Ig Nobel Winner Suggests Plants Can See
The study offers evidence that at least one plant species can see the leaves of neighboring plants, and mimics them.
Hiya!
I love plants. I have many — some may say too many, but I believe there’s no such thing. I love watching them grow and observing the diverse forms they take. And with technological and scientific advancements in the last few decades, scientists have learned incredible things about them.
The more I learn about what scientists are discovering, the more obsessed with plants I become. For instance, this year’s Ig Nobel (Iggy) prize winners in Botany provide convincing evidence that a living plant can see and imitate the shapes of neighboring plants. However, the story behind the research started in 2014.
2014 — Initial Curiosity
A decade ago, in 2014, Ernesto Gianoli, a plant ecologist and biology professor at the University of Concepción in Chile, was exploring a southern Chile rainforest when he noticed something curious. A vine plant called Boquila trifoliolata seemed to mimic the leaves of a nearby and unrelated arrayán shrub. Gianoli explained to Benji Jones of Vox:
“Commonly, the leaves of B. trifoliolata are stubby with three blunt lobes, but here, they looked just like those of the arrayán plant. It was as if B. trifoliolata was trying to camouflage itself in the foliage.”
Following his curiosity, Gianoli wondered whether his observation was a fluke, so he searched the forest for other B. trifoliolata plants, which National Geographic later called “the most mysteriously talented, most surprising plant in the world.”
Incredibly, around half of the other B. trifoliolata vines Gianoli found had leaves that resembled neighboring plants. Gianoli and his student Fernando Carrasco-Urra published a paper about their curious discovery in Current Biology, in which they wrote:
The woody vine Boquila trifoliolata mimics the leaves of its supporting trees in terms of size, shape, color, orientation, petiole length, and/or tip spininess. Moreover, sequential leaf mimicry occurs when a single individual vine is associated with different tree species. Leaves of unsupported vines differed from leaves of climbing plants closely associated with tree foliage but did not differ from those of vines climbing onto leafless trunks.
The paper also includes several photographic examples, which you can see below. The white arrows point to the vine (V) and the host tree (T).
Gianoli and Carrasco-Urra thought chemicals or microbes were behind this mimicking or mimicry effect. They theorized that the tree or bush a B. trifoliolata plant climbs emits airborne volatiles (chemicals) that the vine senses. However, the researchers didn’t know precisely how the vine would translate chemical signals into shapes or colors, or how it changes itself to mimic them.
But nearly a decade later, Felipe Yamashita, a doctoral student at the University of Bonn in Germany, brings us closer to an answer.
2021
Yamashita wasn’t convinced the B. trifoliolata behavior was due to chemical signals. So, he teamed up with Jacob White, who's not a scientist but raises plants at home, to test a different idea. Yamashita told Ari Daniel of NPR:
“[W]e said, ‘OK, let’s do another experiment [that] prove[s] that maybe [the plants] have some vision.'”
You read that right. Yamashita thought B. trifoliolata can see. He further explained to Daniel,
I believe that plant[s] can see. I don’t know how they can see. They don’t have an eye, but I’m pretty sure they can understand what’s going [on].”
To find out, Yamashita, who recently finished his Ph.D. in botany at the University of Bonn, focused his thesis on a simple experiment involving Boquila trifoliolata and published his results in the journal Plant Signaling & Behavior.
For their experiment, Yamashita and White grew several of the vined plants on a trellis separated by opaque shelves that blocked the lower part of the vines from the upper part. They then wove an artificial plastic plant with slender, unlobed leaves along the top of the trellis.
The idea was that artificial plants don’t emit any chemical signals and so would not have the microbes living plants have, which might trigger the B. trifoliolata mimicry response of changing leaf shape, as Gianoli and Carrasco-Urra thought.
Incredibly, as the B. trifoliolata plant grew, the leaves below the shelves were the vine’s typical lobed shape, but Yamashita told Daniels that almost all of the leaves above the shelves that “were growing close to the plastic leaf copied the plastic leaf shape,” which were longer and less lobed.
Yamashita believes the B. trifoliolata somehow detected where light seeped through the plastic leaves and where it didn’t, which allowed the plant to sense the shape of the plastic leaves. He describes it as a type of seeing. He thinks it could be an evolutionary camouflage adaptation that lets the plant blend in with surrounding vegetation, preventing it from being eaten by hungry herbivores.
Earlier this year, Yamashita won an Ig Nobel for his research. Side note: If you haven’t heard of the Ig Nobel, also known as Iggys, I recommend checking it out. The quirky yet serious and respected award honors achievements in science that “first make people laugh, then think.”
Still, if Yamashita is correct, and plants have some form of sight, how does it work? Well, a team of researchers from the University of Lausanne in Switzerland may have an answer.
How (Some) Plants See
In their paper, published in Science in November 2023, the Swiss researchers focus on Arabidopsis — a roadside weed beloved by geneticists for its genome sequence, which makes it the standard reference plant for all of biology — and how it senses light.
The researchers discovered that the plant uses the air pockets between its cells to scatter light, which modifies the light’s path through the plant’s tissues. This allows the air channels to create a light gradient — from bright to dark — which helps seedlings accurately determine where the light is.
By using their air channels to create light gradients, the plants find a way to “see” with their entire bodies rather than evolving complex organs like eyes. If correct, perhaps B. trifoliolata does something similar when sensing the shape of its neighboring plant leaves.
Perspective Shift
The studies discussed today are part of a growing mountain of research suggesting plants are far more complex than we ever thought. Plants like B. trifoliolata evolved elaborate mimicking abilities. Other plants trap and consume animals, while others still display clever strategies for avoiding insects — and all of these traits involve complex behaviors.
Scientists now know that plants communicate with each other and pollinators, along with other qualities we typically associate with intelligence. If plants can see and possess some form of intelligence, might they also be aware, maybe even conscious? We’ll have to wait to find out, but I wouldn’t be surprised if they do and are.
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Fascinating
Life is wonderful! It's a shame the human strain decided baubles were worth more than life!