IRA FLATOW: This is Science Friday. I’m Ira Flatow.

As you sit around with friends and family today, enjoying a cup of cocoa or a hot buttered rum, I’m guessing you may also be keeping company with a certain botanical bringer of good cheer. And I’m not talking about the Christmas tree, though, we like those, too. I’m talking about the poinsettia plant. You ever wonder where it came from or how did they get those bright red flares?

Well, unlike some of those artificially colored flowers you see in the store, the bright red blooms of poinsettias are festive and they are natural. And the plant’s name, well, you can trace it back to a certain Southerner, a politician and diplomat named Joel Roberts Poinsett.

And my next guest is writing a whole book about Poinsett and the plant named after him. And he’s here to tell us a little lore about the majestic poinsettia plant. Jim Faust is an associate professor of floriculture physiology at Clemson University in South Carolina. Welcome, Jim.

JAMES FAUST: Well, thank you so much for having me.

IRA FLATOW: Let me get out of the way first thing the idea of how to pronounce the name. I remember on the Tonight Show, with Johnny Carson– so over all these years– he used to have a big running argument with Ed McMahon about how to correctly– poin-set-tee-ya, poin-set-ah– where do you come down on it?

JAMES FAUST: Horticulturalists will always call it a poin-set-tee-ya. I think we insist on enunciating all the letters. So it does end in an I-A, so poin-set-tee-ya is most accepted. The interesting thing, though, is the founder of the plant, I guess you could say– or the plant, who it’s named after– Joel Poinsett, we have one documented case where he actually is in a letter referring to the plant. And in that letter he refers to it as a poin-set-ah. So I guess either is correct.

IRA FLATOW: Yeah. But you used to see poinsettias all over the place, on the stage and every other– I guess that that is what brought it into the American culture.

JAMES FAUST: Yeah. The plant naturally flowers in November and December. So it’s always been associated with Christmas since it came to the US, basically, in the early 1800s. But it really wasn’t until the mid-1900s, where it really became “the” Christmas plant, not just “a” Christmas plant.

And a lot of that was attributed to a family in Southern California, named Ecke. Paul Ecke and his son, Paul Ecke, Jr., really promoted the plant. And part of their promotions in the in the ’60s and ’70s was to get the plant on any television stage that they could.

They would donate plants to nightly newscasts, to all those Christmas specials that we used to watch in the in the ’70s and ’80s. And Johnny Carson was one that, yeah, they would donate it, get the plant on the television screen across America in the month of December, so that people would just associate Christmas with that plant.

IRA FLATOW: Wow, that is quite interesting. So tell us about who Joel Poinsett was and how he got a plant that we all think of his name.

JAMES FAUST: Yeah. He was a South Carolinian and really a politician and a statesman. But in 1825, he was sent to Mexico as the first minister, or ambassador, to Mexico. And while he’s there doing his political stuff, he also– the man is a believer in agriculture. He really sees agriculture as the key to the economic development of civilization.

And so while he’s there, he really facilitates the communication and the travel of scientists and businessmen back and forth between the US and Mexico. And while they’re visiting him, he basically is loading them up with plants to carry back to the US. And then he’s encouraging them to bring plants to Mexico. So it’s an exchange both ways that these guys are carrying plants back and forth.

And Poinsett wasn’t a botanist. He wasn’t one to go traipsing out into the wild, looking for exotic plants like a lot of European botanists had already done in the 1820s, when he’s down there. He’s really a pragmatic horticulturist. He really sees the value in plants as to what they can bring to people and society.

And so, by 1828, he sends the plant that will eventually be called the poinsettia– he sends it to Philadelphia, to a place called Bartram Botanic Gardens, which was a famous place in the day. The Bartrams had built a business over the previous century, basically traveling across North America and collecting New World plant species, and then selling them to wealthy Europeans, who were really excited about the new plants that were over here that they had never seen before.

So the Bartrams actually then– just a few years after Poinsett sends them the plant– they list that plant– they call it “poinsettia,” and they list in the catalog. And they sell it for $2 a piece. Which is pretty amazing for– it was 1836. And considering, this past holiday season, we saw a Black Friday sale at Kmart, where they had a Blue Light Special on poinsettias for $0.89 a piece.

IRA FLATOW: But he didn’t just pluck this plant out of the wild, did he, when he went to Mexico?

JAMES FAUST: No. Actually, he pretty much was collecting plants out of marketplaces. He wasn’t going out into the wild at all. The plant had already been domesticated, I believe, by the Aztecs and later the Mexicans.

The Aztecs were quite sophisticated horticulturists. They, in the 1400s, had botanical gardens. So when the Europeans first came over, they kind of stole the idea and took it back to Europe. And so the first botanical gardens in Europe started popping up in the 1500s.

They had thousands of plants that they used as medicinal herbs. And they certainly were known to have domesticated other flowers, like marigolds and dahlias, into more showy plants, having higher petal counts, things that would attract humans.

