Dan MaloneyOK, let's get started. Greetings all, and welcome to the first Hack Chat of 2021! I'm Dan and I'll be the mod today as we welcome back Lex Kravitz, whom we've had on a few times but never before to talk about Plant Communications.
Lex, are you out there yet?
heh
Yes sorry!
haha right on the dot
Great timing, no worries!
Thanks :)
Happy New Year!
Howdy
Happy New Year all. I am a neuroscientist at Washington University in St Louis, studying obesity in rodents. I make a lot of open-source stuff you can see here: https://hackaday.io/projects/hacker/294140. Today we’re going to talk about plants, which do not become obese (as far as I know), but they do move and behave, have electrical signaling, and can learn things (depending on your definition of learning).
Hey Again!
I dunno, avocados can be pretty fatty...
I can tell you a bit about plants and electrical signaling, and maybe we can all talk about plant intelligence, to be clear I'm not an expert in this, I have just played around with some plant experiments at home. But I think it's a cool topic and it's very accessible if anyone is interested in starting to do this stuff on their own
Hmm
Interesting
A tiny bit of background reading: In 2013 I read an article by Michael Pollan on the intriguing topic of “plant intelligence”, you can find it here: https://www.newyorker.com/magazine/2013/12/23/the-intelligent-plant. He remarks on the uncontroversial knowledge that plants can sense and respond to many stimuli: “light, water, gravity, temperature, soil structure, nutrients, toxins, microbes, herbivores, chemical signals from other plants” and also talks about the more controversial questions or whether plants have intelligence or can demonstrate the building blocks of intelligence such as learning and memory.
So after reading that article I purchased some seeds and grew two of the plants noted in that article (Mimosa Pudia or “sensitive plant” and Codariocalyx motorius or “telegraph plant”). These are special plants that both exhibit rapid movements (you can see them move by eye and capture amazing movement videos with a timelapse camera), and they also have robust electrical signaling. I’ve been recording electrical signals from these plants with cheap amplifiers from Backyard Brains, a company that produces affordable neuroscience equipment for hobbyists and educators (https://backyardbrains.com/products/plantspikerbox). To get us started I can also share a few videos from backyard brains showing the type of electrical responses these places make. ,
I put some photos and videos of my experiments up here: https://kravitzlab.com/plants
I did not record from any avocados unfortunately!
Back in the 70s for a science fair project I built a galvonometer and attached it to a geranium plant. (I was in 7th grade...) I recall observing that various stimuli affected the readings on the galvo. I haven't yet looked at your links, but are you doing something like that?
After our chat yesterday, I'm getting really interested in picking up a plant spiker box for my own experiments with electroculture.
Quick question on the fast movements of the Mimosa spp. -- any idea what the mechanism is for that? I mean, they don't have contractile tissues AFAIK, so is it like a hydraulic change that moves the leaves?
Food for thought? French bean plants show signs of intent, say scientists
They've provided us with companionship and purpose during the darkest days of lockdown, not to mention brightening our Instagram feeds. But the potted cacti, yucca, and swiss cheese plants we've welcomed into our homes are entirely passive houseguests. Aren't they?
@scubabear Yup exactly like that. I am using a small amplifier from BackYard Brains instead of building my own, but basically just wrapping a small wire around the stem of the plant and recording the signals that the plants make
Have you tried recording 24/7 to observe the circadian rhythms?
@Dan Maloney Yup it's hydraulic! There are "water cells" at the base of the stem and they plump up with water to keep the stem upright and then rapidly export water via transporters to deflate when triggered
Here's a question, do plants still get nutrients from the ground even if the are off the ground, say in a hanging pot?
How would I go about measuring that?
Cool, thanks. How do you differentiate between signals the plant makes and, say, the plant acting as an antenna for RF or EMI in the environment?
@martin.timms I love that question!!! That was one of my first ideas and I recorded some mimosa plants for ~4 days straight. They had more action potentials at night, when they are in their "sleeping pose".
I remember connecting mine across a single leaf. How do you know where to attach on a plant?
And regarding mimosas, how does the signal to change the pressure propagate?
I know plants respond to electric and magnetic fields. But we have to wait awhile to see if the plant reacts well to dosage, etc. I think the spiker box would be useful to see if there are immediate effects.
This may be way if topic I was just wondering
"...and can learn things (depending on your definition of learning)". Please, why don't you give us your definition of learning that allows us to discuss vegetable IQ?
