Do plants have personalities?

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1:05So this is what we call spawn, and that would be the seed for the mushrooms. After it's been boiled and it's cooled down, you'll see the presence of the thing being colonised over time. I'm standing on a patch of land just behind a church north of Accra in Ghana, and I'm peering at what looks to my untrained eyes like a plastic bag full of decomposing sawdust. Once it's completely colonized, it will turn from this dark brownish thing into some white creamy stuff. And then you know it's ready to be open. And then the mushrooms will start sprouting. But it's not decomposing sawdust. It's actually mushroom spores.

1:49Silly me. You're listening to CrowdScience from the BBC World Service, the program that plants the seeds of your curiosity, waters them with some fascinating science and then watches them bloom into really satisfying answers. I'm Alex Lathbridge and right now CrowdScience listener George is showing me the complex and delicate process of mushroom inoculation. He's a mushroom farmer or at least he is these days. I retired. So after I left I plunged myself into farming to be specific mushroom farming and I just took just like that. So it was love at first introduction. So let's go in here first and I'll show you a bit of the process that I just spoke about.

2:41This is possibly the most impressive amateur shed I've ever seen. And I'm here for a good reason. George is going to show me the inspiration behind the question he wrote in. These mushrooms that we grow, they are the oyster mushrooms, right? Now, although the spawn, that's the seed, are cast the same day, some will shoot up just like that. In a matter of days, they've grown big enough to be harvested. There are others too that will take their time. It's like, why is this one dragging? Why is this one not coming as fast as this one was? and I've seen some plants the same species for instance if I plant corn today there may be three corn seeds that I put in one particular hole but when they sprout up you see one of them just shooting up just like that the other one with floundering it's not really growing as fast as the other one and it kept me thinking could it be that one plant is maybe more boisterous or more assertive or this one is more conservative and wouldn't rise up so fast and it got me thinking that's why I asked the question if individual species of the same plants have distinct personalities now before I get a load of emails from angry mycologists I know that mushrooms aren't plants they're in entirely different kingdoms from one another in fact fungi are closer related to animals, to us, than they are to plants.

4:10But as George has noted, his plants and his mushrooms seem to have something in common. Take identical specimens, give them the exact same environment, same nutrients and the same care and they still seem to behave differently from one another. He showed me his latest crop, in the hot darkness of his growing shed, where row after row of pearly white oyster mushrooms reach from their bags like ghostly hands cupped to collect rain. Look, all these things were spawned the same day. You see how this one is going so fast? You look here, you don't see this one going as fast. You probably might even have here on the same bag, some will get bigger, some will get smaller.

4:55Why? If I do it the same day, I expect the same process to actually cut across every one of them. But that's not what you're seeing here. That's not what I'm seeing. And I decided, okay, there must be some personalities involved in these things too. So why don't I check?

5:13So, do plants, not mushrooms too, but let's stick with plants, have distinct personalities? Are some of them bolder, braver, or shyer than their neighbours? Let's find out. Luckily, just an hour and a half drive north from George's farm, up a partially made road, which nearly killed our car's suspension, is a place where they know everything there is to know about plants. This is Baobab Seeds, collected last year, late last year in December. And you can see the variation in the seed colour that we collected. Could I please get you to introduce yourself? Okay, my name is Dr. Abisa and I'm the head of the Plant Genetic Diversity Division.

5:59I'm here with Eric. Eric Opukumensa. He's also a PhD holder and we work in the division as scientists together. I'm at the Plant Genetic Resources Research Institute or the PGRI in Bunsu, north of Accra, here in Ghana. It's a huge site with grow labs, research centres and testing fields full of growing crops swaying in the sun. It's the National Gene Bank of Ghana and their mission is to collect, catalogue and preserve all the different native and crop plants that the country has to offer and find out a little more about what each of them can do. Our mandate as a diversity division is to profile our crops to know the personality of the crops we have.

