 1871

8. Crepidotus variabilis acerinus Lasch, 1829

9. Crepidotus variabilis albidus (Balb.) Fr., 1821

10. Crepidotus variabilis vulgaris Alb. & Schwein., 1805

11. Crepidotus albidus Balb., 1804

12. Crepidotus variabilis sinuatus (Pers.) Pers., 1801

13. Crepidotus sinuatus Pers., 1800

Photo sources:

Photo 1 - Author: Jason Hollinger (Attribution 2.0 Generic)

Photo 2 - Author: Jason Hollinger (Attribution 2.0 Generic)