IRA FLATOW: This is Science Friday. I’m Ira Flatow. Have you ever ordered an exotic drink at the bar? And no, I’m not talking about the ones with the little umbrellas in them. No. The ones I’m talking about have exotic flavors like terpinolene. That’s the compound in pine needles that makes them very piney. Or limonene, the citrus flavor of oranges, lemon, and cardamom. How about camphene? What’s that? That’s the pungent component of ginger and tea leaves.

My next guests want you to get excited about tasting these and a whole host of other flavors that you may never have experienced, from plants you may not have heard of. And we want you to know this by drinking them. For example, the bitter ingredient in your cocktail bitters, that’s probably Gentian. That’s a root used in Italian liquors for centuries. But you can also make them with Osha, a root found in the Pacific Northwest that bears, you know, they use that medicinally also. Or if you like spicy flavors, try the Szechuan Peppercorn, which also has a numbing effect. And yes, we’re going to talk about botany at the bar.

Whether it’s a homemade cocktail bitters, or infusions that have nothing to do with booze and the science of flavor. And we want to know what’s an under-appreciated botanical flavor that you like? We’ve been asking all week on our Science Friday VoxPop app. Ken in Kansas for example, had these suggestions.

AUDIENCE: How about sumac seeds? I like to suck on them after they’ve come out and turned red. Another fun one this time of year is hackberries. They are sweet and tasty.

IRA FLATOW: Hm. What about you? Give us a call. Our number is 844-724-8255. Or you can tweet us at scifri. 844-724-8255. Let me bring on my guests. Dr. Selena Ahmed, associate professor of Sustainable Food Systems at Montana State University, in Bozeman. Co-author of Botany at the Bar. Welcome, Selena.

SELENA AHMED: Thank you for having us, Ira.

IRA FLATOW: Great book. A lot of great recipes in there. Dr. Ashley DuVal, a plant geneticist and co-author of Botany at the Bar. She’s in Davis, California. Welcome, Ashley.

ASHLEY DUVAL: Thank you so much for having us.

IRA FLATOW: Well let’s start right at the beginning. Selena, what are bitters at their essence?

SELENA AHMED: Absolutely. Bitters is a really broad definition. Is essentially botanical extractions that pull out the flavor and therapeutic properties of plants. And people have been extracting botanicals from their surrounding biodiversity for centuries, actually thousands of years, in civilizations across the globe. And these extractions historically, very much had a medicinal function as well as other attributes. For example, botanicals were extracted in ancient Egypt. Were used for medicinal properties such as for digestion, but were also used for other functions, such as for promoting vivid dreams. And were used topically as well as incense.

And so, doing field research in different communities around the world, we’ve seen different cultures extracting plants from their local biodiversity and really seeing these extractions as a common cultural thread of cultures around the world and through time. And more recently, bitters have really come to be associated with cocktails for recreation. However, historically, cocktails really were for therapeutic reasons. And the earliest definitions of cocktails always had bitters in them.

IRA FLATOW: Mhm. Were there any two cultures that you both, Selena and Ashley, focused in on? To focus in on what their bitters were?

SELENA AHMED: Sure. Ashley, maybe you can start.

ASHLEY DUVAL: Sure. One common thread that we all noticed doing research in very different parts of the world, Selena working quite a bit in China, Asia, and the Himalayas. Myself in Latin America, Rachel in Africa, the Middle East, as well as Asia. We noticed that everywhere we would travel for our ethnographic surveys and field research, often the households would have bottles of roots and herbs infusing on their countertops. Or when Rachel was in Togo in Senegal, the village chiefs would invite her in to join over a cup of bitters. And so, rather than them necessarily being the focus of our research at the time, they were this uniting thread that seem to pop up very persistently in all of the different places that we would go.

And as a result of that, we started to use them as a tool to communicate our research as well. As a way of kind of bringing back flavors from the field and capturing this less concrete, less tangible essence of what a plant or a landscape might taste or smell like when you’re trying to communicate a more serious or dry topic of your research about that particular organism.