@Dan Maloney I suppose you can put the plant into a Faraday's cage before running the test
@Lazer.Coh3n If they aren't touching the ground I don't think they could get nutrients from it
Oh ok thanks
an art/hack project by a friend of mine: |sound fertilizer" for the plants: http://gentlejunk.net/2016/06/12/sound-fertilizer/
@Lex Kravitz According to some recent papers, there is evidence to suggest that the so called 'Wood-wide-web'/MCN (Common Mycelial Networks) that are known to connect plants of the same species (mostly) do not just interchange chemicals (mostly nutrients) , but might also employ electrical signalling to warn eachother of environmental changes (insect-attacks, droughts).. Have you been able to look into that at all ?
@DrG I define learning as a change in the response to a constant stimulus, so processes like “habituation” (where a repeated stimulus evokes a smaller and smaller response) are a form of learning, and the Mimosa plant clearly shows this. Not as exciting as learning to sing songs or do math, but a rudimentary form of learning.
@Vesna Looks like a cool project. I know someone using sound to improve the growth of his crop.
The return of 'Metal or Mozart' for better plant-growth ^.^
I'm wondering if a GSR monitor would be sensitive enough to detect these tiny signals?
@Dan Maloney @David One way around this issue is to put multiple electrodes on the plant! That way if you detect a response on one contact but not the others you can be fairly confident it is coming from something local to that electrode, like probably the plant and not an rf disturbance. I have a 4 channel system so I would put up to 4 electrodes on the plant. See the first photo here: https://kravitzlab.com/plants
I've looked into it somewhat... When plants react to stimuli and form action potentials, calcium signaling, some of the effects are the synthesis of plant hormones that warn other plants in the area or alert insects to come close to help or to stay away.
@Dan Maloney @David and the 4th photo shows all 4 electrode traces, with a nice action potential only showing up on two of the electrodes
Is the spiker box DC or AC coupled?
For circadian and diurnal cycle it is useful to observe the very slow changing DC component.
Decent hardware is available at: https://www.floranium.com/en/?sfw=pass1610568749
Good thought about multiple electrodes.
@scubabear in terms of where to attach the electrodes, for recording from Mimosa I found that putting them along a nice straight piece of stem was good for detecting movement related action potentials. I have seen papers where they put them on the leaf though, and capture responses to damage such as insects biting!
Interesting design on those amps. Stackable?
I suppose a higher form of learning would be a Pavlovian response as shown by some pea plant experiments given y tube choices. Any thoughts?
@ghockings Some people have tried to do this type of learning, there's a nice review article on learning in plants, focusing on Mimosa here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4814444/
@ghockings Unfortunately the evidence that they can make these type of associations is not strong... a few scattered reports but nothing super solid
Lex, there are plenty of examples of learning that may not be too exciting, as you well know. This, however, is not learning and we have no reason to invoke principles of learning to discuss these processes. That's not what you want to hear in this chat, but I am sure you have heard it before. No reason for me to be distuptive, so I'll lleave you to it.
@ghockings I tried doing some of this by changing the light cycle on the plants and seeing if they could learn to move in a certain way to trigger the lights. It was unsuccessful but made some cool videos :) I put one up here: https://kravitzlab.com/plants
@allengd Some experiments long ago by Cleve Backster involved a GSR to sound circuit. Used for "plant ESP" experiments".
How does the plant detect light?
@wassermann cool hardware! Have you used any of that? I've only worked with the Backyard Brains hardware. I'm not connected to that company but I'm a fan, @Dan Maloney you might want to see if they want to do a hackchat at some point, they do more than plants!
Will do. Thanks!
I've read in different places about how mushrooms especially mycelial networks are crucial to the ability of plants to signal/communicate between eachother especially in a living ecosystem vs an individual plant in a box - do you know anything about the difference between plant responses/signalling with vs without other organisms?
/is it even worth differentiating given plants/lichen/fungi's weird ability to just like splice genes and chemical stuff
or to clarify - any projects that could show examples of these differences?
@phoebe.degroot Interested in the same thing. Asked whether Lex has had any experience detecting/observing electrical activity in Common Mycelial Networks (aka: 'wood wide web' . THere's some interesting papers that seem to suggest it's not just chemical activity.
@phoebe.degroot I don't know much about this, although there are amazing ways they communicate through roots to detect and even assist members of the same species, etc. In a very hand-wavy way it's chemical signaling, so excreting chemicals that other plants can detect
So do plants have excitable tissues? Or are they passing electrochemical signals in a fundamentally different way than neurons do it?
