This essay on how all cells in our body can think and not just Brain Cells made for an interesting read. 

It turns out that regular cells—not just highly specialized Brain cells such as neurons—have the ability to store information and act on it. Now Levin has shown that the cells do so by using subtle changes in electric fields as a type of memory. These revelations have put the biologist at the vanguard of a new field called basal cognition. Researchers in this burgeoning area have spotted hallmarks of intelligence—learning, memory, problem-solving—outside brains as well as within them.

Recalling sad or painful memories can make the heart ache quite physically - we have experienced that. Maybe the cells in the heart can act on the memory and be triggered in a way that manifests a pain. People do have gut feelings about things and are known to act on it and often to their advantage. 

..a team of scientists at the University of Western Australia and the University of Firenze in Italy conditioned the plant by jostling it throughout the day without harming it, it quickly learned to ignore the stimulus. Most remarkably, when the scientists left the plant alone for a month and then retested it, it remembered the experience. 

I do believe that houseplants can tell when they are truly forgotten and abandoned versus when you genuinely help them thrive but missed a watering or two for reasons beyond your control. In the later case, they often rally and get back on track even they got in bad shape. If there is actual, willful neglect they won't bother. Maybe there is more than just wild imagination to such observations.