IRA FLATOW: I mean, if you go around the world talking to different cultures about what bitters and flavorings they’re using, how do you narrow it down? You must find a whole lot of them that’s far into what we usually use here in the United States.

ASHLEY DUVAL: Yes, absolutely.

IRA FLATOW: Selena?

SELENA AHMED: Yeah, absolutely. So there is about 360,000 species of flowering plants, and out of that about 25,000 have been used for food and medicine throughout history. So you can really begin to understand the huge breath of biodiversity and plants that really come into play in making these bitters from around the world. And you know, some bitters have many– and recipes that we create have many plants in them. Maybe 10 or 20 or 30. Whereas other bitters really might just be a single ingredient. And really, understanding the variation and complexity of flavor of just one botanical species is also really rewarding.

IRA FLATOW: So why are we talking about bitters? What is there about bitters and not sweet or salty or sour flavors? Ashley.

ASHLEY DUVAL: Well, that’s a great question, and I think that a lot of the plants that we’ve observed being used in bitters, in a traditional context, are having a different pharmacological or medicinal effect. There’s a number of different chemical compounds with known therapeutic effects in different ways that have bitter tastes. It’s actually one of our more highly evolved senses. We have about 25 different bitter taste receptors as opposed to just one or two for sweet, or salty, or sour. So, on the taste side, it has a lot of importance on the botanical side as well. This is a very diverse class of compounds that plants typically use as an aversion strategy. It’s in many cases, it’s a signal to not consume a particular one of the plants.

IRA FLATOW: Don’t eat me.

ASHLEY DUVAL: Right. Exactly.

IRA FLATOW: Don’t eat me.

ASHLEY DUVAL: Stay away.

IRA FLATOW: Stay away. OK. A lot of people interested with their own ideas. Let’s go to the phones to Gabriel in Palo Alto. Hi, Gabriel.

AUDIENCE: Hi, Ira. Thank you very much for having me on.

IRA FLATOW: Yeah. Go Ahead.

AUDIENCE: Yeah, so when I was a kid growing up in Mexico, we used to have eucalyptus flavored chewing gum that was sold commercially. And I haven’t seen it in over 20 years but I remember it was delicious. It was literally just eucalyptus flavor.

IRA FLATOW: Was it a bitter flavor?

AUDIENCE: It was kind of minty, oily. It wasn’t bitter. It was– and they used to mix it also with peppermint. So they had eucalyptus or eucalyptus peppermint.

IRA FLATOW: Wow. Ashley, Selena, have you heard of that?

ASHLEY DUVAL: Not the chewing gum, but we love to use eucalyptus. In fact, we have several cocktails that use different species of eucalyptus. You usually only see maybe one or three around the world, but there’s a wide variety of them in Australia. And in fact, one of the oldest, fermented beverages from Australia was made out of eucalyptus gum. So it has a long tradition of use in alcohol and bitters. Let’s go to Andrew in–

SELENA AHMED: And then–

IRA FLATOW: I’m sorry. Go ahead.

SELENA AHMED: Oh, also just a tap on. So bitters have a bitter taste and sometimes that’s the dominant taste profile. But there’s also hundreds of thousands of volatile aromatic compounds, such as the terpenoids found in eucalyptus, that give bitters a much more complex flavor than just bitter.

IRA FLATOW: Mhm. Let’s go to Andrew in Cleveland. Hi Andrew.

AUDIENCE: Hi. My wife and I enjoy growing what are called ground cherries. And they’re a plant from the tomatillo family. They grow these little, tiny, little versions of tomatillos. Sometimes as big as a basic marble-sized fruit. And they’re ripe when they fall to the ground in kind of a papery husk. And the fruit inside is a yellow to greenish berry and it tastes like– the best way to describe it is sort of a baked pineapple.

If you can imagine like a very sweet tropical flavor, but also carrying kind of the savory bready flavor that you would get from something that was baked kind of in a dough. And they’re very easy to grow and they reseed themselves very easily. If you plant them, you will be without them.

