One to Grow On

Understanding how food production impacts ourselves and our world

28: The American Chestnut Transcript

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Hallie: Hello and welcome to One to Grow On. A show where we dig into questions about agriculture and try to understand how food production impacts us and our world. My name is Hallie Casey and I studied and currently work in agriculture.

Chris: I’m Chris Casey, Hallie’s dad. Each episode, we pick an area of agriculture or food production that confuses a lot of people and try to get Hallie to explain it to us. And this week we are focusing on chestnuts roasting on an open fire, but just the chestnut part.

Hallie: That was so cute.

[Background music].

Chris: Thanks.

Hallie: Yeah, but we are just talking about the American chestnut today.

Chris: Wait, there’s international chestnuts?

Hallie: Well, yes.

Chris: Oh, like from Europe and Asia and stuff.

Hallie: Exactly. From those two places. Yes, correct.

Chris: Really?

Hallie: Yeah.

Chris: Wow. So what makes them different?

Hallie: I mean, that they’re from somewhere else.

Chris: Okay.

Hallie: There are some morphological differences as well, but like basically the Asian chestnuts are from Asia. The most common one and the ones that we see here in US stores are Chinese chestnuts.

Chris: So wait. I thought you said we were talking about American chestnuts though.

Hallie: I know, but I was just sharing a fact.

Chris: But then you said that the ones we see here most of the time are Chinese.

Hallie: Yes.

Chris: But we’re going to talk about the American ones because we’re American.

Hallie: What do you know about chestnuts?

Chris: That roasting on an open fire is a Christmas thing and I guess you can eat them maybe after you’ve roasted them. That’s all I got. I mean, they’re nuts. I assume they’re nuts.

Hallie: They are nuts.

Chris: Okay. But yeah, I guess now that I think about it, I don’t really know about a chestnut. I think it comes off a tree. It’s a nut that comes off a tree. Do you make chests out of the wood?

Hallie: No.

Chris: Just called the chestnut.

Hallie: Well, you know I did not actually look into the etymological root. I mean, you probably could make a chest from the tree. You probably would not make a chest from the nut. I don’t know where the term chestnut came. I’m just now thinking about how that’s the word chest right up front. I don’t know on that one. Sorry.

Chris: Alright.

Hallie: The other thing I was brainstorming. I was like, what do people know about chestnuts? The other thing I thought it was the term that old chestnut.

Chris: What is that term? I’ve never heard that.

Hallie: That like if someone tells a joke, you go, oh, that old chestnut or if someone says, oh. You know what I am saying?

Chris: Are you making this up?

Hallie: You’ve never heard this?

Chris: I’ve never heard this. I’m pretty sure it’s not a thing.

Hallie: No, it’s 100% a thing. I’ve definitely said it before.

Chris: Okay. It’s a thing that Hallie Casey has said and no one else has said.

Hallie: [Laughs]. No, there was a Wikipedia page. I Googled it to find out where the term where that old chestnut came from. There was a Wikipedia page.

Chris: Hang on. Let me look this.

Hallie: Oh my God. Well, it’s a British slang term that means like an old joke according to Wikipedia.

Chris: Oh, now that you say it’s British, it makes sense.

Hallie: That’s a thing people say that old chestnut. Oh, that old chestnut. I can’t believe you’ve never heard of oh that old chestnut.

Chris: No, it’s on urban dictionary. It must be a thing.

Hallie: It’s a thing regardless of whether or not it’s on urban dictionary, it’s a thing.

Chris: Okay. But this is talking about people. It’s a thing. I believe you.

Hallie: Those are the two I guess things people know about chestnuts. Oh three, I guess. One, they are nuts. Two, you can roast them on an open fire and at some point in British slang, they are referred to an old joke.

Chris: Alright.

Hallie: The chestnut tree is in the Fagaceae family, so it’s related to beaches and oak trees. They’re in the genus Castanea and physiologically on a chestnut tree, you have these beautiful, lovely, big leaves. Right.

