Plant sentience – a slippery slope

I maintain a “Garden Professors blog” group on Facebook, where people can pose questions and make suggestions. Ellyn Shea asked about the trend towards calling plants sentient, especially given the new book by Daniel Chamovitz – What a Plant Knows: A Field Guide to the Senses

Dr. Chamovitz is a respected scientist, and there is no doubt that plants sense and respond to their environment in ways we are still learning to understand. But couching plant responses in language associated with human sentience is a slippery slope.  Yes, it makes plant physiology more understandable to nonscientists, but it also leads to increased belief in pseudoscientific ideas. For example, here’s a response to an on-air interview with the author (the link is my own insertion):

“Over a hundred years ago Rudolf Steiner wrote about biodynamics and plant growth. Their sensitivities to the seasons, their environments, and humans…”

Here’s another:

“I have been talking to plants for years…our experimental garden overflows, the cellular intelligence, the capacity to communicate is deeply satisfying when you learn how to listen and feel what the plant is saying…they give us much information at a spiritual level as well as physical, i thank my flowers verbally, i sing to them,they respond in healing ways…water has the same living intelligence…talk to a glass of water with love before you drink it and it actually improves the feelings of health and flavor ….”

And another:

“One who understands this far more thoroughly than Chamovitch is Stephen Harrod Buhner, author of The Lost Language of Plants and the Secret Teachings of Plants, in which he details the most cutting edge cardio-neurological science which demonstrates that the heart (more neurons than muscle cells) is the body’s primary resonator and capable of direct energetic communication with the rest of the living community. All indigenous and ancient peoples knew this.”

Plant physiology is drastically different from animal physiology, and what we’ve learned about how plants work comes from centuries of careful scientific study – not from folklore and superstition.  For those of us Garden Professor types who spend time educating the public about plant sciences, anthropomorphizing plants or using imprecise language just makes our jobs more difficult.

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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

21 thoughts on “Plant sentience – a slippery slope”

  1. Linda:
    You’ve hit on one of my pet peeves. I’ve spewed a lot of red ink on sentences like “The tree thinks it’s under stress so it tries to grow more roots to reach water”.

    I think a lot of this hinges on what do we mean by to ‘know’. I haven’t read Chamovitz’s entire book – just the two chapter preview. But it seems like in every case he is just using the word ‘know’ where most people would commonly use the word ‘sense’. Do plants sense light? Of course they do. Do they know it’s light out? They do in the same way that I know my office is too warm right now. But not like I know if I go out without a coat today I’ll freeze.

  2. Kevin, in your experiments keep in mind that few mature plants in nature grow long taproots. This is a seedling adaptation; the taproot disappears in most perennials. Mature trees and shrubs have wide, shallow root systems more like a pancake than a carrot. This enables them to collect water and nutrients most effectively. Deeper soil layers generally don’t have much oxygen and they don’t support root growth.

  3. How does one talk lovingly to water? “You pretty little glass full of water?”
    Maybe you’d get better vibes if you talked dirty to it. “You clear, hot mess of covalent bonds and microscopic organisms. I’m getting wet just looking at you.”

  4. Ray, I got a bit derailed over the last few months. I’m hoping to have the complete draft done before the holidays.

  5. Clearly semantics is a big obstacle to considering plant sentience. No one will argue that plants take in food. They don’t have mouths or stomachs, so they don’t “eat,” they “photosynthesize.” We have to create new words to describe how plants “know” “sense” “decide” “communicate” etc. so we can discuss the issue rationally.

    The truth is probably somewhere between “Plants have no nervous system so they are not conscious in any way” and “Plants can psychically communicate with me.”

    Personally, I have an open mind. It is species-centric to think there is only one way to be conscious, or that what humans can prove to be true is the only truth. On the other hand there’s not much evolutionary advantage to feeling pain but having no means of locomotion and limited defenses. So I’m hoping that carrot isn’t screaming when I take a bite.

