WEBVTT - From the Vault: Plant Memories, Part 1 0:00:06.080 --> 0:00:08.000 Hey, you welcome to Stuff to Blow Your Mind. My 0:00:08.080 --> 0:00:11.480 name is Robert Lamb and I'm Joe McCormick, and it's Saturday, 0:00:11.680 --> 0:00:14.360 so we are heading into the vault for an older 0:00:14.360 --> 0:00:18.400 episode of the show. This one originally aired on April twelfth, 0:00:18.440 --> 0:00:20.880 twenty twenty two, and it's part one of a series 0:00:20.920 --> 0:00:24.720 we did on the question of whether plants have memories 0:00:24.800 --> 0:00:28.680 or anything analogous to memories. I remember thinking the series 0:00:28.760 --> 0:00:31.319 was really fascinating, so it should be a treat to 0:00:31.320 --> 0:00:37.560 re explore. Here you go. Welcome to Stuff to Blow 0:00:37.560 --> 0:00:47.520 Your Mind, a production of iHeartRadio. Hey, welcome to Stuff 0:00:47.560 --> 0:00:50.000 to Blow your Mind. My name is Robert Lamb and 0:00:50.200 --> 0:00:52.680 I'm Joe McCormick, and today we're going to be talking 0:00:52.720 --> 0:00:57.720 about an interesting and perhaps hidden property of plants. And 0:00:57.840 --> 0:01:01.560 to start us off, I wanted to read a selection 0:01:01.680 --> 0:01:04.600 from one of the lesser known works by the English 0:01:04.720 --> 0:01:08.319 Romantic poet Percy Bis Shelley. This is a poem called 0:01:08.360 --> 0:01:11.160 the Sensitive Plant. Rob Am, I write that you'd never 0:01:11.160 --> 0:01:13.679 heard of this one before. No, I you know, obviously 0:01:13.720 --> 0:01:16.039 I've read a little bit of Shelley here and there, 0:01:17.080 --> 0:01:20.039 but this must I'm assuming this is a deeper cut 0:01:20.319 --> 0:01:22.360 it is. I think it was one of the final 0:01:22.440 --> 0:01:25.440 things he wrote before his death, so this would have 0:01:25.440 --> 0:01:28.959 been I think sometimes in the early eighteen twenties, and 0:01:29.080 --> 0:01:32.040 it was published I believe as a standalone work at 0:01:32.120 --> 0:01:33.960 least at some point it was. I was reading through 0:01:34.000 --> 0:01:36.440 like a book version of it on that had been 0:01:36.480 --> 0:01:39.119 scanned into Google Books, and every other page on it 0:01:39.160 --> 0:01:42.040 was like washed out on the scan, so that was beautiful. 0:01:42.080 --> 0:01:45.720 But yeah, this one's kind of weird. It's it's not 0:01:45.760 --> 0:01:47.760 one of his best poems, but it has some really 0:01:47.760 --> 0:01:50.280 great lines in it. So I just wanted to read 0:01:51.120 --> 0:01:53.280 just a selection from it. It's too long to read 0:01:53.320 --> 0:01:56.120 in full, but this is an exerpt from the end 0:01:56.160 --> 0:01:59.680 of Part one of The Sensitive Plant by Percy BIS. Shelley. 0:02:00.360 --> 0:02:03.880 For the Sensitive Plant has no bright flower. Radiance and 0:02:04.040 --> 0:02:07.600 odor are not its dour. It loves even like love. 0:02:07.880 --> 0:02:10.760 Its deep heart is full. It desires what it has 0:02:10.880 --> 0:02:16.079 not the beautiful, the light winds, which from unsustaining wings 0:02:16.200 --> 0:02:19.960 shed the music of many murmurings, the beams which dart 0:02:20.040 --> 0:02:23.160 from many a star of the flowers whose hues they 0:02:23.200 --> 0:02:27.560 bear afar, the plumid insects, swift and free, like golden 0:02:27.600 --> 0:02:30.880 boats on a sunny sea, laden with light and odor, 0:02:30.960 --> 0:02:34.400 which pass over the gleam of the living grass, The 0:02:34.560 --> 0:02:37.919 unseen clouds of the dew, which lie like fire in 0:02:38.000 --> 0:02:41.320 the flowers till the sun rides high, then wander like 0:02:41.480 --> 0:02:45.400 spirits among the spheres, each cloud faint with the fragrance 0:02:45.440 --> 0:02:49.840 it bears, The quivering vapors of dim noontide, which like 0:02:49.960 --> 0:02:53.280 a sea over the warm earth, glide in which every 0:02:53.320 --> 0:02:56.720 sound and odor and beam move as reeds in a 0:02:56.800 --> 0:03:00.960 single stream, each and all, like ministering angels, were for 0:03:01.040 --> 0:03:05.040 the sensitive plant, sweet joy to bear, whilst the lagging 0:03:05.080 --> 0:03:08.239 hours of the day went by like windless clouds over 0:03:08.280 --> 0:03:12.320 a tender sky, And when evening descended from heaven above, 0:03:12.680 --> 0:03:15.000 and the earth was all rest, and the air was 0:03:15.040 --> 0:03:19.000 all love and delight, though less bright was far more deep, 0:03:19.360 --> 0:03:22.120 and the day's veil fell from the world of sleep, 0:03:22.600 --> 0:03:25.000 and the beasts and the birds and the insects were 0:03:25.080 --> 0:03:28.799 drowned in an ocean of dreams without a sound, whose 0:03:28.840 --> 0:03:32.400 waves never mark, though they ever impressed the light sand 0:03:32.440 --> 0:03:38.000 which paves it consciousness only overhead. The sweet nightingale ever 0:03:38.080 --> 0:03:41.520 sang more sweet as the day might fail, and snatches 0:03:41.600 --> 0:03:44.960 of its elysien chant were mixed with the dreams of 0:03:45.000 --> 0:03:49.240 the sensitive plant. Ah, very nice. Yeah, so I don't 0:03:49.280 --> 0:03:51.360 think it's one of Percy's best poems. Like I was saying, 0:03:51.440 --> 0:03:54.480 the rhythms a little too regular and singsongy. Sometimes. Some 0:03:54.520 --> 0:03:56.160 of the rhymes are a little obvious, you know, the 0:03:56.240 --> 0:03:59.520 rhyming love with above and all that. You could imagine 0:03:59.560 --> 0:04:03.560 like a an eighties rat bait thrown in the background 0:04:03.800 --> 0:04:05.720 some of those, or this could be a song like 0:04:05.760 --> 0:04:09.000 every Rose has its Thorn, you know, a monster ballad. 0:04:09.440 --> 0:04:12.000 But there are also lines. I really love the dew 0:04:12.160 --> 0:04:15.160 which lies like fire and the flowers, and the nighttime 0:04:15.240 --> 0:04:18.880 as an ocean paved under with the sands of consciousness. 0:04:19.640 --> 0:04:23.080 But it's esthetic qualities aside. I think it's really interesting 0:04:23.640 --> 0:04:28.240 that Percy is suggesting, in his unorthodox and emotionally charged 0:04:28.320 --> 0:04:32.280 view of the world, that this particular plant, the sensitive plant, 0:04:32.279 --> 0:04:35.159 which is a species of plant, may somehow have a 0:04:35.240 --> 0:04:38.279 kind of humanity of its own, like a soul or 0:04:38.320 --> 0:04:41.200 a mind, or, as I believe he implies later in 0:04:41.240 --> 0:04:44.840 the poem, an afterlife. So you might wonder why would 0:04:44.839 --> 0:04:46.880 he say that about this species of plant, which he 0:04:46.920 --> 0:04:50.640 acknowledges is not a particularly beautiful flower. It's it's a mimosa, 0:04:50.680 --> 0:04:54.960 so it's got a little pink, puffball kind of thing. Well, 0:04:55.640 --> 0:04:58.719 I think the answer is actually tied to some of 0:04:58.720 --> 0:05:02.360 the biological qualities of the sensitive plant as a species. 0:05:02.360 --> 0:05:04.760 So the sensitive plant is one of the mani names 0:05:04.839 --> 0:05:10.719 of Mimosa pudica, pudica being Latin for chaste or modest, 0:05:10.960 --> 0:05:15.280 shamefaced or bashful. And this is a flowering plant in 0:05:15.320 --> 0:05:19.239 the family Fabasi, which is the pea or lagume family, 0:05:19.560 --> 0:05:22.000 which means yes, this plant is a cousin of the 0:05:22.080 --> 0:05:24.680 common being. So we are we are dealing in bean 0:05:24.800 --> 0:05:28.680 can today, we're getting into into supernatural territory then, oh boy. 0:05:29.320 --> 0:05:32.479 Mimosa pudica is native to South and Central America and 0:05:32.520 --> 0:05:36.560 the Caribbean, though since transatlantic contact it has spread to 0:05:36.800 --> 0:05:39.200 all other parts of the world. I think it's pervasive 0:05:39.240 --> 0:05:42.919 throughout the tropics, and it's also known by tons of 0:05:42.920 --> 0:05:46.279 different names. It's called the humble plant, the shame plant, 0:05:46.640 --> 0:05:50.680 the touch me not, and all of these names connect 0:05:50.839 --> 0:05:54.159 to the most striking feature of this species, which is 0:05:54.200 --> 0:05:58.880 that it is a plant that recoils when touched. And 0:05:59.360 --> 0:06:01.960 this is one of a handful of examples of rapid 0:06:02.160 --> 0:06:05.919 