Oyster Mushroom

Pleurotus ostreatus

Also known as: Tree Oyster, Pearl Oyster Mushroom

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Edibility edible

Phylum Basidiomycota

Family Pleurotaceae

Conservation Least Concern - common, widely distributed and cultivated

Complete Taxonomy

Kingdom: Fungi

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

Family: Pleurotaceae

Genus: Pleurotus

Species: P. ostreatus

Description

Pleurotus ostreatus is a popular edible mushroom that grows in shelf-like clusters on dead or dying hardwood trees. Named for its oyster-like appearance and subtle seafood aroma when fresh, it is the second most cultivated mushroom globally. Remarkably adaptable, it can grow on diverse substrates including coffee grounds, straw, and even petroleum-contaminated soil.

Physical Characteristics

Cap Shape: Fan or oyster-shaped, sometimes lobed

Cap Color: White, gray, tan, or pale brown; 5-25 cm across

Size: 5-25 cm diameter

Gill Attachment: Decurrent (running down the stipe)

Spore Print: White to lilac-gray

Stipe: Short, eccentric or lateral, often absent; white, tough

Habitat: Grows on dead or dying hardwood trees, especially beech, oak, and maple

Fruiting Season: Fall through spring, year-round in cultivation

Distribution

Cosmopolitan; found worldwide in temperate and subtropical regions

Habitat

Saprotroph on dead and dying hardwood trees, logs, and stumps. Occasionally weakly parasitic on stressed trees. Cultivated on agricultural waste substrates.

Ecological Role

Important decomposer of hardwood, breaking down lignin and cellulose. Can be weakly parasitic on stressed trees. Notable for ability to digest complex pollutants including petroleum products and heavy metals.

Medicinal & Nutritional Properties

Contains lovastatin, which lowers cholesterol
Polysaccharides with immune-modulating properties
Antioxidant compounds
May have anti-inflammatory effects
Source of ergothioneine
Rich in B vitamins, vitamin D (when exposed to light), and minerals

Cultural Significance

Second most cultivated mushroom worldwide. Popular in Asian cuisine for centuries. Increasing popularity in Western markets. Important in permaculture and sustainable agriculture movements.

Fascinating Facts

Can break down petroleum products and remove heavy metals from soil (mycoremediation)
One of few carnivorous mushrooms - paralyzes and consumes nematodes
Grows on coffee grounds and other agricultural waste
Produces enzymes being researched for biofuel production
Can fruit in as little as 7 days under optimal conditions
Name comes from shell-like appearance, not flavor (though some detect subtle seafood notes)