Omphalotus illudens

Scientific name:  Omphalotus illudens (Schwein.)
Bresinsky & Besl
Derivation of nameOmphalos means "navel" and otos means
"like" or "resembling" in reference to the depressed centers
("belly-buttons') of the caps. Illudens means "deceiving" although
I'm not certain why this specific epithet is applied to this
species. I once heard a person say it's because it looks like
the European species O. olearius, which grows only grows
in association with olives.
Synonyms:  Clitocybe illudens (Schwein.) Sacc.
Common name(s):  Jack O' Lantern mushroom; False
Phylum:   Basidiomycota
Order:   Agaricales
Family:   Marasmiaceae
Occurrence on wood substrate:  Saprobic; in dense
cespitose clusers at the base of deciduous trees and stumps
or on the ground from decaying underground roots; July
through November.  
Dimensions:  Caps 7.5-20 cm wide; stipes 7.5-20 cm long
and 0.5-2.3 cm thick.   
Cap:  Smooth; bright orange to yellow-orange.      
Gills: Decurrent; same color as cap.
Spore print: Creamy white.
Stipe: Yellow-orange.
Veil: Absent.
Edibility: Poisonous.
Comments:  The gills of this mushroom are bioluminescent
giving off a green glow. Care must be taken to not confuse
this poisonous mushroom with edible chanterelles.
Chanterelles are not associated with decaying wood, they
have blunt gill-like folds or ridges instead of true gills, and
they do not occur in such dense cespitose clusters. Jack
O' Lantern is also sometimes confused with
Hygrophoropsis aurantiaca. Jack O'Lantern does not
have forked gills (Fig. 11) whereas H. aurantica does.

More information at   
More information at

Figure 1. The orange coloration of Omphalotus illudensis
is striking, even when viewed from a distance.
Photo © Gary Emberger.

Figure 2. Up close, the large brilliantly orange clusters of Jack
O' Lantern are a beautiful visual treat. Photo © George C.

Figure 3. This cluster is in a typical location at the base of a
stump. Photo © David Work.

Figure 4. Young specimens appearing in cespitose array
near the base of a tree trunk. Photo © Gary Emberger.

Figure 5. In contrast to Figures 1-4, another typical
location is on lawns where the fungus arises from dead
roots. The owner of this house indicated there was a large
pin oak tree on the front lawn which had been removed
recently. Photo © Gary Emberger.

Figure 6. Very young specimens with inrolled/incurved
margins. Photo © Gary Emberger.

Figure 7. Maturing speciemens with even margins.
Photo © Gary Emberger.

Figure 8. Quite mature specimens with uplifted and wavy
margins. Figures 6-8 illustrate the changes in shape which
so often accompany mushrooms as they develop.
Photo © Gary Emberger.

Figure 9. A typical cespitose cluster in which the stipes
arise close together but are not joined. Photo © Gary

Figure 10. Decurrent gills of the Jack O' Lantern
mushroom. Photo © Gary Emberger.

Figure 11. The gills of Omphalotus illudens are not
forked. The gills of Hygrophoropsis aurantiaca, a species
sometimes confused with Omphalotus illudens, are
repeatedly forked. Photo © Gary Emberger.

Figure 12. A mycology class sitting among the specimens
observed in Figure 1. Photo © Gary Emberger.


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