IRA FLATOW: OK. Thanks for telling us about that. Are you familiar with that?

ASHLEY DUVAL: Sure. Physalis. There’s some different species and it’s a fun one. I think actually, there have been some efforts to grow it more commercially now. And in the last couple of years, I’ve started to see it on shells in specialty stores. So that is one of the crops we’re kind of keeping an eye on as being another potential, under-utilized food that is gaining some traction.

IRA FLATOW: Well I have in front of me three different– I have herbs, dried herbs, and bitters that you guys have provided with me. Now I’m going to try to taste them and see what they taste like. The first one I have is Raisin in the Sun. I’m sure you’re familiar with that one. Let me give it a taste. [SIPS DRINK] It doesn’t taste like the raisin or a sun. [LAUGHS] It’s kind of a woody taste to it, I would describe it. What should I be tasting?

ASHLEY DUVAL: Well, this blend was actually one of our attempts to recreate, or put a new spin on an old classic. Because as much as we try to steer people away from the very common bitters varieties that are available today, we also acknowledge that there are some recipes that you just can’t make without that certain blend. And so this is sort of a reformulation of a Peychaud’s. And this is an important bitters for a Sazerac cocktail.

IRA FLATOW: I could see why that would, from the taste of it. It’s really interesting. Let me move on to what I have. The second one here called, Toba Chai. Let me try a Toba Chai. [SIPS DRINK] Oh, that’s distinctive. That’s very nice. I could see that as a mixed drink if you’re using it in a mixed drink.

SELENA AHMED: So the Toba Chai has a lot of different botanicals that were historically used in Ayurveda to stimulate appetite as well as boost immunity, such as clove and black pepper. And so it is a really nice sort of spice addition to our cocktails. But sometimes we also use it sort of as liquid seasoning in other culinary elements in our kitchens, such as for salad dressing or marinades.

IRA FLATOW: It’s too bad I’m using this in seltzer water and not in you know–

SELENA AHMED: Not in a cocktail.

IRA FLATOW: Well, I wouldn’t be– I’m such a cheap drunk, I’d never get out of here with the recipe show. [LAUGHS] All right. The third one. Third one I’m going to do is Citrus Grove. [SIPS DRINK] That is a little citrusy. Mm, that’s a nice flavor. I could see you taking all these home tonight. [LAUGHS] Tell me about that one.

ASHLEY DUVAL: You know, the origin of that blend came out of requests actually, from our bartender and mixologist community that we regularly bounce ideas off of. While most of our blends are based around themes and botanical stories, this one’s actually revolving around diversity within a species or a clade. And one of the complaints that we were hearing is that there really aren’t very many good citrus bitters out there that are complex and layered. And so, we wanted to bring in more citrus species. There are many species that are hybrids between orange and lemon, mandarin, pomelo. And so we tried to capture as many–

SELENA AHMED: Kumquat.

ASHLEY DUVAL: Kumquat– as many different variants of a normal citrus bitters to add different layers to what would normally be maybe one species and then an extraction.

IRA FLATOW: Interesting. I’m Ira Flatow. This is Science Friday from WNYC Studios, talking with doctors Selena Ahmed and Ashley DuVal about bitters. If people want to try this themselves, you have agreed that your book has great recipes in there for making different drinks. How hard is it to come by these ingredients?

SELENA AHMED: So, that really varies. We have some recipes in our bitters book, or just bitters recipes in general, that are very common. That you may be able to get at your local supermarket or different ethnic grocery stores in your community. And more and more online a lot of these ingredients are available for some of the more complex bitters recipes. And then we also really encourage people to explore their local biodiversity and you know, really using the bitters recipes that exist sort of as an inspiration to create your own formulas off what may be available to you locally in your surrounding landscape.

IRA FLATOW: So people can make their own plant flavor concoctions and you can get an idea of how diverse biodiversity there is out there.

SELENA AHMED: Yeah, absolutely. We really see bitters really as this link of cultures and really for people to sort of taste their biodiversity and have this relationship to their ecology through bitters.

