Demia testudo, I think Selenicereus testudo now. Since you cannot plant this outside, don't worry about the flowers. I think that in the 18 years I have been online, I have seen exactly one pic of these kept as a houseplant that bloomed. They get big, and the roots that come out of the sides help it climb your walls.

Hmmmn...a wall of cactus...now that would be a sight to see! Thanks, Dzitmoidonc for the id. Think I'll put my dog tail cactus in a hanging pot while he's still a puppy ;-).
regards, seedmoney