If I'm not mistaken, there have been some study on plant communication and data elaboration from their roots, enough to classify them as at least primitively intelligent. Anyway, since they are in fact living and autonomous being, I don't see why they shouldn't be considered subjects of ethical reflections...
If we don't say bacteria need ethical reflections, then it is very unlikely that plants will either.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.