MR. KOJO NNAMDIFrom WAMU 88.5, at American University in Washington, welcome to "The Kojo Nnamdi Show," connecting your neighborhood with the world. There are some 80,000 plant species in the Amazon, many of them unknown to us here in the U.S. But they are not unknown to the indigenous people living there. We've moved pretty far from relying on herbs, spices and other plant-based remedies to treat what ails us, but we are, in fact, in the minority.

MR. KOJO NNAMDIAround the world, more than 80 percent of people use medicinal plants and natural remedies exclusively. That may be changing. Many people are looking to the health benefits of natural foods and remedies, and scientists are seeking cures for everything from cancer to inflammation by exploring the chemical compounds of the tens of thousands of plants in the Amazon and elsewhere.

MR. KOJO NNAMDIJoining us to discuss this is Holly Shimizu, executive director of the U.S. Botanic Garden. Holly, good to see you again.

MS. HOLLY SHIMIZUThank you. Great to see you, Kojo.

NNAMDIAnd Mark Plotkin, who I've had the pleasure of working with in previous years, he's an ethnobotanist and president of the Amazon Conservation Team. That's a nonprofit that works with indigenous peoples of the Amazon to protect the culture and the land. He's the author of the books, "Medicine Quest: In Search of Nature's Healing Secrets" and "Tales of a Shaman's Apprentice." Mark, great to see you again. And tomato, tomato, shaman, shaman.

MR. MARK J. PLOTKINThey're both correct. Potato, potato, Kojo. It's good to be back.

NNAMDIGood to see you again. You, too, can join this conversation by calling us at 800-433-8850. That's 800-433-8850. You can also send email to kojo@wamu.org. What plants, herbs or spices do you use for health reasons? We're talking with Holly Shimizu and the real Mark Plotkin. 800-433-8850, you can also send us a tweet, @kojoshow. As we have said, we have spent decades moving away from natural remedies in this country.

NNAMDIBut are we moving back in the direction of appreciating what plants can do compared to medicine that comes from a lab, Holly?

SHIMIZUWell, I can speak for the visitors to the U.S. Botanic Garden and say that the medicinal plant house is where people spend the most time and want to learn the most. That's where they really say, I need more information. I want to dig deeper. I want to hear a lot more about this. And so I can say with confidence that, yes, people have a whole renewed interest in the medicinal use of plants.

NNAMDISame in your view, Mark?

PLOTKINAbsolutely. It's kind of back to the future, Kojo, the idea that, in the 21st century Internet biotech age, people are more and more interested in plants for a variety of reasons, basically, I think, because plants can do things that the most modern medicines and most modern medical technologies cannot.

NNAMDIAnd I mentioned that Mark and I worked together earlier. That was back in the mid-1990s when we took a trip to Guyana together and worked together with Conservation International. That was before I started working with the fake Mark Plotkin, the one who allegedly works in radio. This is the real Mark Plotkin who works in the Amazon where there are tens of thousands of potentially beneficial plants. Tell us about that.

PLOTKINWell, you know, the closest link to the Amazon here in Washington, D.C. is the U.S. Botanical Garden because that's a place you can go and see those rainforest plants close up. But the bottom line is, in this ever shrinking world in which we live, there are still plants which have never been seen by the scientific eye. There are still plants -- in fact, most of the plants in the Amazon, in Africa, in tropical Asia have never been examined in the laboratory in great detail.

PLOTKINAnd in an age where drug-resistant bacteria is on the rise, in an age where we can't cure pancreatic cancer, in an age where new diseases, like bird flu, rise up to bite us, we still need new medicines, and many of those medicines of tomorrow are living in the rainforest today.

NNAMDIAnd you noticed I said potentially beneficial plants and not undiscovered plants because they have, in fact, been known and used by the indigenous people for as long as people have lived there. And that was, in fact, the "Tales of a Shaman's Apprentice," correct?

PLOTKINWell, that's true, Kojo. That was my first book. And if you go to a place like the National Zoo, if you go to the U.S. Botanical Garden, you'll see people congregate around signage that said this is how the Indians use these plants, this is how the peoples in tropical Africa use these plants because there's a connection between people and plants. And plants do heal, and there is a hunger for knowledge to learn about these things and to be able to use them safely and effectively.

NNAMDI800-433-8850 is the number here. What plants, herbs or spices do you use for health reasons? You can also go to our website, kojoshow.org. Holly Shimizu, tell us about the medicinal house at the Botanic Garden.

