Episode 142: leaf botany part one - shape

Transcript

EPISODE 142

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Hello, and welcome to On the Ledge podcast. My name is Jane Perrone, but my school nickname was Botany.

In this week's show, Episode 142, we're talking about leaves. Delving into the botany of the leaf. I talk to Professor Enrico Coen of the John Innes Centre about why leaves are shaped as they are. By the way, prepare to have your mind absolutely blown by what Professor Coen tells me,

I offer up a little glossary about the names we give to plant shapes, Stephen from Plant Daddy podcast joins me to answer a listener Q&A with a leafy theme, and last but not least, we meet listener, Mikaela.

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[Rippling water]

When it comes to leaf talk, and God knows I love a bit of leaf talk, there are a lot of terms bandied around that you may or may not be familiar with. I'm going to run through some of them now just to give you an idea of the range of terminology that you can use to describe leaves. I mean, why bother? You can say, "Well, a leaf is round, or it's pointy, or it's holey. Why bother with all these specialist terms?"

Well, part of the reason is that as you get more into this hobby, no doubt you'll start reading up online and in books about plants and you'll find these terms start to come up. Learning these terms just helps to enhance your understanding of what you're reading.

So what are the some of the terms that you're likely to come across? Well, let's start at the very basic level with the leaf. What makes up the structure of the leaf? Well, the lamina is the blade of the leaf, the flat bit. the bit that we're possibly most interested in and the stalky bit, well that's the petiole. But do you remember not all plants have petioles. Some of them join straight onto the stem, and it's an adaptation that often saves the plants some water.

Listener, Bobby, reminded of another useful pair of words when describing leaves, and that's abaxial and adaxial. Yeah, you have to have your teeth in when you say those. So the upper surface of the leaf, that's the adaxial and the underside, that's the abaxial. Again, you might come across that one when you are reading about plants and that just helps you to know what is what.

And then there's a whole set of words just describing the shape of a leaf. The first thing to notice about a leaf when you're looking at it is, is it simple or compound? Now simple, well, that's fairly obvious. It just means the leaf is one whole thing together rather than having some complex kind of design. Whereas a compound leaf, well, that's formed by a number of leaflets that join together and then attach on to the stem, and there's a couple of different kinds of compound leaves you're probably going to come across in the house plant world.

Probably the most notable is compound palmate. Now, and as is often the case, the clue's in the name, a compound palmate leaf looks a bit like a hand. So, if you think of a horse chestnut leaf or in the house plant world, a Schefflera leaf, you are along the right lines. You can, of course, get palmate simple leaves - think Fatsia japonica, for example. That's a great example of a leaf that looks like a hand, but it's simple. It's all one leaf.

The other form of compound leaf is the pinnately compound leaf, and I guess the best example I can think of this one is the sensitive plant Mimosa pudica, where the leaflets are all arranged in a straight line. Out in the garden, the best example probably is a rose. Some of the names are quite poetic, I rather like peltate, which means a leaf where the petiole joins not the edge of the leaf, but somewhere in the centre like a nasturtium leaf, if you can picture that.

I also like hastate, which means a spear shaped leaf. So think of Philodendron hastatum being the perfect example. Again, the Latin's telling you something about the leaf. And then we have the wonderful lanceolate, which means quite simply shaped like a lance. So in other words, it comes to a point at the end. So think about your busy lizzies, your Impatiens, classic lanecolate leaves. There are loads more - linear? Well, that's the spider plant's leaves right there, it's fairly obvious.

And then you've got something like Hoya kerrii with its obcordate leaves, which means they're heart shaped with the stem at the pointy end rather than the other end. If you want to go deeper into leaf shape names, then do check out the show notes where I'll include some links to some wonderful pictures and diagrams of different types of leaf shapes, and you can spend hours learning them all. But how is a leaf shaped determined? And why is there so much variation? Well, this was where I needed to call in an expert.

Enrico: Hello, I'm Enrico Coen. I'm a research scientist at the John Innes Centre, where we try and study and understand how plant forms are produced, how leaves grow, how flowers, get their shapes.

