Posted: 07/11/2015 at 17:25
They are musa basjoo. They put a lot of energy into flowering and the pseudostem will die back in time, but it also will through up a lot of pups in return. The flower can be cut off...I am not sure if the seed will be fertile or not and you already have a good clump.
You can cut off the flower to see if it stops the pseudostem from dieing back but as it has already put in so much energy into flowering I suggest it is too late. I would let them die back and allow the pups to grow.