@Dan Maloney I know that plants have cells that are sensitive to the presence of electric fields. Not sure if it's all cells or certain ones.
That translates to tissues, stems, leaves... as they react before approaching thunderstorms.
@insensitiveclod One issue with recording from fungi like that is that it's hard to put an electrode on it. This is not an approach that can be done with all plants (they need to express a foreign fluorescent protein) but electrical signals can be observed through fluorescenct imaging, see here:
@David I'm thinking more of cells that specialize in transmitting action potentials. Just wondering if there's a plant equivalent of neurons.
@Dan Maloney I don't know if it's some cells in particular, but I do know that they do transmit action potentials throughout the plant.
Not a very helpful message, but just saying This is cool!
Take two plants that are electrically insulated from each other. Monitor the two plants, then connect the two plants together using only electrical conductors. This experiment allows observation of synchronisation between the two plants via only electrical means.
@Dan Maloney They have excitable tissue! Although they do not have single cells with axons like neurons, they pass electrical signals in a multi-cellular way, either via electrical junctions that pass from cell to cell, or via extracellular passageways like the phloem. The plant action potential can last 1-10s in duration, vs. neurons which are typically ~1ms. So one thing that's nice about recording from plants is that you can see the responses by eye and record them with low speed using a Arduino and the serial monitor connection
@martin.timms That sounds like an interesting test. As there are potential differences between different portions of a plant, one may stimulate the other and vice-versa.
So Treebeard was right -- it takes a very long time to say anything in Old Entish ;-)
@Dan Maloney there are specialized cells that help propogate the signals, for instance those lining the phloem, but there isn't an all in one cellular solution like a neuron in plants
@blorgggg !!!!!!!
My initial observation was that the two plants start off completely out of sync, but within a few days they become synchronised as if they are one plant. This experiment needs duplication.
I wonder if they would produce buds, flowering cycles, etc with the same exact timing.
@martin.timms I love the idea! To really go over the deep end though, there is evidence that plants may communicate acoustically too https://en.wikipedia.org/wiki/Plant_bioacoustics
@martin.timms That would involve the assumption that the electrical signals are 'broadcast' to whoever wants to hear it; but if the signals are very soft (which they likely will be), is it is likely that they are brought along fungal paths to be delivered only to those 'who have a need to know' ?
I've also heard that there can be forms of bioluminescent communication at play.
Other side note from panama, not directly plant electro-physiology, but monitoring movement (or growth/swelling) i've heard the rainforest trees here, if you measure their DBH (diameter at breast height) continuously with high precision (think of a VCLN -proximity sensor tied to a band), trees fluxuate a whole bunch throughout the day, more than we realize! and they will swell anticipating rain just from clouds and stuff
Of course, if you DO get a response, that'd be a very compelling bit of evidence to suggest that electrical signals are employed, and at least partly using 'broadcast'
@blorgggg I've heard the same thing about plants growing during the onset of thunderstorms.... I suspect they react to the increase charges in the atmosphere - to be better prepared to take a big drink!
That's awesome (and slightly creepy.. How do they know ?)
@blorgggg That's a cool idea! I'm not aware of this but this would be a great application of a simple sensor to measure plant behavior
@insensitiveclod , yes the experiment is artificial in that plants are not normally connected together with metal wires. The experiment is to show that the electrical output of one plant can influence the electrical behaviour of another plant.
@martin.timms Ack; understood. Some effort might have to be taken to prevent effects from electrolysis-products producing false-positives in detecting 'an effect'
(making a loop between two soil compositions, producing a current and introducing metal ions into soil/moisture)
@insensitiveclod Interesting thought... using highly conductive ground as the 'wiring' between the plants, right?
@David Yes/no. That is to say: that might work, but research on communication between plants via fungal fibers seem to suggest that it's really transported along the paths of the fungus, not directly just 'general soil'.
+ "Kinnomic Botany tests new educational tools for crossdisciplinary knowledge production, drawing from indigenous cartographies to create a set of alternative maps that shift attention away from enlightenment architectures and towards more than human infrastructures in the garden" https://twitter.com/UCL_mal/status/1345462262664810496
Both things would be interesting to study/detect , of course.. One a lot more complex to achieve than the other. As Lex pointed out (I wouldnt know, havent tried), measuring on fungus is likely to be ...well..tricky.