Jane: I often look around my growing collection of house plants and just wonder at the amazing variety of leaf shapes that are demonstrated even in my relatively modest collection. Do you have any insight for us about why certain leaves are shaped as they are? What are the factors that determine leaf shape and indeed leaf size?

Enrico: Leaves are fascinating in terms of, as you say, the variety of shapes that are produced.

And one of the big questions which we still don't know all the answers to, is how these shapes are generated. If you think about manmade shapes, we have a notion of how we make a spoon or plate because there's an external hand, our own hand that guides the process, but with a leaf - as with most biological structures - there is no external hand, It all has to figure out how to produce these shapes internally. And just as in a sense, you could imagine how... We use the musical scale, a single musical scale, to produce all the different music that we hear, from symphonies to concertos to pop music, and it's the same notes. It's the way in which they're organised and put together that generates this amazing variety of music.

In the same way, leaves have a set of basic ingredients, and it's the combination of these ingredients that allows so many different forms to be generated. So although we marvel at the variety of forms, underlying that are some basic rules that get combined in all sorts of glorious ways to produce the shapes we see.

Jane: Are there any particular kinds of leaf that are typically useful to study when you're trying to understand how leaf shape works?

Enrico: You're absolutely right. We can't study all leaves. We study a few to understand the basic principles, and one of these is a kind of workhorse plant, genetic and developmental studies and that's a weed called Arabidopsis thaliana. Because it cycles rapidly, we can study how something like its shape of leaf is generated.

The other plant that we have been spending some time on is a carnivorous plant, Utricularia gibba. This is what's known as a bladderwort and it has remarkable cup shaped leaves that can trap small animals, it doesn't have roots. It gets its nutrients by basically trapping these small animals. and we studied that shape as well.

So we studied two extreme shapes as it were. a flat leaf of this weed and how you go from a flat leaf into the more intricate shape that traps animals.

And in general, you find that the more complicated shapes and leaves are often associated with interactions with other organisms, like the pitcher plant or Venus Flytraps. All these things are quite elaborate in their mechanism and shape because they're dealing with animals. It's dealing with enticing animals to their doom in most cases. Just as a flower, you have lots of different complicated shapes of flowers because they're also enticing animals. The bees, or pollinators. in that case, whereas many leaves are flat because that's to do with photosynthesis or maintaining their nutrition.

So if a leaf is mainly involved in photosynthesis, you tend to get a flattish shape but the outline can vary, whereas if a leaf has been adapted to interact with an animal, you'll often encounter a more intricate shape. But all those shapes we're discovering are produced by these common rules combined in different ways.

Jane: I have this rather naive thing that the larger a leaf, the greater amount of shade the plant likes because it's trying to collect more light if by being bigger. I'm sure that's a gross oversimplification, but is there something in that?

Enrico: Oh, there absolutely is something in it. The interesting question is, if you're a plant, is it better to produce one big leaf or lots of little leaves? You'll get the same surface area in both cases. The question - do you put all your eggs in one basket? in fact, there are some plants that only have one leaf. I think they grow on cliffs, and they just grow from the base and the leaf gets bigger and bigger and bigger. But the problem with that strategy is sometimes in terms of the circulation, if you want to interact with the atmosphere, it's often better to have multiple spaced leaves rather than having them just a single leaf produced at one level.

And so there's issues like that, gas exchange and raising the leaf above a certain height in order to compete with others. So the shape and number of leaves, not just the size, it's also the number of leaves, is quite a complicated thing and what the best strategy is can vary from one situation to another - which is why you'll find, if you just step into your garden or in a wild meadow, you'll find plants with all sorts of different shapes and sizes of leaves. That's because of these different trade-offs What do you go for? Do you go for size or number?

Jane: Ah, that's an interesting one, isn't it, because I suppose you've got something like the sensitive plant, Mimosa pudica, which has got all those tiny little leaflets, which I imagine if you lose one or two of those it's not the end of the world. But if an animal comes along and pulls off one giant leaf off a plant that's taken off half its foliage, that's a more severe attack. That's really interesting.

Is there any way of when you're looking at a plant, presumably you can calculate total leaf surface and make some comparisons, Say, "Well, okay, this plant's got ten times the number of leaves of this plant, but actually its surface area for photosynthesis is actually greater overall because it's just got so many leaves."

