Elm Oyster

(Hypsizygus ulmarius)

Conservation Status
Elm Oyster
Photo by Kirk Nelson
  IUCN Red List

not listed

 
  NatureServe

not listed

 
  Minnesota

not listed

 
           
           
           
           
 
Description
 
 

Elm oyster is a large mushroom. It is widespread but not common in eastern United States. It usually occurs in a small cluster of three or more. It is found from August to December growing from a branch scar or other wound high in a living hardwood tree, especially elm and box elder.

The cap is 2 to 6 in diameter. When young, the cap is convex and the margin is rolled under. The upper surface is white and smooth. As it ages it flattens out and the center becomes slightly sunken. The upper surface turns creamy buff or tan and develops cracks, forming a pattern of small scales or patches.

The stalk is stout, 2 to 4 long, and to 1 thick. It is whitish, solid, fibrous, smooth, dry, and usually hairless, sometimes finely hairy. It is attached centrally or slightly off center, and is sometimes enlarged at the base. There is no cup-like covering (volva) at the base of the stalk, and there are no remnants of a universal veil clinging to the stalk.

The flesh is firm and white. It is edible but tough.

The gills are closely spaced and whitish at first, becoming cream-colored with age. They are attached to the stem but do not run down the stem.

The spore print is white to buff.

 
     
 

Similar Species

 
 

Brown Beech Mushroom (Hypsizygus tessellatus) is virtually identical in size and appearance. Fresh specimens often have a pattern of round watery spots on the cap. It grows on aspens, cottonwoods, and sugar maple, and it occurs singly, not in clusters.

 
     
 
Habitat and Hosts
 
 

Hardwoods, especially elm and box elder

 
     
 
Biology
 
 

Season

 
 

August to December

 
     
 
Distribution
 
 

Distribution Map

 

Sources

4, 24, 26, 29, 30, 77.

 
  9/23/2021      
         
 

Occurrence

 
 

Widespread but not common in eastern United States

 
         
 
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 Tricholomatineae  
  Family Lyophyllaceae  
  Genus Hypsizygus  
       
 

Printed field guides and online sources often erroneously refer to Elm Oyster as Hypsizygus tessellatus.

 
       
 

Synonyms

 
 

Agaricus ulmarius

Dendrosarcus ulmarius

Lyophyllum ulmarium

Micromphale ulmarium

Pleuropus ulmarius

 
       
 

Common Names

 
 

Elm Oyster

 

 

 

 

 

 

 

Glossary

Universal veil

An egg-like structure that envelopes all or most of a developing gill mushroom. Remnants of the universal veil sometimes visible on a mature mushroom are patchy warts on the cap, a ring on the stem, and a volva at the base of the stem.

 

Volva

Also called cup. A cup-like covering at the base of a mushroom stem, sometimes buried. It is the remnants of the universal veil ruptured by the mushroom pushing through. It is found on Amanita, Volvariella, and some other mushrooms.

 

 
 
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Miranda Sieh

 
 

I have been enjoying the photos and info on your website. I have been learning about wild mushrooms and growing cultivated mushrooms for the last few years with an experienced mentor.

  Elm Oyster  
         
  Today (Oct 3) I found 2 mushrooms that I think are elm oysters growing on a living box elder on my farm in East central MN. The feature that gives me pause is the texture of the stipe. It is not smooth but almost scaly or shaggy. I can not find an elm oyster look alike with a shaggy stipe. The weather has been humid, but we are in need of rain. Any advice would be appreciated.   Elm Oyster  
 

Wags

 
    Elm Oyster   Elm Oyster  
 

Mark Volesky

 
 

Found four in western Becker county. All attached to three maple trees.

 
    Elm Oyster   Elm Oyster  
 

Kirk Nelson

 
    Elm Oyster   Elm Oyster  
           
 

Growing on a boxelder

 
    Elm Oyster   Elm Oyster  
 

Jessica Marquez

 
 

Cluster of elm oyster mushrooms growing surprisingly low (4’) off the ground on a box elder tree near Silver Creek in Quarry Hill; found Dec. 20th, 2019.

