Witches' Butter (Flat) (Exidia plana)
Exidia plana
Visual Identification
What is Witches' Butter (Flat)? A Complete Overview
Morphological Characteristics
Exidia plana is a distinctive species of jelly fungus that belongs to the family Auriculariaceae. Often referred to as 'Witches' Butter (Flat)' or sometimes simply as 'Flat Jelly Fungus', this species is both intriguing and somewhat elusive. It forms gelatinous fruiting bodies that are flattened and irregularly lobed, differing from its more inflated cousin Exidia glandulosa. The fruit bodies of Exidia plana are translucent or dark brown to black, often forming aggregated patches that can coalesce into large amorphous masses on dead hardwood, particularly on broadleaf trees. Optimal growing conditions are maintained in all in one mushroom grow kits and monotub containers.
The texture of Exidia plana ranges from rubbery-gelatinous when moist to more leathery-rubbery when dry. When conditions become dry, the mass contracts significantly and takes on a tougher, wrinkled appearance, but rehydrates rapidly with rainfall. Under magnification, the upper surface might even appear covered in fine papillae. Importantly, it lacks the glandular warts seen on Exidia glandulosa, which helps differentiate between them. Its spore print is white, and under microscopy, the spores are allantoid (sausage-shaped), in line with other members of the Auriculariales.
Reproductive Structure and Growth Pattern
Exidia plana is a saprotrophic fungus, meaning it derives nutrients from decomposing organic material. It predominantly thrives on dead or decaying hardwood branches and logs, particularly those in late stages of decomposition, where the environmental moisture favors jelly fungi. The fruiting typically happens in cool, moist conditions, and although often solitary, it's not unusual to find it growing in dense contiguous clusters, especially where tree bark has retained dampness. Spores are distributed via wind or water splashes, and the fungus's tendency to rehydrate immediately makes it persist well in rainy seasons.
Taxonomic Classification
Historical and Cultural Significance of Witches' Butter (Flat)
Historical and Folkloric Associations
While fungi like Tremella mesenterica and Auricularia auricula-judae have long-standing records in traditional medicine and cultural mythologies, Exidia plana lacks a robust folkloric footprint. There are, however, some indirect associations worth noting. The colloquial name "Witches' Butter"—sometimes extended loosely to include E. plana—derives from a centuries-old European folklore belief that soft, dark, jelly-like growths appearing on homes or fences were signs of hexes or curses laid by witches. These fungi were occasionally burned or swept away to lift the perceived curse.
Over time, this superstitious tradition faded, but the name stuck in several jelly fungi species regardless of their taxonomic correctness. In many rural parts of Northern Europe, jelly fungi—especially black or dark brown ones—carry eerie reputations, sometimes seen as omens or forest spirits.
Returns in Modern Ecological Thought
Today, Exidia plana's cultural significance is mainly restricted to its importance in biodiversity studies and forest ecology. It is viewed as a critical decomposer in temperate hardwood forests and is gaining appreciation among amateur naturalists and mushroom enthusiasts for this quiet ecological role. Various mushroom foraging communities, especially in Europe, document and share sightings of Exidia plana as part of citizen biodiversity science.
Where Does Witches' Butter (Flat) Typically Grow?
Ecological Zones and Geographical Range
Exidia plana is native to Europe and has a widespread distribution in temperate deciduous forests, with increasing reports from parts of North America and Asia. It thrives best in mature, undisturbed woodlands where deadwood is abundant, supporting its saprobic role in the ecosystem. The presence of broadleaf trees like oak, beech, alder, and hornbeam provides an ideal substrate.
This species has adapted to regions with a temperate climate, particularly where humidity and precipitation levels are sufficient to support the survival of gelatinous fungi. It is more likely to be found in lowland and hilly areas than in high-altitude environments due to the moisture requirement and temperature sensitivity. Occasionally, Exidia plana may appear in managed woodlands, parks, and hedgerows, but its primary and most frequent habitats remain dense, shaded hardwood forest zones.
Microhabitat Conditions
Exidia plana shows a strong preference for fallen or dead attached branches of deciduous trees that retain moisture well. Humus-rich forest floors and shaded understory environments are favorable microhabitats. Since it often fruit under or around loose bark, its appearance signals a late stage in wood decomposition, usually after bark has begun sloughing off. Consistent rainfall or damp misty conditions vastly enhance its proliferation, sometimes causing rapid appearance and spread within a few days.
