Ever wonder—at length—about what really is going on inside plants? Until I read this intriguing book on a doesn’t-really-feel-like-spring-yet day, I would answer that question glibly with, “Sure, photosynthesis.” But Stefano Mancuso, a neurobiologist, now has changed all of that for me. The work’s sub-title promises a “New Understanding of Plant Intelligence and Behavior,” and it fully delivers on that promise. Having read it, I will be visiting Bedrock with a new appreciation of what I see there.
The author starts with the premise of something we all know, but have perhaps not fully appreciated: Plants differ from animals in a couple of ways that are most significant to their evolution. The first is the obvious one that plants do not possess mobility; here the author further points out that this attribute (never call it a lack of an attribute) has led plants to evolve a survival strategy that emphasizes adaptability instead of migration. The second major difference is that plants do not exist on the model wherein single organs perform specific functions; all forms of the more complex animals, for his main example, have a brain, which functions via a connected neural network.
In contrast, the model for plants is a diffusion of function. This characteristic has been of paramount significance to the evolution of plants, and necessary for the success of plants’ adaptation strategies. It is especially significant with respect to what he terms “diffuse intelligence.” The diffuse nature of a plant’s intelligence and the functional repetition in a plant’s body are essential to its evolutionary success and survival. Mancuso does not go so far as to say the evolution of plants is in anyway superior to that of animals, but he demonstrates how their evolution is equally successful, given the fundamental differences that exist. I found his points on diffuse intelligence and plant behavior most intriguing.
Citing a few examples here should draw you in to reading this fascinating book. First, can plants learn? Can they receive cues from the environment and adapt with an effective survival strategy? Consider Mimosa pudica, which reacts to vibrations or being touched by closing its leaves. Going back to Lamarck’s days, botanist found that repeated touching led it to cease that reaction. Originally attributed to a notion of “fatigue,” more recent studies have confirmed that what seems to be going on is that the plant is learning that the source of stimulation is not a threat, but instead, a benign, newer aspect in the environment, and something it can live with. Some sort of “learning” is taking place in the diffuse intelligence of the plant. Even more fascinating was the finding that Mimosa pudica retained something like a memory for up to forty days. Only partially understood, this behavior is felt to be actuated by some form of tropism that alters genes controlling such action in the plant’s cells (a process he terms epigenetics).
Mimicry by one organism of another as a survival mechanism is not that uncommon in the animal kingdom, and in fact has been known to exist with plants as well. Mancuso introduces the reader to what he terms the “King of Mimesis,” Boquila trifolata, found in the temperate rain forests of Argentina and Chile. Boquila rates the royal title due to its distinct and astounding ability to mimic different plants it grows near. This feat of botanical legerdemain really depends on two abilities, first to “perceive” the plant it will mimic, and then to manipulate its genes to alter leaf shape in different ways. The process is not fully understood. Epigenetics can generally serve as a description of the mechanism of the mimicry, but the perception of a different object to mimic relies on structures Mancuso terms ocelli, which provide a possible means of that perception. While he stops short of calling this seeing with eyes, he makes a case that there is something like that taking place. Boquila gives the impression that it perceives something and somehow then actually synthesizes that information.
Here one should provide a couple of caveats; one, that scientists have yet to fully understand some of the processes described, and two, because we have always conceived of intelligence along a certain, centralized paradigm, our very language in describing what I would term “plant-think” is somewhat limited in its effectiveness, and, as a result, one can fall into too much anthropomorphism in descriptions. These two aspects might limit the book’s impact with some readers. Nevertheless, the story of Boquila is fascinating.
There are several other interesting behaviors Mancuso cites: how plants manage moisture, especially in arid climates; how they use different cell structures with what amounts to hydraulics to adjust position and open and close at different times of day; how they manipulate insects for pollination as well as for protection from predators and even competing plants. Much of the book is about what we can, and have, learned from plants and their evolutionary strategies. Further, Mancuso cites several engineering and architectural designs that were inspired by plant structures. Did you know that London’s famous Crystal Palace was based on a design inspired by the structure of a plant named Victoria amazonica?
Sometimes the digressions go a bit far for my taste, especially in the final chapters, and so, if you’d rather not dive too deeply into different kinds of tropisms for example, perhaps this is not the book for you. Yet I found the book intriguing by and large and the science on an approachable level. It has given me a deeper appreciation of what I see when I walk through Bedrock Gardens, knowing now that the flora there represent much more than a passive beauty. An extra, nice plus of the book are its beautiful photographs. “The Revolutionary Genius of Plants” is published by Atria publishing (a Simon and Shuster imprint), runs around two hundred pages and costs $30.00.