Kai Ryssdal: Time now for a little Freakonomics Radio. Every two weeks, we're talking with Stephen Dubner, co-author of the books and blog of the same name, about the hidden side of everything. Dubner as always, good to talk to you.

Stephen Dubner: Great to be here Kai. Hey, seems like you talk about your mom on the show quite a bit, am I right?

Ryssdal: I don't know, maybe.

Dubner: And it sounds from what I hear, you have a fairly loving relationship, I'm also right on that?

Ryssdal: No. 1, she's listening, so watch yourself. And No. 2, yeah, we get along, me and mom.

Dubner: I'm just thinking, with Mother's Day coming up, two Sundays from now, I'm guessing you're thinking about maybe sending her some flowers. Yes?

Ryssdal: OK, two things: 1) It's all I can do to remember to get my wife flowers on Mother's Day, let alone my own mother; and 2) The dirty secret which I will deny if you repeat it -- my wife actually does the flowers for my mom.

Dubner: Ah, but she gets something?

Ryssdal: Yes.

Dubner: Well, she is not alone. Every year in the U.S., we spend about $12 billion on cut flowers alone -- Mother's Day is obviously a huge part of that. But here's something you may not know, Kai: about 80 percent of these cut flowers are imported, mostly from equatorial countries that get 12 hours of year-round sunlight.

Mario Valle is a flower wholesaler in Los Angeles; he handles about two million flowers a year. Here's how they get to him.

Mario Valle: Anything that's coming out of South America is generally air-freighted into Miami, then it's trucked over to California.

Ryssdal: Really? They fly to Miami and then drive it to here?

Dubner: And I do not want to rain on your mother's parade or anybody's mother's parade, but there is something going on here. We live in a day and age where people are obsessed with "food miles" and the carbon footprint of everything we consume. So if that's the way we're going to be, here's what I want to know: Where is the outrage over these globe-trotting Mother's Day flowers? I mean, if you ship food across the planet, at least we eat it -- it's our sustenance. But flowers? You look at them for a couple of days and then plop, into the trash!

Ryssdal: So this is you up on your high horse here, you are now killing all the joy and glory that is Mother's Day and cut flowers in this country?

Dubner: Kai, it is not my nature to scold. I hope you know that by now. But I do find it curious that cut flowers have somehow escaped the environmental scrutiny that accompanies what we eat, how we transport ourselves. It may be a halo effect from the flowers themselves -- I mean, how can you hate on roses and tulips, they're so pretty!

Ryssdal: So here's the thing -- if I don't, well let me rephrase that -- if my wife doesn't send my mother flowers for Mother's Day, then I'm in deep and serious trouble.

Dubner: I don't want that to happen. It's the last thing I want to happen. So let's look to a different holiday for a potential solution: Christmas. Every year, we buy about 35 million Christmas trees in this country, about $2 billion worth. Again, we're talking crops that are harvested and transported solely for our viewing but not eating pleasure. But every year, the share of artificial Christmas trees rises -- and now we're up to about 40 percent fake Christmas trees. Meaning there's no need to grow and transport another tree next year, or the year after.

Ryssdal: Wait now, stop -- I'm not doing a fake Christmas tree, I'm just not going to do it.

Dubner: Let me try to persuade you of a little something. Kai, you have a little package there in the studio. We sent you something. It's a good time to open it up.

Ryssdal: OK. No. 1, I'm a little disappointed because it's clearly not beer, but all right, that's fine. Is this a corsage? Or something equally sensitive?

Dubner: What do you think? How do they look?

Ryssdal: They look lovely. They're yellow roses.

Dubner: And what are they made of?

Ryssdal: Yeah, they're not real.

Dubner: They're plastic flowers. And they're beautiful, right? They do wonderful things with plastic these days. So here's the thing, we may associate flowers with nature and plastic with the opposite, but is in fact a very simplistic view of how the world actually works.

Here's Susanne Freidberg, she's a Dartmouth professor and author who's been studying how carbon footprints are calculated. Here's what she thinks of the idea of giving plastic flowers instead of real ones.

Susanne Freidberg: They're so lightweight, they wouldn't need to be flown anywhere. They wouldn't decompose and produce greenhouse gases in any landfill. There's the endless lifespan, so the possibilities for regifting them.

So Kai, listen: If you really love your mother -- and I'm not implying you don't, by the way -- I want you to think about sending her, or having your wife send her some plastic flowers this year. If you want, you can even regift this bouquet, like Prof. Freidberg suggests. Because I know you're a bit of a cheapskate as well.

Ryssdal: Hey! I am, actually, how did you know? Stephen Dubner, our Freakonomics correspondent. He puts out a podcast, too -- you can get that on iTunes and hear more at Freakonomics.com. Dubner, we'll talk to you in two weeks. See ya man.

Dubner: See you Kai.