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A Peek Into the Forest Cauldron: Witch’s Butter

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Black witch’s butter, Exidia glandulosa. Photo by Kevin Lewis.

What could that globular, oozing, alien-like substance be emerging from that dead tree or log you are passing? There’s a good chance that it is one of the spookiest condiments of the forest: witch’s butter, known also as jelly fungi. 

Is it orange, black, white, yellow? There are a variety of types of jelly fungi which are umbrellaed under the common name of witch’s butter. These fungi have slightly different characteristics, ranging from parasitic to edible, but all share the commonality of revival. They can survive for months without any water, conserving their energy by drying up into a hardened ball, but within two hours of rain, they begin reconstitution and start reproducing spores. These are the zombies of the woods, their ability to come back to life within hours is creepily impressive.

The most well-known type of witch’s butter is the yellow witch’s butter, Tremella mesenterica, which translates directly to ‘trembling middle intestines.’ It is mainly found on dead angiosperm hardwoods and does not decompose the wood, but rather parasitizes on actual wood-decomposing fungi. 

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Tremella aurantia parasitizing on Stereum hirsutum. Photo by Thomas Lodge

Commonly mistaken for Tremella mesenterica is its close relative Tremella aurantia, which parasitizes Stereum hirsutum (commonly known as false turkey tails), often growing directly out of the Stereum fruiting bodies.