Witches’ Butter, scientifically known as Tremella mesenterica, is a widespread and striking fungus often encountered in forests across temperate and tropical regions. This species is commonly identified by its bright, golden-yellow color and signature gelatinous texture. Tremella mesenterica is generally classified as non-toxic and is considered an edible jelly fungus, though proper identification remains paramount for safe consumption.
Accurate Identification of Tremella mesenterica
The correct identification of Tremella mesenterica relies on a combination of its physical characteristics and its specific ecological niche. When fresh and wet, the fruiting body appears as a convoluted, brain-like mass, typically measuring between one and three inches across. The texture is gelatinous, feeling tough and somewhat greasy or slimy, and its color ranges from deep yellow to vibrant orange-yellow.
This fungus is highly hygroscopic, absorbing and holding moisture, which allows it to swell significantly after rain. During dry periods, however, the structure shrivels dramatically into a hard, inconspicuous, thin film or crust.
A unique and distinguishing feature is its parasitic relationship with other fungi. Tremella mesenterica does not decompose wood directly; instead, it is an obligate parasite on the mycelium of crust fungi belonging to the genus Peniophora. This means that Witches’ Butter is always found growing on dead, decaying hardwood, such as oak, beech, or maple, where its host fungus is present.
The Edibility Status and Culinary Preparation
While Tremella mesenterica is non-toxic and edible, its culinary value is generally considered low due to a lack of distinct flavor. Instead, its primary appeal in cooking is its unique gelatinous, chewy, and slippery texture. The rubbery consistency allows it to maintain its structure through cooking, making it an excellent textural component in soups and stews. The fungus can be added to broths where it absorbs the surrounding flavors, contributing a pleasant chewiness without dominating the dish.
Some people also prepare it as a dessert by first boiling it and then soaking it for several hours in a sugar solution or simple syrup before candying it. This focus on texture is shared with the closely related Snow Fungus, Tremella fuciformis, which is highly valued and commercially cultivated in Asian cuisine.
Known as “Silver Ear” in China, T. fuciformis is used in sweet soups and desserts, demonstrating the traditional use of tremelloid fungi for their gelatinous properties. Though T. mesenterica is used less frequently, its safe edibility is well established, provided the specimen is correctly identified and thoroughly cleaned before preparation.
Important Look-Alikes and Foraging Safety
Foraging for any wild fungus requires absolute certainty in identification to avoid consuming a look-alike, even if most jelly fungi are considered non-toxic. One common confusing species is Dacrymyces palmatus, often called Orange Jelly Fungus. This species shares a similar yellow-orange color and gelatinous appearance, but it typically grows on conifer wood, whereas Tremella mesenterica is found on hardwood.
Another look-alike is Tremella foliacea, known as the Leafy Brain Fungus, which shares the convoluted, lobed form. This species is easily differentiated by its coloration, which is typically a deep amber, brown, or reddish-brown, starkly contrasting with the bright yellow of T. mesenterica.
A third similar species is Tremella aurantia, which is yellow-orange but is parasitic on a different host, Stereum hirsutum, and has a matte, not greasy, surface. For safe foraging, it is imperative to never consume a wild mushroom unless you are 100% certain of its identity. Due to the difficulty in distinguishing between similar species, observing the host wood is a non-negotiable step in the identification process.