By Dan Zarlenga, Missouri Department of Conservation
Photo caption: Witches’ butter fungus grows on dead wood in the October woods.
Photo by Dan Zarlenga
October is the month to celebrate all things creepy, as darkness begins to manifest itself in the shortening of days and browning of many florae. The full moon is the 17th, and of course, Halloween finishes out the month. But what could possibly be creepier than a fungus with a sinister name that grows on tree corpses? It’s even a parasite of a parasite.
Autumn is a wonderful time to get out into the woods and marvel at nature’s color. But every so often, consider turning your gaze downward, toward dead logs and branches you may find laying on the forest floor. Do you see small, irregularly lobed, gelatinous masses clinging to the decaying wood? It might look like the lobes of a brain, the color of pale yellow or sulfur. You’ve just happened upon witches’ butter. Aptly named since it only grows on wood that’s pretty much toast!
Tremella mesenterica is the scientific name for witches’ butter, a jelly fungus that tends to be found on deciduous wood, particularly dead oaks. The brain-like lobes are tough, greasy, and slimy when they are wet, and hard when dried out. Sometimes it’s even called brain fungus. What we’re seeing is the “fruiting” parts of the fungus, which create and disperse spores that float away on currents of air to churn out more witches’ butter.
Witches’ butter can appear in forests throughout Missouri, often in late summer and during the fall. Like a true sorceress, this fungus also has the power to defy nature, sometimes even emerging during warmer periods in the middle of winter.
Not only is witches’ butter a parasite, it actually lives off another parasite. This jelly fungus grows on the mycelium, the root-like structure, of wood decay fungi. These are any species of fungi that digest moist wood, causing it to rot. Even as they extract nutrients from the decomposing wood, like casting an evil curse witches’ butter steals these vital, life-giving substances from the wood decaying fungi to nourish itself.
How did witches’ butter get its name? It turns out that this fungus also grows in Europe, and legends from that continent may reveal the origin of its moniker. They tell us that if this 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 broken was to pierce the fungus with straight pins to cause its inner juices to leak out, killing the fungus. The curse would then be lifted. In Sweden, people sometimes burned witches’ butter in an effort to ward off evil spirits.
But of course, these are all merely superstitions, aren’t they?
In the true spirit of the spookiest month of the year, take a hike through a forest near you and go on a witch hunt for the parasite of parasites. Witches’ butter is lurking in the woods, feasting on the corpses of trees. Just maybe though, it would be a good idea to get back home before dark…