Tuleyome Tales: The sulphur shelf fungus
- Mary K. Hanson
- Posted On
NORTHERN CALIFORNIA – Before most of the other fungi make their appearance in the Berryessa Snow Mountain National Monument region, specimens of sulphur shelf fungus (Laetiporus gilbertsonii) appear like bright yellow-orange halos on the sides of trees.
They’re unmistakable, large and very colorful.
Different species of sulphur shelf fungus used to be lumped under the old classification name of Laetiporus sulphureus, but in 2001 they were separated out into their own distinct classifications based on DNA evidence.
Laetiporus gilbertsonii is the one we find in California, mostly growing on hardwoods like oaks and eucalyptus trees. There’s another species in California called Laetiporus conifericola that grows on conifers trees like fir and redwoods.
The fungus can grow on any part of the tree, from the base to the high trunk, wherever its spores have settled in. Most often, it is found on dead or dying trees. It’s a kind of “saprotroph,” which means it’s a decomposer, getting nutrients from decaying organic matter. But it’s also considered a “weak parasite” that can also grow on living trees and slowly sap nutrients from them.
Sulphur shelf doesn’t like it when it’s very wet outside, so it usually shows up around October or November before the rainy season starts. At first, you don’t see the fungus at all as it’s living inside the tree and bark, doing its thing as a web of tiny hair-like mycelium. When the fruiting body of the fungus finally emerges onto the surface of the tree, it looks like small yellow-orange swellings that over a period of a few days turn into larger lumps with lobes, like small brains.
In about a week the lobes expand, thin out, and stretch into half-moon shaped shelf-like structures. Sometimes you’ll see a single shelf; sometimes the shelves are stacked up one on top of the other in groups of two to 12 or more.
The shelves are somewhat thick and fleshy and feel something like cork. Sulphur shelf is a kind of bracket polypore, so if you look at the underside of the shelves you’ll see their surfaces are riddled with hundreds of tiny pores. It’s in these pores that the fungus’s white spores are produced.
You may also see what look like tears or sweat coming from the fungus. These droplets of nearly clear liquid are actually beads of excess moisture the fungus exudes when its growing.
The phenomenon, known as guttation, is common in plants, but less understood in fungi although many forms of fungi do exhibit it. In some fungi, this guttation can appear as clear sweat, as it does in sulphur shelf, or as black, orange or even red tears (as in the Bleeding Tooth fungus, Hydnellum peckii.)
As the sulphur shelf fungus ages, it loses its bright yellow-orange coloring and all evidence of guttation vanishes. It turns dry, chalky white and can crumble in your hand.
Sulphur shelf is known by many different common names including crab of the woods and chicken of the forest, which reflect its supposedly edible nature. Some say it tastes like chicken, others say it tastes like lobster.
Old chalky specimens are inedible, however, so stick to the bright, young ones that show a lot of guttation if you’re inclined to try a sample. Keep in mind, however, that whether the fungus is truly, safely, completely edible is widely disputed.
Some reports suggest that much depends on what sort of substrate of the fungus is growing on. If it’s growing on oak trees, for example, it’s supposed to be more edible than specimens growing on conifers or eucalyptus trees.
Other studies suggest that it’s edible, no matter what the substrate, but can cause mild to severe gastrointestinal distress in people who are sensitive to it.
Regardless, all of the studies say that the chicken of the forest – as is true of the barnyard fowl – should never be eaten raw (sautéing it or boiling it are suggested). And if you’re not sure about your level of sensitivity to fungi in general, you shouldn’t risk your health by trying it out.
Maybe the best way to enjoy this large, beautiful, native fungus is just to take photos of it and leave it where it is.
Mary K. Hanson is a Certified California Naturalist, author, nature photographer and blogger (https://chubbywomanwalkabout.com/). She also teaches naturalist classes through Tuleyome, a501(c)(3) nonprofit conservation organization based in Woodland, Calif. For more information, visit www.tuleyome.org .