Pleurotus ostreatus

Oyster Mushroom

Beneficial

HabitatIn overlapping shelved clusters on dead and dying hardwoods — logs, stumps, and standing trunks — especially in cool weather.

Background

The oyster mushroom is one of the most common shelf fungi on dead hardwood across North America, growing in tiered, overlapping clusters of soft, fan- or oyster-shaped caps in shades of white, grey, tan, and brown. Its gills are white and run decurrently down a short, off-centre stem or attach directly to the wood. It is a vigorous saprotroph, and unusually it is also nematode-trapping — its mycelium can paralyse and digest tiny roundworms for nitrogen.

It is a prolific decomposer of logs and one of the great recyclers of woody debris, turning fallen hardwood back into soil. There is a superficially similar toxic species, the jack-o'-lantern, but that is bright orange, grows in dense clumps from soil over roots, and has true thin gills and a central stem; the oyster is pale, shelf-like, and grows directly out of the side of wood with a stubby lateral stem.

Beneficial — decomposer

A fast, efficient recycler of dead hardwood, returning woody debris to soil. Its mycelium also traps and digests soil nematodes, giving it a minor role in below-ground pest balance.

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