Plant Consciousness ✨

It’s a few years since I first became acquainted with the concept of ‘masting’.  Andrew, having driven off to the village shop one day, arrived home courtesy of the local garage proprietor. Our car had gone into limp mode ie put itself on an obligatory go slow. The reason for the ‘limping’ was a revelation for both the garage mechanic and us. The car’s innards - every ledge, every gap but most significantly the air intakes, were stuffed with acorns. It was unbelievable. Mice? Or the work of a very slim and bendy squirrel? Either way, the evidence of industry was incredible - and not least from the tree! So many acorns! Thousands of them.

        But this little mouse or squirrel must have gone on to the great acorn store in the sky because, as previously mentioned, the products of what looks like another mast year are currently all over the drive.

       A mast year is when trees produce a significantly larger-than-usual amount of their fruits or nuts (called mast) And at up to 10,000 acorns per tree for oaks, the expression ‘larger-than-usual’  is a gross understatement. Why, having been here for over twenty years with the same oak tree, we weren’t acquainted with this concept before, I can’t explain. But I do remember occasionally thinking that we seemed to have an oak tree that didn’t produce acorns.

    And yet, having a small creature industriously stuffing the car with them was possibly the least surprising aspect of the phenomenon. The bigger surprise was learning that oak trees can coordinate their masting across areas covering hundreds of miles. How?

    The obvious ‘go to’ coordinating factor is the weather. Weather does play an important role, especially for wind-pollinated trees like oaks. Factors such as spring temperature, drought and frost influence whether a tree will have a mast year. Favorable weather cues at critical times (like flowering or seed setting) can cause populations of trees to mast at the same time.

    Yet, the weather can be very localised in this country and to comment significantly on the mapping of the mast phenomenon over local weather patterns would need elaborate meteorological equipment everywhere, repeated acorn counts and such painstaking scientific assessment of endless minutiae that even the most dedicated ecologist might flinch at the task. In short, it hasn’t been done to any extent.

     It is, in fact, acknowledged that environmental factors cannot be the whole answer. Other forms of long-range coordination, even communication, are being looked at. It is known that trees communicate through chemical signals - mostly volatile oils - to warn each other about pests or drought, so it’s plausible that they use chemical signals to synchronise seed production. Chemical signals don’t sound much but think of pheromones in people and animals. Just a vague whiff of something that isn’t produced by Dior and which people can neither see nor consciously smell, yet suddenly it’s mating time.

   Then there’s the "Wood Wide Web” of mycorrhizal networks - fungi which connect tree roots - enabling the transfer of water, nutrients and, potentially, signaling chemicals. There is growing evidence that these networks allow trees to "share information," which could help explain mast year synchronisation across a forest. But again, proof that this drives masting specifically is not yet definitive.

     This coordination of seed production is obviously helpful. A lot of creatures eat acorns (though the tannins in them make them toxic to others (New Forest ponies for example) so producing thousands of acorns across an area creates what is termed ‘predator satiation’. Producing predator satiation every year would be too exhausting for a tree, hence the mast years. Work on the English oak (Quercus robur) over 27 years in southern England found strong mast years about every 5–7 years, with partial/medium crops in between. Coordination of mast years is just an evolutionary step up that serves the entire oak tree population.

     Of course, nobody would believe that this mutual benefit was any form of intentional altruism or cooperation. A collective payoff is simply mediated through genes - genes that favour coordination have higher survival odds ie it’s natural selection.There are other aspects of plant behaviour that give rise to similar discussions eg kin recognition: Some plants (e.g. sea rocket Cakile edentula) grow fewer roots when next to kin, but aggressively extend roots against non-kin.

      Again, this is really genes “helping themselves” because the genes in one plant are also present in its relatives. And there is no need for anything approaching consciousness. The “decision” is built into growth rules triggered by recognition cues like root exudates, volatiles and mycorrhizal mediation. There are narratives in science that have to be followed and the evolutionary principle of natural selection and the ‘selfish gene’ is one of them.

