Bob, I think the first two are 'Undulata Univittata' and the last one is plain 'Undulata'. The white strip is wider on the last one, That stripe will, in time, likely become narrower and the plant will be called 'U Univittata'. And it will likely , in time, become completely green, 'Undulata Erromena'.
This essay on the undulata variations is interesting -
https://www.delvalhosta.org/un...