@insensitiveclod Yes I would imagine you'd need an optical approach like was done in the video I shared above
@insensitiveclod Unfortunately that approach requires genetic modification which is not applicable to all species, would need to be developed in the species of fungus you'd be looking at. But if it could be done it would create some really cool soil movies!
What experiments/projects are you working on now?
That prompts me to wonder how the method/ location of the connection affects the signals and communication - intrusive/non-intrusive methods - on the root/stem/bud etc?
@Lex Kravitz Ack. I believe that it was with Beech-trees that there was one specific fungus that basically 'takes over' the surrounding woods; making it perhaps possible to focus on that specific one (and not have to sieve through hundreds of possible candidates)
@David , the volatile compounds produced by plants are charged and provide good connectivity to the Earth's atmospheric field. The volatile compounds act similar to the ionising sources they used to have on lightning rods. Most plants are a fractal shape concentrating the electrical currents in the main stem. The flow of current through the main stem of the plant is influenced by atmospheric electrical potential. If you place the plant on an insulating surface, you can then measure this flow of current to an Earth rod. A plant might have 50 pA current flow to Earth, and several nA during a thunderstorm.
@ Phoebe I've only done the external "wrap the wire around the stem" type of recording. Professional plant researchers have many methods for doing more invasive recordings so they can get at the mechanisms of electrical transmission. You can think of the external method that I'm using like a single EEG electrode, vs. recording from single neurons. The benefit of the crude external recording method though is you can get going for ~$100 and some wire :)
@martin.timms You, sir, are givig me a great excuse to put my uCurrent-meter to good use, some time soon
....Just realized.... uCurrent ...is not going to cut it when pA/nA is involved.. Bah ;)
@martin.timms That's pretty awesome - do you know of a paper that talks about that experiment?
@mceldoon Currently I've been focused on my job and being in a pandemic unfortunately. I'd like to get back to the plant recordings though and record more circadian rhythms, in my last batch of experiments I detected that the Mimosa plant is much more electrically active at night (which is odd because its leaf movements are larger during the day). I'd like to do more recordings of that and see if I can mess with the light cycle to alter the circadian response. For instance, if I left a plant in constant light would it still have a daily cycle?
@insensitiveclod you should find how interconnected everything is at these current levels!
@martin.timms Capacitance-coupling, a lot of it, right ? DC ? Or are there AC-fields involved as well ? (semi-high-freq; not on minute-time-scales)
Also this reminded me of these plant cyborgs from mit media labs:
https://www.media.mit.edu/projects/cyborg-botany/overview/
@David , this was my own design of experiment. I have not found any papers describing similar.
@mceldoon Would be cool to make a display out of 20 x 20 venus flytraps :)
NeoVenusPixels.
Hahaha amazing
I love it. Like flip dots, but with plants
@martin.timms Pretty cool. Do you have any pictures of the test... I'd love to see & share on my FB group.
@Lex Kravitz @mceldoon Long ago I thought it would be cool to do something similar with electrically stimulated plants. The better growing plants via hidden electrodes would create a picture.
@insensitiveclod The plant has a DC current flow continuous due to discharge of surrounding field from the conductivity to the atmosphere over it's own height. There is an AC component due to locally static disturbances or up to several km during a thunderstorm.
However this is perhaps an aside experiment from the plant intelligence as it just shows one element of connectivity.
@David Reminds me of this, although they just used shadows to do the work! https://www.treehugger.com/grass-art-heather-ackroyd-dan-harvey-4855970
@martin.timms What is your FB group?
@martin.timms Vesna just privately suggested I could try to do something with my Lightningmaps/Blitzortnung detector (and API-access) to try and correlate these kinds of influences in some way... It'd seem I'll be in the market for a plant-ecg soon...hmmm
I have a group called Energetic Agriculture.... https://www.facebook.com/groups/953499178440170
@insensitiveclod Here's a simple way to measure picoAmps using a DVM: https://hackaday.com/2016/02/01/need-a-nano-ammeter-you-already-have-one/
David
@martin.timms Might have a stab at that !
Davidthanks
We're just about out of time, so I want to say a big thank you to Lex for this cool discussion today. I'll post a transcript in a few minutes in case anyone needs to refer back to links.
Lex, thanks a bunch! Great way to kick off the 2021 Hack Chat season!
Thank you Lex, it was fascinating!
Thanks all, and thanks for having me Dan!
Thanks to everyone, very interesting
Thanks, @Lex Kravitz and everyone else - learned a ton!
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