Let’s begin with a simple experiment.
Take a look at the pictures above and note what you see.
Were your answers humans, moose, frog, deer?
You’re not alone. When Italian botanist Stefano Mancuso posed the same question to his university students, 96%-98% said the same. If your mental image of animals is sharper than that of plants, welcome to being human. As Christina Ro points out in her article “Why ‘plant blindness’ matters – and what you can do about it”, this begins young. Children recognise that animals are living creatures before they can tell that plants are also alive.
Recall tests tend to show that people remember pictures of animals rather than of plants. A US study testing “attentional blink” – the ability to notice one of two rapid-fire images – using pictures of plants, animals, and unrelated objects, proved that participants more accurately detected images of animals than plants.
Back to Mancuso. In his TED talk, “The Roots of Plant Intelligence”, he showed his audience an illustration of animals trundling into Noah’s Ark, and asked: “What is wrong with this picture?”
“The problem is…” he said, “Where are the plants?”
While a passage in the Bible’s Genesis declares that two of every kind of bird, of every kind of animal and of every kind of creature that moves along the ground will come to Noah to be kept alive – there is no mention of plants.
Because, Mancuso said, plants weren’t, still aren’t really, seen as “living creatures”.
A point that doesn’t necessarily come from the Bible, but one that has largely, he said, “accompanied humanity.” All the way back to Aristotle, and De Anima, a text which sets out his theory on the souls possessed by living things, where he marginalises plants to the edges, between living and non-living, with “low-level” or vegetative souls.
An image from a Renaissance-era book that Mancuso also shared, illustrated this “order of nature”, placing stones at the lowest point in the hierarchy, and immediately after, plants. Then animals. And in case you were wondering, at the peak of the pyramid is man, though not just any common man, but “homo studiosus”, the scholarly man.
Our plant blindness
Let’s cast a quick glance back at the images opening this article.
Maybe you’ll notice now what they all have in common – they comprise 80% of plants. But our brain, as Mancuso explained in “Are Plants Conscious?”, is extremely adept at filtering out this information. In fact, it’s a tool that protects us from being overloaded with details about “un-useful green stuff”. We evolved in forests and the outdoors, and it was much more important for us to be aware of animals and other humans.
This tendency is so widespread that Elisabeth Schussler and James Wandersee, US botanists and biology educators, coined a term for it in 1998: “plant blindness.” The inability to see or notice plants in the environment. Though these days, the term has become increasingly controversial, based as it is on a disability metaphor; that is, it reflects deficit-based thinking around blindness. Botanist and science communicator, Beronda Montgomery, in her newly published Lessons from Plants, offers us another term for our tendency to overlook plants: “plant bias”.
Plant bias leads, unsurprisingly, to a general under-appreciation of plants – it prevents us from noticing that, as Mancuso stresses, “the earth is made of plants.” In fact, all of 99.7% of it. It’s a green planet, and all the animals, humans included, form merely 0.3% of life here.
Mancuso is also founder of plant neurobiology, a relatively new focused field of plant biology, which explores signalling and communication at all levels of biological organisation, from genetics to molecules, cells and ecological communities. For him, it is unbelievable that plants and their extraordinary abilities have gone under-appreciated for so long.
His books, Brilliant Green: The Surprising History and Science of Plant Intelligence; The Revolutionary Genius of Plants: A New Understanding of Plant Intelligence and Behaviour; and The Incredible Journey of Plants, attempt to redress this oversight. His findings are fascinating.
Bodies without movement
To begin with he reminds us that given plants are largely sessile – ie, they can’t move from place to place – they are often easily subjected to predation. And so, as protection, they evolved not to have any organs that concentrate particular functions within them – a stomach to digest or lungs for breathing. “Having organs is too dangerous.”
The lack of organs doesn’t mean they have no “bodily” functions though. Plants are also able, Mancuso claims, to see without eyes, hear without ears, and taste and smell, and breathe – as well as, most startlingly, to learn and memorise. How are they able to do these things?
Well, though plants may be sessile they move immensely in situ, in both passive (the opening of a pinecone) and active (a Venus flytrap closing over an insect) ways. They respond to humidity, temperature, gravity, light and darkness – all without using energy (muscle), dependent only on what plant material is made up of. Young sunflowers “play” as they grow together in a cluster, plants sleep, they can hear, and respond to sonic vibrations (growing towards the sound of running water, for example), they communicate with other plants, animals and insects, and can distinguish kin from non-kin all by producing chemical volatiles (metabolites that plants release into the air).
Their sessility also makes them, we learn, much more sophisticated in sensing than animals. Every single root apex, for example, is able to detect concurrently and continuously, at least twenty different chemical and physical parameters.
And all this without a brain?
According to Mancuso, the root apex of a plant contains a “transition zone” within which “action potential” signals are emitted, the same signals that the neurons of our brain use to exchange information. Added to this is the fact that even a small plant, like rye, would grow about 13,815,672 roots (a length of 622 kilometres!), which translates into a very large surface area.
Each root apex works in a network with the others – much like the internet – and in this way evolved to survive predation. You can take away 90% of the root apparatus and the plants continue to survive. (Fortunate given how ineptly I repot my house plants.)