IRA FLATOW: We have one last listener who sent us in an audio clip. John from Columbia, Maryland shared his favorite hiking snack.

AUDIENCE: My favorite leaves to eat are pine needles. In fact, pine needles have more vitamin C, ounce-per-ounce, than orange juice. I also love steeping pine needles in my hot chocolate. Mm delicious.

IRA FLATOW: I would have never thought of that.

SELENA AHMED: Absolutely.

IRA FLATOW: Pine needles? Yeah?

ASHLEY DUVAL: Mhm.

SELENA AHMED: Absolutely. The First Nation communities in Montana, where I live, have long used pine needles for exactly for their nutrients and more and more we’re starting to integrate pine needles into our recipe. So yeah, it definitely has a lot of terpenoid chemistry that’s delicious, but I have not tasted it with hot chocolate and that’s going to be on my list of things to do.

IRA FLATOW: Now is it safe to just go out and pick these on your own off a tree? I mean, could you be getting into trouble with some kind of species of pine tree that’s deadlier? You know, just– you don’t know much about the botany there.

ASHLEY DUVAL: Well, with all of the foraged ingredients we recommend people do their due diligence. Even with species that may be common or they may have a good familiarity with them, we still recommend always making sure that you’ve keyed it out to the species level. And that means not just shooting a picture with a naturalist based on a single leaf, you’ve got to look at the flowers, the morphology, and be sure. Because there are plenty of examples of close relatives to one another that have very different properties.

For instance, Chinese star anise is edible. It’s one of the most common and popular spices. And it’s relative, Japanese star anise, which is only differentiated by two additional stars on the dried illicium fruit, is potentially lethal. It has strong levels of euganol and other chemicals that are known to be–

IRA FLATOW: Uh oh.

ASHLEY DUVAL: –carcinogenic. And so, even with sourced things, you have to watch out for adulterants. But definitely when foraging, know your flora.

IRA FLATOW: We have a lot of people who have their own suggestions on the phone. 844-724-8255. We’ll be back, with us, Selena Ahmed and Ashley DuVal, authors of Botany at the Bar. Stay with us. We’ll be right back after this break. This is Science Friday. I’m Ira Flatow. We’re talking about the science of flavor. Botany you can drink and tasting biodiversity with botanists, Selena Ahmed and Ashley DuVal. They’re both co-authors of Botany at the Bar. And you can see some recipes and an excerpt from the book on our website sciencefriday.com/bitters.

I want to bring on one more person to the conversation. A professional drink-maker. A mixologist, who helped you pair these flavors with the cocktail recipes. Christian Schaal, a mixologist and beverage director at Zebulon, Los Angeles. Welcome, Christian.

CHRISTIAN SCHAAL: Hi Ira, pleasure to be here.

IRA FLATOW: Nice to have you. As someone who makes drinks for people used to more, shall I say conventional palates, how do you take something completely new and make it into a balanced drink?

CHRISTIAN SCHAAL: That’s a great question, and it was a challenge that was posed very often with creating the drinks for this book because we have some very esoteric ingredients we’re working with. I think it’s really identifying the ingredients and then going to see, what does this tastes like? What does this smell like? What does this remind me of? We worked with something called Ajwain in the book, which is a seed– actually a fruit from Africa and the Middle East. And so, I didn’t know anything about it.

I had to really get in there and say, what does this remind me of? So, I heated some up in a pan. I was like OK, this kind of has some coriander, cumin, oregano-type notes to it. And then I started cycling through what liquors I could pair it with. And gin and vermouth were the first things that came to mind because both are infused with botanical ingredients, common to what Ajwain tastes like. So then going from there, what type of drink can I make with it? And a gin drink is either going to be something that’s martini-based or something a little lighter, gin and tonic style drink.

IRA FLATOW: Well you know, you have such experience with making these drinks. I have a phone load of people who have all kinds of suggestions here. I’m going to cycle through as many as I can and then get your comments on them. Let’s go first to Lisa in Winter Haven, Florida. Hi Lisa.

