The difference between white mushrooms, baby Bella or cremini mushrooms, and portabellas may surprise you. In fact, these familiar varieties are actually are not different mushrooms, but different cultivars of the same mushroom. A cultivar is a plant, or in this case, mushroom, of a particular species that is selected and/or bred for certain desired characteristics.
The white button, cremini (often called Baby Bella, and the Portabellas, all come from the most important and widely used genus of cultivated mushrooms in the western world: Agaricus. There are estimated to be above 200 species of Agaricus in North America. The name comes from Latin and means “gilled mushroom.” At first, all gilled mushrooms were placed in this genus but that quickly got out of control since there were lot of different but related groups of gilled mushrooms. So, other genera and families were designated.
Mushroom Species Agaricus bisporus
However, our three familiar cultivars are all of the genus Agaricus. What’s more, they are all the same species: Agaricus bisporus. These are not only cultivated in the U.S. but also heavily in Europe, China, and many other places.
I’ve noticed that many food blogs get this wrong. They say that all three of these mushrooms are just the same mushroom at different ages. That is at least half right but it is not quite the whole story. In this version, the white button mushroom is the young mushroom, the baby Bella is the middle-aged one, and the portabella is the oldest. This is incorrect. If you’ve ever seen really big white mushrooms and really small baby bellas, you’d have to wonder how this age thing worked.
Saying that they are the same mushroom of different ages makes it seem as if the growers have white button mushrooms growing, and if they wait, the mushrooms turn brown and so they are cremini (crimini/baby bella) and then if they wait a little longer the mushrooms open their caps and get much larger. Actually what happens is that in a bed of Agaricus bisporus, only the second or third crops will form brown caps and brown gills if they are not picked in the button stage. These are called the “fruiting bodies” of the fungus. When these mature they become the large open portabella, hense the name “baby Bella” for the smaller ones.
Portabella mushrooms have a similar history to lobster in that they used to be considered junk. They would be taken home by the growers, being unfit to sell to the public! The cremini, as mentioned, is a younger stage of the portabella, before the caps have opened. Call it clever marketing if you would like, but I love portabellas and I am glad they are no longer withheld from sale.
Ever Heard of a Champignon Mushroom?
Before you rush out to find this fancy French mushroom, yes, you have heard of it. It is Agaricus bisporis again. There are lots of other names. Table Mushroom, Roman brown, Italian brown, or just “cultivated mushroom,” among others. It’s also called the “French Mushroom” sometimes. The word mushroom itself is not scientific, but colloquial. The mushroom itself is the spore carrying “fruiting body” of a fungus.