I remember reading about the banana crisis perhaps a year ago. Seems there are plenty of banana varieties but none exactly like the 'common banana' _ I forget the name - that is prevalent in a lot of places. I seem to remember there was at least one that was pretty close. Thing is, the growing areas are have been primarily dedicated to one variety.. so changing that would take time.
(I didn't read the article yet, maybe I'm just repeating what it said.)
Just read it.. Cavendish, I thought it started with C.
Well, hey, that's what can happen with little diversity in planting.