WITCHES’ BUTTER

As autumn rushes in many naturalists think of fungi, those fascinating and ubiquitous organisms whose sporophytes suddenly appear all over the place to surprise us, in a prodigious range of shapes and sizes. The one I want to mention in this note is a species you may have seen as it is fairly common, especially in autumn. Look for it on recently fallen dead tree branches.

This fungus, also known as yellow brain fungus or golden jelly fungus for obvious reasons, is Tremella mesenterica Retz. (1769), a member of the large fungal phylum, the Basidiomycota. It is not, as you might think, feeding directly off the decaying wood though, but is a parasite on other fungi that are consuming the dead branches, notably various species of the crustose corticolous genus Peniophora. You can see that the fallen branch in my photo is covered in crustose fungi and it is from these that the witches’ butter is taking  nourishment parasitically. Although it looks fragile, T. mesenterica is quite tough and rubbery and, when dry, it is hard. It has pale oblong spores that measure some 10 to 16µm long by 6 to 9.5 µm wide. It is not considered poisonous but rather simply “inedible” although it is used by some in cooking (soups) and medicine in China.

At Betts Ecology we record fungi whenever we can, even though all naturalists and ecologists will agree, I think, that mycology and its vast range of species is a challengingly difficult topic. If there are any mycologists out there on our sites who would volunteer to do some reliable recording for us to help build up our biological records database, we would love to hear from you.

© Betts Ecology