IRA FLATOW: Wow. So the Aztecs really were ahead of us on all of this. I understand that you recently went hunting for poinsettias in the wild down in Mexico. What was that like?

JAMES FAUST: Well, that was fabulous. I had worked in the poinsettia industry for the past 30 years, and know people that have spent their careers focused on poinsettia– breeding them, growing them. And I, nor anyone I’d ever met, actually had seen a wild poinsettia.

When you travel in Mexico or Guatemala today, you’ll see plants associated with landscapes and human habitation, but they look a bit like commercial varieties that are currently available. And so we weren’t sure, well, does the wild one– did it look like that from the start?

And so I made arrangements with a botanist in Mexico to travel down there last year. And so my wife and I flew into this little airport on the coast of the Pacific. And he was going to take us up into the mountains to look at some plants. And this is in November, when the plants are naturally flowering, so that it’ll be easy to see.

And so we pick up our bags in the baggage claim area and we’re heading out of the airport. And we see this guy. We’d never met him before. But he’s holding up a sign above his head. And it says “euphorbia,” and it has a drawing of the unique flowering structure that all euphorbs have that we call a cyathium. And a poinsettia is a euphorb. So he was holding this plant up in kind of the secret language of plants people, I suppose.

And so we’re walking out of the airport and he says– the first question he asks is actually, so how risk averse are you? And I look at my wife and it was like, well, why do you ask? And he said, well, where I’m wanting to take you is kind of right in between where two drug cartels control. And we can only probably go out there for maybe an hour or two. Because if the car sits there for very long, they’re going to get suspicious and bad things can happen. So it’s going to be a really quick trip.

And so we get in his old VW van and drive inland an hour or so. And you kind of drive up into the mountains, where you’re at about 1,000 meters above sea level. And this is a tropical dry forest. So it’s tropical plants, but where they have wet and dry seasons. So the fall is when it’s wet, and so it’s quite conducive for plant growth. And then, in the spring, it’s a dormant season and the leaves fall off and it’s quite a dry forest.

So we parked the car and start to hike into this kind of deep canyon. And we’re not in there but a few minutes and you start to see blotches of red up on the side of the mountains. And you go in a little bit further and, soon, you find yourself really surrounded by hundreds of these plants, beautiful red poinsettias, that are arching off of these steep canyon walls.

The plants don’t look at all like what we see today. They grow about 10 feet tall. They don’t branch at all. They basically have one or two stems. And then they have one flower on each of those stems. So it was certainly a very magical moment to be there.

IRA FLATOW: I’ll bet. A lot of people think that poinsettias are poisonous. But I hear that you have investigated this firsthand, in the name of science, of course.

JAMES FAUST: Well, yeah. Yeah, it’s an urban legend. There’s been studies done of over 20,000 different cases of exposure to poinsettia, and there haven’t been any fatalities. You can certainly get an upset stomach. The plants ooze latex, and so you can get an eye irritation of some sort.

So recently, I decided, we talk enough about poinsettias not being poisonous. I guess a way to prove it is just to eat one. So I ate one and survived. And it wasn’t all that good. I wouldn’t recommend it. And it’s probably not going to replace arugula in your salad anytime soon.

IRA FLATOW: You ate the whole thing?

JAMES FAUST: Well, not the whole plant.

[LAUGHTER]

Just a couple of leaves.

IRA FLATOW: Now, I know we have a lot of botany nerds out there that talk about the plants. Let’s talk about the red parts of the poinsettia.

JAMES FAUST: Sure.

IRA FLATOW: They aren’t actually flower petals, right? So what are they?

JAMES FAUST: Yeah. We call them bracts. They’re modified leaves. So it’s really just a leaf that has started out green and then transitioned to red. The true flowers are those little pea-sized buds in the center of the flower. They’re kind of greenish yellow, and we call those cyathia. That’s the true flower structure.

IRA FLATOW: Wow. Is there still something you haven’t found out about it that you need to know about the plant?

JAMES FAUST: Oh, gosh. That’s a good question. There’s still a lot of interesting scientific things that we’re still trying to understand– flowering and controlling flowering and things like heat stress.

IRA FLATOW: I was surprised you said it was a euphorbia. I mean, that’s sort of like a succulent. I had no idea they were related.

JAMES FAUST: Yeah. It’s one of the few tree forms of euphorbia. Most euphorbia– most of them are not very attractive at all. I mean, they don’t have any colorful petals or bracts at all. Most of them are fairly ugly. And a lot of them are cacti-like.

IRA FLATOW: Yeah.

JAMES FAUST: But it’s a huge family. There’s a huge amount of diversity within the euphorbias.

IRA FLATOW: I mean, who knew this much about poinsettias? Obviously, you do.

JAMES FAUST: Yeah.

IRA FLATOW: Jim Faust is an associate professor of floriculture physiology at Clemson University in South Carolina. Thank you for joining me today. And Happy Holidays to you.

JAMES FAUST: Thank you. It has been my pleasure.

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