movement in the plant kingdom, movement on the timescale that 0:06:05.960 --> 0:06:09.400 we would normally associate only with animals. So, if you 0:06:09.400 --> 0:06:12.080 want to picture it, the sensitive plant is a spiny 0:06:12.120 --> 0:06:15.000 little shrub that grows up to about a foot off 0:06:15.000 --> 0:06:18.640 the ground. It has these pink flower puffs and small 0:06:18.760 --> 0:06:23.640 forking branches with compound leaves. So to picture the leaves 0:06:23.640 --> 0:06:26.520 of this plant, they are the ones that kind of 0:06:26.560 --> 0:06:28.880 like a feather, you know, with a stalk running up 0:06:28.880 --> 0:06:32.680 the middle, and then lots of tiny, little pinile leaflets 0:06:32.720 --> 0:06:35.600 shooting out from that middle stalk, parallel to each other 0:06:35.880 --> 0:06:38.560 and perpendicular to the stalk, like the teeth of a comb, 0:06:39.040 --> 0:06:41.680 or like the barbs of a feather. And to see 0:06:41.720 --> 0:06:45.159 the sensitive plant in action, all you need to do 0:06:45.440 --> 0:06:48.400 is touch a finger on one of these branches, and 0:06:48.600 --> 0:06:52.640 suddenly what happens is the leaflets all fold inward like 0:06:52.680 --> 0:06:56.479 a closing suitcase. And then sometimes even the branch or 0:06:56.520 --> 0:07:00.719 the stalk that they're on will droop away, the stimulus 0:07:00.720 --> 0:07:04.599 will droop down. From what I can tell, there is 0:07:04.720 --> 0:07:08.800 not yet a full consensus on the main function of 0:07:08.800 --> 0:07:11.600 this shrinking behavior in the wild, like, why does it 0:07:11.680 --> 0:07:16.120 do that? But botanists have long suspected that it's some 0:07:16.240 --> 0:07:19.520 kind of defensive action by the plant to protect its 0:07:19.600 --> 0:07:23.760 leaves from grazing herbivores or insects. And this could actually 0:07:23.760 --> 0:07:27.680 work in multiple ways. So one of them is that 0:07:27.760 --> 0:07:30.840 maybe it works by physically moving the leaves away from 0:07:30.840 --> 0:07:33.440 a grazer. You know, something comes, spides, it's munching on 0:07:33.480 --> 0:07:36.000 the leaves, and this causes the leaves to kind of 0:07:36.080 --> 0:07:38.960 pull away from the mouth. Or it could work by 0:07:39.080 --> 0:07:42.280 hiding the leaves so you know, it is disturbed something 0:07:42.360 --> 0:07:44.200 is around, it might be trying to eat the plant, 0:07:44.400 --> 0:07:47.440 and by closing up it makes it less obvious where 0:07:47.480 --> 0:07:51.080 the leaves are. Yeah, and I guess one can imagine 0:07:51.240 --> 0:07:54.640 this working within the context of a you know, an 0:07:54.800 --> 0:07:58.080 enormous grazing animal that is eating a lot of plants. 0:07:58.240 --> 0:08:01.440 And it's maybe not gonna opt to really get particular 0:08:01.520 --> 0:08:04.920 about this one if this one has made itself smaller, 0:08:05.160 --> 0:08:09.360 you know, retreated into you know, amidst other plants, et cetera, 0:08:09.520 --> 0:08:11.600 Like it's just going to keep eating whatever is readily 0:08:11.600 --> 0:08:14.880 available to eat, right, But I think there's also a 0:08:14.920 --> 0:08:18.440 focus on insects maybe insects or also the reason it 0:08:18.480 --> 0:08:22.080 does this, and it could also work maybe by startling 0:08:22.120 --> 0:08:24.720 a predator like an insect or grazing her before because 0:08:24.920 --> 0:08:28.040 of course plants don't usually move rapidly like animals do. 0:08:28.160 --> 0:08:30.760 So you know, if you're an insect or whatever that's 0:08:30.800 --> 0:08:34.240 grazing and then suddenly there is movement on the timescale 0:08:34.240 --> 0:08:37.400 of animal movement in your in your vicinity, that might 0:08:37.520 --> 0:08:40.520 startle you and send you on the run. Yeah, on 0:08:40.640 --> 0:08:43.840 the timescale of animal movement. That's that's key. Because of course, 0:08:43.880 --> 0:08:46.800 the other main plant we think of in terms of 0:08:46.800 --> 0:08:49.280 this is the venus fly plant, which you know, we'll 0:08:49.320 --> 0:08:51.720 come back to, uh that. You know, that is a 0:08:51.760 --> 