SHIMIZUWell, we're in the process right now of revamping it, and we're going to group the plants according to categories. For example, we'll have one that has plants with tales, the kind of stories that Mark tells, plants from the rainforest with all of these incredible uses, which are very different, and the perception and the knowledge and the way that we look at them is very, very different.

SHIMIZUWe want to tell those stories, but we'll also have plants in the news. These are plants that are currently being used successfully in the treatment of different forms of cancer. That's such an important thing. And what we have experienced is people will walk through that house, and they will melt when they see a plant that has saved the life of someone that they loved.

NNAMDIIs that what you're trying to teach people with the medicinal garden?

SHIMIZUWe're trying to make this connection between plants and people and health and well-being and really further this knowledge and this appreciation to understanding because we really need to make more of a connection to plants in our lives.

NNAMDIYou have one particularly interesting plant in the garden, the Happy Tree. Can you tell us about that?

SHIMIZUOh, we do. And that tree has saved many lives. It is a tree that is used successfully now. It was being studied in the 1960s and '70s by the USDA, the NIH, and it is now an over-the-counter drug used to treat two kinds of cancers. And I have had numerous visitors whose lives have been saved by the Happy Tree. And the Latin name is Camptotheca, and it's just an incredible tree.

NNAMDIWhat's the Chinese name for the Happy Tree?

SHIMIZUYou help me.

NNAMDII think it's (unintelligible) is might be -- that's the way it looks.

SHIMIZUOkay.

NNAMDIX-I-S-H-U.

SHIMIZUOkay.

NNAMDIXishu, the Happy Tree. Well, that's my pronunciation of it, anyway. But, Mark Plotkin, scientists here are only just beginning to work through the many species in the Amazon and elsewhere. Aspirin, of course, is an example. We all know of how science sometimes has to catch up to what people knew for centuries, correct?

PLOTKINYeah, here at the National Institutes of Health, they had a major program screening plants to see what their potential for cancer might be. And this is what led them to the Pacific Yew. Now, as a forester, you're trained to think of a certain group of plants as slash. In other words, it's trash. You cut it down. You leave it to rot. The Pacific Yew is considered slash, in other words, trash.

PLOTKINWell, it's now an anti-cancer superstar, market value, probably over a billion dollars. And when my buddy, Jim Duke, who is one of the world's greatest ethnobotanists, and who has probably written more books on medicinal plants than the presidential candidates -- most of the presidential candidates have ever read, asked the Indians, do you guys use this medicinally? And they said, sure, but you're the first white guy who ever asked us. So we ignore this knowledge, and we ignore these plants at our peril.

NNAMDIAre there many more (word?) out there, you think?

PLOTKINI think there's lots more out there. It's a numbers game. You can't possibly think that our ignorance to the natural world has still led us to everything that's out there to learn. As a medicinal plant, as a biodegradable pesticide, as a renewable fuel source, Mother Nature is waiting.

NNAMDIMark Plotkin is an ethnobotanist and president of the Amazon Conservation Team, author of, "Medicine Quest: In Search of Nature's Healing Secrets" and "Tales of a Shaman's Apprentice." He joins us in studio to discuss medicinal plants with Holly Shimizu, executive director of the U.S. Botanic Garden. We're taking your calls at 800-433-8850. Do you grow any healing plants?

NNAMDIWe'd love to hear from you, 800-433-8850. Mark, it might surprise people to know how many well-known pharmaceutical drugs are, in fact, synthetic versions of the chemical compounds found in plants.

PLOTKINWell, important medicines, Kojo, range from completely synthetics based on natural product, to semi-synthetics, where they took a natural product and then twisted the molecule to make it less poisonous or more effective, to things which are still 100 percent natural. Now, the number that's 100 percent natural are dwindling if you look at strict pharmaceuticals sold with a prescription over the counter, but why would you do that?

PLOTKINYou know, you can go to the U.S. Botanical Garden. You can see stuff that you probably have growing in your backyard or should have growing in your backyard or like aloe vera, that you should have growing on top of your kitchen sink. And as I said, we need new medicines all the time, and the natural world, both plants and, indeed, some animals, offer great, great potential.

NNAMDIThere's some interesting plants you know of in the Amazon that have a lot of promise for curing serious diseases. Can you tell us a little bit about what scientists are looking at right now?