    So, the concept of an academic discipline called plant neurobiology - as if plants had some sort of neural network akin to that in people and higher animals - went down like a lead balloon amongst certain scientific hierarchies in the USA. Plants are aneural organisms so the concept of plant neurobiology ‘a priori’ cannot exist! Members of a plant neurobiology faculty would have to sneak about the corridors and have their coffee on their own. Which, as Peter V Minorsky of the Department of Natural Sciences, Mercy University, Ferry, NY, USA clearly stated in his paper, ‘The Plant Neurology Revolution’, is exactly what happened. To such an extent that fear of reputational damage precipitated a faculty name change to Plant Behavioural Biology.

    Minorsky reviews this scientific battleground quite extensively and he begins his paper with revolutionary questions : ‘Are plants intelligent? Can they learn? Are they sentient? These are just some of the unorthodox questions considered by proponents of the modern plant neurobiology movement.’

       It is in the academic space created by this movement that plant neurobiology (or “plant behaviour/plant signaling and behaviour”!) touches philosophy and even cognitive science. According to Minorsky there are three main sub-disciplines of biology holding this space : plant ethologists, plant electrophysiologists and plant comparative psychologists. But there are others and, worldwide, a number of researchers are explicitly trying to bridge the gap between observable physiological responses and the possibility of awareness, sentience, or proto-consciousness in plants.

     My curiosity about plant sentience was actually aroused before my acquaintance with masting. It’s been years, around the early sixties in fact, since it was demonstrated that plants respond to sound waves ie vibrations. And to the extent that, according to measurable parameters, they had preferences in music. Certain sound waves stimulate plant cells, encouraging nutrient movement and activating their metabolic processes towards easier absorption of water and nutrients and so on. But not all music or, more correctly, all sound waves.

     Gentle music, especially violin music, will increase growth and fruiting whilst heavy metal hardens the cell walls and can even be fatal. This has to be disappointing for gardeners who, like me, are one time fans of Black Sabbath. I first came across this music concept as it related to white mice. Laboratory mice subjected to Mozart and suchlike became very smart at finding their way through mazes. Those who got heavy rock ate each other. Didn’t stop me from watching a video of Ozzie Osbourne’s last performance even though it made my cell walls harden and brought on an urge to bite Andrew’s head off.

      Talking to plants hasn’t done the King’s reputation a lot of good in most quarters but in 2009 the RHS (Royal Horticultural Society) conducted an experiment with tomato plants and recorded human voices reading different texts. Plants that were ‘talked to’ grew faster than controls growing in silence. Plants exposed to female voices grew slightly taller than those exposed to male voices - it was hypothesised that the frequencies of female voices were closer to the range plants are known to respond to (~200 Hz). Whilst not peer-reviewed, this was a controlled, public experiment that got a lot of attention.

      So why would plants, rooted and silent, be sensitive to sound ie vibration at all? Basically, it helps them thrive in their environment - the same way seeing and hearing help us. Roots head towards the movement of underground water locations, leaves increase their level of unpalatable defence chemicals when the vibrations of caterpillar munching or approaching herbivores are picked up. When the the wing beats of pollinating insects are in the vicinity plants boost their level of reward sugars. But not when it’s non pollinators.

        Smart? Any sort of consciousness? Not at all. Mainstream plant physiologists are in full agreement with the selfish gene narrative of the evolutionary biologists. Though plants might be highly responsive, everything can be explained by well-known physiological mechanisms (hormones, ion fluxes, gene regulation) and words like “intelligence,” “awareness,” or “consciousness” are just misleading anthropomorphism.

        Nevertheless, the philosopher Michael Marder, a professor at the Universty of the Basque Country argues for a “philosophy of vegetal life”. He suggests that we should take seriously the idea that plants have a form of subjectivity or awareness, though radically different from animals.

     A leader in the plant neurobiology movement is Stefano Mancuso of the University of Florence. He talks about plants as ‘networked organisms’ with distributed sensory systems, and he’s open to the idea of plant awareness in a broad sense  - not necessarily consciousness, but perception and integration of information.