0:08:56.080 plant that is acting aggressively on the timescale of of 0:08:56.080 --> 0:09:00.319 of animals in an attempt to capture set an. But 0:09:00.640 --> 0:09:02.760 here we see the reverse. Here we see something that 0:09:03.000 --> 0:09:06.319 is that is acting, you know, defensively, that is moving 0:09:06.320 --> 0:09:08.800 away from us, that is not saying I want to 0:09:08.800 --> 0:09:11.160 touch you and envelop you, but I would rather not 0:09:11.200 --> 0:09:13.120 touch you at all. Yes, I would rather not. I 0:09:13.120 --> 0:09:17.200 would prefer not to. Yeah. So usually after a sensitive 0:09:17.200 --> 0:09:20.640 plant closes up its leaflets and droops away, it will 0:09:20.760 --> 0:09:24.680 reopen within some short time period, maybe only a few seconds, 0:09:25.360 --> 0:09:28.400 sometimes a few minutes, but it doesn't take long. It'll 0:09:28.440 --> 0:09:31.360 it'll open back up, get those leaves out there again, 0:09:31.440 --> 0:09:35.240 and start all over. And the sensitive plant also has 0:09:35.280 --> 0:09:39.200 a circadian rhythm to its closure, because it will close 0:09:39.240 --> 0:09:41.920 its leaves in the darkness and then reopen them in 0:09:41.920 --> 0:09:45.400 the daylight. Now, I found a wonderful post on j 0:09:45.559 --> 0:09:50.360 Store Daily by Rebecca Friedel about the history of Mimosa 0:09:50.360 --> 0:09:55.880 putica and also a similar Old World plant called Biophytum sensitivum, 0:09:56.160 --> 0:09:59.800 which is actually not a close relative of the sensitive plant, 0:09:59.800 --> 0:10:02.360 but does almost exactly the same thing with its leaves. 0:10:02.360 --> 0:10:03.800 So it looks like this would be a case of 0:10:04.160 --> 0:10:08.640 convergent evolution. But this article points to the work of 0:10:08.679 --> 0:10:13.200 a sixteenth century Portuguese naturalist living in India named Christo 0:10:13.280 --> 0:10:16.880 baal Acosta, who authored a book in fifteen seventy eight 0:10:16.920 --> 0:10:21.240 called Tractado de las Drogas e Medicinas de las Indias 0:10:21.320 --> 0:10:24.679 Orientales or Treatise on the Drugs and Medicines of the 0:10:24.679 --> 0:10:27.800 East and East Indies. I really wanted to find an 0:10:27.800 --> 0:10:30.160 English translation of this so I could quote it directly, 0:10:30.200 --> 0:10:33.160 because it sounds like it's a hoot, but I could not, 0:10:33.320 --> 0:10:34.720 So I'm going to have to rely on a couple 0:10:34.720 --> 0:10:38.280 of secondhand summaries, including a Friedel's article here. But anyway, 0:10:38.320 --> 0:10:41.079 in this book by Christo Baal Acosta in the sixteenth century, 0:10:41.320 --> 0:10:45.720 he describes a plant among the medicinal herbs of India 0:10:45.920 --> 0:10:49.280 called the yerba della more or the herb the herb 0:10:49.360 --> 0:10:54.280 of love? Do you ever say herb with the H pronounced? Sometimes? 0:10:54.360 --> 0:10:57.000 I'm afraid I'm going to keep doing that. Yeah, sometimes 0:10:57.040 --> 0:10:59.640 it slips out. Yeah, I don't know why. I try 0:10:59.640 --> 0:11:02.160 to fix this in my brain by like saying the 0:11:02.280 --> 0:11:05.800 name herb without the H pronounce. So like I go, 0:11:07.280 --> 0:11:12.800 I said, herb Herbert Hoover, Herbert Hoover. That'llfens it. Well, yeah, 0:11:12.800 --> 0:11:16.760 I mean it's easy to fall into because herbivore, herbivorec Anyway, 0:11:16.840 --> 0:11:18.920 why the herb of love? Why would it be called 0:11:18.960 --> 0:11:22.400 the herb of love? Well? Acosta says that, according to 0:11:22.440 --> 0:11:25.199 an Indian physician he talked to, the herb of love 0:11:25.640 --> 0:11:29.160 was a potent seduction drug with a one hundred percent 0:11:29.280 --> 0:11:34.160 success rate never fails. And after this passage, Acosta has 0:11:34.160 --> 0:11:37.320 an aside to assure readers of this medicinal catalog that 0:11:37.400 --> 0:11:41.040 he definitely never personally tried to use the sex herb, never, 0:11:41.440 --> 0:11:44.840 not once. Probably a good thing considering that other more 0:11:44.880 --> 0:11:47.400 well known sex herbs, if you will, are you know 0:11:47.480 --> 