Even in midwinter, when the woods look like they have given up, they can still manage a bit of a show. There are splashes of colour if you bother to look. Bright fungi flare up against the gloom, set among the stubborn brown leaves still clinging to oak and beech, and the thick brown carpet of dead bracken. All this breaks up the dark damp mass of trunks, branches, and roots.
My ‘Seek’ app confidently tells me this loud orange growth is Witches’ Butter. It feels rude to argue with a phone that sounds so sure of itself.
Witches’ Butter goes by the scientific name Tremella mesenterica, thanks to its resemblance to the human mesentery, which is not a word I expected to add to my life today. Early naturalists were thoroughly foxed by fungi like this. They did not seem properly animal or vegetable, which made everyone nervous. Country people, never keen on the unexplained, decided they must be the work of dark forces. The folklore says witches or fairy folk crept into farm dairies at night to steal the tools and make their own butter. On the way home, they dropped bits of it on trees, gateposts, or the ground. When these strange blobs were found the next morning, a spell was assumed. The cure involved stabbing the fungus with straight pins until it vanished. In Sweden, the preferred solution was to burn it, just to be on the safe side.
Another name for Witches’ Butter is Yellow brain, which is not especially flattering but visually fairly accurate. It is a parasitic fungus that feeds on other fungi already busy rotting the wood. It is usually considered inedible, not because it is dangerous, but because it has all the taste and substance of damp jelly. In China, however, it is valued for the texture it gives to soups, proving once again that taste is a slippery thing.
Despite its dubious reputation, Witches’ Butter has caught the eye of medical researchers. It produces compounds that show anti-inflammatory and anti-allergic effects. Not bad for something once blamed on witches sneaking about with stolen dairy gear.
Sources:
- The Woodland Trust. Yellow brain. https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/fungi-and-lichens/yellow-brain/ [Accessed 22 December 2025]
- Wikipedia. Tremella mesenterica. https://en.wikipedia.org/wiki/Tremella_mesenterica [Accessed 22 December 2025]
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