Book Review: What A Plant Knows, by Daniel Chamovitz
If you enjoyed Peter Wohlebben’s The Hidden Life of Trees, as I did, then you will find much to appreciate in What A Plant Knows, by Daniel Chamovitz. Chamovitz, Director of the Manna Center for Plant Biosciences at Tel Aviv University, presents an explanation of the scientific evidence regarding plants’ abilities to see, smell, feel, hear, remember, and understand where they are.
Plants do not experience these senses as we do. They don’t have eyes or brains; so they cannot see by creating mental pictures the way animals can. However, plants do have photoreceptors very much like the ones people have in the back of their retinas. In plants, these photoreceptors can be found in growing tips and in leaves.
Plants do not grow toward the light because of photosynthesis, they do so because the photoreceptors in the growing tip sense the light. If you cut off the tip, the plant will no longer move toward sunshine. Plants detect different kinds of light and respond to them in different ways. They can also measure the amount of light they are exposed to.
One of the really interesting things is the similarity in how the senses work at the cellular level in both plants and animals. Chamovitz explains that these similarities derive from a shared genetic heritage that goes back millennia to a time before organisms evolved into the plant and animal kingdoms.
For instance, the lobes of a Venus Flytrap close because an electrical current is generated when a potential prey touches two of the inner filaments – a process very similar to muscle contraction in an animal. An animal brushing past or an insect chewing on a leaf – all generate an electrical response in plants at the cellular level.
The ability to hear is one sense that plants lack. In fact, plants possess some of the genes that are associated with deafness in humans. Chamovitz reviews some of the studies purporting to show otherwise (including some claiming to show that classical music is good for plants, while rock and roll is harmful) and finds them flawed. So don’t bother with that outdoor sound system, unless it’s for your own enjoyment.
The author closes with a discussion of whether plants can be considered intelligent. He argues that the question is not very useful. Plants are more like us than we generally imagine, but they are not just like us. Scientists and gardeners alike imagine that their plants are happy or sad (I certainly do). The relationship, however, is entirely one-sided. Chamovitz argues that plants have a complex sort of awareness, qualitatively different from that of an animal, but remarkable all the same.