AUDIENCE: Yes. My question is about Jerusalem artichokes.

IRA FLATOW: Go for it.

AUDIENCE: Essentially, many of us, we love the fresh, crunchy flavor of the Jerusalem artichoke, but the flatulence is a problem. Is there something that we can pair with Jerusalem artichokes in our digestive systems to keep from having that horrible flatulence?

IRA FLATOW: Bet you weren’t expecting that question. [LAUGHS]

ASHLEY DUVAL: Actually, you’d be surprised how often these issues come up with bitters making. That was one of the primary uses of bitters, in fact.

IRA FLATOW: That was a usage of it. So it’s actually doing what it’s made for.

ASHLEY DUVAL: Well, I would suggest pairing it with some other known carminatives and ingredients to relieve flatulence and have some complementarity between them. Cumin and cardamom.

SELENA AHMED: Fennel.

ASHLEY DUVAL: Fennel.

IRA FLATOW: OK. Let’s go to Houston. To Colby in Houston. Hi, Colby.

AUDIENCE: Hi, Ira.

IRA FLATOW: Hi, there. Go for it.

AUDIENCE: So I’ve been playing with caraway and cumin in my drinks. I’ve made a caraway liqueur, kind of a riff on the Danish aquavit. And then I tried making a cumin bitter, that turned out really nicely. Paired well with pineapple rum of all things.

IRA FLATOW: Christian, are you surprised by that?

CHRISTIAN SCHAAL: No. Not at all. I mean, I think cumin has a very under-explored– it’s a very under-explored flavor in cocktails and I think that there’s definitely a world of things you can do with it. I could see it– I totally agree. I could see it in rum. I could see it in mezcal. Yeah. I think it’s a great idea. Whiskey as well.

IRA FLATOW: Yeah. Let’s go to Lisa in Kenville. Hi, Lisa.

AUDIENCE: Hi. It’s Kernville, California.

IRA FLATOW: I’m sorry.

AUDIENCE: That’s all right. We’re at 3,000 feet and we, as a group of older women, pick elderberries and make jam. But we also make a tonic for winter that’s a syrup, that we use. But it seems that elderberries are very– they don’t taste good when you just pick them. They’re never sweet and we have to use sugar with it, or honey. Is there any suggestion to help it be sweeter?

IRA FLATOW: Hm. Christian, you have any ideas? Or Ashley, someone?

CHRISTIAN SCHAAL: I mean, I think that’s a very– I think ripe elderberries are a very bitter, sort of tangy fruit to begin with. I think adding, I mean, the only way to balance that, that I could imagine, is what they’re already doing. Agave could be another sweetener they might want to play around with.

ASHLEY DUVAL: You can play off of some of the taste modulations as well. So salty can suppress a little bit of that bitterness. And then sweet and bitter tastes can cancel each other out as well. So I think finding a balance that has a sweetener that might be sweeter than something you would normally use would be toned down a little bit in a combination like that. Monk fruit, perhaps.

IRA FLATOW: Mhm. Ashley, you also encourage people to find plants local to the areas and try experimenting with them. How do you go about doing that? What’s the best way?

ASHLEY DUVAL: Well, I think there’s lots of resources for people that are interested in getting out to nature. Native plant societies in different communities often take hikes. And certainly guidebooks and different resources to learn about your local flora are good ways to get started. But if it’s something that doesn’t exist in your area, make a meetup group, find like-minded friends, get a key to plant, and have some fun with some drinks dissecting flowers.

IRA FLATOW: Well let me get to the practical aspects of this then. Let’s say you want to experiment on your own. What kind of bar tools do you need or cutlery or grinding devices? How do you do it? Give me an idea. What would be– Christian how would you do it?

CHRISTIAN SCHAAL: Are you talking about just finding a botanical and then making an abstraction of it?

IRA FLATOW: Yeah.

