What common edible mushroom is also known as the portobello?

What common edible mushroom is also known as the portobello? The answer is Agaricus bisporus. Portobello is the mature, fully grown brown form of this cultivated mushroom species. When harvested younger, the same species is sold as a cremini, chestnut, or baby bella mushroom; white immature specimens are commonly called button or champignon mushrooms.

Agaricus bisporus is a basidiomycete fungus native to grasslands in Eurasia and North America. It is now cultivated in more than 70 countries and is among the world's most widely eaten mushrooms. As the mushroom matures, its cap expands and darkens, developing a firmer texture and deeper flavor that suits grilling and stuffing.

The name portobello is a marketing name rather than a separate species. Spelling variants include portabella and portabello. Wild mushroom hunters should not assume that every similar-looking Agaricus is edible: poisonous lookalikes can cause severe illness, and identification requires more than appearance alone.