Gymnopus dryophilus

Scientific name:   Gymnopus dryophilus (Bull.) Murrill
Derivation of name: Dry- means "oak," and phil means
"loving."  
Synonyms:   Collybia dryophila (Bull.) P. Kumm.
Common name(s):  Oak-loving Collybia (Gymnopus)
Phylum:   Basidiomycota
Order:   Agaricales
Family:   Marasmiaceae
Occurrence on wood substrate: Saprobic; scattered to
numerous on wood, landscape wood chip mulch,
sawdust, leaf litter, and twigs in hardwood or conifer
forests; sometimes forming fairy rings; spring through fall.  
Dimensions: Caps 1-7 cm wide; stipes 3-9 cm long and
2-8 mm thick.    
Cap: Smooth; dry to moist; reddish-brown to ochre-brown
when young, fading to tan or yellow.       
Gills: Attached to nearly free; crowded to close; whitish to
yellow-tinged. 
Spore print: White to pale cream.
Stipe: Dry; smooth; reddish-brown to ochre or whitish;
whitish mycelium or rhizomorphs at the base.
Veil: Absent.
Comments: The variation within this species is accounted
for in the recognition of a "Collybia dryophila complex."
The species is perhaps most easily identified when
parasitized by Syzygospora mycetophila (Collybia Jelly),
which induces jelly or tumor-like growths to form on the
stem, gills, and cap (see Figures 4 and 5).

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Figure 1. A collection of  Gymnopus dryophilus on
display at the 2003 NAMA foray in Quebec, Canada.
Photo © Gary Emberger.   

Figure 2. Gymnopus dryophilus as it might appear in a
field setting. Photo © John Plischke III.

Figure 3. A beautiful, young specimen of Gymnopus
dryophilus growing in a conifer woods. Photo © Pam
Kaminski.

Figure 4. Gymnopus dryophilus parasitized by
Syzygospora mycetophila. The growths, made of
Gymnopus tissue, are stimulated to form by the parasite.
Photo © David Work.

Figure 5. Extensive tumor formation induced by
Syzygospora mycetophila. An older name for the parasite
is Christiansenia mycetophila. Photo © John Plischke III.