Enrico: That's right. I mean, they can go further than that. People can simulate the growth of the plant so that you can take into account the shading, the angle of the leaves and so forth. And so you can calculate the sort of photosynthetic capability of different architectures and different strategies. We don't do that type of research ourselves, but there are people that that's their main concern - trying to understand how these different canopies interact and what the effective amount of light you're getting is.

And also, it may be in some cases, a given leaf will only be able to extract a certain fraction of the light that passes through it, So sunlight will pass through one leaf and then hit the leaf below it. So the first leaf doesn't take everything, the next leaf can take some. So it's quite a complicated calculation, but people do study those things, Our interest more is in how you generate the leaf to begin with. What are the principles by which it constructs itself, rather than necessarily the adaptive features, which are a consequence of that.

So it's a bit like trying to understand how a fertilised egg turned itself into you, for example, versus how you function every day in terms of your job and your constraints. Clearly the two are connected, because if you hadn't developed inside your mother, you wouldn't be doing all these things. But on the other hand, we can separate them out to some extent and try and understand what are the basic principles of construction, and how that then relates to functions. Our research is much more concerned with how you are formed more than necessarily how you function.

Jane: One of the things that people seem to get very confused about quite frequently is one of the key plants of the moment, the Swiss cheese plant, Monstera deliciosa. They kind of have this idea that a leaf is going to grow and then it's going to emerge, and then It's suddenly going to start developing holes in it rather than what actually happens, which is the leaf in its unfilled state is the shape it's going to be once it's out. if you see what I mean. Presumably because that that is all pre- determined in the gene of a plant and it's already set in stone, and therefore, people get a bit disappointed when you say, "Well, no, that particular leaf isn't going to change. It's not going to suddenly develop fenestration. Your future leaves might become fenestrated, but that leaf is going to stay that shape forever." People are sometimes a bit disappointed by that, but I guess that's taps into what you're saying about -- those decisions have already been made far further back than the leaf unfurling,

Enrico: Oh, that's absolutely right. The form and shape of the leaf is established very early on.

Monstera, the case you gave, is actually a very interesting one with the hole. They arised through a process called cell death, programme cell death. So if you look at your hands, you see the gaps between your fingers. Well, those gaps originally when you were an embryo, there was some tissue between your fingers. Gradually the bits between your fingers died. Those cells were programmed to die. If they don't die, you'd end up with webbed hands like a duck.

So there's a specific set of genes involved in killing the cells between your digits. That creates these holes between your fingers, so you can think of it that way. Now that is unusual in plants as they develop, but some leaves do this. That's why Monstera, the cheese plants, look so weird compared to many other leaves because they're one of the few species that undergo this cell death. So very early on in their development, a leaf, certain cells will die as a consequence of gene activity. That creates these holes. But that is all established quite early in development. You won't see, as you say, unless you go and tear your leaf physically - the leaf won't spontaneously generate holes once it's come out.

Jane: Right, and again this is another one that people seem to get confused about is - this occurred to me recently that once a leaf is damaged, it's not like human skin. It doesn't really repair itself. It'll stay damage for forever, but the nature of leaves being as they are, and plants growing, is that the plant will grow past the problem and grow some new leaves. So it has a different strategy for dealing with damage than us as humans. That sounds ridiculous, but I have had people say to me, "Oh, look at this leaf. It's damaged. Will it heal?" You have to say, "Well, no, your cat has scratched it and that's the way it's going to be until some new leaves come and you don't notice it anymore."

Enrico: It's not in the least ridiculous, It's a fascinating feature about plants versus animals. You see if we have a problem, if we see somebody coming with a knife towards us or some sharp teeth, we run away. We have an option of avoidance. Now a plant cannot avoid. It's stuck in its place. So how do you deal with it? Well, one way a plant can deal with it is to taste unpleasant so that the thing doesn't want to eat. But if that fails, and you are eaten, then how do you deal with it? And what plants do is they have what's called meristems. These are small growing regions that can regenerate the lost part.