     A UK proponent of “plant intelligence” is Anthony Trewavas of the University of Edinburgh. He argues that plants exhibit decision-making, learning, and memory via distributed signaling networks - not consciously as in our understanding of the word but certainly cognition-like. He points to roots doing ‘risk-sensitive’ foraging. Perhaps we couldn’t really call this risk awareness - roots may explore multiple patches at random and when one patch provides a higher return in terms of nutrient availability, feedback mechanisms simply reinforce root growth in that patch.

    Yet it isn’t that straightforward - not a physiological response to more nutrients. Experiments with wheat and maize have shown that their roots ‘prioritise’  growing into phosphate rich soil over nitrogen rich soil because they ‘know’ that nitrogen is more water soluble and stands a greater chance of coming to them from seepage than do phosphates. They don’t, of course, do any ‘prioritising’ or any ‘knowing’. It’s all explainable by physiological feedback systems selected for during evolution. Plants in phosphate rich soils built up more carbon (got bigger/stronger) ie were more successful survivors. Their physiological feedback systems were thus ‘selected’ for by The Blind Watchmaker.

       Mainstream plant physiologists stick rigorously, one might even say religiously, to “mechanism-only” language to avoid any accusations of anthropomorphism.

      As Minorsky discussed in his paper, to be a reputable plant scientist you must, at all costs, avoid the philosophically charged territory of calling plant responses anything approaching cognition, decision-making, or awareness.

        Plant electrophysiologists looking at the signals passing along the phloem cells of a Venus Flytrap as it closes on a fly, or the sensitive plant, Mimosa pudica as it responds to touch, have recorded action potentials and even neurotransmitter-like substances. But these phloem channels must not, in any way, be equated with the nerves of animals.

      As blinkered, and sometimes aggressive, as adherence to accepted scientific narratives can sometimes be, science conducted along such lines has given us great things. The broader, exploratory brush strokes of the polymaths of the past are no longer effective currency because being accused of pseudoscience is a career killer.

      For the modern researcher at his bench, the ‘evidence based everything’ approach requires the foundation of a million minutiae on which to build progress. One ends up looking deeper and deeper into less and less and it’s the rare scientist who becomes the one who puts it all together in the grand theory of everything in the way Watson and Crick got to do with DNA.

     The plant ethologists for example still seem to be discussing the fact that plants, unlike other organisms without a brain eg amoeba, might not even be within their remit because they can’t move. You’d be surprised how much can be said about not being able to move in this context. But covering basic territory like this is what a claim to bona fide science requires before work can be accepted. As with science in general, most scientists in the field of plant behavioural biology will end up as one of the unsung and not as the one who finally gets to demonstrate that plants are having subjective experiences.

     All of which means that it’s obviously much easier to have everything  come to you at once in a trance.

   Edgar Cayce, often called “The Sleeping Prophet”, believed that all life, including plants, existed within a universe fundamentally composed of vibration and energy. His readings, delivered in trance states between 1901 and 1944 in Kentucky and Virginia Beach, described a metaphysical view where consciousness and vibration permeate all things, including the plant kingdom. It’s probably over twenty years since I read a book called Vibrational Medicine which, whilst not denying that biochemical equations summed up the body’s metabolic activities nicely, suggested that they were far from the whole story.

    Edward Cayce claimed that everything in existence is held together and animated by vibration. Plants, according to him, have unique vibrational signatures that not only define their physical presence but also their spiritual and healing qualities. Each plant’s “life force” vibrates at a particular frequency that interacts with the wider spiritual ecosystem. Cayce further insisted that plants are not merely physical entities or sources of medicine, but conscious and spiritual beings. He described them as “conduits for specific energetic qualities” that humans can sense, resonate with, and even use for soul-level healing.

      According to Cayce, plants “speak” an ancient, vibrational language that operates beyond ordinary perception. This language is not verbal but transmitted through frequencies, intention, and presence - what some might now call energy or vibrational medicine. Cayce advised that cultivating close relationships with plants - by tending, talking, and being mindful with them - could harmonise a person’s own vibrational state and foster spiritual growth and healing.