When is Witches' Butter (Flat) in Season?
Late Autumn – Early Spring
How to Cultivate Witches' Butter (Flat)
Challenges of Cultivating Exidia plana
Unlike more frequently cultivated fungi like oyster mushrooms (Pleurotus spp.) or reishi (Ganoderma spp.), Exidia plana is rarely, if ever, grown commercially or domestically. Its wild rarity, unattractive culinary profile, and ambiguous market appeal diminish interest in its propagation. Furthermore, its preferred substrate—rotting hardwood—requires specific humidity, temperature, and timing conditions that are hard to replicate outside of its natural habitat.
Theoretical Cultivation Method
If one were to attempt cultivation:
1. Substrate Preparation: Use sterilized logs of hardwood tree species like beech or oak. Inoculation should follow the standard dowel/spawn plug technique, introducing a mycelial culture into carefully drilled holes.
2. Environmental Requirements: Maintain a shaded, moist woodland-like environment with high humidity and ambient temperatures around 10–18°C. Protect the inoculated logs from direct sunlight and desiccation. A greenhouse could replicate this microenvironment with proper misting.
3. Fruiting and Maintenance: Fruiting can take up to 12–24 months under ideal conditions. Once colonization is complete, outdoor exposure after a rainstorm may stimulate fruiting. Periodic soaking or simulated rainfall can assist in triggering growth.
However, given the difficulty and low edibility or nutritional value, enthusiasts typically focus on cultivating more productive or commercially viable jelly fungi like Auricularia species.
Is Witches' Butter (Flat) Edible or Toxic?
Safety Information:
Known Toxicity and Safety
To date, Exidia plana has not been categorized as toxic, but neither has it been vouched for as edible. While there are no recorded cases of poisoning or severe allergic reactions from this specific species, virtually all field guides caution that more research is needed before consumption should be considered safe.
Due to the lack of comprehensive toxicological studies and subtle differences from other black jelly fungi, foragers are recommended not to consume it unless professional identification is confirmed. Furthermore, fungi that decay hardwood may absorb and bioaccumulate pollutants or heavy metals from substrates, raising additional questions about potential toxicity from environmental contaminants rather than the fungus's chemistry alone.
Confusion with Other Species
One of the more subtle dangers associated with Exidia plana is the possibility of confusing it with other similar-looking 'black jelly fungi' such as Exidia glandulosa. Some species can be mistaken for each other visually but differ in edibility or toxicity risks. Since accurate ID often requires microscopy or close inspection of physical traits (such as presence of warts), misidentification can lead to health risks.
How to Cook and Prepare Witches' Butter (Flat)
Culinary Reputation
Exidia plana is not widely known for its culinary properties, and its edibility is often listed as 'unknown' or 'not recommended' in mushroom identification guides. This is largely due to both its dubious edibility status and its gelatinous and often rubbery consistency that most foragers do not find particularly appetizing. There have been few to no records of its use in traditional cuisines.
Flavor, Texture, and Cooking Style
In the rare instances when tried, it was described as nearly tasteless or possessing a very faint earthy flavor. Its consistency mirrors other jelly fungi—slippery, chewy, and gelatinous. While these textures are appreciated in some Asian culinary contexts, like in soups and stews that incorporate jelly fungi (e.g., Tremella species), Exidia plana has not been embraced in this regard. Due to the texture, it may be possible to prepare it similarly to other jelly mushrooms—by boiling or simmering in broths—but this is purely theoretical and not based on documented culinary practice.
Given the ambiguity around potential health risks and the lack of demand in gastronomy, Exidia plana is not considered a culinary species. Foraging guides often recommend avoiding its collection for food purposes, especially given the existence of safer and better-known jelly mushrooms such as Auricularia auricula-judae.
Nutritional Value of Witches' Butter (Flat)
Macros and Calories
Since Exidia plana is not a widely studied or consumed species, specific nutritional data is unavailable. However, as a jelly fungus in the Auriculariaceae family, we can infer general nutritional trends shared by similar fungi such as Auricularia auricula-judae:
- Calories: Roughly 15–30 calories per 100 g (raw)
- Protein: 1–2 g per 100 g
- Fat: Less than 1 g per 100 g
- Carbohydrates: 5–7 g per 100 g
- Dietary Fiber: Up to 5 g per 100 g
These calories primarily come from complex carbohydrates and polysaccharides.