If you take a good example, the experts at this are these grasses. Now you go out and you mow your lawn. Just imagine if you were a blade of grass or a grass plant. Every week this relentless sawing of your parts occurs. But actually what happens is because these plants keep their meristems, they're growing tips below the cutting level of the blade, they can easily regrow and replace what's been taken, which is an which is an adaptation to herbivores - which we exploit when we grow our lawns. So that's a remarkable strategy. It's why, for example, grasses are so successful worldwide. It's because they have this ability to keep their growing points, as it were, quite low down.

Other plants have their growing points higher up so that when you cut them, they don't grow from the base. They will grow from the next branch points down, but grasses are particularly good at this regeneration game. It's really a regrowing game that derives precisely so the plants can't move or can't translocate and so they have this strategy.

There are a few animals by the way that can regenerate, like salamanders. If you cut limbs off these things, if you're so inclined, then they can regenerate them. But humans, vertebrates in general, have a very poor regeneration capability. And so we also have to defend ourselves by avoidance because once we lose a limb, that's it. We can't grow another one, but a plant... Well, you might feel sorry for the plant being chopped relentlessly, but on the other hand it has this relentless ability to grow back as well which is fantastic.

Jane: It is. This is something we sometimes do discuss in On The Ledge because this location of the meristematic tissue is important to us as houseplant growers in terms of understanding how we can propagate different plants. If you haven't got that material, then the plant's not going to be able to grow another type of cell, ie, roots from a stem or from a leaf or whatever. Sometimes it's quite sad when you see people trying to try to propagate things that won't work.

Enrico: Plants vary in their ability to switch meristem. Geraniums, for example, you just need to put in water and what was a stem will start to sprout roots. That means that essentially it can reprogramme its meristem, so rather than producing shoots, they can now start to produce roots. So plants vary in that ability. Some plants are less capable of doing that unless you dip them in hormone. Sometimes you have to give them a hormone powder, dip them in that, and that can help them then produce routing merit stems. So not only is it that plants have meristems, they can also sometimes switch the type of meristem, so whether you generate a shoot or a root.

Jane: It's very clever stuff. It's amazing. I never cease to be astounded by the amazing things that plants can do right in front of our eyes, which is very special. Is there anything else we haven't talked about, Enrico, that we should cover on in terms of your research or leaves?

I know we haven't gone tremendously deep into what you've actually done, but it's really interesting to hear about how leaf shape is determined by what the plants are actually trying to get from the world in terms of the carnivory versus photosynthesis. Is there anything else we need to mention though?

Enrico: There's a couple of things that maybe we could say. One is, when you say that plants and maizes, by their intelligence, in a way, their ability to do the whole these amazing things - it's maybe partly a reflection of the fact that when we look at the world, we're driven by the assumption that movement is the most important sign of life and intelligence. We're mobile animals and we judge people by their actions.

Plants don't exhibit that behaviour. Some plants do move at a rapid rate, but a lot of them move much more slowly, or grow much more slowly than we can see by eye. We have this rather condescending view of plants that because they don't move, they can't be very smart in what they do. But in fact, they're amazing. They can produce the most amazing structures and they exhibit their 'intelligence,' through the variety of different structures that they generate, that we could not generate.

I mean, we, we can't grow chairs, for example. We can assemble chairs. We can't take a seed, put it in the ground, and it'll turn into a three piece suite. You'd think that was miraculous if somebody could do that. Just imagine if you went into a shop and they gave you a seed and you took it home. You water it and it turns into an iPhone. That would be viewed as a complete miracle. But that miracle is happening around us all the time, every time a plant construct itself. And so it is a marvel and we sometimes take it for granted because we're so familiar with it. But it's something that just continually, continually amazes.

And that's really the basis of our research, trying to understand how they do this, how they do this remarkable thing. One insight, one way of thinking about it, is a bit like the musical analogy I was giving you earlier. Just as an orchestra can produce an amazing piece of music by the coordinated activity of the players, so plants produce these amazing structures through the coordinated activity of their cells or their cellular components. Whereas an orchestra, the key thing is what instrument you're playing, what tune you're playing, with a plant the key question the cell has to ask is. 'how much do I grow this way, or that way. in this direction or that direction?'

