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Jack o' lanterns - Omphalatus illudens

Good evening, friends, and Happy Halloween.

This week we're looking at Jack o' lantern mushrooms (Omphalatus illudens). The photographed specimens were found in Blue Mountain Reservation on 9/20/2022, but "jacks" - as they're colloquially called - can also be found in Central Park and other NYC parks. Not only do these mushrooms possess haunting traits appropriate for the holiday, but they're another species that can be mistaken as a chanterelle so learning some of their key features can help you avoid mistaken consumption and subsequent gastrointestinal distress.

Omphalatus illudens

Before delving into a more serious aspect of these mushrooms, one spooky feature is that the gills are bioluminescent in the dark. Similar to this occurrence in Panellus stipticus, this phenomenon can be hard to observe and is typically best seen in complete darkness or with a long-exposure camera. The mechanism through which they glow is the enzyme luciferase and it is only found in the gills. The purpose for which they glow is unknown, however, but perhaps they want to attract insects at night? Oh and while we're talking about jack o' lanterns, I did carve a pretty sweet owl perched on a grave.

Carved pumpkin

Back to the jack o' lantern mushrooms, they're toxic when ingested. Unlike the false chanterelles (Hygrophoropsis aurantiaca) from last week which some people consider edible, these jacks will certainly make you sick. A PubMed article documents an instance where 14 people ingested these mushrooms and it resulted in vomiting among 8 of them, diarrhea in 5, and general tiredness/weakness in more than half. The symptoms subsided within 18 hours after ingestion. These mushrooms won't kill ya, but they're going to make your tummy turn.

Omphalatus illudens

An important distinction that separates these mushrooms from highly regarded chanterelles are that they grow in a cespitose fashion. "Cespitose" means that they grow in bunched clusters and all of the stipes (stems) originate from one point. Unlike the false chanterelle (H. auriantiaca), you won't find these growing as stand-alone, individual mushrooms. The stipes are orange, but in the above photo the white spores released from the gills have landed on the stipes and give them a ghostly white appearance. The gills are true gills, unlike the folds/ridges on chanterelles, and do not fork as they extend from the stipe to the cap like we saw last week.

Omphalatus illudens

O. illudens is saprobic and the mushrooms grow cespitose out of dead tree roots or stumps. You can see just how visible these were below as the orange makes them pop out from the rest of the forest floor. You may even think, from afar, they're actually pumpkins. This species is technically called the "Eastern American" Jack o' lantern because there are a couple of sister species - Omphalatus olearius, Omphalatus subilludens, and Omphalatus olivascens - that grow in Europe, the Southern US, and Western North America respectively (they're physically similar but genetically and geographically distinct).

Omphalatus illudens

Central Park Walk

I said last week that I'd do a walk in the park this Sunday, 11/7. I was promptly, and thankfully, reminded that the NYC marathon will be running through the park that day. It's a nuisance to try and navigate the park/city during the marathon so we'll just wait until the following Sunday, 11/13. We'll meet in the Ramble and I'll provide more specifics next week. Hope to see you then.

Happy Halloween. I dressed up like Scooby Doo this weekend, how about you?



1) Kuo, M. (2015, March). Omphalotus illudens. Retrieved from the MushroomExpert.Com Web site:

2) French AL, Garrettson LK. Poisoning with the North American Jack O'Lantern mushroom, Omphalotus illudens. J Toxicol Clin Toxicol. 1988;26(1-2):81-8. doi: 10.3109/15563658808995399. PMID: 3290510.

Roooooooobyyyyyy doooooobbbyyyy dooooooooo

Aubrey dressed as Scooby Doo


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