Daisy, I am truly looking forwards to his answer.
I figured maybe schilleriana is one of those thick leaved plants/Cacti which go through CAM cycle by closing their pores during the hot days to preserve moisture. I always thought that the thick velamen on Orchid roots also has pores/stomata, facilitating nutrients and water exchange. Isn't that one of the characteristics of epiphytic Orchids?
I am certainly confused here too....
