Tremella mesenterica, commonly known as Amber Jelly Fungus, is a vibrant, gelatinous organism often encountered in wooded areas. Frequently called “Witch’s Butter” or “Yellow Brain,” this species belongs to the jelly fungi group. Its distinct, striking orange-yellow appearance makes it a popular subject for foragers.
Identifying Features of Amber Jelly Fungus
The fruit body of Tremella mesenterica is instantly recognizable due to its bright coloration and distinctive form. It generally appears as a convoluted, lobed, or brain-like mass that can measure up to three inches in diameter. The color ranges from pale yellow to bright orange-yellow, becoming lighter as the fungus ages. When damp, the surface feels greasy and has a firm, rubbery, gelatinous consistency. When the weather is dry, the fungus shrivels into a thin, hard film, but it can rehydrate and regain its original form after rainfall.
This species is typically found on dead hardwood, especially the fallen branches of trees like oak and beech. Its ecological role is specific: Tremella mesenterica is not a primary decomposer of wood but is instead a parasite on the mycelium of other fungi, particularly those in the genus Peniophora. The presence of the bright yellow jelly mass on dead wood, often emerging from bark crevices, is a strong identifying clue.
The Verdict on Edibility and Nutritional Profile
The Amber Jelly Fungus is generally considered non-toxic and safe for consumption, though its edibility is debated due to its lack of flavor. The primary appeal of Tremella mesenterica in cuisine is its unique physical characteristic: a slippery, rubbery, and gelatinous texture.
From a nutritional standpoint, the fungus is primarily water, making it extremely low in calories, fat, and carbohydrates. A typical 100-gram serving of the cooked mushroom may contain only 15 to 25 calories, with minimal protein. Research has focused on the polysaccharides present in the Tremella genus, which have shown potential immunomodulatory effects. These compounds, such as glucuronoxylomannan, are believed to have health benefits, including antioxidant and anti-inflammatory properties, which has driven its use in traditional practices.
Common Look-alikes and Foraging Safety
Foraging for any wild fungus requires careful attention to detail, as several other jelly-like species can be easily confused with Tremella mesenterica. One common look-alike is Dacrymyces chrysospermus, or Orange Jelly, which shares the vibrant orange-yellow color and gelatinous consistency. A key distinction is that Dacrymyces species typically grow on conifer wood, whereas Amber Jelly Fungus is almost exclusively found on hardwoods.
Another similar species is Tremella aurantia, often called Golden Ear, which is also generally considered non-toxic and edible. Distinguishing between these two can be challenging without microscopic analysis, but T. aurantia often has a matte surface and parasitizes a different host fungus, Stereum hirsutum. Foraging safety dictates that any jelly fungus that cannot be definitively identified should not be consumed. Foragers should also avoid collecting specimens from polluted areas, such as roadside ditches or chemically treated wood, as fungi are known to absorb environmental contaminants.
Preparation and Traditional Culinary Uses
Preparing Amber Jelly Fungus for consumption often begins with a thorough cleaning to remove any debris or insects from its convoluted surfaces. Given its high water content, the fungus is frequently dried for long-term storage, shrinking significantly, but it rehydrates effectively when soaked in water. The fungus is particularly popular in traditional Asian cuisine, where it is valued for its rubbery texture and its ability to absorb the flavors of surrounding ingredients. It is commonly added to soups, stir-fries, and broths, providing a pleasant, slippery chewiness. In Chinese cooking, it is sometimes used in sweet preparations, such as cooling soups with ingredients like lotus seeds and jujubes, functioning as a textural agent.