It points to an inadequacy in the theory of animal rights. Even if we succeed in no longer having a world based on the exploitation of animals, it will still be a world based on the exploitation of plants on a massive scale. Plant exploitation parallels animal exploitation. Agriculture is a constant battle against the plants, insects and other animals that initially lived on the land. One can say that individual plants are not aware, but they are alive and try to remain that way, which differentiates them from, say, rocks.
Plants have all kinds of chemical defense systems that go in to action when the plant is damaged.
Plants are extraordinary. They do a lot of responding to their environment. They can do almost anything you can think of. If anyone should be at least open to the possibility that plants have some level of awareness, it is vegans since we continually chide others for not acknowledging animal awareness. But whether or not plants are aware is not really the issue.