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Omphalotus illudens: The Jack O'Lantern

[ Basidiomycetes > Agaricales > Marasmiaceae > Omphalotus . . . ]

by Michael Kuo

Commonly called the "Jack O'Lantern Mushroom," this species is fairly easy to identify. It grows in clusters on wood, its colors are bright orange, its gills run down the stem, it has a white to pale yellow spore print, and its flesh, when sliced open, is orange (or at least orangish). It is a common fall mushroom east of the Rocky Mountains, and is frequently found in urban settings, sprouting from dead trees and stumps. West of the Rockies, the very similar Omphalotus olivascens replaces it, and is distinguished by its olive shades, which are mixed in with the orange.

The Jack O'Lantern mushroom is sometimes confused with chanterelles--especially when it appears to be growing terrestrially rather than from wood (see the top illustration). However, chanterelles rarely grow in dense clusters, and feature false gills, while the Jack O'Lantern is usually clustered and features true gills.

The Jack O'Lantern is the focus of the largest and most insidious conspiracy in the mycological world. According to every field guide, and every other source of literature available for the species, its gills glow in the dark. I'm not making this up; pick up any mushroom book that describes the Jack O'Lantern, and you'll find the author coolly mentioning the "luminescence" of the gills, or telling stories about 19th-Century pioneers finding their way back to their cabins, in the dark, following the Jack O'Lantern's glowing gills.

All of these authors are lying, and they are in cahoots. See, what they enjoy is knowing that hundreds of amateur mushroomers, every fall, shut themselves into closets, bathrooms, and garages, eagerly peering through the darkness for hours, waiting for the Jack O'Lantern's gills to luminesce.

I have wasted at least three hours of my life in this endeavor, over the years. Three hours! Every time I collect Omphalotus illudens, I think to myself: "These are fresh specimens; surely this time I'll see it." Then I seclude myself in darkness and hover, waiting . . . and waiting, and waiting. This last time, after nearly half an hour, I finally began to see the gills glow in the dark, an eerie green color--until I held my hand over my eyes and noticed that the glowing gills were still there.

I am here to tell you: The emperor is naked! Don't make a fool of yourself, as I regularly do. After years of trying to see the luminescent gills I have reached the obvious conclusion: mushroom authors are out to make me feel like an idiot. And don't bother sending an e-mail to tell me you have seen the Jack O'Lantern's glowing gills, or to send a photo of the phenomenon, because I will know you are part of the conspiracy, and that the photo was produced by the same people who made the photos of the Loch Ness Monster.


Ecology: Saprobic; growing in large clusters on the stumps or buried roots of hardwoods, especially oaks; late summer and fall; widely distributed east of the Rocky Mountains (replaced by Omphalotus olivascens to the west).

Cap: 5-20 cm; convex but soon flat, eventually vase-shaped; the margin incurved; smooth; bright orange.

Gills: Running down the stem; crowded; bright orange.

Stem: 5-20 cm long; 1-2 cm thick; more or less equal, but tapering to base; solid; bright orange or darker below; smooth.

Flesh: Pale orange.

Odor and Taste: Not distinctive or disagreeable.

Spore Print: White to cream or pale yellow.

Chemical Reactions: KOH green on cap surface; ammonia greenish on cap surface.

Microscopic Features: Spores 3.5-5 µ; round; inamyloid.

There is some debate about whether this mushroom and its western companion Omphalotus olivascens are simply North American forms of the European Jack O'Lantern, Omphalotus olearius (see links below).

REFERENCES: (Schweinitz, 1822) Bresinsky & Besl, 1979. (Saccardo, 1887; Kauffman, 1918; Smith, Smith & Weber, 1979; Weber & Smith, 1985; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Metzler & Metzler, 1992; Horn, Kay & Aberl, 1993; Barron, 1999; Roody, 2003; McNeil, 2006; Miller & Miller, 2006.) Herb. Kuo 08309701, 07290701.

Further Online Information:

Omphalotus olearius at Tom Volk's Fungi
Omphalotus illudens at Roger's Mushrooms
Omphalotus olearius at Roger's Mushrooms
Omphalotus olivascens at MykoWeb


Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

Omphalotus illudens

© MushroomExpert.Com

Addendum, 2003

Five months after writing this page, I looked again at the scan I made to illustrate the Jack O'Lantern mushroom (above). This time, however, I looked more closely--why, I don't know. But when I looked at the scan and focused on the young gills, I noticed something peculiar, which you can see if you enlarge this image:

Omphalotus illudens gills luminescing

Though I had stared at these mushrooms in the dark for at least 20 minutes, seeing nothing, my scanner saw something. The scan probably took about 40 seconds to make; in that time the young gills luminesced enough to distort the image, clearly visible in the enlargement!

Obviously, my scanner is in on the conspiracy, too.

Addendum, 2005

The conspiracy deepens. Also involved with perpetuating the glow-in-the-dark myth are several prominent mycologists, the entire Missouri Mycological Society, some mushroom loving students from Indiana, and--well, my own eyes. This summer I walked ("stumbled" is a better descriptor) 100 yards through pitch-black woods between my cabin and a camp fire, holding aloft a brilliantly glowing clump of Omphalotus illudens. The trick, it seems, is to wrap the mushrooms in damp paper towels when you collect them. Then study some other fungi (particularly the Ascomycetes that are used to ferment beverages) as thoroughly as you can. If you follow this process, anyway, the luminescence is undeniable.

Cite this page as:

Kuo, M. (2007, November). Omphalotus illudens: The jack-o-lantern. Retrieved from the MushroomExpert.Com Web site: