The secret powers of flowers

Flowers are known for their beauty, but biologist David George Haskell argues they are also critical to the diversity of life as we know it.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  WNYC is supported by Bayer. Science is about asking questions, testing, trying again. It's not easy, but it's relentless. It evolves, and that's why science delivers. Learn more at sciencedelivers.com.

• 0:14Ira Flatow?

  Science Friday is supported by MathWorks, creator of MATLAB and Simulink software for technical computing and model-based design. MathWorks, accelerating the pace of discovery in engineering and science. Learn more at mathworks.com. Hi, it's Ira Flatow, and you're listening to Science Friday. We're waiting impatiently for signs of spring beneath the melting snow. I mean, I'm looking for you, crocuses and daffodils. These colorful blossoms would surely brighten all of our moods. But my next guest argues that flowers are not just beautiful.

• 0:55Ira Flatow?

  They are critical to the diversity of life as we know it, and to food and agriculture. Let's learn all about that with Dr. David George Haskell, biologist and author of How Flowers Made Our World: The Story of Nature's Revolutionaries. He's based in Atlanta, Georgia. Welcome to Science Friday.

• 1:14Speaker 02

  Thank you, Ira. It's a delight to be with you to chat about the world-changing power of flowers.

• 1:21Ira Flatow?

  One of my favorite topics, because I grow a lot of them, so let's get right into this, because when I think about the evolution of life on Earth, flowers are not typically front and center in my mind. So tell me what we have been getting wrong all these years.

• 1:35Speaker 02

  Yes, we think of Earth's evolution often. We're thinking about Tyrannosaurus and animals and maybe microbial revolutions billions of years ago. And I think flowers belong in that pantheon of revolutionaries, because they were later rivals on planet Earth. They evolved maybe 130 million years ago. After they evolved, they swiftly took over most of the habitats on the planet and are the foundation of most rainforests, prairies, seagrass meadows, mangroves all over the world now. So they truly are revolutionaries. They opened opportunities for other animals and created most of the most productive ecosystems

• 2:16Speaker 02

  on the planet. So we think of them as ephemeral and merely ornamental, but in fact, flowers are extraordinarily powerful world changers.

• 2:26Ira Flatow?

  Let's talk about that because I'm wondering, does the fact that flowers are pretty and they smell good, does it distract us from seeing them as evolutionary powerhouses?

• 2:37Speaker 02

  Perhaps. I mean, there's nothing wrong with enjoying flowers as pretty, as ornamental, as enjoying their aromas. It's an important part of our individual and cultural expression. And those aromas and the colors that we're so attracted to are also the source of much of flowering plants' world-changing power. It was through experiences of beauty connecting to bee aesthetics and butterflies and beetles and so on, that flowers drew other species into cooperative networks and through that cooperation then revolutionized the world. So in a way, you know, we think about revolutions in a human context, often through violence

• 3:18Speaker 02

  and domination, authoritarianism. Flowers offer an alternative view of how the world can be changed and transformed, and that is through interconnection, often mediated by interspecies experiences of beauty.

• 3:33Ira Flatow?

  Now, if I remember correctly, from my biology, non-flowering plants came first, right? Like ferns. So that raises the question, why did flowers emerge? And when did flowers first come onto the scene? What happened?

• 3:50Speaker 02

  Yeah, absolutely. There are, I mean, mosses, ferns, cycads, there are lots of non-flowering plants, and they were around building the earth's forests and creating habitats for hundreds of millions of years before flowers came along. And then what flowers did was have a, there's a convergence of innovations. Some of them were about attracting pollinators into the flower itself, using petals and aroma as visual signals, combining male and female into the same flower, which is a much more efficient way of pollinating the flower, transferring pollen from one flower to another. But they also revolutionized botanical motherhood by enclosing their seeds inside fruits. Some of those fruits are flashy, some are protective,

• 4:34Speaker 02

  some are, some are wing-like to catch the, to catch the wind. And so through a series of different innovations, flowers quickly became some of the dominant creatures on the planet. And by some, some estimates, it only took a handful of million years after they evolved for them to become the dominant vegetation around much of the planet. And then they catalyzed the evolution of whole new animal groups like bees and butterflies and later grazing mammals and even humans. We wouldn't be here without flowering plants.

• 5:08Ira Flatow?

  So was this evolution quite rapid?

• 5:12Speaker 02

  Yes, they exploded onto the scene. And in a Darwin back in, in the 19th century called it an abominable mystery how flowers appeared so late and so explosively in the fossil record. Now, of course Darwin didn't know anything about modern genetics. And so we have some, some insight now that he didn't, that flowers have these genetic superpowers. They are especially genetically nimble within themselves that allow them to, to, to diversify very, very rapidly. And the earth changed from a planet covered mostly in cycads and mosses and various forms of ferns and other non-flowering plants into one where first the understory and then the overstory of most forests were dominated by flowering plants.

• 5:57Speaker 02

  And that's still the world we live in today. Before flowering plants, there were no rainforests, prairies, steppes or mangroves. So flowering plants were not only

• 6:10Speaker 02

  Innovative, they were, to use sort of a jargon from human economics, they were disruptors. They came along and overturned many ecosystems and created enormous opportunities for other creatures.

• 6:23Ira Flatow?

  One really interesting idea I learned from your book is that grasses are considered flowers. I didn't think, I ever thought of my lawn as a sea of flowers.

• 6:33Speaker 02

  Yes, so, you know, lawns are kept in a state of perpetual youth. We erase all signs of sex and death from them, creating this ecological illusion, which of course, you go out into a forest, mostly what you see is sex and death. And so a lawn is a strange, strange thing, a reflection of parts of our psyche, maybe. But if you were to not mow your lawn or go out to a natural area where the grasses are free to grow, of course, later in the season, the grass would send out flowering stalks. And grasses are pollinated by the wind, not generally by bees or other insects. So they have very inconspicuous small flowers, but anyone with hay fever knows

• 7:17Speaker 02

  that grasses can make quite a lot of pollen. That pollen drifts through the air and is received by other, by other flowers. And then the amazing thing with, with grasses is that after fertilization, the little embryo grows and the mother grass supplies an enormous amount of food that goes along with the embryo, which is why grass seeds, when you plant them, whether it's grass for your lawn or wheat or maize or rice, can explode. It's like rocket ships taking off from the soil because they've got these amazing storehouses of food. And that's another innovation of flowering plants is to give many of their embryos little food hampers to give them a boost as they start off their lives.

• 8:03Ira Flatow?

  After the break, the integral role of grasses to human evolution. Don't go away.

• 8:12Speaker 00

  Science Friday is supported by PBS, presenting Going Wild. If you love learning about the natural world and meeting the scientists who help us understand it, be sure to check out the new season of Going Wild with Dr. Ray Wynn Grant. It's the chart-topping and Webby Award-winning podcast from the folks at Nature on PBS, now with a video companion series. In this season of Going Wild, host acclaimed wildlife ecologist Dr. Ray Wynn Grant heads out into the field to explore the animals, people, and stories that make nature worth saving. Stops include a hibernating black bear den in Arkansas and an underwater shipwreck site off the Florida coast. If you're looking for a place to start, check out the season's debut episode, where Ray joins beloved biologist and influencer Jordan King in the Florida Everglades to learn about

• 8:57Speaker 00

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• 9:23Ira Flatow?

  So, grasses played this huge role in human evolution, then, because we're talking about rice, which is a flower, which I didn't really think about, and wheat is their grasses?

• 9:34Speaker 02

  Yes. If you count up all the calories that humans eat worldwide, two-thirds of those calories come from just three species of grass: wheat, maize, and rice. And a lot of the rest of the calories come from sugar cane, and oats, and barley, and millet. And then, if we're eating grass-fed beef, for example, well, that cow is also made from grass. All flesh is grass, the sacred texts tell us. And that's an ecological truth, as well as having some theological overtones. And so in the present day, we are sustained by grasses. But our evolution was also catalyzed by grasses. Because why did we or our ancestors come down from the trees?

• 10:19Speaker 02

  Our ancestors were living happy lives up in the trees in tropical forests. And a few of them decided to come down from the trees and become bipedal primates in grasslands. So without the grasslands and the savannas, there would be no incentive for early pre-human hominins to evolve. And then the diet of those pre-human ancestors was also mostly grass-based, either eating the grass and grass seed directly or eating a lot of the animals that were feeding on that grass. So yes, we are grass apes, Homo poeciae, if we were to name ourselves for the family of plants that sustain and created us.

• 11:00Ira Flatow?

  That is really interesting. You know, I'm a big fan of orchids and I know you devoted a large chunk of your book to orchids. I grow them on my windowsill. What can they tell us about the relationship between flower and pollinator?

• 11:14Speaker 02

  Absolutely. Orchids are the sort of the apex of the complexity of relationships with with pollinators. Of course, and we're attracted to them. I mean, you keep them on your windowsill. I've got a whole load on my windowsill here. Orchids have magnificently, often very large, conspicuous displays with their petals and their sepals. Some of them are aromatic, but the sexual parts are actually miniaturized. They only produce a tiny little piece, bit of pollen. And the the the egg is buried sort of right in the center of the flower there. And the stigma receives the pollen from other orchids. And orchids lure and manipulate and bribe

• 11:58Speaker 02

  all sorts of different insects to come and pollinate them. If you think about the orchids on your windowsill, that usually there's a central portion, which is often tube-like or a little bulbous lip that encourages the bee or other pollinator to pass in and and receive the pollen. Now, and some of the, some orchids are doing this, quote unquote, honestly, by offering nectar rewards to to reciprocate with the pollinator. But others are a lot more devious. Some orchids look like they've got pollen and nectar, but in fact have none. Others look and smell and feel just like female insects.

