Pleurotus eryngii (also known as king trumpet mushroom, French horn mushroom, eryngi, king oyster mushroom, king brown mushroom, boletus of the steppes, trumpet royale, aliʻi oyster) is an edible mushroom native to Mediterranean regions of Europe, the Middle East, and North Africa, but also grown in many parts of Asia.
Pleurotus eryngii is the largest species in the oyster mushroom genus, Pleurotus, which also contains the oyster mushroom Pleurotus ostreatus. It has a thick, meaty white stem and a small tan cap (in young specimens). Its natural range extends from the Atlantic Ocean through the Mediterranean Basin and Central Europe into Western Asia and India. Unlike other species of Pleurotus, which are primarily wood-decay fungi, the P. eryngii complex are also weak parasites on the roots of herbaceous plants, although they may also be cultured on organic wastes.
Its species name is derived from the fact that it grows in association with the roots of Eryngium campestre or other Eryngium plants (English names: 'sea holly' or 'eryngo'). P. eryngii is a species complex, and a number of varieties have been described, with differing plant associates in the carrot family (Apiaceae).
Pleurotus eryngii var. eryngii (DC.) Quél 1872 – associated with Eryngium ssp.
Pleurotus eryngii var. ferulae (Lanzi) Sacc. 1887 – associated with Ferula communis
Pleurotus eryngii var. tingitanus Lewinsohn 2002 – associated with Ferula tingitana
Pleurotus eryngii var. elaeoselini Venturella, Zervakis & La Rocca 2000 – associated with Elaeoselinum asclepium
Pleurotus eryngii var. thapsiae Venturella, Zervakis & Saitta 2002 – associated with Thapsia garganica
Other specimens of P. eryngii have been reported in association with plants in the genera Ferulago, Cachrys, Laserpitium, and Diplotaenia, all in Apiaceae.
Molecular studies have shown Pleurotus nebrodensis to be closely related to, but distinct from, P. eryngii. Pleurotus fossulatus may be another closely related species.
The mushroom has a good shelf life and is cultivated widely.