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It seems silly to ask if plants can count, but even the New York Times has called Venus flytraps 'Plants That Can Count.' Is counting a thing plants can do?

Hosted by: Hank Green

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Sources:
https://www.nytimes.com/2016/02/02/science/the-venus-flytrap-a-plant-that-can-count.html
https://www.sciencenews.org/blog/wild-things/catch-meal-venus-flytrap-counts-five
https://blogs.scientificamerican.com/artful-amoeba/the-venus-flytrap-can-count-past-2/
https://www.cell.com/current-biology/fulltext/S0960-9822(15)01501-8
https://www.sciencenewsforstudents.org/article/eating-venus-flytraps-must-count
https://psycnet.apa.org/record/2005-04876-001
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3527185/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3228256/
https://onlinelibrary.wiley.com/doi/full/10.1111/pce.13065
https://www.pnas.org/content/94/7/2793
https://www.khanacademy.org/test-prep/mcat/organ-systems/neuron-membrane-potentials/a/neuron-action-potentials-the-creation-of-a-brain-signal
https://www.cell.com/trends/plant-science/fulltext/S1360-1385(17)30280-7
https://www.ncbi.nlm.nih.gov/pubmed/17263772
https://blogs.scientificamerican.com/observations/plants-cannot-think-and-remember-but-theres-nothing-stupid-about-them-theyre-shockingly-sophisticated/
https://elifesciences.org/articles/00669
https://www.bbc.com/news/health-22991838
https://science.sciencemag.org/content/282/5389/662
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4914563/
https://www.cell.com/neuron/fulltext/S0896-6273(18)30741-4

Image Sources:
https://www.istockphoto.com/photo/the-new-york-times-weekly-edition-in-delo-newspaper-gm157773702-16126249
https://www.istockphoto.com/photo/venus-flytrap-gm515908567-48058944
https://www.videoblocks.com/video/time-lapse-of-growing-venus-flytrap-dionaea-muscipula-plant-1x3w-in-4k-format-with-alpha-transparency-channel-isolated-on-white-background-hk7yet26-j95e6nw2
https://www.istockphoto.com/photo/sour-drops-gm179437493-26669314
https://www.istockphoto.com/photo/green-leaf-gm465846859-33415672
https://www.istockphoto.com/photo/venus-flytrap-with-trapped-fly-gm508792460-85444167
https://commons.wikimedia.org/wiki/File:Arabidopsis_thaliana_JdP_2013-04-28.jpg
https://www.istockphoto.com/photo/venus-fly-trap-gm172730339-5126104
{♫Intro♫}.

You might have heard that plants can count. And yeah, I know, it sounds silly to ask if that’s true.

But even the New York Times has called Venus flytraps ”Plants That Can Count”. The thing is...they can, but it’s not counting the way you know it. Which is to say, they don’t have some kind of mental representation of numbers in their brains, because as far as we know they don’t have brains, they’re not sentient.

We’re not talking like Groot here. Can Groot count? There’s evidence for some sort of counting mechanism in plants, though— and a lot more work needs to be done to properly understand it.

This whole idea of counting plants went viral after a 2016 paper in Current Biology. The title of the study itself literally has the words “Venus flytraps count” in it. So like, you can’t really blame the headline writers here.

And yes, we’re talking about those infamous flytraps that snap up unsuspecting flies with their leafy-mouths. You see, the study found that an insect needs to bump small trigger hairs on the plants’ leaves at least 5 times before the plant would begin secreting enzymes to digest it. And this built on knowledge already known within the botany community that the plants close those leaf-mouths if an insect bumps trigger hairs twice within 15 to 20 seconds.

If the plants can discern one or five different triggerings, well, they’re counting, right? And presumably, that means they think about and process numbers somehow—which would mean they’d have to think. Well, as awesome as the idea of sentient plants might seem, they’re probably not thinking or really understanding numbers—not the way we do, anyway.

You see, your brain actually has specific neurons that fire when you look at certain quanities—one set will fire when there are three lemon drops on a plate, another when there are four. Intriguingly, these are different than the neurons that fire when you simply look at numbers written out. But both seem to give you some kind of mental representation of the amount.

There just doesn’t seem to be much concrete evidence for these kinds of mental representations of numbers in plants, though at least one study says you can never be sure. What plants do have are sophisticated biological mechanisms that enable them to react to changes in their environment. And while these responses may look like plant intelligence at first glance, they fall short of what you and I might associate with conscious thinking.

There are some similarities, though. Like, both you and plants can transmit information quickly thanks to electrical signals called action potentials. The process isn’t exactly the same for plants and humans since the chemicals involved are a little different.

But they’re similar, and they’re how a flytrap counts; it generates and transmits action potentials every time a trigger hair is touched. The number of action potentials not only dictates if a trap should close but also how much digestive juice it should secrete—presumably, more triggering implies a larger insect that will require more enzymatic activity to break down. Basically, having a measure of the size of their meal lets them meter their investment in it so they don’t waste energy.

But the electrical communication networks in plants are much simpler than humans and other animals—they’re not considered true nervous systems. Those signals never arrive at some central hub or brain where they’re processed and translated into action. So even if we know that Venus flytraps can count and why, how it counts is still up for investigation.

And it’s not just the Venus flytrap. Many other plants use action potentials and other types of electrical signals. And even without brains, plants can do things that involve some pretty impressive math.

A 2013 study used mathematical models to show that a small mustard relative can do something akin to division to partition its food so it lasts through the night. Other plants have the equivalent of an internal thermostat that lets them regulate their temperature. So yeah, so plants can’t really count numbers or think about them the way that we do, they’re still pretty remarkable.

And they still ”know” how much their little hairs get pushed around by a fly. Thanks for watching this episode of SciShow, which was brought to you by another remarkable lifeform, SR Foxley! SR is our longest running Patreon President of Space and we appreciate everything he’s done to help keep SciShow running.

Thanks SR! If you want to check out our community of patrons and maybe become one yourself, just head on over to patreon.com/scishow. {♫Outro♫}.