A giant mushroom

A wild shelf-mushroom.

Dear Naturalist,

I photographed this orange monster just two days ago when I was walking in the woods about a hundred yards from our house. It measured 18 inches in diameter at its widest point and 8 inches in height. Any light you can shed on its identity would be much appreciated.

P.R., Blowing Rock

There is currently a mushroom extravaganza in our backyards. Depending on the species, they appear as puffballs, truffles, cups, shelves, or corals. All mushrooms deserve a second glance!

Mushrooms are fungi because they contain no chlorophyll and obtain their nutrients by metabolizing non-living organic matter. Most fungi build their cell walls out of chitin – the same material as the hard outer shells of insects.

Funnily enough, the mushroom that caught your eye has been living underfoot all this time! The main body of the fungus is called its “mycelium.” This is a web of tiny filaments that are hidden underground and absorb and store nutrients. The mycelium can cover acres of subterranean territory.

The part of the mushroom that you have found is the “fruit” of the organism and contains reproductive “seeds” called spores.

How did your monster mushroom appear so quickly?

The fruiting body of mushrooms develop differently than plants and animals. Instead of growing by cell division, they grow by cell enlargement. Very little energy is involved in the process in which water causes the fungal cells to balloon up. They can literally pop up overnight.

The fruiting bodies of fungus lack protective skin, which is why they grow during periods of high humidity. If the humidity is too low, the growing cells will begin to lose water, dry up, and die.

Your mushroom is a type of shelf-mushroom or polypore. It is very similar to the edible “chicken-of-the woods” polypore except that the “chicken” usually grows high on a tree. Your mushroom is growing at the base of the tree, revealing that it is probably Laetiporus cincinnatus. I would guess that the nearby tree is an oak – another telltale sign of Laetiporus.

A fun experiment can reveal even more about your shroom. If I am right about your mushroom’s identity, it should have white spores. You can test this by collecting a small piece of the cap. Place the cap on a piece of black paper and put a cup over it. The mushroom will continue releasing spores as you watch and wait.

After about 24 hours, the spores will be plainly visible on the contrasting black paper. This work of art is called a “spore-print” and will capture the eye of any Rorschach aficionado or budding naturalist.

Amy Renfranz is the Director of Education and Natural Resources at the Grandfather Mountain Stewardship Foundation. Contact Amy and stay up to date with the natural world by following “Dear Naturalist” on Facebook. Learn more at www.dearnaturalist.com.

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