0:11:53.040 essentially poisons? Right? But aside from the dubious allegations about 0:11:53.280 --> 0:11:56.600 Cupid's aero type powers, this plant, the Herb of Love 0:11:56.880 --> 0:12:00.560 is remarkable for its ability to close its leaves rapidly, 0:12:00.679 --> 0:12:03.240 moving at the speed of an animal recoiling from a 0:12:03.280 --> 0:12:06.760 needle prick. And I was looking at another source which 0:12:06.800 --> 0:12:11.200 mentions Acosta. This is by JF. Veldkamp called Notes on 0:12:11.240 --> 0:12:14.920 Biophytom of the Old World, published in Taxon in nineteen 0:12:15.000 --> 0:12:19.360 eighty nine. I cite this just because Veldkamp tells a 0:12:19.440 --> 0:12:23.520 story that Acosta claimed he knew of a philosopher in Malabar, 0:12:23.679 --> 0:12:28.640 so region along the southwest coast of India. A philosopher 0:12:28.679 --> 0:12:31.679 who lived in Malabar who was so tortured by the 0:12:31.720 --> 0:12:35.120 mystery of the Herb of Love's rapid movement that he 0:12:35.200 --> 0:12:38.200 literally lost his mind trying to study it. He was like, 0:12:38.240 --> 0:12:41.040 how does it move? And that was it for him. 0:12:41.559 --> 0:12:43.680 No word on whether that guy ever used it for 0:12:44.120 --> 0:12:47.280 Cupid zero type purposes. Yeah, because again, and this will 0:12:47.600 --> 0:12:50.240 going to be something that will will discuss later as well. 0:12:50.280 --> 0:12:52.439 I mean it's it's acting in a way that other 0:12:52.520 --> 0:12:56.800 plants do not act. It seems unnatural, right, I mean 0:12:56.840 --> 0:12:59.440 if I had never seen a rapidly moving plant before 0:12:59.480 --> 0:13:01.520 and I just stumbled across one of these in the 0:13:01.600 --> 0:13:03.640 wild saw it folding up like that, I would be 0:13:03.679 --> 0:13:06.120 freaked out. I don't know what to think of this. 0:13:06.160 --> 0:13:09.040 I mean, it's hard to imagine because I grew up 0:13:09.040 --> 0:13:13.040 with venus flytraps, you know, Like I remember when I 0:13:13.080 --> 0:13:15.880 was a kid and I would have like one of 0:13:15.880 --> 0:13:18.760 those really boring weekend days where my mom wanted to 0:13:18.800 --> 0:13:22.000 go to the plant nursery and get some plants around 0:13:22.040 --> 0:13:25.000 the house. And I think my consolation there was that 0:13:25.080 --> 0:13:28.480 a couple of times I got a little potted venus flytrap. Yeah. 0:13:28.520 --> 0:13:31.320 They're pretty fun little plants. They always have a huge 0:13:31.640 --> 0:13:36.040 container of them out at the at the Bananical Garden 0:13:36.120 --> 0:13:39.160 in Atlanta for the kids to interact with and inevitably 0:13:39.200 --> 0:13:42.840 stick little sticks into their into their their their mouths, 0:13:42.880 --> 0:13:45.240 if you will. Right, so, we know about that one. 0:13:45.280 --> 0:13:47.800 But if you're previously unfamiliar with a plant like that, 0:13:48.080 --> 0:13:51.200 or or one of these leaf closing plants like Mimosa 0:13:51.200 --> 0:13:56.520 pudica or biophytum. I imagine it would be shocking. Yeah, 0:13:56.520 --> 0:14:01.680 I mean, we are hardwired really to topact that sudden 0:14:01.800 --> 0:14:05.679 movement in the grass might be something dangerous. It might 0:14:05.720 --> 0:14:07.959 be a snake, for example, Like, that's the first place 0:14:08.040 --> 0:14:10.280 my mind goes. If I'm on a walk and there's 0:14:10.280 --> 0:14:13.120 some sort of rustling in the bushes, it might be 0:14:13.240 --> 0:14:16.280 a snake, or it's something like a chipmunk or a squirrel. 0:14:16.360 --> 0:14:18.760 Probably not a squirrel because they're a bit bolder, but 0:14:19.320 --> 0:14:22.560 certainly the snake is never far from one's mind. Very true. 0:14:22.960 --> 0:14:26.720 So anyway, for several centuries there was confusion about how 0:14:26.760 --> 0:14:30.080 to taxonomize this plant that Christal ball Acosta was talking about, 0:14:30.080 --> 0:14:32.960 the Herb of Love, and Freedell points to an eighteen 0:14:33.040 --> 0:14:37.200 twenty five volume of the Botanical Register which says, hey, 0:14:37.240 --> 0:14:39.920 we know about this plant from South America called the 0:14:40.000 --> 0:14:43.800 Mimosa pudica. It does that leaf shutting thing. So maybe 0:14:43.800 --> 0:14:46.680 this herb of love that Acosta is talking about in 0:14:46.680 --> 0:14:49.720 India in the sixteenth century is actually the same plant. 