Fauna
Fungus

Witch's Butter

Tremella mesenterica

Also known as Yellow Brain Fungus, Golden Jelly Fungus, Yellow Trembler

Bright yellow-orange gelatinous folds erupt from rotting hardwood branches after heavy rains. This fungus parasites wood-decaying crust fungi in the genus Peniophora, absorbing nutrients from their concealed mycelium rather than breaking down wood directly. During dry spells, the damp rubbery lobes shrivel into a dark, inconspicuous crust, only to revive into plump jelly when moisture returns.

Jelly FungusParasiticBright Yellow
Witch's Butter reference1 / 7
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyPeniophora mycelium
Predators
  • Fungus gnats
  • Slugs
  • Snails
ThreatsDeforestation and clear-cutting
HabitatsDeciduous woodlands, forests, hedgerows
Life spanEphemeral fruit bodies (persists via host mycelium)
Classification
  1. OrderTremellales
  2. FamilyTremellaceae
  3. GenusTremella
  4. SpeciesTremella mesenterica
Range & activity
Range data is not available yet.
Safe observation
Interaction riskLow
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is low
Many wild fungi have toxic look-alikes; never eat wild mushrooms based on app identification alone.
Responsible observation
  • Observation: Look for vibrant yellow brain-like folds on fallen hardwood branches after autumn rain.
  • Handling: Gently feel the slippery texture without tearing the fragile body from its substrate.
  • Drying Cycle: Revisit dried crusty specimens after rain to watch them rehydrate within hours.
Related species
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