  6. I’ve enjoyed this. I’ve been telling people from my area to view plants in the environment where they are, notice the geology, species, sun shade etc and figure out what the plant is telling you about itself and it’s requirements and what does and doesn’t make it happy. I’m presently experimenting with a long tubular a meter long inside a long plastic pipe as a mean of growing Mesquite, Acacia or Palo Verde the desired way they want to grow in the wild. I used a long tall glass jar to illustrate the point where the root grow almost 3 foot in length with only a small sprig of leaf growth above. I then ask the folks to explain what the instructions are in the plants DNA for growth in order of importance. Obviously roots are more important in Desert environments than top growth. So I’ve created a container system to allow for that. i’ll test it next year when I go back home in April. Clearly there are ways they can speak to you if you observe and know what to look for. Thanks for this post. Also the facebook page.

  7. Hi Linda, thanks, yes I know that about not all producing taproots. That’s why my experiments are specifically with desert species and their deeper roots. I have a fascination with all things desert, yet here I am in Svenskland. Plant’s are also limited by the geology underneath the surface, yet the recently in the Cornell University study showed how plant roots have a mechanism for buckling and twisting to compensate when encountering an obstacle like clay or fractured rock. So kool. I made sense of what I saw in deep layers of fractures rock and clay where I viewed roots in deep bulldozed cuts into a mountainside on someone’s property in the San Jacinto Mtns. Made me realize to the challenges of some of the southern California housing tracts on mountainside where sterile crush granite boulders after being dynamited are made to use as foundation for housing pads with viewpoints. My sister had one of those pads and I installed the landscape. The top layer of soil was a reddish-brown clay loam which was meant to look like top soil. It was only about 6 inches deep. Underneath this faux topsoil layer was the blue gray of crushed compacted granite stone, some of which were giant chunks of rock the size of airline luggage case. Still the native plants from the area did better than the commonly used ornamentals she purchased at the nurseries early on. Still I’m amazed at the challenge some plants have in penetrating complex soils.

  8. There are some other factors about root networking that intrigue me, but you will not exactly find these subjects like Hydraulic life & resdistribution and/or descent in most discussion. Yet research work is everywhere, but apparently shelved. Still I’m intrigued. Reading about the ability of Mangroves to transport oxygen from the surface to the roots makes you wonder if this is also a mechanism some land plants also employ from files and programs in their vast genetic library. That’s what makes researching all the more fun knowing that not everything is known. The greatest challenge however is the ability to dump a lot of the intellect speak and make it interesting to the average person who is distracted more and more away from out natural world. Great subject again Linda.

  9. Many of the reviews on Amazon come from people who seem to have a science background, yet they praise the book.

    And the plant on my desk was reading along with me, and it wants me to say (because it can think and feel, but not type) “Boy, Linda really doesn’t get us.” That is the plant talking, not me.

    And my keyboard says “Stop poking me!”

  10. I have been waiting for a book like this to be written! Hooray! Finally, some common sense and science rather than emotional reaction! Good job.

  11. Hi Linda, I’m glad my book has sparked discussion. Just curious to what interview you refer to as having the link would probably be fairer so as to allow your readers to see all comments (and not just the kooks), and the original interview. I’ve NEVER talked about Steiner or championed pseudo-science, as could potentially be misconstrued.

  12. Hi Danny, thanks for commenting! I’ve included the link here (I should have done it earlier):
    I really don’t have a problem with the scientific content (I’ve not seen the entire book yet) – it’s just the way the information is framed. Words matter. As Bert pointed out in the first comment, saying that plants “know” rather than sense something can be construed by many people as evidence that supports their pet belief, whether it’s biodynamics or water memory or some other pseudoscience.
    I do appreciate you and other scientists who write for popular audiences – there aren’t enough of us doing this important work. I just like to see writing that doesn’t immediately lead some to think that “plants are people, too.”

  13. There’s a debate I’d like to watch between Dr. Chalker-Scott and Dr. Chamovitz, perhaps with a panel discussion afterwards of GP’s and invited guests. Resolved: The pedagogical advantages in using anthropomorphic imagery in educating the general public about consumer horticulture outweigh the complications that ensue from the general lack of knowledge between Science and Pseudoscience from the target audience, within the context and constraints of the Land Grant University mission.

  14. Ray, I like this idea. Danny, if you’re game, drop me an email. You can find it on my web page (linked to my name above). It will be a couple of months before I can put this together, but it could be fun!

