Cornell University

An adventure with Omphalotus

I was wandering through the Fall woods near Ithaca, New York when I stumbled upon what looked like a delicious surprise. Growing from a stump in the middle of the woods was what appeared to be a giant bunch of delectable chanterelle mushrooms. I greedily picked the entire clump, which must have weighed at least 5 pounds. The mushrooms smelled slightly fruity and inviting, and I was excited to bring them home and fry them up. However upon closer inspection (and the observations of a trained mycologist), I realized that I had made the amateur mistake of confusing the tasty Chanterelle with the poisonous Jack O’Lantern mushroom Omphalotus illudens.1

A clump of poisonous Jack O'Lantern mushrooms

The Jack O’Lantern is a mushroom of note in mycological circles largely for two reasons. First because of the tendency for mushroom hunting novices to mistake it for a Chanterelle (and consequently become quite sick for a day or so) and second because of the mushroom’s unusual ability to bioluminesce (glow in the dark).

The tendency for people to confuse the Chanterelle with the Jack O’Lantern is understandable because of their similar color and general appearance. Both are some shade of yellow-orange (more orange than yellow for Jack O’Lanterns), and both have decurrent gills that ease their way down the stalks. However the mistake can be quite uncomfortable as Jack O’Lanterns induce painful stomach cramps, diarrhea and vomiting. The symptoms pass within a day or two, but are pretty awful and most victims end up in the emergency room. Checking for several key characters can save you from confusing the two mushrooms. First, Chanterelles grow singly on the forest floor, whereas Jack O’Lanterns grow on rotting wood, usually in distinct clumps (tricky if the clump is small, or the wood is a buried root). Secondly, the gills of the Jack O’Lantern are clearly defined and have sharp, thin edges, whereas the gills on Chanterelles are blocky or fat or at least not so sharp.

The Jack O’Lantern’s ability to create luminescence is another factor which makes the mushroom interesting to mycologists (and anyone else who likes things that glow in the dark!). The specific molecules responsible for the glow of Jack O’Lanterns haven’t been characterized yet, and why a mushroom might bother to glow at all is another unanswered question. We took a long-exposure photo of my clump of mushrooms, revealing the yellow-green glow of their gills. To see the glow in real time, locate a living clump of Jack O’Lanterns, and sit with them in the woods on a dark night. Give your eyes 5 or 10 minutes to adjust (that’s how faint it is).2 Don’t rely on the glow to distinguish Jacks from Chanterelles, because it fades after the mushrooms are picked, and, as Michael Kuo can tell you, it can be hard to see.

Jack O'Lantern mushrooms glowing in the dark

Jack O'Lantern mushrooms in the light

Editor’s Notes

  1. Jack O’Lantern poisoning is my most common mushroom poisoning call here in the Northeast. Happily, it tends to pass without any lasting effects.
  2. A couple of years ago, I went out at night to sit with a clump of jack o’lanterns around a stump in my neighbor’s lawn. It took about 10 minutes for my eyes to be able to make out the glow. During that time, I counted shooting stars, meditated on the answer to the ultimate question (42), and listened to night sounds. Among those sounds was a persistent shushing, coming from all around me. When I had basked long enough in the glow and switched on my flashlight, I found I was surrounded by hungry giant slugs, slithering softly through the grass as they homed in on the Jack O’Lanterns, which apparently don’t upset slug tummies at all.

Photos by Kathie Hodge (in the field) and Kent Loeffler (glow/no glow). Kent explains that the long exposure (5 minutes) needed to capture the groovy glow results in a snowy effect when using a digital camera.



11 Responses to “ An adventure with Omphalotus ”


Most people don't pay much attention to fungi, which include things like mushrooms, molds, yeasts, and mildews. Here at Cornell we think they're pretty fascinating. In fact, even the most disgusting foot diseases and moldy strawberries are dear to our hearts. We'd like to talk to you about fungi, so that like us, you too can tell gross stories at the dinner table. Afterwards, maybe you'll notice some things you would have overlooked before, and we think this could be good for the planet.

Kathie T. Hodge, Editor

Beneath Notice, our book of borescopic mycology.


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