Unwinding The Cucumber Tendril Mystery

How a cucumber creates its curling tendril has stumped scientists for centuries, including Charles Darwin and Asa Gray. With the help of time-lapse photography and prosthetic tendril fabricated in the lab, physicist Sharon Gerbode, biologist Joshua Puzey and colleagues figured out why tendrils twist, according to a new study in Science.

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IRA FLATOW, HOST:

Up next, it's time for the Video Pick of the Week. Flora Lichtman is here. Hi, Flora.

FLORA LICHTMAN, BYLINE: Hi, Ira.

FLATOW: Interesting as always - the video pick.

LICHTMAN: Yes. This is - opposed to bridges, our feet are planted firmly on the ground for this video pick. It's a backyard science this week about - it's the twisty tale of why tendrils curl.

FLATOW: Why tendrils...

LICHTMAN: Cucumber tendrils.

FLATOW: Cucumber, well, you know, when they grow cucumber and you see the - it climbs up a vine or...

LICHTMAN: Yeah.

FLATOW: ...it climbs up the string you put out for it.

LICHTMAN: Yeah, yeah, yeah. So they - just for a little anatomy, a little review of that. The cucumber has the plant part, but then it also has these climbing appendages. And when it's growing, it sorts of swings them around, grabs on to a support. And when it does that, something changes in that tendril, and it starts to curl. And that is exactly what physicist Sharon Gerbode in Harvey Mudd College and biologist Joshua Puzey at Harvard and some colleagues looked at and published this week in the journal, Science.

Why does that cucumber tendril curl? And, you know, you might be thinking, well, whatever. But Charles Darwin was interested in this question, you know.

FLATOW: Yeah, yeah. It's an old question. You know, if you grow stuff, you know that the stuff, you know, goes out and curls around things.

LICHTMAN: Yeah. So they did the - this is an amazing study and a beautiful video because of their research. They have really lovely time-lapse movies of cucumbers growing. And, you know, you think of plants as planted...

FLATOW: They stay there.

LICHTMAN: ...stationary, kind of boring.

FLATOW: They don't move. Right.

LICHTMAN: But if you speed up time, they're really moving a lot. And so what the researchers did was watched them in time-lapse. They dissected them, and they even built - I think this is probably my favorite part - maybe the first ever prosthetic tendril - not meant for transplant, but to understand how they work. And they figured out that, actually, what's happening is that the internal structure of the tendril changes when that tendril grasps on to a support.

FLATOW: Wow. And if you go - it's our Video Pick of the Week. If you go to the website at sciencefriday.com, you'll see this time - beautiful time-lapse video. And the tendrils are - they're like helicopters, right?

LICHTMAN: Yes, that's right.

FLATOW: They're swirling around, looking for things to grasp on. And things that we normally think, plants that are sitting still, they're really not sitting still.

LICHTMAN: Yeah. And we owe a debt of gratitude, also, to Roger Hangarter of Indiana University, who gave us some other time-lapse of other plant motions. Because I started looking into this, and, you know, even the tulips in your vase are moving around if you speed up time. Their leaves are flopping. He told me this amazing story about sunflowers that I never knew. The reason that they are called that is that they actually orient towards the sun throughout the day. Their leaves do. So they start facing east and then end up facing west.

FLATOW: They have the ultimate solar panels.

LICHTMAN: That's totally right.

(LAUGHTER)

FLATOW: They figured out how to actually how to move with the sun...

LICHTMAN: Yeah.

FLATOW: ...during the day.

LICHTMAN: So if you're sitting in your backyard for hours looking for something to do, you can watch your plants.

(LAUGHTER)

FLATOW: You can be reading your book this weekend - you're reading a book, you got your cucumbers out there, and suddenly, they're not in the same spot they were before.

LICHTMAN: It takes about 15 minutes for it to do kind of a rotation of its tendril, and this is how Darwin actually studied them.

FLATOW: Mm-hmm. All right. Let's - while we have you here, let's talk about a new Book Club pick.

LICHTMAN: That's right, Book Club is coming...

FLATOW: SCIENCE FRIDAY Book Club has picked the September read, right?

LICHTMAN: Yep. It's "Flatland."

FLATOW: Ooh, that's an old one.

LICHTMAN: Yeah, Edwin Abbott and voters' chose on our website. And you can actually go to our website. We have a link to a free eBook version. So if you don't want the hard copy, go to our website and check out that link and be ready to read when - is it September 21?

FLATOW: That's right. September 21st is our date for talking about "Flatland," which is a book about mathematics. It's really fascinating. It came out a long time ago. And so it's a free book. You can get it, as we say, you can download it for nothing.

LICHTMAN: Yeah. I've never read it. I'm excited.

FLATOW: I think I was 15. I think it's a geometry...

(LAUGHTER)

FLATOW: You know, my geometry professor said...

LICHTMAN: Yeah.

FLATOW: ...you got to read this book...

LICHTMAN: Yeah.

FLATOW: ...about different dimensions of space and all kinds of fun stuff.

LICHTMAN: An old classic.

FLATOW: An old classic. So our Video Pick of the Week is about the cucumber tendrils. Go up there and watch it on our website,@sciencefriday.com. And over the weekend, you can pick up "Flatland," and start reading it for our Book Club that will be on September 21st. Thank you, Flora.

LICHTMAN: Thanks, Ira.

FLATOW: That's about all the time we have for now.

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