PLOTKINYou know, when I was at Harvard 20 years ago, and the Tiriyo Indians of the Northeast Amazon showed me a plant they said was a male aphrodisiac. I came back to Harvard, called the medical school, and they said, there's no such thing as a male aphrodisiac. And then when some of the Maroons near where you come from, told me about another plant used as a male aphrodisiac, they said, there's no male aphrodisiac. It doesn't exist.

PLOTKINIt's physiologically impossible. Then when they got the dose of a blood pressure medicine wrong and noticed all these old guys getting very happy, eureka, it was Viagra. So when an Indian or an Afro-Guyanese shows us a plant and says it's good for us, we say, well, he doesn't have a Ph.D. He can't know anything. But when a doctor gets something wrong and finds new medicine, he or she may get the Noble Prize.

NNAMDIYou know, Holly Shimizu, turmeric is another of your favorites. What exactly is turmeric, and what kinds of benefits does it have?

SHIMIZUWell, turmeric is actually the root of a kind of ginger, and it is a plant which will not grow outside here. We grow it in our greenhouses. But I use it a great deal in my Indian cooking and was thrilled to find out it's actively being researched for benefits in the treatment of Alzheimer's disease -- and I definitely need memory improvement -- as well as cancer and arthritis because it is known to relieve inflammation.

SHIMIZUSo in a talk we had at the Botanic Garden by Dr. James Duke, he was going on and on about turmeric. And I said, good, I'm going to use more of it. I don't need to take capsules. I just need to spice up my food more.

NNAMDIYeah, you can find turmeric in food in Indian restaurants, in particular, turmeric.

SHIMIZUExactly.

NNAMDIStar anise is another fruit that has a lot of interesting qualities.

SHIMIZUYes.

NNAMDIWhat do you -- uh-oh, show and tell. She brought a sample, star anise.

SHIMIZUOh, I gave -- I brought one. You have one in front of you. It's this most beautiful thing that smells so...

NNAMDIIt really is pretty.

SHIMIZUIt smells like sweet licorice.

NNAMDIYes, it does.

SHIMIZUAnd I learned about it many years from a chef who was making wonderful Vietnamese soup and used it to give this great licorice flavor. But the reason that people get excited about it in our medicinal house is that extracts from star anise have been used in the medicine called Tamiflu, to cure influenza or bird flu.

SHIMIZUAnd there is now an alternative way to produce it because one thing that does happen when something is discovered from a plant, like anise, the wild populations are at risk. What will happen when we go out and harvest all the plants? So we've got to protect while, at the same time, letting people know about these incredible plants.

NNAMDIOn to the telephones now. Here is John in Hyattsville, Md. John, you're on the air. Go ahead, please.

JOHNThank you for taking my call. I had a question. I've got a lot of plants in my yard, some that just come up, including -- that I have read have some potential medicinal uses, like pokeweed and black walnut and things like that. But my question has to do with the testing of medicinal plants for efficacy, especially tests that are either conducted or authorized by the alternative medicine division at NIH, in particular, jewelweed, which I have found, you know, it may be anecdotal, may be subjective.

JOHNI use it when I get poison ivy, which is fairly rare. But I've found it to be useful in reducing the itch and reducing the length of time I have blisters from poison ivy. And yet, when it was tested, I don't know whether they tested the whole plant or an extract, and that's the main question I have about testing.

NNAMDIMark Plotkin?

PLOTKINWell, two answers to your question. The first is that there's a real problem with medicinal plants, and that is the literature because the literature is really awful. It's people that really don't know anything about plants or healing. They're not shamans. They're not botanists. They're not ethnobotanists. And then they copy each other's homework. So you get this perpetuation of errors, misidentification. There's a lot of nonsense out there.

PLOTKINSo I want to give you three names. It's just a big three to start with in terms of medicinal plant references, and that's, Jim Duke, as we've mentioned, who's been on this program, Mark Blumenthal, who publishes "Herbalgram," which is the best herbal medicine magazine, and Steven Foster, who has written many books on this. And if you start with their books and their publications, you know you're getting good science.

PLOTKINNow, part of the problem with testing is that we have a reductionist approach. It's the way we patent things. It's the way we analyze things. We want the alkaloid. We want (unintelligible) from plants, and plants are chemical factories. So plants make a lot of stuff, and we want to reach in there and find the magic bullet. Well, one of the reasons that plants are so effective so many times is it's not a magic bullet. It's a magic shotgun blast.