As a leaf grows from its bud, that's what's going on. There's an orchestrated pattern of growth in all these cells that is coordinated between them, and there are also tensions. There can be tensions between them, just as you can have tension between the string instruments and the woodwind, in terms of the tunes they're playing - and that can be a creative tension. So as a plant grows, certain cells will be growing one way, some will be trying to grow another way. And that results in bends and waves and all sorts of shapes and undulations. So really, when you're looking at a leaf, you were looking at the symphonic output from this orchestrated pattern. We're trying to understand the principles of how that music is played, as it were,

Jane: As you're talking about that, I was thinking about the particular drama, the genetic drama that must be going on therefore in any sort of leaves that show Kaimeral variegation. I know when I speak to botanists sometimes who grow house plants inside their houses, they don't like variegated plants. I think they find them a bit much. That I find fascinating, the fact that you've got... Well, in my very basic understanding, you've got two different sets of genes competing in a single leaf to create these incredible patterns that you get on something like a variegated Monstera, which kind of takes that to another level for me. Another level of complication and amazement that plants actually manage to put out leaves which have got so much going on.

Enrico: Yeah, I think that's a very good illustration of the fact that even with a single leaf you're able to visually see the two layers because when you look at one of these variegated leaves, you see the white or the green parts. That's visually telling us that there are these two types of tissue that are somehow coordinated that you still generate at least at the end of it, even though these things are perhaps growing slightly differently, the white and the green part. But that's just the tip of the iceberg. That's just what we see by eye. It's like we're getting a privileged view in that case. What's actually happening is every leaf is doing that through internal mechanisms, creating all these differences and patterns, but we just don't see them. What we see is the outcome. "Oh, look, that leaf has a certain shape. This leaf has a different... This one bends, this one has a lovely jagged outline" and so forth.

We look at the outcome, but we miss the drama. Drama's a very good word. We miss that genetic drama that's going on all the time as the cells grow and interact during the development of the bud.

Jane: Well, I'm not going to look at a new leaf on any of my houseplants in quite the same way again, Enrico. That was really fascinating. Thank you very much for sharing that. I'm going to go and look at some leaves now even more renewed fascination.

Enrico: Okay, well, it's a pleasure talking to you. Thanks a lot.

Jane: Thank you so much to Enrico Coen, who provided such an interesting insight into leaf shape there. If you want to check out Enrico and what the John Innes Centre does, then do look at the show notes where I will include some relevant links.

And now it's time for question of the week which has to do with a very particular kind of modified leaf, the pitcher plant or Nepenthes. This question, this plea for help, came from Rachel. Her pitcher plant is in a bright bathroom with an east facing skylight but very little sun. The room gets steamy from the bath and Rachel tries not to let the plant dry out. She says it's always been healthy and throws out new leaves regularly. but no pitchers and she's had it for a couple of years.

I am not a carnivorous plant expert by any means, so I called on someone who is and that someone was Stephen from the Plant Daddy podcast. Over to Steven to commiserate with Rachel.

Stephen: Hi, first of all. I feel for this listener. I have been in this situation before. You'd definitely buy the plant wanting the pitchers. That's the main part of the show for most people.

There's a bit of a checklist that we tend to run down when this is happening. First of all, this is a gorgeous plant. It's huge. Jane, you were nice enough to send me pictures. So yeah, Wow, nice job overall. I think this this person probably has eight out of ten pieces correct.

First thing I would change here, I would increase the light. I think many of us living in northern latitudes, so often we read or we're told to keep these out of direct light, to keep these in sort of under store conditions where they grow, but we have to remember that these are from equatorial regions. The sun is so much more intense there. So where we live, I wouldn't be afraid to put these in more intense light. So that's probably the issue. I would say 50 per cent chance at least. Increase the light, you're going to see pitchering after a month or two.

And I think, keeping it in a bathroom. I think that makes sense. We think of these as tropical plants, they look leafy and tropical. I wouldn't worry about humidity so much. I have mine pitchering in as low as I would say, 35 per cent humidity. Just as long as they get that sun. I think that's the key component.

And again, you can't bake them. I wouldn't put this in a south or west facing window that gets uninterrupted light all day, but maybe something a bit more than the east facing window that I think the question mentions, so I would start there,

Jane: Stephen, I love the fact that you're using pitcher as a verb. Pitchering! I'm loving that. Is that a plant-y thing that people say, "Oh, I'm just pitchering right now." Or is that your own invention?

