Welllll...from a narrative viewpoint it's kind of ingenious, but Evolutionarily it makes no sense because plants always adapt themselves to attract they prey and/or symbiotic partners.

Although on second thoughts it still makes no sense as a narrative, because the standard plot trope is that a person confronted with their worst fears will attempt to confront them an thereby break free (as I presume Superboy does).

A far better trick would be the one presented in last year's Doctor Who episode, "Amy's Choice" - where there were multiple dreamers, and the initial dilemma is that both the dream-world AND the real-world seemed normal to one or more of them. If you're tricked into living a life that is merely different - no better, no worse, just an alternative - you could live that one for decades without realising.