Exidia thuretiana

Description

Exidia thuretiana is a jelly fungus in the family Auriculariaceae. The fruit bodies are white and gelatinous with brain-like folds. It is a common, wood-rotting species in Europe, typically growing on dead attached or fallen branches of broadleaf trees, especially beech.

Common names: White Brain Fungus.

Mushroom Identification

1. Fruitbody

   Pure white when wet, drying to almost invisible, the fruiting bodies are cushion-shaped, becoming contorted with age and fusing with neighboring fruiting bodies to form a large mass several cm across. Individual fruitbodies grow to between 0.2 and 1cm across.

2. Spores

   Cylindrical to allantoid (sausage-shaped), smooth, 13-18 x 5.5-7µm; inamyloid.

3. Spore Print

   White.

4. Odor and Taste

   Not distinctive.

Look-Alikes

1. Tremella mesenterica

   Usually yellow and has a brain-like structure, but it does also have a (rare) white form.

2. Exidia nucleata

   Fruit bodies are similarly colored, but are typically pustular or lobed (never appearing pleated) and usually contain conspicuous, white, granular inclusions. Microscopically Exidia nucleata can be distinguished by its stalked basidia.

History

The basionym of this species was established in 1848 by the French physician and mycologist Joseph-Henri Léveillé (1796 - 1870), who described this jelly fungus and gave it the binomial scientific name Tremella thuretiana. Then in 1874 Swedish mycologist, Elias Magnus Fries transferred this species to the genus Exidia, and so its scientific name became Exidia thuretiana, which remains its generally accepted name today.

Synonyms of Exidia thuretiana include Tremella thuretiana Lév., but this jelly fungus has also been described by various authors under several other binomials including Exidia albida, Tremella albida, Tremella cerebrina, and Tremella hyalina.

Exidia, the generic name, means exuding or staining, and both seem appropriate because these jelly fungi do look like exudations when moist and like dark stains on wood when they dry out.

The specific epithet thuretiana honors Gustave Adolphe Thuret (1817 - 1875), a noted French botanist and founder of the Jardin botanique de la Villa Thuret. M. Thuret was also the owner of the Château de Rentilly, in the grounds whereof Exidia thuretiana was first collected.

Photo sources:

Photo 1 - Author: zaca (CC BY-SA 3.0)

Photo 2 - Author: Stephen James McWilliam (CC BY-SA 4.0)

Photo 3 - Author: Stephen James McWilliam (CC BY-SA 4.0)

Photo 4 - Author: 2009-01-10_Exidia_thuretiana_1.jpg: (CC BY-SA 3.0)

Photo 5 - Author: Donald Hobern from Copenhagen, Denmark (CC BY-SA 2.0)