Well, do you plants have a central nervous system? All vegetarians can rest at ease â€“ the answer is invariably no. I have to give it to them â€“ plants are often more aware than people realize. They are often aware of what is going on around them and can respond to light and shade, can mobilize chemical defenses to ward off predators, and sometimes seem to be able to communicate. But their response is purely chemical. They lack the brain, spinal cord, and neurons that need to be present to experience pain. In fact, they don’t even have anything that slightly resembles them.