King oyster

Overview

The king oyster, also called king trumpet, is Pleurotus eryngii. It is a firm-fleshed mushroom with a thick stem, and the stem is the part most often cooked. The species is native to the Mediterranean basin and nearby regions, and it has spread through commercial cultivation to many countries.

Its name is tied to the plants it grows with. The catalogue associates it with the roots and remains of plants in the Apiaceae, and sources connect it to Eryngium, the sea holly. The name is therefore a clue to its habitat, not a description of its shape.

Taxonomy

The catalogue notes that the eryngii complex contains distinct lineages and varieties. Records under the name P. eryngii can therefore refer to more than one genetic line, and a result for one strain does not automatically carry to another.

The catalogue treats the name as a research label, not as a checked accepted name. Cultivated strains are often sold under variety names, so a commercial product should be matched to its species before its record is used.

Ecology and wild range

Sources place the wild range of the king oyster across the Mediterranean basin, North Africa and the Middle East, with records in parts of Asia and Europe. The species grows in association with the roots or remains of plants of the Apiaceae family.

Sources disagree on the host. One account describes it as a weak parasite on Apiaceae roots rather than a wood decomposer, while another says it grows from hardwood tree roots. The catalogue's record points to the Apiaceae association, and the second account is not supported by the others.

History of use and cultivation

One source records wild foraging of the king oyster in southern Italy since antiquity. The sources do not give a dated text for that foraging, so the statement rests on the source's own account.

Accounts of when cultivation began conflict. One says that the first scientific cultivation trials took place in Italy and France in the 1970s. Another says cultivation began seriously in Italy and France in the early twentieth century. The sources do not reconcile these dates, so none is given as settled here.

Most sources credit Japan with the technique that made commercial production reliable. One account says that Japanese researchers refined fruiting on supplemented sawdust blocks in the 1990s, and that the method then spread to Taiwan, China, Australia, Europe and North America.

Cultivation and substrates

Commercial growers usually use sterilised substrates made from hardwood sawdust enriched with wheat or soy bran, in bottle or block systems. In China, substrates include large quantities of sawdust and sugarcane bagasse.

A subtropical study found that paddy straw gave the highest biological efficiency of the substrates it tested. Results depend on the substrate, the strain and the climate, so the study does not establish a universal recipe.

Food use

The catalogue records the species as a firm mushroom with stems and caps used for cooking.

The sources read give no recipe that is specific to the species beyond cooking. The catalogue records no traditional preparation, and no preservation method is given here.

Scale of production

The China Edible Fungi Association reports 1.52 million tonnes of P. eryngii cultivated in China in 2022. The Mushroom Almanac calls the king oyster one of the four most commercially important mushroom species in the world.

These are production figures, not a measure of food safety or quality. They describe a cultivated product, and wild and farmed material should be kept distinct in any record.

Safety

The catalogue's caution is that the eryngii complex contains distinct lineages and varieties, and that the record is a food, market and cultivation record rather than a safety assessment. The sources read raise no safety concern specific to the cultivated species.

Wild material should be identified by a specialist before it is eaten, and wild and cultivated material should be kept apart in any record.