I feel like Spock’s interest in plants in this episode is both a call back to The Cage (the way Spock grips the office plant before melding with it felt very similar to the way he gripped the signing plants in that episode) and possibly a call forward to TAS The Infinite Vulcan, where we learn that Spock’s ultimate fate is to live among a planet of sentient plants in a giant cloned body.

(It’s interesting to consider that a copy of his consciousness was returned to his original, diminutive body at the end of that episode. I wonder what adventures that small version of Spock might have had? We may never know…)