It isn’t difficult to discern that at the heart of Mancuso’s research is the desire – and rightfully so – to dismantle the hierarchical “order of nature” that has dominated scientific and cultural discourse through the ages, particularly in the West. And to reinstate plants as beings more than worthy of our appreciation, admiration, and awe.
For Beronda Montgomery, plants can do all this and more. In Lessons from Plants, she provides for us a companion term to “plant bias”, a term that encourages a deepening awareness and appreciation of the plants around us: “plant awareness”. Reducing plant bias and increasing plant awareness are important not only for plants, she states, but for humans – for our physical, mental, and intellectual health.
In a similar vein to Craig Holdrege’s excellent Thinking Like a Plant: A Living Science for Life, Montgomery encourages us, after careful, close observation, to ask questions to learn from plants about how to live with purpose, agency, and intention. “And maybe we can take on some of these behaviours,” she adds. “Their lessons are ours for the learning.”
Which is a noble idea, though perhaps given that she inserts these “lessons”, thoughtful as they are, at the end of every chapter, they begin to read, after a point, slightly sententious. While I appreciate her highlighting the importance of intentional self-reflection while observing a bean sapling, something like “nurse plants remind us that we thrive better when we work together” reads more as platitude.
Nevertheless, the chapters are still bountifully engaging – and though I may have skipped the “lessons”, there is much to learn. That plants, for example, can sense “where” they are and respond to more than mere environmental conditions, that their awareness extends to “who” the plants and other organisms are that surround them.
Plants, Montgomery says, may even have a form of memory – if we consider memory as cellular communication about prior experiences – mediated in some cases by epigenetic changes (changes that modify how genes are expressed or activated, though they do not alter the genetic code itself). One of the best-known examples of this is vernalisation: certain plants will not flower until they have been exposed to a length cold period.
The winter is “remembered” as a sign that the plants should flower in spring. Thus, they also “learn” – if we understand learning as a change in behaviour based on active recall.
Signs of sentience
While it may seem to the uninformed eye that plants are just “sitting there”, they actually exhibit awareness and intelligent behaviour from the very earliest stages of development until senescence or death. They are constantly exploring, monitoring, making dynamic decisions in response to a dynamic environment.
Montgomery acknowledges that the idea that plants “behave” rather than passively existing or growing has only recently become more widely accepted among biologists. They’re only just beginning to understand “behaviour” more broadly – as the ability to gather and integrate information about the internal and external environment and then using that information to alter internal signals or communication pathways.
Once we acknowledge this, Montgomery asks, does that mean plants are also able to “choose”, “make decisions”, and have “intention”? Some botanists – and she goes on to explain why – would say yes!
Lessons from Plants explores a range of other plant behaviour. How they decide to compete or collaborate – constantly assessing whether neighbouring plants, insects, fungi, and bacteria are friends or foes, and making choices about how best to focus their energies to gain required resources. How they assess risk – botanists have become aware, Montgomery says, that they do so in much the same way as animals do so.
How plants construct new habitats, whether that be in an abandoned factory or after a natural disaster like a volcanic eruption – a principle of ecology is that no two species can occupy the same niche or play the same ecological role in the same location; one will outcompete the other. And how this niche complementarity leads to complex and maximised allocation of resources.
The unique abilities and behaviour of different species work only to enhance and benefit the collective. And most extraordinarily, how plants “plan” for the future – whether via accelerating their life cycle, or changing colour in the fall to prepare for winter, or sharing resources – via the root apparatus—between older trees and younger plants in less-than-optimal conditions.
Montgomery’s attempt to raise and deepen our plant awareness couldn’t have come at a more necessary time, sadly. Plant bias may have started out as a useful survival tool at the beginning of our evolution, but is now a problem. This general under-appreciation of plants, as Ro notes, results in plant biology courses around the world shutting down, public funding for plant science drying up.
Increased urbanisation and time spent with devices means that “nature deficit disorder” – the harm caused to humans by being alienated from nature, the outdoors, the wild – is on the rise. And with less exposure to plants comes greater plant bias. Worse is that it leads to limited interest on our part in plant conservation, which, as many will point out, matters for environmental health, but also, ultimately, for human health.
If you’re looking to awaken or deepen your plant awareness, Mancuso’s and Montgomery’s books are a good place to start – as are the wealth of scientists drawn from, and paid homage to in Lessons in Plants. Robin Wall Kimmerer, and her astonishing Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants, which serves to remind us that many indigenous traditions around the world have known, celebrated, and storiated plant awareness for thousands of years.
Among the others, Evelyn Fox Keller’s A Feeling for the Organism, her acclaimed biography of scientist Barbara McClintock, Hope Jahren’s revelatory Lab Girl, Amy Leach’s book of essays Things that Are, that urges us to reconsider our kinship with the wild world, Andrea Wolf’s The Invention of Nature, revealing the forgotten life of visionary German naturalist Alexander Humboldt, the little known but thought-provoking I will not Die an Unlived Life: Reclaiming Purpose and Passion by Dawna Markova, and even Japanese “pseudo-scientist” Masaru Emotu’s controversial The Hidden Messages in Water.
These books necessitate a reordering of the natural world, where man, studious or not, shares common space with plant, animal, and yes, even thing, a reweaving of the web of life, as it were, with little to no place for arrogant speciesism. The pyramid is replaced by a network apparatus, intricate, breathtaking, awe-inspiring, infinitely fragile, and infinitely connected.