0:14:50.320 --> 0:14:54.320 After all, it does seem that pretty quickly after transatlantic contact, 0:14:54.600 --> 0:14:58.640 the mimosa spread all around the globe. But now that 0:14:58.680 --> 0:15:00.840 doesn't seem to be the case. Botton are pretty clear 0:15:00.920 --> 0:15:03.280 that the herb of love was actually this other species 0:15:03.320 --> 0:15:07.840 I mentioned a minute ago, Biophytum sensitivum and Freedel rights. 0:15:08.040 --> 0:15:11.640 This was funny quote. Perhaps the erotic claims Acosta made 0:15:11.720 --> 0:15:14.560 so enthralled some that they failed to turn the page 0:15:14.600 --> 0:15:18.520 to the next entry on Erba mimosa, a likely description 0:15:18.600 --> 0:15:22.440 of the actual mimosa putica. Do your homework, guys, come on. 0:15:23.120 --> 0:15:26.800 But anyway, I was thinking about this mechanism, so immediately 0:15:26.920 --> 0:15:29.760 when I see a plant with rapid movement like this, 0:15:29.840 --> 0:15:32.960 the leaf closing behavior, I wonder how on earth does 0:15:33.000 --> 0:15:36.440 it do that? Because, of course we can move rapidly, 0:15:36.520 --> 0:15:38.400 but we can only do that because we have a 0:15:38.440 --> 0:15:43.280 nervous system and a muscular skeletal system muscles. Plants don't 0:15:43.320 --> 0:15:45.480 have either one. There are no muscles and a plant. 0:15:45.600 --> 0:15:50.520 So what mechanism could a plant use to contract on 0:15:50.560 --> 0:15:54.160 the order of seconds. Well, scientists have actually figured out 0:15:54.160 --> 0:15:57.680 the answer to this one. The types of movement on 0:15:57.760 --> 0:16:01.040 display in the sensitive plant and the rapid moving plants 0:16:01.040 --> 0:16:06.720 like the venus flytrap are known as seismoonastic movements, and 0:16:06.920 --> 0:16:11.040 these are an example of a bigger category of nastic movements, 0:16:11.080 --> 0:16:13.760 which can be defined by their difference from another type 0:16:13.760 --> 0:16:17.440 of plant movement called tropisms. Now, tropisms, I think we've 0:16:17.480 --> 0:16:21.080 all seen in action. You know what this is? View 0:16:21.080 --> 0:16:24.680 ever had house plants? A tropism is growth in a 0:16:24.720 --> 0:16:29.640 specific direction based on an external stimulus. So plants will 0:16:29.760 --> 0:16:33.000 grow toward a light source. In fact, right in front 0:16:33.000 --> 0:16:35.280 of me. Right now, I have a potted plant here 0:16:35.280 --> 0:16:39.520 on my desk, and over time its leaves all start 0:16:39.720 --> 0:16:42.880 reaching out for the lamp next to it, until I 0:16:42.960 --> 0:16:45.800 turn the pot around, and then gradually they all start 0:16:45.840 --> 0:16:50.080 to hook back in the opposite direction. And it just 0:16:50.200 --> 0:16:52.000 now struck me for the first time. That might sound 0:16:52.080 --> 0:16:54.040 kind of cruel, like I'm toying with it, but I 0:16:54.080 --> 0:16:57.000 really don't think the plant's feelings are hurt. Another example 0:16:57.080 --> 0:17:01.320 this would be trees seeing to grow around up power lines. Sure, yeah, 0:17:01.480 --> 0:17:06.360 So plants can grow in different directions responding to objects 0:17:06.480 --> 0:17:12.159 or stimuli in their environments. Nastic movements, in contrast to tropisms, 0:17:12.200 --> 0:17:15.800 are not oriented in the direction of a stimulus, but 0:17:16.040 --> 0:17:21.280 rather are fixed reflexes that are determined by the plant's anatomy. So, 0:17:21.680 --> 0:17:25.520 for example, a venus fly trap shows a nastic response. 