Stephen: Yes, guilty. Yes, that is one that is tossed around a lot. So okay, thank you for translating,

Jane: I must not be not be reading the right Reddit threads or something. I don't know where these people are gathering, but anyway, that's interesting.

Well, that's a really good point. I don't think I've been in many bathrooms that have anywhere near decent light really. I mean, most bathrooms are pretty gloomy, aren't they? When my husband was doing his PhD, and I lived in his place for a while he lived in a vicarage, which was ancient and falling down. That had a really nice light bathroom because it was a really big window. It probably wasn't even a bathroom in the 17th century or whatever. It also had fungus growing up from the ceiling, like a dead bat trapped in the door. So it wasn't your average bathroom, but most bathrooms -, mine included, they're pretty gloomy.

I guess if you could find some way of getting a grow light on that plant within the bathroom. that could work, but bathrooms and electricity, it's not always easy.

Stephen: Yeah. You know, it might just be a place that's suited for another plant. Honestly. I mean, you're so lucky to have a bathroom with any light, but maybe there's some humidity loving plant that can deal with a little bit less light. And really, if you look at that plant, it's gorgeous. You know, if you don't mind the pitchers not being there.

Jane: Well, I guess that's the thing, isn't it? It's just I can imagine visitors going, "Oh, that's an amazing plant in the bathroom. What is it?" And you go, "It's a pitcher plant." And they go, ""Where's the pitchers?" So yeah, that's the only downside.

So, light. Is there anything else to say about this plant in terms of encouraging pitchers? Is it a seasonal thing? As you say, it's equatorial, so there's not really that much seasonality going on, presumably in it home environment. So presumably you can prompt pitchers at any time by getting that light right?

Stephen: Yeah. I think, unfortunately, there are a couple of other wrinkles. I think if those first steps don't work, I think they will. But if they don't, you can also try letting the temperature dip at night. This also might be difficult in the bathroom, but I think a lot of people find that maybe when the summers get warm, pitchers sometimes can die and pitchering can stop a little bit. They can rest.

Often what we buy in stores, these kind of hardier species are Highland Nepenthes, and they're highland and lowland species. If you get more into the hobby, you'll find that. Maybe you're familiar already, listeners and you, Jane, but these highland species, the temperature really dips at night in their native conditions. So they're used to that, they tend to grow better that way. People find here in Seattle and the northern part of the United States, that in the wintertime when those temperatures dip more, pitchering can improve. Sometimes the rest a bit in the summer when the temperatures higher and more stable. Stably high like that.

So I think that's the third lever I would try. Again, I would try light first. As you go down the list, that's something that you could try as well.

Jane: Okay, that's great advice, and hopefully some pitchering will be occurring. I'm going to be using that in a conversation today. I don't know when or how, but I'm going to be putting that into a conversation.

Well, it's really nice to speak to you and thank you for giving us your wisdom and hopefully pitchering will occur shortly.

Stephen: Yeah. To that listener, gorgeous plant. I have a lot of hope, so I think it will work out.

[Music]

Jane: And now we hear from listener, Mikaela.

Mikaela: Hi there, On the Ledge. My name is Mikaela. I'm a listener from Chicago here in the US, and I am so excited to be a part of the Meet the Listener series.

I have been a listener of On the Ledge since right near the very beginning. I found it through a couple of other plant-y friends that told me about it, and it has become one of my absolute favourite podcasts. I get excited for every episode every week, and it really is just one of the highlights of my week. I love just being able to listen to Jane, share all of her knowledge and all of the experts that she has on - just share their plant-y knowledge as well. And it just makes me feel like a much better plant parent from learning all of the things that I can through the podcast. So I'm very excited to be a part of it.

Jane: Question 1. There's a fire and all your plants are about to burn. Which one do you grab as you escape?

Mikaela: Oh, this is a really hard question for me. I have a lot of plants. I live in a very small apartment and I have plants in pretty much every nook and cranny that I can cram them into. But I'd say that if I had to pick only one. I would probably pick my Monstera deliciosa. I know it's kind of the most commonly loved plant, but it is my oldest plant and it is my largest plant. I've had it for almost three years now and it is just huge and full and beautiful, and I've watched it grow from when it was a baby little cutting. So I would definitely take that.