6:49We grow them out in the field and then we document the characteristics at three levels. The morphological characterization with a set of descriptors, the biochemical characterization and then the DNA profiling. Currently, we are focusing on the morphological characterization because we don't have the full set of equipment, complement of laboratories to undertake biochemical and DNA profiling. If we develop our own laboratories, we'll be able to profile these materials in terms of sugar, protein, in terms of all the nutrients that are useful to humans. We'll be able to do that. Now, our listener George, his question was, do plants have personalities?

7:39What are your thoughts? Yes, plants do have personalities, and their personalities are constituted by a set of traits. You can identify one material that is early maturing, has good taste or sweet or sour. You can have one that is tolerant to diseases, one that is tolerant to drought or salt. stress. For instance, we have some cassava germplasm that are tolerant to ACMV, African cassava mosaic disease. We have some that are high-yielding. We have some that are tolerant to fusarium for rice. We have high-yielding ones. We have salt-tolerant ones. So all these characters together constitute their personality.

8:26Dr. Abisa and her colleagues here have prepared a little demonstration for us. laid out in the courtyard in front of the seed processing room is a long table absolutely covered with all sorts of produce there's some giant hairy looking seeds some enormous fruits and some tiny clusters of nuts some I can recognize but most of them are a mystery to me if it wasn't for the fact that everyone here is in lab coats I would assume we were at the market We are showing the diversity of the crops we have in the gennibus. And you can see the variation in the seed colour of the different assertions that we collected.

9:08So what am I seeing here? Is that a seed? It's very big. It's almost the size of a toddler. We have the chaffroot here. And then even the colour indicates that there are different types. You see this one a bit brownish? Okay. This one which is green. So not only about the colour but even the shape. This one is more cylindrical and then you see this one is a bit more over and then if you look at this one also a different type. So we think about the colour, the shape and so many other things. This is just what George was talking about. The same kinds of plants grown from the same kinds of seeds and given all the same growing conditions and yet they can turn out really different.

9:52Whether you think of these as different personalities or just different traits, it all comes from the same place, from variation at the genetic level. Traits are constituted by genes and during typing of genes, mistakes happen. So you may have mutations in the copying And this causes the variation in the different traits you observe. So for instance, in seed coat colour, we have different colours, different shapes, representing differences in the genetic makeup. As Dr Ibiza explained, every new seed will have tiny genetic variations from the seed next to it. And it's that variation which leads to the differences in colour, size or speed of growth.

10:41one plant might sprout just a bit quicker or produce a fruit that's just a bit sweeter. If a genetic variation produces something useful the PGRI can breed from it reproducing those genes and then distribute those seeds to farmers to help them get the very best crops in the ground just where they're needed. So for instance if you have an early maturing variety which has a short duration you can deploy them in areas that have short rainfall in drought areas so that they can mature early within a short time and then farmers can get appreciable yield even if the weather conditions are not good and now here i've got three very big green seeds and they look exactly the same so this one is called a breadfruit so if you don't have the yam then you can use this one as a yam.

11:36You can cook and then you eat and you can even use it as a flour to prepare some of these fisheries like cake and others. So it is also a very important plant. These genetic strains they're working on here don't just make you a juicier breadfruit or an early sprouting rice. They're also researching ways that plants could survive droughts, resist disease and leach toxic heavy metals out of the soil where it's been polluted by gallamse or illegal mining. So this is some really serious science. But you know what? There's something that feels just a little bit unserious about listener George's question.

12:15The idea of a plant having a personality. I couldn't help myself from bringing along just a bit of his whimsical spirit. And Dr. Eric Opukumensa was well up for the challenge. This is not a scientific question. I want you to give them a sort of personality. What sort of personality would you say? so let's start this is the breadfruit right yes what sort of personality would you say is important here you know sometimes if you are in trouble somebody comes in to assist you so in times when we don't have the jam which we actually use now breadfruit will come in to assist us so it has that special personality that assists us when we are in trouble then what am i seeing here because these are tiny little orange things what are they yeah so this is an african star fruit But, you know, before the white men came with their chimingan, we also had our home.