0:17:25.800 --> 0:17:28.760 It doesn't go off in a particular direction to catch 0:17:28.760 --> 0:17:31.680 a fly, but rather, when it senses movement in its 0:17:31.720 --> 0:17:36.160 trap area, the hinge closes. So it has a predetermined, 0:17:36.280 --> 0:17:40.639 a directionally predetermined movement that is in keeping with the 0:17:41.040 --> 0:17:46.080 plant's anatomy, not in an adaptable direction. And the sensitive 0:17:46.080 --> 0:17:49.159 plant is another example of a nastic response. And I 0:17:49.160 --> 0:17:54.280 think it's interesting to note that the stimulus direction dependent 0:17:54.400 --> 0:17:58.160 movements of plants tend to be very slow, very very slow, 0:17:58.200 --> 0:18:01.320 and based on growth. Well, the few plants that are 0:18:01.480 --> 0:18:04.600 able to move rapidly in all cases that I'm aware of, 0:18:04.680 --> 0:18:08.480 certainly in most cases their movement is constrained to these 0:18:08.600 --> 0:18:12.600 directionally fixed reflexes. Now, of course, we animals have the 0:18:12.640 --> 0:18:15.440 best of both worlds, right, We can move rapidly and 0:18:15.560 --> 0:18:19.080 we have the flexibility to respond in whatever direction makes 0:18:19.119 --> 0:18:21.600 sense given the stimulus. But you know that's because we're 0:18:21.640 --> 0:18:25.439 different types of creatures, different anatomy, different energy requirements and 0:18:25.480 --> 0:18:35.760 so forth. But okay, that's nastic movements now, seis monastic 0:18:35.800 --> 0:18:39.439 movements are nastic movements that are triggered by touch or 0:18:39.480 --> 0:18:45.280 by vibration. Now again without muscles. How it all this work? 0:18:45.359 --> 0:18:48.359 How does the nastic movement actually happen? Well, here we 0:18:48.400 --> 0:18:50.919 come to a really excellent new word I learned. The 0:18:50.960 --> 0:18:56.199 word is terger spelled tur gr. It's a good like 0:18:56.320 --> 0:18:59.879 a leather diaper, Barbarian name. But it also it is 0:19:00.040 --> 0:19:02.600 a name for something that happens within plants. It's related 0:19:02.640 --> 0:19:06.479 to the word turgid or turgidity, and so within plants 0:19:06.600 --> 0:19:10.639 there is a principle called turger pressure. And one simple 0:19:10.680 --> 0:19:12.919 way to think about turger pressure is that it is 0:19:12.960 --> 0:19:17.440 like water pressure inside a plant. So you think about 0:19:17.480 --> 0:19:21.480 the difference between a wilted flower baking dry in the sun. 0:19:22.040 --> 0:19:24.640 You know it's parched, and you see it drooping over, 0:19:25.280 --> 0:19:27.640 and then you think about what that flower does after 0:19:27.720 --> 0:19:30.400 you water it. If things go well. Usually you give 0:19:30.440 --> 0:19:33.280 a wilted plant water and its leaves and stems stops 0:19:33.320 --> 0:19:36.360 sagging and they become rigid again. It stands straight up 0:19:36.440 --> 0:19:38.840 the you know, the it's it's almost like it's inflated 0:19:38.920 --> 0:19:41.160 like a balloon. Yeah, And in some plants it's it's 0:19:41.280 --> 0:19:45.480 it's amazing the difference just a quick watering can have. 0:19:46.359 --> 0:19:49.800 We have a linen bomb, and I always find that 0:19:49.800 --> 0:19:51.760 that one among our plants is the first to just 0:19:51.840 --> 0:19:54.720 immediately seem to give up the ghost and start wilting away. 0:19:55.359 --> 0:19:57.040 But then you know, you give it enough water and 0:19:57.080 --> 0:19:59.920 it's just back, just a bushy and full of fly 0:20:00.119 --> 0:20:02.600 as ever totally. In fact, you might have even observed this, 0:20:02.680 --> 0:20:06.639 not with a live plants, but giving some veggies in 0:20:06.680 --> 0:20:09.040 the kitchen a soak or even just to wash. This 0:20:09.119 --> 0:20:12.119 is a good trick for resurrecting what appeared to be 0:20:12.280 --> 0:20:15.040 wilted salad greens that are past their prime. You might 0:20:15.040 --> 0:20:17.320 think they're no good, you know, you got to toss them. 0:20:17.760 --> 0:20:21.200 You would be surprised how salvageable some greens are after 0:20:21.240 --> 0:20:24.359 a soak in cold water. Really like like spinach, the 0:20:24.440 --> 0:20:26.360 surf of spinach. I don't know if I ever tried 0:20:26.359 --> 0:20:28.120 it on spinach, but I've tried it on other types 0:20:28.160 --> 0:20:30.800 of greens, like you know, arugula and things like that 0:20:30.800 --> 0:20:33.679 that are you