PLOTKINAnd you take out those other 79 things and throw it away, and then it doesn't work. Now, that's not always true. When we went back and analyzed hallucinogenic plants at the World Botanic Gardens at Kew in London, they were as mind-bending, 100 years after they've been collected, as ever, because that was due to alkaloids that persist for a very long time. So you have to understand that when you use the whole plant, it's often quite different than just using an extract or a single component.

NNAMDIJohn, thank very much for your call. We move on to Rick in Washington. Rick, you're on the air. Go ahead, please.

RICKGood afternoon, in particular to Ms. Shimizu, I've been talking to Rep. Robert Brady, who is a ranking member on the House Administration Committee, about converting the south house fountain area to a national representative garden. And he likes the idea, and a lot other people like the idea because it's about four acres, I believe, of lawn area that doesn't get much use.

RICKAnd I would suggest that it start off next season as staple crops of North America, and you can do it -- you can kind of represent the country as kind of a schematic map of crops, and then as the project progresses, you can add native flowers and medicinals and so on.

SHIMIZUThat's a great idea.

NNAMDII was about to ask. I saw you've developed this idea pretty far long, right?

SHIMIZUYeah. Well, I love it, so I've taken notes because, if anything, I would like to convert a lot of the world into a garden.

SHIMIZUAnd I would say that's part of my mission in life. And I particularly like your interest in the staple crops of the -- of North America and natives. And I would like to make a little plug for our National Garden -- Regional Garden, which is a native garden, and it is outstanding. And so I support your idea.

NNAMDIRick, thank you very much for your call, and good luck to you. Mark, what plants are being looked at to treat cancer?

PLOTKINWell, the National Cancer Institute goes on, and they have tested many, many, many, many, many plants. They had a couple of hits developed into effective treatments, but, as we know, cancer is not going away. So I think that more testing is needed, and many of the things they test are with very primitive technology, they need to go back and look at because, as I said, plants are complex chemical factories.

PLOTKINI mean, you just find that one powerful thing, or you may be throwing out the baby with the bath water. Sometimes it's the secondary things in a plant that energize the primary thing. And a perfect example of that is quinine, where we have terrible problems with resistance. Like, we have bacterial resistance. We have malaria resistance. Well, physicians in Columbia use the whole bark.

PLOTKINAnd they say, because all those other 79 things in there, besides the quinine and alkaloids, potentiate complex chemical reactions. So scientists are throwing away quinine and quinine bark. They need to go back and look at it again. So even many of the hundreds of things that have been looked at for cancer in the past need to be looked at again.

NNAMDIHere is Art in Alexandria, Va. Art, your turn.

ARTHi. How are you?

NNAMDII'm well.

ARTI want to make a couple of comments. I believe that -- I wasn't able to listen to that, the whole part. The Happy Tree extract is -- I doubt if it's an OTC drug. It's probably a dietary supplement.

SHIMIZUNo. I'm actually certain of that. I can guarantee you that it is. There are two drugs that are extracted from it, one for ovarian cancer and one for colorectal cancer. It's FDA approved.

ARTYes, but they're not over-the-counter.

NNAMDIDo they have to -- they're prescription drugs. Yes.

SHIMIZUNo. I'm sorry. You have to have a prescription. I apologize. You're correct. You need a prescription.

ARTOkay. And that's important.

SHIMIZUVery important. Thank you.

ARTAnd the other is that I'm a chemist. And while it's true that we know that people knew about the extract of witch hazel for treatment of pain, it was only after it was chemically modified to make aspirin that it became a more useful product. So while there are many useful chemicals in plants, often, they need to be modified in order to be tolerable and absorbed effectively.

NNAMDII think that's a given. Correct?

PLOTKINThat is a given sometimes. But it was the willow bark that was the source of this as well as other plants that have the same compounds, where my understanding is, did relieve pain, but it didn't do it as effectively as the purified compound does. And it was very hard on the digestive system. So, truly, the chemical manipulation -- the chemical magic in the laboratory greatly augmented the efficacy and safety of that drug, which is probably the world's most important drug at this point in time.

NNAMDIArt, thank very much for your call. We're going to take a short break. We are in the middle of our fall membership campaign. And so when we come back, we'll be asking you to become members of WAMU 88.5. But we will be continuing this discussion on medicinal plants. So if you have called, stay on the line after just a very short while. We'll be back with you. You can still call us at 800-433-8850. Send us email to kojo@wamu.org.

