formation), then plants definitely remember.
For example a Venus Fly Trap needs to have two of the hairs on its leaves touched by a bug in order to shut, so it remembers that the first one has been touched. But this only lasts about 20 seconds, and then it forgets. Wheat seedlings remember that theyâve gone through winter before they start to flower and make seeds. And some stressed plants give rise to progeny that are more resistant to the same stress, a type of transgenerational memory thatâs also been recently shown also in animals.
While the short term memory in the venus fly trap is electricity-based, much like neural activity, the longer term memories are based in epigenetics â changes in gene activity that donât require alterations in the DNA code, as mutations do, which are still passed down from parent to offspring.
6. Would you say, then, that plants “thinkâ?
No I wouldnât, but maybe thatâs where Iâm still limited in my own thinking! To me thinking and information processing are two different constructs. I have to be careful here since this is really bordering on the philosophical, but I think purposeful thinking necessitates a highly developed brain and autonoetic, or at least noetic, consciousness. Plants exhibit elements of anoetic consciousness which doesnât include, in my understanding, the ability to think. Just as a plant canât suffer subjective pain in the absence of a brain, I also donât think that it thinks.
7. Do you see any analogy between what plants do and what the human brain does? Can there be a neuroscience of plants, minus the neurons?
First off, and at the risk of offending some of my closest friends, I think the term plant neurobiology is as ridiculous as say, human floral biology. Plants do not have neuron just as humans donât have flowers!
But you donât need neurons in order to have cell to cell communication and information storage and processing. Even in animals, not all information is processed or stored only in the brain. The brain is dominant in higher-order processing in more complex animals, but not in simple ones. Different parts of the plant communicate with each other, exchanging information on cellular, physiological and environmental states.
For example root growth is dependent on a hormonal signal thatâs generated in the tips of shoots and transported to the growing roots, while shoot development is partially dependent on a signal thatâs generated in the roots. Leaves send signals to the tip of the shoot telling them to start making flowers. In this way, if you really want to do some major hand waving, the entire plant is analogous to the brain.
But while plants donât have neurons, plants both produce and are affected by neuroactive chemicals! For example, the glutamate receptor is a neuroreceptor in the human brain necessary for memory formation and learning. While plants donât have neurons, they do have glutamate receptors and whatâs fascinating is that the same drugs that inhibit the human glutamate receptor also affect plants.
From studying these proteins in plants, scientists have learned how glutamate receptors mediate communication from cell to cell. So maybe the question should be posed to a neurobiologist if there could be a botany of humans, minus the flowers!
Darwin, one of the great plant researchers, proposed what has become known as the “root-brainâ hypothesis. Darwin proposed that the tip of the root, the part that we call the meristem, acts like the brain does in lower animals, receiving sensory input and directing movement. Several modern-day research groups are following up on this line of research.