Thank you. Rhyn retusa is super cool too. Last July, my retusa sent out a healthy spike but it was aborted when was about 5" long. I still don't know what I did to it (or didn't do.)
How do you grow yours?
I just fastened it to a tree outside here in semi shade. I live in the subtropics. Seems to be liking where it is at the moment. It had two spikes this spring though its just starting to establish its roots on the tree.