13:05We can chew it for a long time. Locally, we call it alasa. So starfruits, you see, there are some people who say, OK, you want to go so beautiful. You want to enjoy life. And if you look at starfruits, you see it's so beautiful, so attractive. So that is the personal nature of starfruits. Now, there are a few beige-coloured seeds there. And I do know what they are because there's a label there that says nutmeg. Yes, very important. So nutmeg is a spicy plant and we have the fruits here. I'm going to answer this next one myself. I think nutmeg is just hardy. It's there when you need it. It's cooperative.

13:44It's adaptable. That's what I think the personality of nutmeg is. Would you agree? Well, yes, I do agree. But it can also put something in your pocket. So not make fruits all year round. So anytime you need it, it will tell, yes, I am here. I'm ready to assist you. I'm ready to take you from poverty. So take me, go and sell me, get something into your pocket. So not make is our very important friend. It is always there. A friend indeed. It's a friend in need. so far in the show we found out that plants even plants of the same species can look and act very different from one another they have different traits different characteristics but can we really describe them as having different personalities this is summer at its peak Whole Foods Market Summer Fruit Fest is your invitation to eat the season.

14:42Fresh, organic, and bursting with flavor. Start your day with peaches and organic blueberries and yogurt. Build a grazing board with fresh fruit, prosciutto, and artisanal cheese. Then fire up the grill with no antibiotics ever proteins and fresh produce. Savor the season. Shop Summer Fruit Fest at Whole Foods Market. The United States is about to mark its 250th anniversary. And so on the Global Story podcast from the BBC, we're telling surprising tales of American influence on the world stage and in ordinary people's lives all across the globe. We have this ability to export our story and a lot of people have bought it.

15:21I feel like the American dream is alive, but not well. From the BBC, it's the United States at 250. Listen on BBC.com or wherever you get your podcasts.

15:36You're listening to CrowdScience from the BBC World Service. I'm Alex Lathbridge and I'm trying to answer a question from listener George, nature lover, mushroom farmer, and owner of a truly well-built shed. He wants to know if plants have personalities. So let's bring it back to the human world. When we think about our own human personalities, it's not just about what's encoded in our DNA. It's also about how you behave, the way you communicate with others and the choices you make. All of those things require some uniquely human qualities, like the power of thought, intelligence, a brain. And these are qualities that plants just don't have, right?

16:26People make a big fuss about it when I say we study plant intelligence and people go crazy. oh my God, plants cannot possibly be intelligent, they have no neurons, they have no brains. This is a man who thinks that plants might have a lot more going on than you think. Of course, if you are thinking that the plant is rationalising, is thinking with words, hey, should I do this or that, then that's the mistake. They make their own decisions in their own way. Well, I'm Paco Calvo. I'm the director of the Minimal Intelligence Lab at the University of Murcia. we study plants that's what we do not just plants but their intelligence in Paco's lab at the University of Murcia in Spain they think that if you want to understand plant personality you have to understand plant behavior and if you want to understand their behavior you have to slow right down to their pace of life we need to make the effort not to speed plans up, but to slow ourselves down.

17:28I tell my students, if you simply time lapse plans and then watch the footage real fast, you're going to miss it. You need to slow yourself down to appreciate their efforts on their own time scale. And I do that. I sit on a stool next to the climbing bin and watch it to the naked eye. Then you will get to see things that you could miss otherwise. So we've got to sit back and relax, chill out. Slow down enough and what might look like automatic mindless growth patterns begins to look a lot like intelligent behavior. Plant behavior is intelligent behavior insofar as it's not just adaptive but anticipatory and flexible I may add.

18:13So if behavior is not flexible enough you might simply be following a pre-programmed routine encoded in your genes. But that's not the way it works because things happen out there. You never know if what did work for you yesterday might still work tomorrow. Things do change. That means you might need to flexibly change gear as the situation demands and anticipate the best course of action. One of the plant models that I love is Cuscuta. That's a parasitic plant. So it doesn't have chlorophyll. It cannot make its own food. That means it's so important for Cuscuta to find a host plant to latch onto and suck up its sugars.

