King oysterPleurotus eryngii

The cap of king oyster is 4 to 12 centimeters across, up to 15 centimeters in cultivated specimens. When young it is convex with an inrolled margin; with age it becomes flat or funnel-shaped and depressed. The surface is smooth, dry or faintly velvety, and matte. The color is grayish brown, light brown or beige, darker in the center, often with fine radial fibers. In wild mushrooms the cap is usually smaller and darker than in greenhouse-grown ones.

The hymenophore is gilled. The gills are white or cream, fairly crowded, and run noticeably down the stem (decurrent), often all the way to its base. The spore print is whitish or pale pink. Decurrent white gills combined with a thick central stem set king oyster apart from the side-stemmed, wood-dwelling oyster mushrooms.

The stem is the most distinctive feature of the species: thick, dense, white, central or slightly off-center, 3 to 10 centimeters tall and 1–3 centimeters thick, often club-shaped and swollen. It provides most of the edible flesh. Unlike other oyster mushrooms with a short lateral stem, here the stem is well developed and meaty. There is no ring and no volva.

The flesh is white, dense, springy, almost cartilaginous, and doesn't change color when cut. The taste is pleasant, nutty and mushroomy, with a rich umami note that only fully comes through during cooking. Thanks to its dense texture, the flesh hardly cooks down or turns mushy and holds its shape well, which is why the mushroom is so valued in the kitchen.

The smell is faint, pleasant and mushroomy, somewhat indistinct in the fresh mushroom but becoming rich during cooking. Aroma is not a defining feature; the mushroom is recognized by its thick white stem, decurrent gills and growth on the ground among steppe umbellifers.