Yellow Brain Fungus / Spring / Summer / Autumn / Winter / Inedible
The Yellow Brain Fungus (Tremella mesenterica), also known as Witch’s Butter, is a striking jelly fungus that’s hard to miss with its vibrant, golden-yellow colour and gelatinous, brain-like texture.
Found growing on dead and decaying hardwood, especially oak and beech, this fungus thrives in damp, shaded areas of woodlands across the UK, often appearing after heavy rain.
While it may look like something straight out of a magical forest, the Yellow Brain is inedible due to its rubbery texture and lack of flavour.
In this post, we’ll explore how to identify the Yellow Brain, where to find it, and its fascinating role in the woodland ecosystem.
Scientific Name
Tremella mesenterica
Common Names
Yellow brain, golden jelly fungus, yellow trembler, witches’ butter
Family
Tremellaceae
Habitat
Yellow Brain fungus grows on dead wood that has been attacked by wood-rotting fungi of the Peniophora genus. Very little or none of the Peniophora may be visible; this is because Yellow Brain feeds on the mycelium rather than the fruiting body, and that can be deep inside the timber rather than on its surface. The fruiting body of the crust fungus does not even have to be present, therefore, it may look as though Yellow Brain is feeding directly on the host wood.
Description
This fungus doesn’t have the typical shape or structure of other woodland fungi. It looks like an orange gelatinous mass. It is not a wood-rotter itself, but a parasite on the mycelium of crust fungi.
Identifying Features of the Yellow Brain Fungus:
Overall it has an irregular shape and is smooth. The lobes are tough and greasy or slimy when wet and harden as it dries out. It ranges in colour from a pale yellow to bright orange, then rusty orange when dry.
Smell:
No distinctive smell.
Spores:
White to pale yellow
Uses
In food
Although some claim the fungus to be inedible or non-poisonous while other sources say that it is edible but flavourless.
In China, the fungus is apparently used by vegetarians to prepare an immuno-modulating cooling soup with lotus seed and lily bulbs.
Medicinal Uses for the Yellow Brain Fungus
Some Tremella species produce polysaccharides that are of interest to the medical field, because of their biological activity; several patents have been filed in China regarding their potential use for cancer prevention or immune system enhancement, although further research is needed.
Known hazards
No known hazards.
Yellow Brain fungus Potential lookalikes…
They are quite distinctive about the only look-a-like is its close relative Tremella aurantia, this is another parasitic species that attacks members of the Tremella genus, most often The Hairy Curtain Crust (Stereum hirsutum)
Extra Notes
According to European legend, if Yellow Brain fungus appeared on the gate or door of a house it meant that a witch had cast a spell on the family living there. The only way the spell could be removed was by piercing the fungus several times with straight pins until it went away. This is why yellow brain also has the common name of ‘witches’ butter’.
In Sweden, yellow brain fungus was burnt to protect against evil spirits.
References:
https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/fungi-and-lichens/yellow-brain/