18:54So they have to grow to find those hosts. And it will choose the more juicy one, so the one that has more sugars. So if it's a tomato plant and a cereal like wheat or something, it will go for tomato, of course. But if tomato is not an option, it will reconsider. So it will pick the best considering the possibilities, right? Now, you may just think that, sure, a plant can grow towards something that it needs, like water, sugar, the sun. But this isn't necessarily intelligence. That could be an automatic action, no thinking required. But Paco thinks it's more sophisticated than that. That would be the case if they were responding to sources of stimulation on a one-to-one basis.

19:43So, I sense light, I grow towards light. I sense a chemical gradient, I grow towards that chemical. I sense water, I grow towards water. But plants don't do that. Plants have to integrate all those incoming sources in order to provide a response that is adaptive. So, the same amount of water in a given situation might mean, hey, this is the way to go. And in a different situation, it might mean I don't care because something else is catching my eye. So an integrated response allows the plant to decide which way to grow. Paco thinks that plants make choices and that different plants of the same species might choose slightly differently in the same scenario.

20:28This is beginning to sound a lot more like personality to me. There is a field called phytoacoustics, so plant acoustics. And plants can tell whether some insect flying around is my pollinator or not through the specific vibrational patterns flying nearby the flower. If it's my pollinator, the flower will start to increase the concentration of nectar because that comes handy to my pollinator. If it's somebody else flying around and it's not my pollinator, they won't increase the nectar. So through many different channels, they can tell what's going on and make decisions accordingly. Back in Ghana, I wanted to find out more about the supposed intelligence of plants, about whether their unique personalities could be more than just genetic programming.

21:22Whenever there's light, they are programmed to sense the light and then move towards that pathway. but they may not have a choice to do otherwise. So that is where the debate is getting at. The question is, can plant make choice beyond the biological programming? I'm with Dr. Achampong Atabwating, a plant physiologist, ecologist and engineer. We're resting in the shade of a tree in a particularly beautiful botanical garden. We are in the eastern region, a very popular town called Abri. A brie is famous for its botanical garden, which was established during the colonial era. So we are in a brie garden and we are sitting below a beautiful tree.

22:08And then we are hearing beautiful birth songs. And oh, the breeze is wonderful. You've done my job for me. This is fantastic. I don't have to describe anything. Now, one of the things I think about a lot when it comes to intelligence is the ability to respond to change. What sort of examples do we have of plants relying on their senses and changing their behaviour based on them? Yeah, I'm going to give an example in herbivory. So we know that when plants are attacked by herbivores like a caterpillar, they feed on the leaves, they tend to emit VOCs that are volatile organic compounds. They are supposed to deter the herbivores and then stop browsing the leaves.

22:49So they actually copied the munching sound when the caterpillar was feeding on the leaves. They recorded it, amplified it, they played the sound. Guess what? The plants, even without physical munching, immediately responded by emitting the chemicals. This could be evidence that there's a form of memory, because they can remember the experience to the point that they react similarly, even though the condition is not there. Plants changing their behaviour when faced with a variable stimulus is pretty smart for an organism with no neurons, no nervous system and no brain. Aceh has other examples too.

23:30We have a group of plant species called tracheophytes that has evolved the capacity to sense touch. So the mimosa group has about 600 genus and they are extremely sensitive to touch. What we have here in Accra is a common species that when we were kids we used to play with. When you touch it then it folds up, you know. It says don't play with me, I'm not your friend. And so when you touch it, it closes. Growing up, I remember playing with these plants too. One little tap, a little stroke, and the leaves fold themselves away, one by one, like a tiny Mexican wave. Some people call it the sensitive plant or the shy plant or the touch-me-not.