NNAMDISend us a tweet, @kojoshow, or simply go to our website, kojoshow.org. Join the conversation there. Do you grow any healing plants or do you prefer to rely on pharmaceutical drugs that have been tested and approved as safe by the FDA? 800-433-8850. I'm Kojo Nnamdi.

NNAMDIWelcome back to our conversation about medicinal plants. We're talking with Holly Shimizu, executive director of the U.S. Botanic Garden, and Mark Plotkin. He is an ethnobotanist and president of the Amazon Conservation Team, which is a nonprofit that works with indigenous peoples of the Amazon to protect the culture and the land. He is the author of "Medicine Quest: In Search of Nature's Healing Secrets" and "Tales of a Shaman's Apprentice."

NNAMDISeveral of you have been waiting on the phone, and we will get to your calls in a second, 800-433-8850. But if the lines seem to be busy, so you may want to go to our website, kojoshow.org, and join the conversation there. Or simply send us a tweet, @kojoshow. Before I get back to the phones, Mark Plotkin, many people think of herbs and national remedies as fairly benign. You often have people say to you, it's natural, so it can't hurt me. But the chemicals in plants can be quite potent, can't they?

PLOTKINYou know, Kojo, every time I get a lecture in Berkeley, somebody comes up out of the audience and says, yeah, man, I'd never go to a doctor. I take plants 'cause they can't hurt you. And my first response is, well, if you never go to a doctor, I hope you don't get appendicitis 'cause you're going to die. And my second is, if you think plants can't hurt you, have you ever heard of the stuff called strychnine?

PLOTKINBecause that comes from plants. Plants are powerful, and like anything that's powerful, they can be used for good, they can be used for bad -- for evil. And...

NNAMDIWe got a comment from an email from someone who describes herself as a suburban Maryland mom. "Can you, please, comment on the use of nutmeg as a hallucinogen? Some seemingly harmless spices can be very dangerous. My son ingested so much nutmeg that he became psychotic. And none of his doctors were aware of how nutmeg worked and could find very little research about it, even though the incidents of its use seem to be -- seems to be on the rise."

PLOTKINWell, you know who's to blame for that, don't you?

NNAMDINo.

PLOTKINMalcolm X.

NNAMDIReally?

PLOTKINBecause it was in his autobiography that he talked about the fact that they were so desperate to escape boredom in prison, that they would ingest nutmeg, which indeed is a mind-altering substance. Now, in the Amazon, there is an Amazonian nutmeg -- nutmeg as we know it, and grow it and use it, used correctly is a wonderful spice -- is a powerful mind-altering substance that's used in religious ceremonies constantly by the Yanomami peoples. And it does take you to other places.

NNAMDINow, I've got to go re-read the autobiography of Malcolm X. I've forgotten that part. Holly Shimizu, you don't need to go as far as the Amazon to cultivate interesting and beneficial plants. What do you grow in your garden at home?

SHIMIZUWell, I grow a lot of things that I like to harvest for the kitchen. I grow things like stevia, which is the sweet herb. And so if you want sweetening in your tea and you don't want to use sugar and you don't want to use fake sugar, you can use stevia. And so that's a great thing to grow. I also grow a lot of plants like fennel, which I love fennel seed. I have -- they're very good for digestion and health. My entire garden is filled with things I eat and brew.

SHIMIZUGinger -- I grow ginger, of course. And the Botanic Garden is where we can grow things from every corner of the world. One of the plants of interest is the vanilla orchid. Most people don't know vanilla, the flavoring -- vanilla ice cream -- it actually comes from the seed pod of an orchid, a vining orchid. And the seed is fermented, and it gives us that flavor. But it's also in the medicinal house because it's thought to lessen inflammation, anti-acid and to settle the stomach. Can you smell it?

NNAMDII'm smelling it, even as you speak.

SHIMIZUYeah.

NNAMDIIt is vanilla.

SHIMIZUIt is, yeah. And it's an orchid. So, yeah, I find that people's knowledge of useful plants is something that, you know -- it's like you just build a book of knowledge because it grows and grows. It just never ends.

NNAMDIWe've talked about this on the air before. But you also don't need a large garden to cultivate most of these plants.

SHIMIZUNot at all. As a matter of fact, I don't have a lot of sun in my garden, so I grow a lot of these on my roof. And I have a roof garden with containers where I grow all different kinds of basils and lemongrass and all these amazingly fabulous plants because that's -- they need sun.

