Thanks for the inputs. At the top of the entry I linked, it says, "
⚠ Version 1 of The Plant List has been superseded.
This name is in version 1.1 of The Plant List, record tro-8900496, and has not been changed."
I took it at face value, silly me, I guess.
Also curious why, if flapjacks is just the common name, they would punctuate the sign as a cultivar name. Is that the convention throughout the gardens' signs? And still curious why there are plants in the MOBOT garden that aren't in their database.