Ever since I started studying neuroscience, plants have always fascinated me. These guys don’t have a nervous system, really, but they are able to do a lot of things we would normally expect to require a nervous system. A recent book – which I hope to read soon, by god I put it near the head of my 300+ goodreads “to read” list – has a lot to say on how plants experience the world:
When Chamovitz introduces the baffling way that irises appear to “remember” what color of light they last saw or how the parasitic plant dodder (Cuscuta pentagona) can “smell” whether it’s next to a tomato (one of its preferred hosts) or a stalk of wheat, it’s hard not to share his enthusiasm for unraveling these mysteries. He elaborates on elegant early experiments in plant biology as well as modern-day discoveries, providing a window on the work of the many scientists who clarified the mechanisms driving these perplexing phenomena. The latter include the use of genetic mutants of the botanical workhorse Arabidopsis to unveil 11 different photoreceptors that allow the plant to discern, among other things, whether it was last exposed to the red light present in the morning or the far-red light present in the evening. Finely tuned gas chromatography has revealed how dodder differentiates between the attractive chemicals in eau de tomato and the repulsive ones ineau de wheat.
…Consider proprioception, the sense of the relative position of our body parts in space that allows us to complete coordinated movements without tripping over our own feet. Do plants have something like proprioception? Certainly, says Chamovitz, but for plants, it’s about the position of their parts relative to gravity.
Photoreceptors? Odor receptors? Proprioception? These all seem like fundamental attributes of our sensory nervous system. And yet what use does a plant have for a nervous system? It moves too slowly to really need one, I imagine. They can also sense and communicate with each other in a way that seems similar to how bacteria sense and communicate with each other. I imagine we have a lot to learn from plants about basic principles for nervous system integration of social and sensory inputs.
PS. There’s more here!