• 12:40Speaker 02

  There's one, the bee orchid, that looks and feels and smells just like a female wasp. So amorous male wasps try to mate with these orchid flowers and of course, just get a little dab of pollen put on their head. Complete waste of time for the male wasps, but the orchids are then pollinated. So orchids take a deliciously varied approach to pollination and it's often very specific to individual pollinators, which then leads to sort of a powder keg for evolution. When you get specificity between a pollinator and a flower, a slight genetic change in the flower or the pollinator can cause that species to split, which is why there are tens of

• 13:23Speaker 02

  thousands of species of orchids around the world, often with very small numbers.

• 13:27Ira Flatow?

  More than any other flower, I think, yeah.

• 13:28Speaker 02

  Yeah, it depends how you count it, either them or the sunflowers.

• 13:32Ira Flatow?

  You know, you talked about specific pollinators and specifically about the orchid. I remember getting an orchid. I think it was called Darwin's Orchid.

• 13:42Speaker 02

  Yeah.

• 13:42Ira Flatow?

  Because it had a huge bulb at the bottom, you know what I'm talking about? And there had to be a moth that could stick its nose all the way into the bottom?

• 13:53Speaker 02

  Yes, this is an orchid from Madagascar that at first, Western scientists only knew about the flower and it had this big, long spur with nectar in the end. But no one knew what pollinated it and Charles Darwin said, "I predict that there is a moth out there with a proboscis of exactly the right length to fit into this flower." And of course, this was after he died, he never lived to hear the end of the story. But 20 years after he died, Western scientists found the moth, described the moth, and there was an almost perfect match between the moth and the orchid, which at the time was sort of a triumph for the predictive power of evolution, because there were some

• 14:34Speaker 02

  creationists who at the time were arguing, "Look, this moth disproves Darwin in evolution." And of course, Darwin had the last laugh on that one.

• 14:44Ira Flatow?

  Right, so I mean, to be so specific for a pollinator that there could only be one pollinator, just is an amazing thing.

• 14:52Speaker 02

  Yeah, and it's extremely efficient. It means that the orchid is not giving nectar to pollinators that aren't going to be diligent and faithful couriers of its pollen, but it's also very, you know, it's a risky strategy in terms of long-term evolution, because if your pollinator goes extinct, or the habitat changes, and your aroma doesn't carry quite so well, you've put yourself at risk compared to a flower, like say a magnolia flower or a rose, that welcomes all kinds of pollinators.

• 15:28Ira Flatow?

  To wrap up and looking toward the future, is it silly to ask if flowers are endangered by climate change or changing world?

• 15:37Speaker 02

  Not at all. Fifty percent of orchids, fifty percent of magnolias, as far as we can tell, are threatened with extinction. And then, on the other hand, there are flowering plants that are extremely nimble and are adapting to the various changes, whether it's climate, or salty soils, or increasing droughts, so that, as flowering plants always have done, they've adapted, but we are having such an extraordinarily powerful effect on the planet that we are indeed pushing many flowers towards extinction, which is improvident, to say the least, because flowers made our world, created the most productive habitats on the

• 16:19Speaker 02

  planet, including human agriculture. And so, to cause so many of them to become threatened and endangered is not treading a very cautious path. By partnering with flowers, we can find solutions, and that's the great genius of flowers, is to draw animals into cooperative partnerships. We can, we have been, and we can be even more, one of those cooperators, working towards a better future with flowering plants.

• 16:46Ira Flatow?

  Last question. Do you have a favorite flower?

• 16:51Speaker 02

  Oh, I've got lots of favorite flowers. I mean, one that really in writing this-

• 16:54Ira Flatow?

  It's like you're asking about your children, right?

• 16:56Speaker 02

  Yeah, no, one that really shocked me, I learned a lot about in writing this book, with the seagrasses. These, they look very inconspicuous, unremarkable. These are flowering plants that flower literally under the water, in the seawater, and they are-

• 17:11Ira Flatow?

  No kidding?

• 17:12Speaker 02

  They're incredible at storing carbon, storing sediment, stabilizing the edges of continents, providing habitat for marine animals to breed in and to feed in. And until recently, we knew very little about seagrasses, and they too are also endangered, their populations are in decline. But there are some amazingly inspiring stories about restoration of seagrasses. So I like them because they're obscure, that, you know, they're not very conspicuous, and they have this great story about humans working with flowering plants to solve some of the problems that we've created. So they're one of my many favorites.

• 17:51Ira Flatow?

  I'm glad I asked. You know, I learned so much today, Dr. Haskell. Thank you for taking time to be with us today.

• 17:57Speaker 02

  Thank you. Always a pleasure to chat. Thank you.

• 18:00Ira Flatow?

  Dr. David George Haskell, biologist and author of How Flowers Made Our World: The Story of Nature's Revolutionaries. He's based in Atlanta, Georgia. If you like flowers, you'll love this book, even if you don't like flowers. Shoshana Buxbaum produced this episode. I'm Ira Flatow. We'll see you again.