You have flowers that are called catechins and they’re self-incompatible. Basically, you have to have two different trees in order for the two flowers to pollinate. You have some plants where the flowers can pollinate themselves, but in chestnuts, you have to have two separate trees in order to get a chest nut from the flowers.

Chris: Is that having a male plant and a female plant?

Hallie: No, you have the same sex organs on both plants, but they can’t fertilize themselves. If they fertilize themselves, it’s not compatible. I think we call that self-infertile if I remember correctly. The actual nut itself, it is a nut. It is like a proper nut. Some of the nuts that we talk about are not technically nuts, but this is a proper actual nut. It has like an outer burr that is actually still removed by hand, but if you look at it, do you know what a sweet gum looks like?

Chris: I do not. Okay.

Hallie: If you live in North America, you might know what a sweet gum fruit looks like. They’re kind of round and pointy and they hurt really bad when you step on them. That’s kind of what a chestnut looks like with the burr on the outside.

Chris: Oh, like the thing that almost looks like a flower that is dropped from a tree, except it’s a piece of prickly wood.

Hallie: It’s like a big round ball of prickliness.

Chris: It’s like a round ball of spiky death in a stem.

Hallie: Yeah.

Chris: I’ve never heard it called a sweet fruit.

Hallie: No, sweet gum.

Chris: Never heard it called that either.

Hallie: It’s not related to chestnuts, but the fruits look similar when the chestnut has the burr on the outside. There are these spiky burrs that all chestnuts have and those are still actually removed by hand and then on the inside, you actually have the fruit itself, which is the nut.

Chris: Between this and the cashew with the apple with the poison death skin. People like their danger nuts.

Hallie: Yes, you got to get in there. You got to really want it. The American chestnut was a really significant food source for first nation’s folks in Eastern US. The trees grew up to 100 feet tall and they were called the redwoods of the East and before the turn of the century in the 1900s, they made up about 25% of the forest from Mississippi up to Maine.

Chris: That sounds like a lot of trees.

Hallie: Those are a lot of trees. Post-contact after colonialization of North America, settlers used chestnuts for building materials. It was really, really straight and very sturdy and it was just a generally celebrated tree. It was one that people ate. People made a lot of houses out of chestnut. It was also quite pest resistant in terms of things that can eat wood and kind of get in wood, so it was just a very popular tree. Because of that, it was something that was really a big part of the American identity. Like how here in Central Texas, live oaks are a real part of the identity of the area. If you have something that’s so ingrained into your view of the landscape and your eating habits and the buildings and the things that you use are made of this wood, it was a really big part of American culture.

Chris: They ate it. They made houses out of it. I’m guessing they probably made chess out of it.

Hallie: Oh my God. Probably. I guess so. [Laughs]. You don’t know much about the American chestnut though.

Chris: I mean, I had no idea it was such a common tree and so commonly used.

Hallie: Yeah, well it was. In the early 1900s, around the turn of the century on Long Island, there was an Asian chestnut tree that was planted. There was actually a group of them and it was discovered in 1904 that they had a fungal blight.

Chris: In the early 1900s.

Hallie: In 1904, it was discovered that these Asian chestnut trees had a fungal blight called cryphonectria parasitica.

Chris: That does not sound good.

Hallie: No, so at the beginning of the 1900s, it was estimated that in North America, there were 4 billion with a b American chestnut trees.

Chris: Wow.

Hallie: By the 1940s, there were virtually none.

Chris: Oh, wow. That’s horrible. That’s massive repeated decimation, like very rapid. Jeez.

Hallie: There are still like pockets of American chestnut strands. There’s a list on Wikipedia that you can find of the dozen or so American chestnut strands. It still exists. There’s one that’s in Wisconsin. I was actually near there this last summer and I tried to go, but the University of Wisconsin keeps it very hidden, not hidden. You know where it is, but they just don’t let anyone go for obvious reasons. They don’t want any contamination.

Chris: They want to keep it protected.

Hallie: Yeah, but this tree was such a huge part of American culture and American iconography I guess that since the 1930s, since it was really clear that this was a major problem threatening the American chestnut and then basically, it successfully threatened it and now is virtually non-existent. Since the 1930s, American scientists have been trying to find different methods to repopulate the chestnut species.