CHRISTIAN SCHAAL: Yeah. I think really you know, you’re going back to what we were just talking about. Depending on where you are, you could really just go to your local park. Like I can walk out my door in L.A. here and go into the park, and I can grab eucalyptus, rosemary, artemisia californica. And then what I would do, would be go home and I’d– say I wanted to take the eucalyptus and if I had some vodka at home, just straight vodka, and a blender. I could take some of the eucalyptus, put it into the blender with the vodka, blend it, taste it, and then see where it was at. If you wanted more eucalyptus, you could add more. You start with a little. And then filter it out. And then immediately, within five minutes, you have eucalyptus infused vodka.

IRA FLATOW: Wow. Not very hard at all. Let’s go to Lorenza in Santa Rosa Beach, Florida. Hi, Lorenza. Or is it Lorena?

AUDIENCE: Hey. No, it’s Lorena.

IRA FLATOW: I’m sorry.

AUDIENCE: Lorena. No, you’re fine. I’m originally from Peru and this is something I haven’t touched here since I moved to the States. Two drinks. One was guarana with whiskey. That is very common over there. And then another drink that I had over there, it was Pisco with camu camu which is an Amazon– it’s something that grows in the Amazon off the road. And it’s something that you have to develop the taste. You grow the taste because it’s kind of bitter at the beginning, but then the more you eat it, the sweeter it becomes. But I never had that here, in the United States, since I moved here in 2006. But whiskey and guarana is something I can only find in Miami Beach. Maybe because they have more, I guess, South Americans over there, and they export guarana from there. But that’s the only area where I can actually find whiskey with guarana.

IRA FLATOW: Interesting. Thanks for sharing that with us. Selena and Ashley, have you heard of that?

ASHLEY DUVAL: Yeah. Actually, two of those ingredients went into one of our blends, the Amazonian Forest Farmer, guarana and camu camu both being native to the Amazon estuary. And they’re actually really hard to work with in a bitters, but I think in some other drinks like a Pisco, you can get that balance right. Camu camu is extremely acidic. Guarana is very bitter.

IRA FLATOW: We have a tweet and an answer to the flatulence question. Why am I not surprised? It says– Shalini tweets, my mom has always used Ajwain, if I’m pronouncing that correctly, to balance the flatulence caused by taro. It may work for Jerusalem artichokes too. A little bit of advice there, Christian?

CHRISTIAN SCHAAL: That’s the ingredient I was just talking about.

IRA FLATOW: Yeah.

CHRISTIAN SCHAAL: Yeah, so that’s great.

IRA FLATOW: Is there something you have yet to try, let me ask all three of you, that you would like to try to see how well it works. Are you still hunting for a plant that you haven’t tried yet? Selena, Ashley?

SELENA AHMED: So, most of the plants that we try are plants that we’ve encountered in our ethnobotanical research, or doing workshops with different people, or working with mixologists. So I would say that I’ve really been privileged to try a lot of different flavors. But what I really haven’t tried is a combination of a lot of different flavors. So I think I’m excited to continue working with people like Christian to really take some of the ingredients that we’re putting in bitters and see how they can be experienced in new ways with some of the flavor innovation that he’s doing and other mixologist are doing through combining different botanical profiles in different cocktails.

IRA FLATOW: Well I want to ask my own question, then I have a question from the phones. Are olives considered ingredients for bitters at all? I mean, olives are used in drinks, martinis, whatever. Would that be considered an ingredient or am I just–

SELENA AHMED: So any botanical can essentially be– that can be extracted can be considered an ingredient for a bitters. And so bitters, we’ve primarily been talking about being extracted in alcohol, but you know bitters are also extracted in water. Like tea and tisane, in vinegars. And so, something that, like the salty water that you know, olives are sitting in, can be considered a bitters extraction.

IRA FLATOW: Dirty Martini. Let’s go to a VoxPop from Matt in Austin, who loves one very bitter flavor in particular.

AUDIENCE: The flavor that I like is the bitter flavor of quinine, which I know comes from the bark of the cinchona tree. I will drink tonic water even if I don’t have gin as a mixer.

IRA FLATOW: I think you found three people who’d do that also.

SELENA AHMED: Absolutely, I do that.

