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
Cap
Usually 6 to 15 (exceptionally up to 30) cm across; convex, expanding but retaining and incurved margin; white; smooth and dry.
Gills
Adnate or only very slightly decurrent; broad, crowded; white.
Stem
6 to 13cm long and 2 to 3cm dia.; white; smooth or finely fibrillose; no stem ring.
Spores
Broadly sublobose, smooth, 3.5-6.5 x 3-5µm, inamyloid.
Spore Print
White to pale cream.
Season
Summer, autumn, and early winter.
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
Grain spawn, ready colonized
Sterilized wood substrate
Bag sealer or strong adhesive tape
Latex gloves
Face mask and hairnet
Disinfectants for workspace and hands
Sterile working area
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)