Back to the original topic. Here is the Jefferies pre-production sketch for the Herbarium from "Is There in Truth No Beauty?"
You can clearly see in the middle the fake door "carniverous plants" as described in the early screenplay (thanks GSchnitzer
) where Kirk had to keep Miranda from running in to.
While the left part is obviously the set of the Season Three Rec Room (I prefer to refer to as "Solarium") that was considered for shooting, Jefferies also wanted to add a bigger section towards the right which most likely didn't happen because of budget restrictions.
So finally Kirk and Miranda entered and left through the yellow double door "Corr." (otherwise used as the side door to the briefing room set and others) and the longer scene was probably deleted because there wasn't the other door Miranda could run to and endanger herself...
(cool, looks like I just got promoted to Fleet Captain)