Pleurotus ostreatus - Oyster Mushroom

Taxonomy

Phylum: Basidiomycota

Class: Agaricomycetes

Order: Agaricales

So variable in size, shape and colour are the many kinds of oyster mushrooms that confident identification of some species is tricky without resorting to microscopic analysis. The process is not helped by the fruiting habit of many Pleurotus species that seem to delight in emerging beyond reach, sometimes high up in the crowns of trees. For the most part the various oyster mushrooms are saprophytic on deciduous trees, and only very rarely are they found on conifers.

Pleurotus ostreatus, the Oyster Mushroom, is edible and said to taste like its bivalve namesake as well as copying its shape. They are very similar in texture, too. These mushrooms are now produced in cultivation and readily available in supermarkets in Britain and Ireland; in many European countries wild Oyster Mushrooms are much sought after in deciduous forests.

The genus name Pleurotus is Latin for ‘sideways’ and refers to the lateral attachment of the stem; ostreatus is a reference to oysters, and in shape the fruitbodies do generally resemble oyster shells.

Identification Guide

	Cap White, cream, brown, or blue-grey (var. columbinus - picture, left, courtesy of Richard Haynes); usually bracket-like with either a radial stem or an eccentric stem; convex gradually becoming centrally depressed with a wavy margin; 5 to 15cm across. Gills White, turning pale ochre with age; crowded; decurrent.
Stem	White or cream; woolly at base; no ring; 1 to 3cm long and 1 to 2cm dia.; tapering towards base.
Spore print	White or pale cream.
Odour/taste	Not significant.
Habitat	On dead wood of deciduous broadleaf trees, particularly Beech and oaks.
Season	Summer and autumn.
Occurrence	Common.
Similar species	Pleurotus dryinus has a frosted cap; its stem has a short-lived ring.