Atkinson’s Fungi

(Cortinarius atkinsonianus)

Conservation Status
Atkinson’s Fungi
 
  IUCN Red List

not listed

 
  NatureServe

not listed

 
  Minnesota

not listed

 
           
           
           
 
Description
 
 

Cortinarius is the largest genus of gilled mushrooms. There are estimated to be over 1,000 species worldwide.

Cortinarius atkinsonianus, commonly known as Atkinson’s Fungi, is a common and widespread mushroom in eastern North America. It is found on the ground either scattered or growing close together (gregarious) but not in clusters. It is sometimes found in rings or arcs. It obtains its nutrients from the rootlets of living trees (mycorrhizal). It appears in the fall under or near hardwoods in deciduous and mixed forests and woodlands.

The cap is 2 to 6in diameter. It is slimy when it first emerges from the ground. When young it is olive-yellow to yellowish and convex, and the margin is rolled inward. The surface is smooth when dry, sticky or slimy when moist. Later it may be dry but with dirt and debris stuck to the cap. As it ages the cap becomes broadly convex or flat and darkens to deep reddish-brown from the center outwards, with the margin remaining olive-yellow.

The stalk 1½ to 4¾ tall and to 1¼ in diameter at the top. When young, it has a conspicuous, abrupt, rimmed, 1¼ to 2¾ wide bulb at the base. As the stalk lengthens, the bulb becomes less abrupt. The stalk is solid and dry, not slimy or sticky. The color is variable, with olive-yellow or pale lavender at the top or throughout its length.

The gills are closely spaced and are narrowly to broadly attached to the stalk. They do not run down the stalk. They are greenish-yellow at first, become pale lavender with yellow edges for a short time, ultimately fading to cinnamon-brown. When young, the gills are protected with a partial veil that is cobwebby or silky in texture (cortina). The cortina is greenish-yellow at first, becoming rusty-brown as it is covered with spores. When it collapses to allow the dispersal of spores, it leaves hairs on the stem that trap the spores.

The flesh is thick, firm, and whitish to pale yellow with lavender or violet areas. It stains lavender or violet when bruised. The edibility is unknown. However, many Cortinarius mushrooms are poisonous. Due to the difficulty of identifying them to the species level, it is recommended that Cortinarius mushrooms are not eaten.

The spore print is rusty-brown.

 
     
 

Similar Species

 
     
     
 
Habitat and Hosts
 
 

Deciduous forests and woodlands

 
     
 
Biology
 
 

Season

 
 

Fall

 
     
 
Distribution
 
 

Distribution Map

 

Sources

4, 7, 26, 29, 30, 77.

 
  11/20/2021      
         
 

Occurrence

 
 

Common in eastern North America. Few records in Minnesota.

 
         
 
Taxonomy
 
  Kingdom Fungi (fungi)  
  Subkingdom Dikarya  
  Phylum Basidiomycota (club fungi)  
  Subphylum Agaricomycotina (jelly fungi, yeasts, and mushrooms)  
  Class Agaricomycetes (mushroom-forming fungi)  
  Subclass Agaricomycetidae  
  Order Agaricales (common gilled mushrooms and allies)  
  Suborder Agaricineae  
  Family Cortinariaceae  
  Genus Cortinarius (webcaps)  
       
 

Synonyms

 
 

 

 
       
 

Common Names

 
 

Atkinson’s Fungi

 

 

 

 

 

 

 

Glossary

Cortina

On mushrooms: A thin, silky or cobwebby veil, attached to the cap and the stalk, that protects the developing gills.

 

Mycorrhizal

A symbiotic, usually beneficial relationship between a fungus and the tiny rootlets of a plant, usually a tree.

 

Partial veil

A protective covering over the gills or pores of a developing mushroom. At maturity it disappears, collapses into a ring around the stem, or wears away into a cobwebby covering and ring zone.

 
 
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MinnesotaSeasons.com Photos
 
 

Habitat

 
    Atkinson’s Fungi      
           
 

Fairy Ring

 
    Atkinson’s Fungi      
           
 

Cluster

 
    Atkinson’s Fungi   Atkinson’s Fungi  
           
    Atkinson’s Fungi   Atkinson’s Fungi  
           
 

Mushroom

 
    Atkinson’s Fungi      
           
 

Cap

 
    Atkinson’s Fungi      
           
 

Stalk

 
    Atkinson’s Fungi   Atkinson’s Fungi  
           
 

Gills

 
    Atkinson’s Fungi      
           
 

Flesh

 
    Atkinson’s Fungi      

 

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