Chris: How’s that going for them?

Hallie: Well, do you want to talk about that after the break?

Chris: I would love to talk about that after the break.

[Background music].

Chris: You know what species is not going extinct?

Hallie: What species is that?

Chris: The species of our patrons.

Hallie: [Laughs].

Chris: Thank you so much to Lindsay and Vikram and Mama Casey.

Hallie: Our newest starfruit patrons, Shianne.

Chris: Oh, hello, Shianne.

Hallie: Also, a huge thank you to our other new patron, RC and Hope. Welcome. Thank you so much.

Chris: Hello, RC. Hello, Hope. Thank you for joining.

Hallie: If you are enjoying the content that we’re producing and you’re interested in supporting us, you can head over to our Patreon, that’s We have very great news. We’re halfway to our goal of 30 patrons and once we hit that goal, we are going to be making some videos of us reacting to the superfoods that we talk about on the show.

Chris: Do you think we can actually find some mangosteen?

Hallie: I feel like I could find us a mangosteen.

Chris: I mean, that was the one that Queen Victoria with knight people can bring it back, right? It sounds like a lot of work.

Hallie: I feel like I could find this one.

Chris: Alright. Well, I’m looking forward to it. I’m looking forward to that.

Hallie: You will knight me when we make that video.

Chris: I will not knight you, although I wouldn’t be able to get my hands on a sword.

Hallie: [Laughs].

Chris: We can make it happen. Back to the episode.

[Background music].

Hallie: Dad, do you have a nature fact for us?

Chris: I do.

Hallie: Will you please tell it to me?

Chris: Sure and I bet you actually already know this one, but the lyric that I sang at the beginning of the show, chestnuts roasting on an open fire is from a Christmas song, which I knew you knew, but I didn’t know who wrote a Christmas song. I assumed it was Nat King Cole.

Hallie: I don’t think he wrote a lot of songs, dad.

Chris: That could be. Maybe people just wrote songs for him or he just found songs to sing, which is great. I’m glad he did, but it was written by Mel Torme.

Hallie: Who is that?

Chris: You’ve never heard of Mel Torme?

Hallie: No, I don’t know Mel Torme.

Chris: He was a jazz singer. Did a lot of scat. In the 1980s, one of the big sitcoms was called Night Court.

Hallie: Night Court?

Chris: Yes, Night Court. It was about a court that took place at night.

Hallie: Why?

Chris: I don’t know. It was funny.

Hallie: Is it a real thing? Is it a real night court?

Chris: Yes, I don’t know. Watch the show sometime, you’ll like it.

Hallie: Okay. [Laughs].

Chris: Except one of the characters he is a real sexist, but he gets put down a lot, so it’s cool. I mean, it’s good that he gets put down. It’s not a character that people are meant to like.

Hallie: Mel Torme.

Chris: No, the main character judge Harry, his favorite singer was Mel Torme.

Hallie: Oh, I thought you were going to say Mel Torme was in this show.

Chris: No, he made several guest appearances. Like they got them on the show and the judge idolized, Mel Torme and said I’m going to marry the first woman that is impressed by the fact that I own all of Mel Torme’s records and stuff like that and so that’s the only reason of course I growing up that I knew who Mel Torme was and it was pretty great.

Hallie: Cool. Great facts, dad.

Chris: Thanks.

Hallie: Absolutely.

Chris: A Christmas song by Mel Torme.

Hallie: There you go. American chestnut, there have been a couple of different efforts at blight resistance in the American chestnut.

Chris: Hang on.

Hallie: Yes.

Chris: Before we get into blight resistance, the fact that they’re having to create trees that are blight resistant, I guess suggests the fact that the blight is here to stay and if you just go try to plant some chestnut trees, they’re going to die.

Hallie: Yeah, it’s pretty much ubiquitous at this point.

Chris: Wow.

Hallie: Yeah.

Chris: Okay. Are Asian Chestnut trees all over America now?

