I figured these are Musa acuminata, probably var. siamea. This was at Tubkwang Swine Research Station in NE Thailand, just outside of the property. We stayed there one night (I still remember the very cold shower!), and I got these pics the next morning before we left. As it drew close to time to leave, I looked around and realized that the grass was 8 feet high and that I was completely turned around and lost. I did eventually make it out, obviously, but that was not fun. Plus, I was covered from head to toe in grass burs. Anyway, enjoy the pictures!
The moral of the story is, if you see a field of wild bananas in Thailand, make sure you know how to get out.