Like all edible bananas, [the Cavendish (AAA group)] members have been long cultivated and are hybrids of Musa acuminata and M. balbisiana. The “AAA” is a genetic designation, which specifies the members of this group as triploids (having an extra set of chromosomes) rather than diploids, the natural genetic state of most plant cells. In contrast, tetraploids would be noted as “AAAA” and diploids as “AA.” The letters in “AAA” also distinguish its relative genetic content from Musa acuminata (A) and M. balbisiana (B). Because Cavendish bananas are triploid, having an extra chromosome copy, they are more vigorous than average bananas and produce larger fruits in greater quantity.
-from the Learn2Grow website.
UPDATE: This afternoon we went down to the Homestead area with Van and Juliet to a nursery called "Katie's Going Bananas". Among other things, Don (Katie's husband I think) told us that bananas are NOT GMOs. He definitely had a few not nice things to say about GMOs and said that the soy and corn here in the US were pretty much GMOs, but that Europe has done a much better job. We learned a lot about growing bananas and bought another plant, this one a different variety. That will be the subject of a separate post, but I needed to inform the world that bananas in the US are still non-GMOs. Whew! (We stopped off at Robert is Here.)