know, they're starting not not like if 0:20:33.680 --> 0:20:36.040 they're getting slimy, you know, but if they're just like 0:20:36.080 --> 0:20:39.520 they're clearly they're getting desiccated and wilted. It looks like, oh, 0:20:39.560 --> 0:20:40.919 these are going to be no good. Soak them in 0:20:40.960 --> 0:20:42.800 some cold water. They might come back to life and 0:20:42.920 --> 0:20:45.520 be crisp again. Okay, I didn't know about this trick, 0:20:45.560 --> 0:20:48.359 but now I will have to try this sometime. But anyway, So, 0:20:48.520 --> 0:20:53.240 turger pressure is when a plant's cells are swollen with 0:20:53.320 --> 0:20:56.080 water so that in the inside of the cells, within 0:20:56.119 --> 0:20:59.880 the plasma membrane, the water pressure is actually pushing out 0:21:00.040 --> 0:21:03.840 against the cell wall. And so when turger pressure is high, 0:21:03.960 --> 0:21:06.840 the plant is said to be turgid, and so to 0:21:06.960 --> 0:21:09.680 come back to the sensitive plant when the leaves are 0:21:09.800 --> 0:21:14.240 touched or disturbed and electrochemical chain reaction is set off, 0:21:14.880 --> 0:21:17.159 It's sensed by cells in the leaves and then it 0:21:17.440 --> 0:21:21.320 sets off this electrochemical chain reaction that eventually ends in 0:21:21.960 --> 0:21:25.840 water gushing out from so called motor cells at the 0:21:25.840 --> 0:21:29.800 base of the leaflets that were previously turgid. So the 0:21:29.960 --> 0:21:33.520 sudden loss of turger pressure the cells purging their water 0:21:33.640 --> 0:21:37.959 contents causes the leaflet to move, basically to collapse at 0:21:38.000 --> 0:21:41.800 it's hinge, and this is known as turger movement. So 0:21:41.880 --> 0:21:44.120 in a strange way, you can think about it like 0:21:44.480 --> 0:21:49.000 the plant moving by causing itself to very selectively and 0:21:49.200 --> 0:21:53.200 rapidly wilt like a parched plant. Then over the course 0:21:53.200 --> 0:21:57.119 of the following minutes, turger pressure can be restored and 0:21:57.200 --> 0:21:59.439 the leaves go rigid again, and they go back to 0:21:59.480 --> 0:22:01.880 their extended state. But to come to the next thing, 0:22:02.800 --> 0:22:07.840 even more astonishing than the plant's ability to behave physically 0:22:07.920 --> 0:22:10.920 in ways that seem more at home in animals with muscles, 0:22:11.680 --> 0:22:15.359 is potential evidence that the Mimosa pudica may also, in 0:22:15.400 --> 0:22:19.760 a qualified sense, behave mentally in ways that seem more 0:22:19.800 --> 0:22:24.400 at home in animals with brains. Specifically, there has been 0:22:24.440 --> 0:22:28.040 research arguing that this plant, an organism entirely without a 0:22:28.080 --> 0:22:31.680 brain or without a nervous system, actually has its own 0:22:31.840 --> 0:22:36.960 rudimentary form of memory. And we'll talk about one of 0:22:37.000 --> 0:22:40.000 the studies allegedly showing this in a minute, But first 0:22:40.040 --> 0:22:42.240 I thought it might be good to spend a few 0:22:42.240 --> 0:22:47.120 minutes disentangling concepts about the alleged mental or cognitive properties 0:22:47.160 --> 0:22:50.119 of plants, because I think once you get into this area, 0:22:50.240 --> 0:22:53.560 you run a whole gamut of different types of claims 0:22:53.600 --> 0:22:59.080 of extremely variable evidential backing. Yeah, and you also get 0:22:59.080 --> 0:23:04.720 into into areas of confusion over like what constitutes animal 0:23:04.760 --> 0:23:08.080 intelligence and human intelligence and so. Yeah, so I thought 0:23:08.080 --> 0:23:10.320 it might be helpful to sort through some sort of 0:23:10.359 --> 0:23:14.359 general ideas regarding the nature of plants in Western thought. 0:23:14.920 --> 0:23:19.440 Fourth century BC thinker Aristotle, of course, casts along shadow, 0:23:19.840 --> 0:23:24.000 and he wrote that plants have a vegetative soul or 0:23:24.440 --> 0:23:27.560 two threpticon, which I believe just means the vegetable soul, 0:23:27.880 --> 0:23:30.520 not to be confused with two megatherion, which means the 0:23:30.560 --> 0:23:34.560