Jane: Question 2. What is your favourite episode of On the Ledge?

Mikaela: My favourite episode of On the Ledge? I have a few. Obviously I am a huge fan of hoyas, so I love the hoya episode. I also really love the episode that Jane did about the Saxifraga stolonifera. That is a plant that I don't hear people talking about a lot and I'm absolutely in love with it. It's one of my favourite types of plants. I have a couple of myself. And that was a really fun episode where she just talked about it because she wanted to like. Nobody asked her to talk about that and I really liked that episode.

And I always enjoy the episodes where she talks to experts, especially the ones where she was talking to the guy from Savage Garden about the carnivorous plants. That was another really amazing episode.

Jane: Question 3. Which Latin name do you say to impress people?

Mikaela: The Latin name that I use the most. I would say is probably Tradescantia. I love saying Tradescantia. It's just a fun word. And I'm not really a huge fan of the common term for that plant. Wandering Jew or whatever. That's not a great name, and I think that it's fun to educate people about the real name of it. Plus, it's just much more fun to say to me and I have told many of you plant friends what the actual name for it is.

Jane: Question 4. Crassulacean acid metabolism or guttation?

Mikaela: This is a hard one for me. I have a few tropical plants that I've seen have guttation on them in the past. I think it's really cool but it does make a mess. Again, I live in an apartment and it gets all over the place. So I'm going to have to say crassulacean acid metabolism. I have a few plants in my bedroom that I have read or learned through the podcast or other plant-y friends, are very good for cleaning the air at night time and I have a few in there. I think my sleeping has really improved because of it.

Jane: Question 5. Would you rather spend £200 on a variegated Monstera or £200 on 20 interesting cacti?

Mikaela: That's also a really hard one for me because I am a huge fan of succulents and cacti. I even have a few succulent tattoos. But I would probably go for the variegated Monstera. I love Monstera a lot and I already have probably way more cacti than I would possibly have room for.

So I would say I would go for the variegated Monstera and go for a little bit of a splurge.

[Music]

Jane: Thank you, Mikaela, and great to meet another fan of the strawberry saxifrage.

Coming up next Friday, do your plants suffer from the fluff? I'm talking about that heinous pest, the mealybug. I am going to help you lick this problem into shape, and if you listen to next Friday's show you will find out how because it's mealybug special.

That's all for this week though, so have a fantastic week with your plants and keep your ledges well dusted.

Bye.

[Music]

The music you heard in this episode was from Roll Jordan Roll by the Joy Drops and Water in the Creek by Josh Woodward.

And the ad music was Dill Pickles by the Heftone Banjo Orchestra. All tracks are licensed under Creative Commons. See the show notes at JanePerrone.com for details.

Subscribe to On The Ledge via Spotify, Apple Podcasts, Player FM, Stitcher, Overcast, RadioPublic and YouTube.

Ever wondered why the leaves of your houseplants are different in shape? Professor Enrico Coen of the John Innes Centre joins to me to explain. Plus, I co-opt Stephen of the Plant Daddy podcast to help me answer a question about a Nepenthes, and we meet listener Mikaela. 

Check out the show notes below as you listen…

Today’s guests

• My leaf expert Professor Enrico Coen works at the John Innes Centre in the UK. You’ll find him on Twitter as @Innerworlds1 and on Facebook here.

• My Nepenthes expert Stephen is co-host of the Plant Daddy Podcast: you can hear more from him and Matthew in episode 113 of On The Ledge.

What’s in a name?

Learning the botanical names for different parts of the plant and shapes of leaf will help you understand what you read as you learn more about your plants. leaves are made of two parts: the lamina, which is the leaf blade, and the petiole, which is the leaf stalk. Not all plants have petioles, and those that do not are known as sessile leaves: in these, the leaf connects directly to the stem. It’s an adaptation of many succulent plants in particular, and can help them save water. The top surface of a leaf is known as the adaxial and the underside is the abaxial.

