Naive question, possibly poorly formed: what is the purpose of the parts of the plant? Eg the leaves are for collecting energy and the flower for reproduction...so is the "thing" that all that work is going to benefit really just the root stem?
Your version of the question has surprising perspective- I think you are asking what the "it" of the plant is. That's an interesting personification of a plant. I think it points to the fact that plants may be safer underground- for anchoring, for not being eaten, for getting shielded from harsh elements.