What is "omphalotus olearius"

Jack-o'-lantern \Jack"-o'-lan`tern\, Jack-with-a-lantern \Jack"-with-a-lan`tern\, n.

1. (Biol.) A large orange-colored luminescent mushroom, Clitocybe illudens, also classified as Omphalotus olearius. It is poisonous and is sometimes found on hardwood tree stumps. [WordNet sense 1]

   Syn: jack-a-lantern, Clitocybe illudens.

2. a pale light sometimes seen at night over marshy ground; an ignis fatuus; a will-o'-the-wisp. [WordNet sense 2]``[Newspaper speculations] supplying so many more jack-o'-lanterns to the future historian.''
   --Lowell.

   Syn: friar's lantern, ignis fatuus, will-o'-the-wisp.

3. A lantern carved from a hollowed-out pumpkin, with holes cut in the rind and so shaped that when it is illuminated by a candle inside, the features of a human face, cat's face, etc. appear in a glowing yellow color. It is used mostly as a decoration at Halloween.

Omphalotus olearius, commonly known as the jack-o'-lantern mushroom, is a poisonous orange gilled mushroom that to an untrained eye appears similar to some chanterelles. It is notable for its bioluminescent properties. It is found in woodland areas in Europe, where it grows on decaying stumps, buried roots or at the base of hardwood trees. A similar, but phylogenetically distinct species found in eastern North America is Omphalotus illudens.

Unlike chanterelles, Omphalotus olearius and other Omphalotus species contains the toxin illudin S, and are poisonous to humans. While not lethal, consuming this mushroom leads to very severe cramps, vomiting, and diarrhea.