There are many names for the different leaf shapes you’ll find among your houseplants, here are the ones mentioned in the show…

Leaves are either simple - they come in one whole section - or compound - they are made up of a set of leaflets. Compound leaves are usually palmate (think Schefflera) or pinnate (think sensitive plant, Mimosa pudica).

Peltate leaves have a petiole that joins the lamina somewhere in the centre of the leaf: this term applies to some Begonia leaves, but if you can’t picture it, think about a nasturtium leaf. Palmate leaves are the shape of a palm, and can be simple (eg Fatsia japonica) or compound. Hastate leaves are spear shaped while lanceolate leaves are long and pointy at the end, like a lance. Linear leaves are fairly straightforward - think spider plant. Obcordate leaves are heart shaped but the petiole joins the leaf at the pointy end - cordate leaves are the reverse!

Want to know more about the names for leaf shapes? There’s a good chart here. Want to know what leaf margins - smooth, jagged or wavy - are called? Check this page.

View fullsize

Rachel’s Nepenthes

Question of the week

Rachel wanted help with a Nepenthes that has been living happily in her bathroom but has not produced any pitchers in two leaves! Stephen, co-host of the Plant Daddy Podcast, joined me to answer this query.

He suggested the plant was looking really great so was obviously healthy, but probably needed a bit more light to ‘pitcher’. We also talked about how humidity is not so much of an issue as many believe with Nepenthes, so this plant could be moved to a higher-light situation out of the bathroom without causing any problems, and this may prompt some pitchers.

If you’re interested in Nepenthes care, do check out my episode with Domonick Gravine: you can find more On The ledge episodes on carnivorous plants here.

Want to ask me a question? Email ontheledgepodcast@gmail.com. The more information you can include, the better - pictures of your plant, details of your location and how long you have had the plant are always useful to help solve your issue!

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THIS WEEK’S SPONSOR - DOG ROCKS

Thanks to Dog Rocks for supporting this episode of On the Ledge. Dog Rocks stop pet urine burning grass, lawns and shrubs. And Dog Rocks are so easy to use - just pop them in your pet’s water bowl and you should start to see the difference on your lawn, shrubs and hedges in three to five weeks. Dog Rocks are a totally natural product with no side effects and they don’t change to the pH balance of your pet’s urine. Intrigued? Find out more in this handy Dog Rocks FAQ.

Dog Rocks have sold more than 2 million packs around the world and deliver to the US and Canada, the UK, Europe, Australia, South Africa and New Zealand. 

To get 15% off your first order of Dog Rocks, visit dogrocks.com and enter the voucher code janep.

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HOW TO SUPPORT ON THE LEDGE

Contributions from On The Ledge listeners help to pay for all the things that have made the show possible over the last few years: equipment, travel expenses, editing, admin support and transcription.

Want to make a one-off donation? You can do that through my ko-fi.com page, or via Paypal.

Want to make a regular donation? Join the On The Ledge community on Patreon! Whether you can only spare a dollar or a pound, or want to make a bigger commitment, there’s something for you: see all the tiers and sign up for Patreon here.

• The Crazy Plant Person tier just gives you a warm fuzzy feeling of supporting the show you love.

• The Ledge End tier gives you access to two extra episodes a month, known as An Extra Leaf, as well as ad-free versions of the main podcast on weeks where there’s a paid advertising spot, and access to occasional patron-only Zoom sessions.

• My Superfan tier earns you a personal greeting from me in the mail including a limited edition postcard, as well as ad-free episodes.

If you like the idea of supporting On The Ledge on a regular basis but don't know what Patreon's all about, check out the FAQ here: if you still have questions, leave a comment or email me - ontheledgepodcast@gmail.com. If you're already supporting others via Patreon, just click here to set up your rewards!

If you prefer to support the show in other ways, please do go and rate and review On The Ledge on Apple Podcasts, Stitcher or wherever you listen. It's lovely to read your kind comments, and it really helps new listeners to find the show. You can also tweet or post about the show on social media - use #OnTheLedgePodcast so I’ll pick up on it!

CREDITS

This week's show featured the tracks Roll Jordan Roll by the Joy Drops and Water in the Creek by Josh Woodward. Ad music is  Dill Pickles by the Heftone Banjo Orchestra. 

Logo design by Jacqueline Colley.