Plants have a reputation for being sedentary, unmoving, planted. But some plants are moving so quickly, their motion is invisible to human eyes. Biologist Joan Edwards and physicist Dwight Whitaker broke out the high-speed cameras to capture the story of exploding peat moss.
IRA FLATOW, host: Joining us now is Flora Lichtman. Hi, Flora.</s>FLORA LICHTMAN: Hi, Ira.</s>IRA FLATOW, host: Flora is here with our Video Pick of the Week. What have you got for us today?</s>FLORA LICHTMAN: This is kind of little bit of a mindblower for me. We dive into the secret life of plants this week. And it really is - this is a little-known secret, I think. Plants, right - I think of plants as things that stay put.</s>IRA FLATOW, host: Right. Well, they're grounded, so to speak.</s>FLORA LICHTMAN: Planted, yeah. Take your pick. But it turns out that some plants are moving so fast that their motions are invisible to our eyes.</s>IRA FLATOW, host: Wait a minute. They are moving? They have parts that are moving so fast that we can't see them move? (unintelligible)</s>FLORA LICHTMAN: Yeah. It's not like they're - they're not zipping down the block.</s>IRA FLATOW, host: They're not zipping - okay. All right.</s>FLORA LICHTMAN: You're right. Let's be specific. Yes, pieces of the plant are moving so fast that we can't see them. So two researchers, Joan Edwards, who's a biologist, and Dwight Whitaker, who's a physicist, took high-speed cameras to a couple of these plants and watched them do these amazing fast motions.</s>IRA FLATOW, host: Like what?</s>FLORA LICHTMAN: Well, what they recently looked at was peat moss, bags of moss, and they watched it explode.</s>IRA FLATOW, host: You know, when I go to the nursery, it just sits there in the bag. It's not exploding. In what way? Shooting - something shooting?</s>FLORA LICHTMAN: It's shooting up spores. So the problem with - I mean, the...</s>IRA FLATOW, host: Wow.</s>FLORA LICHTMAN: ...challenge moss faces is that it can't grow very tall.</s>IRA FLATOW, host: Right.</s>FLORA LICHTMAN: It's low to the ground.</s>IRA FLATOW, host: Right.</s>FLORA LICHTMAN: It's short, which I understand. So what moss has evolved to do is get its spores up into this mini jet stream that occurs above the sort of the ground floor.</s>IRA FLATOW, host: Right.</s>FLORA LICHTMAN: So, about 10 centimeters up, there's this wind, and it's got to get its spores there. But the spores are really tiny, so just getting them up that high is pretty difficult. So it's evolved to this explosion mechanism to get it up there. And the kind of amazing thing is that when they looked at this explosion with the high-speed cameras, they found out that it's not just a simply propulsion. The way that it explodes, it sends out this special puff of air.</s>IRA FLATOW, host: It's like on our web - on our video that Flora produced on sciencefriday.com where we can see it up there at the left. And you look at this as amazing, because it's like it's being shot of a cannon.</s>FLORA LICHTMAN: Yeah.</s>IRA FLATOW, host: You know, it's a boom. I mean, I guess you could be standing next to this thing, and it would shoot this stuff right up into your face.</s>FLORA LICHTMAN: But - yeah, and you would just see the aftermath...</s>IRA FLATOW, host: Wow.</s>FLORA LICHTMAN: ...because it really happens in a millisecond.</s>IRA FLATOW, host: And it's going how fast when it gets shot out of air?</s>FLORA LICHTMAN: It's 60 miles per hour, they estimate. And it's shooting - it's not just any cannon. It's shooting out a smoke ring, like a smoke ring you might blow yourself if you were a smoker. And there's something special about this vortex of air that allows it to travel farther up. So basically, the spores that are in this capsule that explode ride this smoke ring up 10 centimeters, which doesn't sound like a lot, but consider you're a moss, then(ph), that's a lot for them.</s>IRA FLATOW, host: Right. Well, think of the pressure that has to develop inside the plant, right?</s>FLORA LICHTMAN: Yes.</s>IRA FLATOW, host: I mean, the plant has figured out how to create this huge, high-pressure explosion.</s>FLORA LICHTMAN: Right.</s>IRA FLATOW, host: You have to hold it in to the right point, right?</s>FLORA LICHTMAN: Right. Right. And so this is when it mostly happens. The way this capsule work is - works is that it's filled with water and spores, and then during the day or hot days in the summer, it starts to dry out. And as it dries out, it gets smaller and smaller. But as it does that, the pressure gets - goes up, because the air is getting squeezed into a smaller space. And then it gets so intense in there. It's like the pressure in a - in semi-truck tires is what Joan Edwards told me...</s>IRA FLATOW, host: Oh.</s>FLORA LICHTMAN: ...but in this tiny little capsule.</s>FLORA LICHTMAN: A tiny little plant.</s>FLORA LICHTMAN: Yeah.</s>IRA FLATOW, host: And then something triggers it, some - at just the right time, it happens.</s>FLORA LICHTMAN: Yeah, eventually it...</s>IRA FLATOW, host: It dries out at the right...</s>FLORA LICHTMAN: Yeah.</s>IRA FLATOW, host: And the thing explodes. It's amazing. You've captured this - they've captured this on high-speed film, and you can watch this video on sciencefriday.com, where Flora has taken these and put these together, and the interviews with the scientists. And it's just an amazing sight to see this explosion.</s>FLORA LICHTMAN: And that these kind of things are happening. You know, they've described a few different species, and that these kind of explosions or these fast motions are just happening right underneath our noses.</s>IRA FLATOW, host: Wow.</s>FLORA LICHTMAN: One of the researches said that, you know, she'd seen the bunchberry plant many, many times, and then eventually said, what's going on here? What's - what are these little puffs of smoke?</s>IRA FLATOW, host: Wow. Kaboom. If you want to see the explosion - thank you, Flora. It's - you know, maybe we'll walk by them sometime when it's actually happening. Go to our website at sciencefriday.com, where you could see Flora's Video Pick of the Week and that terrific video. Also, while on our site, you can also look at our podcasts and download our podcasts and stick them in your iPhone and all kinds of stuff.