24:14Aceh found a small patch of them growing right here in the Buri Gardens and he reminded me that they have a slightly less radio-friendly nickname. So basically mimosa in a local dialect translates and still I'll be a bit diplomatic. It's like telling a grandmother to cover herself up. Yeah. So let's say granny is exposed and then you are signaling grandma. Please cover yourself. Okay, so you're about to show that to me. So this is the mimosa plant, right? Describe what I'm seeing here. What does it look like? Great. So they have these tiny little leaflets that are arranged in opposite direction.

24:56When you haven't touched it, it's just a regular plant. But the moment you touch it, it's very sensitive and a process that we call thigmotropism. you touch it and then it closes the leaf so okay let me touch one okay just a little tap it curls in it's very slow i guess that's what you expect with plants just a very slow little yeah i can see just the upper portion and then look here that's it yeah so it's not all the leaf shut at once it's that one section so i can touch in the middle and that little bit will shut. I can touch it at the tip and the tip will shut. I can touch it at the bottom.

25:34Why would it do something like that? That's a very interesting question. I think the likely explanation could be protection against heavy worry. You don't even need to time lapse mimosa because they fold in human time. Touch the leaves and they just fold. Back with Paco Calvo at the minimum intelligence lab in Spain and he's also fascinated by the personality of this shy little plant. He says that in the lab, if you repeatedly trigger the folding mechanism without damaging leaves, it learns and stops doing it. But it starts up again straight away should a hungry herbivore actually take a bite out of it.

26:15This kind of learning is called habituation. Habituation is the simplest form of learning. So it makes sense for individuals of any species to learn through experience, not just what comes in their genes, but through their own experience from birth. Because things out there will be different from one day to the next. You cannot resort to some routine that is pre-programmed. So learning has got to take place. So plants can sense their surroundings, make complex decisions about how to behave, and can learn from their experiences and behave differently next time. But if you're still in any doubt about whether plants have got some kind of intelligence, Paco's got one more example up his sleeve.

27:04It turns out that plants can be anesthetized. You put the plant under a glass bell, put a cotton pad soaked with anesthetics and the plant absorbs it through the leaves, right? Then the plant defeats the mimosa and then you touch it, you touch the leaves it won't fold anymore. That part can be perfectly explained electrophysiologically. What's intriguing to me is what happens when you come out of anesthesia. Oh, I'm back to normal. I recover something, right? So the mimosa plant, you touch the leaf and it again goes back to folding more slowly. So it's coming out of anesthesia. So to me, the critical question, more philosophical than scientific, is what does it mean to come out of anesthesia?

27:51You are recovering something that you have lost temporarily. This something that you are recovering is what we call sentience. How can something that isn't in some way awake be made to sleep? And what is it then that wakes up? This is mind-bending. I don't know about you, but this is going to make weeding the garden a bit more of an ethical dilemma for me. The answer is clear. They couldn't possibly not have a personality because they are individuals. They have all been exposed to different factors, different parameters. My behavior only gets explained through which specific world I inhabit. So if I had been raised in a different condition, Paco would be a different person.

28:43that has to apply to any form of life whatsoever. Plants are not like robots, you know, following their software. The way we explain their behavior has to do with the way they interact with their surroundings. Considering that their surroundings will always be different, they have by necessity to be different. Some individuals might be faster, some others might be slower. Not just their genetic constitution, but the richness of their surroundings. So, of course, we find individuals with different personalities and responding in different ways all across the board, right? Throughout the whole tree of life.

29:20To me, it would be shocking otherwise to find it differently, right? The one and only mistake is to use ourselves as if we humans were providing the gold standard. As if the type of consciousness that we have, including self-consciousness, That was like the template that any other form of consciousness needs to fit in. Humans, Homo sapiens, is not the one and only way to inhabit planet Earth. So, we started this program trying to find out why some plants grow a little faster, reach a little higher, or bloom just a tiny bit earlier than the others around them. We wondered, could it be possible that these simple organisms could have something as complex as personality?