Hypsizygus ulmarius

Description

Hypsizygus ulmarius fruits high up on the trunks and large branches of elm trees (Ulmus spp.) and occasionally other broadleaf deciduous trees.

Often the fruitbodies form compact clusters with their stem bases emerging from a single branch scar, and so the stems are nearly always bent rather than straight.

This mushroom grows solitary or in small clusters on wounds of living hardwoods, particularly elm and boxelder. Often found high up in the tree through August to December.

Hypsizygus ulmarius closely parallels the morphology of an Oyster mushroom but is far better in flavor and texture. The Elm Oyster is a delicious edible mushroom that can be used like other Oyster mushrooms. On the market this mushroom is often incorrectly sold as 'Oyster mushroom' but it produces larger fruit bodies than other Oysters.

Common names: Elm Oyster, Elm Cap.

Mushroom Identification

1. Cap

   Usually 6 to 15 (exceptionally up to 30) cm across; convex, expanding but retaining and incurved margin; white; smooth and dry.

2. Gills

   Adnate or only very slightly decurrent; broad, crowded; white.

3. Stem

   6 to 13cm long and 2 to 3cm dia.; white; smooth or finely fibrillose; no stem ring.

4. Spores

   Broadly sublobose, smooth, 3.5-6.5 x 3-5µm, inamyloid.

5. Spore Print

   White to pale cream.

6. Season

   Summer, autumn, and early winter.

7. Similar Species

   The Elm Oyster could be confused with mushrooms of the Pleurotus genus, for example, Branched Oyster Mushroom Pleurotus cornucopiae, which has deeply decurrent gills.

Cultivation Tips

Most fungi do not develop fruiting bodies on rye grain substrate, that's why an adequate fruiting substrate must be inoculated with grain spawn. This method is suitable for most wood-inhabiting mushroom species.

Recommended equipment

1. Grain spawn, ready colonized

2. Sterilized wood substrate

3. Bag sealer or strong adhesive tape

4. Latex gloves

5. Face mask and hairnet

6. Disinfectants for workspace and hands

7. Sterile working area

8. Glove Bag/Glove Box or sterile airflow (HEPA-­filter, laminar flow hood)

Inoculation

Perform this working step under aseptic conditions to prevent contamination. Clean your worktop, wash hands and forearms, put on face mask, hairnet and gloves and disinfect your worktop well.

Separate the grains of the colonized spawn by shaking and plumping them repeatedly (with the bag still closed). Open the sterilized wood substrate bag. Use 2 to10%(of target substrate mass) of grain spawn for inoculation of the wood substrate. Add about 50 –250 g of grain spawn per bag containing 2,5 kg of the wood substrate.

Close the inoculated substrate bag using a bag sealer or strong adhesive tape. Now distribute the colonized grain evenly into the fresh substrate, by shaking the bag, to achieve fast and equal colonization. It could be beneficial to reshake the bag after 5 –7 days.

Mycelium growth

During the mycelium growth stage, store the inoculated substrate in a dark and clean place at a convenient temperature (spawn run) of this mushroom species. Ensure that the incubator in which the mycelium is grown provides enough ventilation.

After about 2–3 weeks the mycelium should have grown through the bag and the substrate should be overgrown by white mycelium (please note that some different species of fungi could have different mycelia colors). Now the mycelium is ready for the fruiting phase.

Photo sources:

Photo 1 - Author: Susulyka (CC BY-SA 3.0)

Photo 2 - Author: Susulyka (CC BY-SA 3.0)

Photo 3 - Author: Susulyka (CC BY-SA 3.0)