This week for Flora and Fauna Friday it’s the incredible, edible, glow-in-the-dark, root rotting, Ringless Honey Mushroom (Desarmillaria caespitosa).
Every year, in sync with the hurricane lilies, Ringless Honey Mushrooms begin to appear from the Earth on our Sea Island landscape. From the start of September through the end of October, they are readily found cropping up from hardwood stumps, upset root plates, and exposed roots in forests across the Southeast. Ringless Honey Mushrooms are saprophytic fungi and plant pathogens. They make their living off of trees and rotting wood. Ringless Honey Mushrooms infect the roots of a wide array of trees, most often hardwoods and commonly oaks. There they penetrate the heartwood and rot the roots and trunk from the inside out. An infection from any of the Honey Mushrooms is known to arborists and horticulturalists as “Armillaria Root Rot”, which is almost always fatal to the tree by the time it’s detected. Although it can be destructive to ornamental trees, Ringless Honey Mushroom is a natural player in our ecosystem and an important part of the nutrient cycling process. They generally only infect weakened trees and thinning out the forest canopy from time to time promotes understory biodiversity and a habitat mosaic. Saprophytic fungi decompose stumps and fallen logs, returning those nutrients back to the soil for the surviving trees to use.
The Ringless Honey Mushroom is somewhat easy to ID for a southeastern mushroom. It’s also edible and tastes quite good in my personal opinion. However, it must be fully cooked to avoid causing indigestion for some people. It emerges directly from rotting wood or the soil below a tree. From a single point, dozens of mushrooms crane upward ankle-high into a globe composed of two-inch flat caps, gilled beneath and set on pencil thin stalks. The mushroom caps are a drab-tan or pale-brown in color and the stalks bone-white. Notably, the stalks lack any form of a ring just below the cap, hence the moniker “Ringless” Honey Mushroom. This separates them from the Honey Mushroom (Armillaria mellea), which has a ring and a honey-colored cap, and also distinguishes today’s subject ‘shroom from all its poisonous or foul tasting lookalikes, of which there are a handful.
Speaking of lookalikes, this species was historically known by the scientific name Armillaria tabescens. However, deeper taxonomic and genetic work revealed that the “ringless” Armillaria were in their own genus, Desarmillaria, and that the Eastern United States harbors a visually indistinct sister species to Europe’s Desarmillaria tabescens. Thus, our American Ringless Honey Mushroom (Desarmillaria caespitosa) was rechristened.
A notable fun fact, the mycelia, the fungal equivalent of roots, of Ringless Honey Mushroom bioluminesce a faint blue-green light. Many of the other Honey Mushrooms and some other lineages of fungi do the same. It’s a phenomenon known as foxfire and it’s not understood why certain fungi produce this light. It may attract spore spreading insects, or function as some form of deterrent, or both, or neither. In the case of Ringless Honey Mushroom, only its mycelia glow, which are buried underground inside of tree roots where the light can’t escape. Maybe they radiate this light to ward off subterranean predators or pathogens. We genuinely don’t know. It’s a mystery.
Lastly my standard disclaimer when discussing a fungus, never ever eat a mushroom you found unless you’re 100% confident you know what it is. If you wouldn’t stake your life on your identification, don’t eat it, because you may very well be doing just that. A pack of mushrooms at the grocery store, even them fancy ones they’ve got at your favorite health food store, are a lot cheaper than a visit to the ER and/or a liver transplant. If you aren’t dead sure, don’t eat it. Another further point of caution, saprophytic mushrooms (like Ringless Honey Mushroom) can repurpose toxins found in the wood of their host trees. So if you don’t know what a mushroom is growing on, you may want to rethink your entrée for the evening.
