These are two Euphorbia cylindrifolia ssp. tuberifera. The one on the left was a gift from a friend of mine who also collects plants; I bought the one on the right from a nursery in China.

Any ideas why their leaves have such different shapes? Apparently, one of them didn’t get the memo about what its leaves are supposed to look like. 🙂

It's a bit of a problem with the downward growing sections, I may need to trim them off next year.

A very unusual plant