IRA FLATOW: What is it about that flavor that’s so interesting? What makes it interesting?

ASHLEY DUVAL: Well–

SELENA AHMED: So–

IRA FLATOW: Go ahead. Jump in there. Christian, do you find that an interesting flavor?

CHRISTIAN SCHAAL: Quinine? Yeah, definitely. And I think there’s a lot of bitter bitterness, bitter flavors that are perfect. You can make liqueurs into– with quinine or with gentian. There’s a fantastic liqueur called China China, which is made from orange peels and cinchona bark. And I would recommend that to our caller who just called in. Very aromatic, spicy, and bitter.

IRA FLATOW: Hm. I’m Ira Flatow. This is Science Friday from WNYC Studios, talking about all kinds of bitter flavors. Let’s go to the phones. There are so many of them. Let’s go to Holly in Mystic, Connecticut. Hi, Holly.

AUDIENCE: Hello, Ira. I love the show–

IRA FLATOW: Thank you.

AUDIENCE: –and this is the first time I’ve ever gotten through to you. So, I spent a lot of time doing culinary research in the Middle East. And I have one vivid memory of a rather posh luncheon with a bunch of women in Bahrain. And it was a household that did not imbibe alcohol, but they were very keen on trying all scents and preserving all sorts of traditional recipes. And one of the things they did in their kitchen was they burned frankincense, that is the resin of boswellia, which is indigenous to southwest, Arabian peninsula.

And they would burn it and use it to scent the unglazed interiors of terracotta water vessels, in which they would store water to keep it cool. And the water itself, would have the slight flavoring from the frankincense. So it’s sort of like drinking honey mask, and really an interesting flavor and an interesting way to get it

IRA FLATOW: Selena, ever heard of that? Yeah, there’s a lot of archaeological evidence that’s been found in the Middle East that has shown resins, such as frankincense, that has been found in vessels. And historically, it was frankincense that was also infused in wines with honey for that flavor profile.

IRA FLATOW: Do you think that making these lesser known ingredients more popular help protect them or the people around the world who rely on them economically? Or does it create more competition, Selena, for a limited resource?

SELENA AHMED: A little bit of both. I think if you don’t use it, you lose it. And so it’s really important to begin to sort of value certain species so we can be more cognizant of their value in our landscapes and in our ecosystems. However, certain plants, when they become very– get a lot of commercial attention, including many of those that are used in bitters, such as yellow gentian or gentinana lutea, they can then undergo harvesting pressures of overharvesting. And so there are sort of responses to that and thinking about good harvesting practices, sustainable harvesting practices, and then sort of domestication and cultivation of some of those species that are threatened in the wild.

And so, I think definitely understanding our biodiversity is really important through bitters. And unlike foods where we’re really just consuming a handful or a few handfuls of species for most of our calories, with bitters you can really explore many different types of flavors. And as we’ve seen with the different callers that are calling in, different people have different preferences. We’re consuming these plants in such smaller amounts and so there really is by having sort of different preferences and consuming them in smaller amounts, there is less harvesting pressures know that biodiversity loss. And hopefully, more reasons to conserve that biodiversity.

IRA FLATOW: Christian, do you have any bitter you want to experiment with tonight?

CHRISTIAN SCHAAL: I’m going to play around with something called, Suze, which is a gentian-based liqueur from France.

IRA FLATOW: OK. Tell us– send us a tweet or something about how that turns out. I want to thank all of you for taking time to be with us today. It was Christian Schaal, mixologist and beverage director for Zebulon in Los Angeles. Selena Ahmed and Ashley DuVal are authors of Botany at the Bar. This is a great recipe book of all kinds of drinks. The two of you’ve done a wonderful job of illustrations and making those recipes, is really an unusual book. And we have an excerpt from the book on our website at sciencefriday.com/bitters. Thank you all for taking time to be with us today.

SELENA AHMED: Thank you.

ASHLEY DUVAL: Thank you.

CHRISTIAN SCHAAL: Thank you, Ira.

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