Witches’ Butter

Because of this mushroom’s shiny, slimy appearance, Erika and I first thought it might be a slime mold. We found it on a small log along a paved path near Olympia’s Capitol Lake on 24 January 2020. After taking the photo, I asked my phone what this fungus was. My phone replied, “Genus Tremella, probably Tremella mesenterica—several similar species exist.” This species often goes by the common name, “Witches’ Butter,” and it occurs across much of the world. The habitat was perfect—a recently fallen deciduous log, where it is a parasite on wood-rotting fungi in the genus Peniohora. Witches’ Butter often appears after rainy weather, which is just what we’ve been enjoying. Mycologists argue if this fungus in inedible or merely non-poisonous. At best, it is said to be flavorless—unknown wild mushroom should never be eaten. Nevertheless, mycologists have found glucuronoxylomannan, a substance found in Witches’ Butter, to have a number of biological activities, including “immunostimulatory, antidiabetic, anti-inflammatory, hypocholesterolemic, hepatoprotective, and antiallergic effects” (Wikipedia).