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Haunted Horticulture V – Jack-o-Lantern Mushroom

By Noah Siegel (Amanita virosa) (Omphalotus olearius (DC.) Singer (33857)) [CC-BY-SA-3.0 (], via Wikimedia Commons
This week’s blog was written by guest blogger Dustin H. Purcell, MS.  Dustin is a Mycologist/Plant Pathologist who studied at the University of Florida.  Many thanks to Dustin for his eerie contribution!
If you ever come across glowing toadstools in the woods, do not be alarmed. You are not imagining things or having an alien encounter. You are one of the few to have observed the bioluminescent (light generating) jack-o-lantern mushroom in person. It earned this name not only because of the spooky iridescent glow it emits but also because of the large clusters of pumpkin-orange mushrooms it produces. They grow on rotting logs and buried stumps and can be found in Florida sporadically throughout the year following rains… unfortunately, due to this year’s very dry October, you are not likely to find any this Halloween.
By Noah Siegel (Amanita virosa) (Omphalotus olearius (DC.) Singer (33856)) [CC-BY-SA-3.0 (], via Wikimedia Commons

Like all mushrooms, this is a fungus and not a plant. Mycologists (scientists who study fungi) have named it Omphalotus olearius, though older field guides may call it Omphalotus illudens or Clitocybe illudens. It is relatively common in wooded areas throughout the southeast: You may have even seen its pumpkin-like masses of mushrooms during the day. However, few have witnessed its jack-o-lantern-like glow. The light is produced very dimly and requires the right combination of total darkness, a healthy growing mushroom, and eyes that are well adjusted to the dark… However, photographers easily capture their eerie green light on film using long exposures to magnify the intensity of this bioluminescent phenomenon. Many Pinellas county residents have witnessed two other bioluminescent phenomena that our area has to offer: fireflies (also called lightning bugs) and the phosphorescent glow of plankton in our warm coastal waters. If you’d like to add the jack o’lantern mushroom to the list of glowing creatures that you’ve seen, you have two options:

1. Wander without a flashlight through a wet forest on a dark moonless night far away from the light pollution of the city while hoping to see glowing toadstools, or

2. Keep your eyes peeled for a pumpkin-looking cluster of mushrooms in your yard and neighborhood

I would be a little reluctant to take option 1, especially on Halloween night. While not nearly as spooky, option 2 still may not be an easy task. Mushrooms, even glowing ones, can be very difficult to identify. Dr. James Kimbrough, a mycologist at the University of Florida, has written a field guide called Common Mushrooms of Florida that can help with the identification. Unless you have access to a mushroom expert, this IFAS book (or another good mushroom field guide) is probably your best bet. Once you find some, I’m told that you can collect them, wrap them in some moist (not soggy wet) paper towels to keep them from drying out, and take them into a dark closet to behold the spectacle of their eerie jack o’lantern glow.

In case you were wondering, this mushroom is poisonous! It is never recommended to eat mushrooms, except those found in the grocery store or farmers’ market… The chance of misidentification is too high, and the risks are too great… But there’s no reason to be scared of wild mushrooms (after all, they are a neat little bonus in the landscape), just don’t eat them.

IFAS Extension Bookstore link for Dr. Kimbrough’s book.

Firefly link.

One Comment on “Haunted Horticulture V – Jack-o-Lantern Mushroom

  1. What a cool looking mushroom. I think I will take the writer’s advice and avoid walking in the dark woods to find it though.