Hallie: No, not really. We have some Asian chestnut orchards in California and a couple of other places, but they’re not really planted ornamentals. They’re only in a couple of places for production and most of the Asian chestnuts that we get come out of Asia. The US is not a very large producer of chestnuts for production.

Chris: Got it.

Hallie: Yeah, so there’s really not a ton of Asian chestnuts, but the blight is just super ubiquitous. There’s really no successful way to plant American chestnuts here in the US that have not been either hybridized or it’s a specific cultivar or we’ll talk about this in a minute or have been like breed some other way. Part of this is just that it was so fast that we did lose a lot of germplasm, so we don’t have a lot of the original DNA.

Chris: We lost a lot of what?

Hallie: Germplasm. That’s like seeds. We just don’t have a lot of chestnut DNA because there’s just so few chestnuts here in America now.

Chris: Got it. So they’re trying to make them blight resistant.

Hallie: Yes, there’s three ways that we’re trying to do this. One of them is called back crossing. This began in the 1970s.

This is basically crossing the few remaining American chestnuts that we have back with Asian chestnuts to try and get something that’s blight resistant that resembles close enough the American chestnut. Some people don’t love this. There currently is an American Asian chestnut, I guess is how you would say it. One of these back crosses. There’s one planted at the White House. I think there’s a couple planted at the USDA in DC. There isn’t anything successful that’s able to go out on the market yet. Another way that we’re trying to do this is inter crossing, so that’s basically taking geographically dispersed specimens that still exist. There is one cluster of American chestnut say in like La Crosse, Wisconsin and say, there’s another one in like South Carolina somewhere and they take these two plants and then in the lab cross the catechins, so they pollinate the flowers. Well, I don’t really know how they do it. Somehow they cross these two flowers or these two plants and they create a hybrid between these two in hopes that those two will because they were both from blight resistant stands, create a healthier tree. If that makes sense. Does that make sense?

Chris: Okay. Yeah.

Hallie: There’s a lot of issues with the current blight resistant stands. They’re kind of scraggly. They’re not super strong and they still have issues with the blight. They’re just able to kind of fight through it. So through this inter crossing, they’re trying to create a tree that’s really healthy. However, this started in the 1970s. It takes at least seven years for American chestnut trees to produce nuts. New trees have to be at least five years old before their resistance can be tested for the inoculation to the blight itself and then the test itself requires two years for evaluation.

It takes a really long time to actually test whether or not it’s working and so we haven’t had any success with that yet.

Chris: Even if there is success, would they still be considered American chestnut trees?

Hallie: Well, with the inter crossing, they would, right? Because we’re just inter crossing between different American chestnut strands. There is some debate with the back crossing, whether they would still be considered American chestnuts, but scientists have been working on this for so long that they’re just like trying to find anything that will work, which brings us to our third thing that is on the table, which is transgenic chestnuts.

Chris: Transgenic chestnuts.

Hallie: Yes.

Chris: That sounds like a loaded term.

Hallie: Yeah, do you know the term transgenic?

Chris: Does it have frog DNA in it?

Hallie: [Laughs]. It actually has wheat DNA.

Chris: Really?

Hallie: Yes, so there are some scientists at the State University of New York that inserted a wheat gene into the chestnut genome and it was passed down to its offspring. Basically, they grew a chestnut tree with a wheat DNA in the genome and then when that tree produced fruit, that baby then had that wheat gene in it, so it was blight resistant.

Chris: Okay. I was going to ask you why on earth did they put the wheat gene in it to begin with and that makes it blight resistant?

Hallie: Yeah. I mean, I’m sure they tried a lot of different genes, but this one worked. There is a lot of debate around this. Currently, both the FDA and the USDA are trying to figure out regulatory what this means. There are a lot of people that are promoting that this tree be planted in wild stands to repopulate chestnut forests.

Chris: I have so many thoughts right now.

Hallie: Tell me what they are.

Chris: My first thought is, would it be called chest wheat? Are they wheat nuts?

Hallie: [Laughs].