 

  Elm Oyster  
           
  (They are a frequent sight here as well as along the Douglas Trail starting in late August, but this is as late in the year as I’ve found them so intact!).   Elm Oyster  
 

Jeff

 
    Elm Oyster   Elm Oyster  
           
 
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slideshow

       
 
Visitor Videos
 
       
 

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Other Videos
 
  Elm Mushroom (Hypsizygus ulmarius) on Tree
Carl Barrentine
 
   
 
About

Published on Sep 20, 2010

Photographed at the Turtle River State Park, North Dakota (12 September 2010).

   
  Elm Mushroom (Hypsizygus ulmarius) on Boxelder
Carl Barrentine
 
   
 
About

Published on Sep 20, 2010

This specimen was found growing 5 meters from the ground. Photographed at the Turtle River State Park, North Dakota (19 September 2010). Go here to learn more about this species: https://www.youtube.com/redirect?q=http%3A%2F%2Fwww.mushroomexpert.com%2Fhypsizygus_ulmarius.html&redir_token=oZnTZUyQLFWY2FAuIgLZVcAA7CV8MTUwOTI4MTM3NEAxNTA5MTk0OTc0&event=video_description&v=w3TFrMESkDY

   
  Elm Oyster foraging - Hypsizygus ulmarius
Corie Mushrooms
 
   
 
About

Published on Nov 10, 2015

This is me. Unsuccessfully being able to reach the common. but illusive, Elm Oysters.

   
  Elm Oyster wild mushroom
RedFree100
 
   
 
About

Published on Nov 1, 2011

Elm Oyster is a Edible wild mushroom but tough https://www.youtube.com/redirect?redir_token=yRR8iZwUoc0P_jTrCsLUJ5Z32uR8MTUwOTI4MTU3M0AxNTA5MTk1MTcz&v=9CIv19tI6aY&q=http%3A%2F%2Fwww.gabodabuilding.com%2FMoreMushrooms.html&event=video_description

   

 

Camcorder

 
 
Visitor Sightings
 
           
 

Report a sighting of this fungus.

 
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Be sure to include a location.
 
  Apricity Apricity
Fall 2021

Location: Martin County, Fairmont, MN

 
  Miranda Sieh
10/3/2021

Location: East central MN

I have been enjoying the photos and info on your website. I have been learning about wild mushrooms and growing cultivated mushrooms for the last few years with an experienced mentor.

Today (Oct 3) I found 2 mushrooms that I think are elm oysters growing on a living box elder on my farm in East central MN. The feature that gives me pause is the texture of the stipe. It is not smooth but almost scaly or shaggy. I can not find an elm oyster look alike with a shaggy stipe. The weather has been humid, but we are in need of rain. Any advice would be appreciated.

Elm Oyster  
  Wags
9/28/2021

Location: near Theodore Wirth Park in Minneapolis

Elm Oyster  
  Mark Volesky
9/17/2021

Location: Becker County

Found four in western Becker county. All attached to three maple trees.

Elm Oyster  
  Kirk Nelson
9/20/2020

Location: Fort Snelling State Park

Elm Oyster  
  Jessica Marquez
12/20/2019

Location: Olmsted County

Cluster of elm oyster mushrooms growing surprisingly low (4’) off the ground on a box elder tree near Silver Creek in Quarry Hill; found Dec. 20th, 2019.

(They are a frequent sight here as well as along the Douglas Trail starting in late August, but this is as late in the year as I’ve found them so intact!).

Elm Oyster  
  nltr
9/7/2019

Location: May Township

found growing out of crotch of young elm and out of crack in young elm. Wooded acreage

 
  Jeff
10/14/2017

Location: Rush City

Elm Oyster  
  Kirk Nelson
9/10/2017

Location: Lebanon Hills Regional Park

Growing on a boxelder

Elm Oyster  
           
 
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Created: 10/28/2017

Last Updated:

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