  Talk of vibration and frequency etc sound all very familiar and scientific so can one draw any analogies between modern physics and Cayce’s metaphysical descriptions? Naturally, one runs into much the same protests as met the plant neurobiologists. Reputable scientific circles forcibly distinguish contemporary quantum and vibrational models from metaphysical or mystical interpretations. Lack of quantifiable grounding forever precludes scientific acceptance - the same factors, in fact, that finally finished the concept of vitalism together with the idea that you could have anything as preposterous as a soul.   

    While quantum mechanics and superstring theory describe reality as fundamentally vibrational at subatomic levels, even with the foundational work of Penrose and Hammeroff on quantum phenomena in the human brain, their proponents baulk seriously at the idea that plants could possess intentional consciousness or energy fields influencing human souls in the manner Cayce described.

      Which, sadly, shows how unfortunate it is that, as Minorsky says in his paper, and I quote : ‘The field of plant psychology got off to a shaky start in the figure of Gustav Fechner [1801–1887], a brilliant German polymath who made important contributions to experimental psychology, philosophy, and physics. Unfortunately, Fechner’s interest in plant psychology arose during a period in his life, from 1839 to 1843, when he descended into a debilitating madness that nearly killed him. As he was emerging from this near-death experience, he had a mystical experience as he walked through his garden: he noted that the flowers were all illuminated from within as if revealing their souls to him.’

    Even though Fechner  wrote a fine book on the subject and dedicated it to Nanna the Nordic goddess of flowers, his insistence that what he experienced during his NDE were wholly supported by science didn’t seem to take.

     More recently the sound scientific plant neurobiological research of Monica Gagliano PhD currently at the University of Sydney may have been tarnished in some eyes by her popular writings where she talks about the spiritual dimensions of the botanical world in which she developed an interest due to her experiences after ingesting the psychoactive brew ayahuasca.

        Science is a jealous god and is far from predisposed to condone the putting of mystical ones before it - or even allowing them into the lab. And yet, ‘visions’ have moved science forward in the past.

       August Kekulé, a German chemist, is said to have suddenly understood the ring structure of the benzene molecule after a daydream in which he saw the ancient symbol of a snake biting its own tail - the ouroboros. This vision came while he was dozing by the fire and it triggered in him the grounbreaking idea that the six carbon atoms of benzene were arranged in a closed ring. 

         Plant neurobiology is, as Minorsky explained, an umbrella discipline for the historically marginalised sub-disciplines of biology. What most of them have in common is that they favour a more natural and holistic approach towards understanding plant function through the use of continuous, nondestructive measurements. Fortunately it’s a time when numerous new and innovative measurement technologies are emerging, so plants don’t have to be dissected and mashed and centrifuged to death to find out what makes them tick. By which point of course, what you find - including the biochemistry - is nothing approaching what you started with. If a plant responds to the wingbeats of insects and the chewing noises of caterpillars within minutes, imagine what biochemical changes getting mashed up and whirled round in a centrifuge can precipitate.

       In their desire to be more natural in their approach these far-from-mainstream disciplines are perhaps a throwback to the era of the Romantic Biologists. This era was at its peak in the early 19th century and included the polymath Wolfgang von Goethe whose fresh perspectives - and they were perspectives in that they stemmed mostly from close observation and thinking - helped plant the seeds of the theory of evolution.

        Whereas the mechanists like Descartes, Newton and Cuvier saw organisms as machines reducible to parts, functions and efficient causes, the Romantic biologists saw organisms as living wholes, self-organizing with inner purposiveness and unity of form. Their attitude to nature was reverent, holistic, and organicist because they saw it as alive, interconnected and creative, not a dead machine.

      Whilst both attitudes/approaches are perhaps necessary for progress, I found it a comfort to learn that, within the halls of the modern mechanists, plant neurobiologists are being brave enough to raise the banner of the Romantics.