Chris: My second thought is I’m being reminded of the plant taxonomy episode in which you said, we’re all just sort of making this up. We can intercross the DNA and the speciation lines are very blurred and hardly matter and that sort of is interesting for me to think about with some of these breeding techniques that are being used to bring back this tree. The other thing I’m being reminded of is Star Trek IV when you talked about, what was it? The one where they take the trees from the different geographic regions and cross them in a desperate attempt to breed them.

Hallie: That was inter crossing.

Chris: Inter crossing in a desperate attempt to breed them. I think of Star Trek IV and when they go back in time in a desperate attempt to save humpback whales from distinction.

Hallie: No, that’s very similar to like what scientists have been trying to do since the 1970s. We talked in a previous episode about ginkgo trees and I feel like the American chestnut tree is similar to the ginkgo tree. Then it’s just like a very poetical tree that a lot of people just love the idea of the American chestnut and I feel like for that reason and that reason only it feels like the only tree where we could even have the discussion of having a wild GMO that just grew wild. Right? That’s what we’re discussing with this transgenic breed is just having a basically newly introduced native chestnut tree that is a GMO and because scientists have been trying so desperately and the American government has been putting so much money behind saving the American chestnut for so long and for so many and because it is such a part of the American story and American iconography, even before colonization, I feel like this is the only way that that door gets opened. You know what I mean?

Chris: If someone invented time travel, do you think they’d go back and try to burn down the Asian chestnuts?


Hallie: I mean, I would.

Chris: That doesn’t surprise me, but then I bet the American chestnut wouldn’t be nearly as poetical.

Hallie: No, that’s probably true. It’s only probably true.

Chris: Are the nuts from the transgenic trees edible?

Hallie: Yeah, they are.

Chris: Do they taste just like Asian chestnuts? Are they different? Do you know?

Hallie: I don’t know. I haven’t read anything about how they’re different. Everything I’ve read makes it seem like it’s very similar to the original American chestnut, but there’s not really anyone alive today who can really speak to what the original American chestnut was really like. There’s probably a handful of people, but it’s not a lot. Right?

Most people don’t remember at this point, it’s been so long. You can see one of these GMO chestnuts at the New York Botanical Gardens.

Chris: Cool.

Hallie: Yeah, if our New York listeners want to go take a selfie with the GMO tree, please send it. I’m so jealous.

Chris: I’d love to see that. I’ve never seen a chestnut tree that I know of.

Hallie: I have not either. I never have and I love the idea of a chest. I’m fully bought into like the poem of this tree.

Chris: You stand chestnut trees.

Hallie: [Laughs]. Yes, I stand chestnut trees. I actually did one time. I cooked chestnuts in my oven one time. It was such a pain. It was so hard. They were Chinese chestnuts because I got them from the store. But yeah, it was a real pain.

Chris: It wasn’t an open fire.

Hallie: No, it was my oven. I didn’t have a fireplace where I was living.

I used the Martha Stewart method where she says you take a paring knife and for each chestnut you have to carve an X and score the chestnut so that they pop open. It was not worth it.

Chris: Martha Stewart makes so many things that are not worth it look totally easy, so I’m with you on that one.

Hallie: [Laughs]. Yeah, but there is all of this work going into saving this species. Honestly, I don’t know where I land on the transgenic chestnut. I hope that the inter crossing comes up with a truly American chestnut that is able to fully resist this blight and produce amazing and beautiful chestnuts and grow a hundred feet tall again and all of that’s true, but there was a great quote from Gary Lovett, who is an ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York. He said that creating resistant varieties is a good thing, but doesn’t do us any good if we keep introducing new pests.

Chris: Moral of the story, be careful when you bring home plants, kids.

Hallie: Yes, clean your shoes before you get on the plane, please.

[Background music].

Chris: Thanks for listening to this episode of One to Grow On.

Hallie: This show is hosted by me, Hallie Casey and Chris Casey.

Chris: It is produced by Catherine Arjet and Hallie Casey.

Hallie: Our music is Something Elated by Broke for Free.

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Chris: Be sure to check out the next episode in two weeks.

Hallie: But until then, keep on growing.

Chris: Bye everybody.