Tom Volk's Fungus of the Month for October 1997

This month's fungus is the Jack-O-Lantern mushroom, Omphalotus olearius

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The jack-o-lantern mushroom

Since it's October (meaning Hallowe'en [=Halloween] celebrations at least in this part of the world), I chose the Jack-O-Lantern mushroom, Omphalotus olearius as this month's fungus. Omphalotus olearius, formerly known as either Omphalotus illudens or Clitocybe illudens, often produces its fruiting bodies in abundance this time of year in large clusters on old rotting stumps of hardwood trees. It should be fairly obvious from the picture where this fungus gets its common name-- it's bright orange like the pumpkins used to make Jack-O-Lanterns. However, it is not so obvious from the picture the other reason for the common name. This fungus actually glows in the dark! Not the whole fungus, but just the gills on the underside of the mushroom. If you find these mushrooms, take them into a very dark room and stare at the gills of the fungus until your eyes become acclimated to the dark-- you should see an eerie greenish glow emanating from the mushrooms. It's a fun class project to do-- or fun to do by yourself or with friends or family. The glow is caused by the presence of luciferases, waste products or secondary metabolites from the physiological activities of the mycelium of the. Putting the wastes into the above-ground fruiting structure is the fungus's way of getting rid of its waste products.

The glowing picture was taken on a long exposure in the dark by Tryggvi Emilsson of Illiniois, whom I met at a foray this fall. He is analyzing the chemicals in this and other fungi for possible medicinal use. He writes, "These were uncommonly bright specimens. As soon as I turned the room lights off I saw the luminescence right through the grocery sack that I had them in. I had previously tried five times, over a ten year period to get pictures of O. olearius. Even with 1000 ASA film and 20 min exposures I had only gotten completely blank negatives. Incidentally, the luminescence of O. olearius is associated with some sesquiterpenes called illudins. One of those, illudin S, has been found to be active against a whole mess of different cancer cells in vitro. Unfortunately illudin S is somewhat too toxic for clinical use. Synthetic analogs have been prepared recently that are less toxic, and yet active." He also believes the color balance in this pictures is a bit off, and he is working on reconstructing the color. Thanks to Tryggvi for providing this great picture!

The jack-o-lantern mushroomOmphalotus olearius Omphalotus olearius can often be found in large quantities, such as you see here. They smell very good, and many people have been tempted to eat this fungus. -- but it's poisonous. Omphalotus poisoning usually manifests itself as severe cramps, vomiting and diarrhea, all of which can last up to a few days.. Unlike last month's Fungus of the Month, the death angel. Omphalotus olearius won't kill you-- it will just make you wish you were dead. At one place I formerly worked, there was a man who we simply called "Jack." I can't even remember his real name. He ate the Jack-O-Lantern one year because he thought they smelled good and he thought the might be chanterelles, but we explained to him that although both mushrooms are bright orange in color, but Omphalotus has true, sharp gills that are not forked and grow directly from wood or buried wood. He seemed to get the idea-- but one year later he returned, poisoned by the Jack-O-Lantern again. He just had to try them again because they smelled so good. Some people never learn. --But maybe "Jack" learned his lesson that time because we never heard from him again.
There are lots of interesting stories in Mycology. The fungi are interesting and do interesting and unexpected things. And people often do interesting and unexpected things with the mushrooms. So get out into the woods and forests while you have the chance. There are lots of fun things waiting for you there!

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