  15. I like the idea of using common ground teaching illustrations. Choosing words carefully and not going beyond the intent so as to give an impression that causes the reader to totally miss the point if it’s original intent. I don’t think this kind of word/terms gets very far except within a new age type of movement where belief is that plants are some sort of sentient being with a soul or whatever other nonsense. I’ve tried talking to some who actually believed plants understood what was being said and there is no way of convincing them otherwise. So I leave them to their story. I just gave some illustrations today in my seedling container post which I have not finished, but we’ll see if the point gets across. Or if it gets totally blown out of proportion and the subject gets totally lost.

  16. I understand the concern with wording and the conclusions that people might jump to. I also agree with Ellyn Shea’s comment above. I’m not so sure consciousness is as easy to pin down as we assume. Even the definition is still murky. And I fail to see human sentience as completely different from that which Dr. Chamovitz describes in the exerpts of the book that I’ve read. What I’ve taken away may be different than what others have, but ultimately its all chemical reactions in different organisms.

  17. Just a further comment on the subject at hand. I of course agree for the most part about some of the New Agey(is that even a word?) ideas, concepts, words, terminology for things observed that they cannot explain. I would imagine it was similar back in history when ferocious thunderstorms developed and ancient Greeks thought it was Zeus and Apollos having a war in heaven throwing lightning bolts at each other. I have a fondness for the work of Viktor Schauberger and I’m with a group who researches his writings and theories on obtaining energy from water. However if you google the man, you’ll run across all manner of websites and groups who are into aliens, spirits, various fascinations with ancient mystics etc. And these are folks in the modren day and age. But let’s be fare. People have huge disappointment with the leadership offered them by politics, religion, Business which includes the Sciences. Going further on into honesty, Scientists and most Researchers don’t exactly encourage people up to their level. They tend to talk down to people(not all, but the majority). Their insistence on Intellect Speak and strict association within their own inner circles leaves the vast majority of mankind out in the cold. They already get this from their political and religious leaders and it’s unfortunately forced them to look elsewhere for answers. Some Scientists have been great communicators of otherwise boring scientific phenomena like Carl Sagan or even today with David Suzuki. The make science things fun and use common words/terms that the average persona can relate to. I’m also guilty of poking fun at some of the odd ball things but have the last couple of years tried to change that. I don’t discount everything automatically that sounds crazy. I look to see if there is another possible explanation for the phenomena. Often times I find research papers that have nothing to do with a certain subject at hand, but rather it does provide an explanation for something totally different, even if the one who wrote the paper doesn’t even realize it. Most of your posts target myths, fables and out right storytelling. But Science also delves into the Metaphysical Storying where data leaves wide gaps on a subject matter. That’s why we have words/terms like inferences, assumptions, assertions, speculations etc. The reason is clear and the public is beginning to take notice. Science doesn’t know everything and it’s as fallible as anything else humans do, though it’s leadership often have a hard time admitting this which makes them the mirror images of other leaders who run this world we live in.

  18. I have just read the book. It’s short and well-written so it doesn’t take long. Here are some of the main points I got: Real scientists confirm that plants are aware. Plants do have senses that function like and unlike human senses, using completely different biological parts and processes than animals. There is no evidence that they feel pain, emotions or have a “soul.” (of course there is no evidence that humans have one either). There are currently no good words to describe these newly discovered plant functions. So I say, let’s make some up. Instead of plant “vision,” let’s call it “photoreception.”And so on. So we can start talking about the science without tripping on the words. And let’s remember that language is mutable: mere decades ago, “gay” “crash” and “tweet” meant completely different things than today.

  19. I have not read the book but have listened to the interview on-line. the underlying science may be correct, but I agree that the author has used incorrect words to describe the process. Statements like plants know and plants see will just give the general public the wrong impression, which will lead them to false conclusions. This is an example of poor transfer of science to the general public.

  20. Steiner was a Nazi sympathizer whose entire “philosophy” (actually a functional cult that still exists today) was based on a bizarre and deeply racist worldview. There is nothing even vaguely wise about any of his teachings. Biodynamics is both the least kooky and the least evil of his contributions…and even then, when you scratch beneath the surface, the crazy racist underpinnings pop up. You constantly give him too much credit here by tempering your criticism. He was L Ron Hubbard of another generation…just more racist.

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