Vitamins and Micronutrients
Jelly fungi typically contain small but notable levels of essential vitamins such as:
- B-complex vitamins (B1, B2, and B3)
- Vitamin D2 (when exposed to sunlight or UV)
Mineral-wise, gelatinous fungi have been noted to retain certain elements from wood substrate, like:
- Potassium
- Phosphorus
- Iron
- Magnesium
- Zinc
That said, caution is advised in generalizing nutritional content from related species, especially since minimal direct testing has been conducted on Exidia plana. Due to its gelatinous and high-water composition, its raw nutritional value may not rival more popular edible mushrooms like Shiitake or Maitake but could potentially serve as a hydration-rich, low-calorie addition—with more research required to validate this.
What are the Health Benefits of Witches' Butter (Flat)?
Traditional and Folk Medicine
There is limited historical evidence to suggest that Exidia plana has been widely used in traditional medicinal systems like Traditional Chinese Medicine (TCM) or Ayurveda. Unlike its more famous cousin in the jelly fungi family—Auricularia auricula-judae—which has an established record in TCM as a blood tonic and cardiovascular aid—Exidia plana does not receive similar recognition.
Scientific Research
Scientific literature presents scant focus on this species in terms of pharmacological properties, largely due to its ambiguous taxonomic clarity and obscurity. However, as a member of the Auriculariaceae family, it's possible that it shares some of the general health-affecting characteristics known in related jelly fungi, including antioxidant, anti-inflammatory, and immune-boosting potential. These effects are usually attributed to polysaccharides, glycoproteins, and beta-glucans found widely among jelly fungi.
Until in-depth biochemical analysis is performed on Exidia plana specifically, any health benefits remain speculative. It is not currently used in any regulated herbal or supplement forms and is generally omitted from catalogs dealing with functional or medicinal fungi. Thus, from both a scientific and traditional perspective, Exidia plana currently holds no confirmed medicinal status.
Precautions and Interactions
Known Medicinal Interactions
Since Exidia plana is not commonly consumed either as a food or supplement and does not have established medicinal uses, there are no documented drug interactions. Compared to well-researched medicinal mushrooms such as reishi or cordyceps, which interact with anticoagulants or immunosuppressants, Exidia plana remains scientifically underexplored in this domain.
Theoretical Pharmacodynamics
Nonetheless, should it be found to possess active polysaccharides or beta-glucans (as in related jelly fungi), theoretical interactions could exist with:
- Immunosuppressive therapy: Potential immunomodulating effects of fungi could interfere with patients on immune-suppressing drugs.
- Anticoagulants and Antiplatelets: Some mushrooms enhance blood fluidity; however, this is speculative for Exidia plana.
Until more targeted pharmacological research is conducted, it is presumed to be neutral in drug interaction considerations. Still, those on chronic medication should avoid experimenting with wild mushroom ingestion, especially from unverified sources.
What Mushrooms Look Like Witches' Butter (Flat)?
Common Misidentifications
Several mushrooms resemble Exidia plana in appearance, particularly to novice foragers. It's important to differentiate these species accurately to avoid health risks.
- Exidia glandulosa: By far the most common lookalike. Both are dark-colored jelly fungi found on similar hardwood substrates. However, E. glandulosa typically features a more inflated, brain-like form and has minute glandular warts on its surface that are lacking on Exidia plana. These warts are the most reliable distinguishing factor under magnification.
- Tremella mesenterica (Witch's Butter): Although T. mesenterica is usually bright yellow-orange, when dried or grown in shaded areas, its color may appear darker and gelatinous texture introduces potential for confusion. However, habitat preference helps—T. mesenterica typically prefers dead wood of conifers and may form more lobed masses.
- Dacrymyces stillatus: Another lookalike, D. stillatus is orange to yellow and forms similarly slimy fruiting bodies. It tends to grow on softwood rather than hardwood and is often smaller in diameter.
Identification Tips
- Use a hand lens or microscope to detect surface ornamentation.
- Observe moisture-related texture differences.
- Take note of tree species the fungus is growing on.
- Consider spore shape and size; these vary subtly across jelly fungi but are significant for species-level ID.
Safety Note: Always use proper identification methods and consult expert mycologists when foraging. Misidentification can have serious health consequences.
Disclaimer: This information is for educational and identification purposes only. Never consume wild mushrooms without expert identification. Always consult with qualified mycologists and healthcare professionals. Foraging and consumption of wild mushrooms carries inherent risks.