Agaricus bisporus

Agaricus bisporus (common name: portobello mushroom) is a mushroom native to grasslands in Europe and North America. It has two color states while immature—white and brown—both of which have various names. When mature, it is known as portobello mushroom.

When immature and white, this mushroom may be known as common mushroom, button mushroom, cultivated mushroom, table mushroom, and champignon mushroom. When immature and brown, it may be known variously as Swiss brown mushroom, Roman brown mushroom, Italian brown mushroom, or chestnut mushroom.