NNAMDIMark Plotkin and I love gardens, but we don't grow them ourselves. Our wives grow them, and then we take credit for their growing of them.

NNAMDIWhat we also share is an interest in New Orleans. So, Mark, tell us a little bit about what you can find in New Orleans in terms of medicinal plants.

PLOTKINWell, you know, Kojo, New Orleans is the home of the cocktail. And the reason is because that's where all the cultures of Europe and Africa and the Caribbean and South America cross paths. And the national drink of New Orleans is the sazerac, and what makes New Orleans sazerac so different is it has Peychaud's Bitters, not the Angostura bitters that most people use. What give it its kick is ginseng and other bitters, which are, first and foremost, medicines, so cocktails can be medicinal in the right dosage.

PLOTKINSecondly, when you look at wormwood, it was really the source of Absinthe, which is the national liquor of New Orleans, which lead to a lot of creativity, a lot of art and a few suicides.

PLOTKINBut the plant used to make Absinthe, the wormwood, is now the new wonder drug for malaria. So this link between alcohol, cocktails, bitters, medicines, foods, arts, creativity is endlessly fascinating.

NNAMDIAnd, see, talking about links, I'll mention that on the next hour, we'll be talking about nanny states and personal freedom. We'll be talking about prohibition and what that meant in terms of alcohol. Here is Arlene in Potomac, Md. Arlene, you're on the air. Go ahead, please.

ARLENEOh, hi. Thank you. I had one major question and another little question. Major question is, I've read in the past and have been concerned that the Amazon -- actually, I've been to but -- is disappearing at a really fast rate. And at this rate, it will become so small that it won't be able to maintain itself as an ecosystem and will kind of collapse within about 80 years. Is that -- first of all, is that relatively true? Or -- I haven't been reading lately, so what about that?

PLOTKINWell, the Amazon -- I'm sorry. The Amazon is being destroyed at a frightening pace, and I do think that if we stand back, it will disappear maybe even in our lifetimes. But also, you have to remember, the media loves bad news, and there's a lot of good news out there. I'm the president of the Amazon Conservation Team, and what we do is work in partnership with indigenous peoples to protect the rainforest and, in so doing, help them protect their culture.

PLOTKINThe Amazon Conservation Team has partnered with 32 indigenous tribes to map, manage and protect their land. That's 70 million acres of rainforest. So when you have guys in breechcloths or less carrying GPSes that we gave them and trained them to use, it's the perfect marriage of ancient shamanic wisdom and 21st century U.S. know-how.

NNAMDIArlene, you had...

ARLENEKojo, can I ask one thing? To find out more about how that's going and your -- that organization, what would I -- do you have a website?

PLOTKINWell, I was trying to plant this question, but I forgot to this time. So thank you for asking it. It's -- amazonteam.org is our website. That's the Amazon Conservation Team. Or you can look up under my name, the real Mark Plotkin, as Kojo now calls me, and find out some of the good things that are happening. But we do need people's help to do more.

NNAMDIAnd...

ARLENEOkay. One other quick question, please.

NNAMDII know you did.

ARLENEIn terms of buying, like, chocolate coffee, blah, blah, blah, could you guide us in terms of that, in terms of being responsible?

PLOTKINI think you have to take responsibility for yourself. I can't give you a list of great products to buy and the rainforest will be saved. There's certainly a lot of shenanigans, buying rainforests and stuff like that I really haven't seen a lot of proof of, but it's an interesting concept.

PLOTKINAnd it needs to be made more accountable when you talk about the nanny state regulation and making sure when you're buying medicinal plants, you know you're getting the species you want or it's not contaminated with some sort of nasty pesticide, as happens with some herbal preps. I think this is where we need some help, guidance and regulation.

NNAMDIArlene, thank you so much for your call. We move on to Stella in Washington, D.C. Stella, you're on the air. Go ahead, please.

STELLAHi. Good afternoon. Great show. Thanks so much for bringing together this topic. I want to share that an aloe vera plant has been on my kitchen window...

SHIMIZUOh, great.

STELLA...whenever I moved for the last 20 years, and it's a wonderful friend and comes in handy quite often, I'm afraid. And, of course, herbal teas are always a part of my kitchen cupboard. And, now, I have a whole new perspective on a jar of nutmeg that...

SHIMIZUYes.

STELLAIt's been sitting there very quietly. But I have a philosophical question, and I think it's one that I ask myself at times because I love medicinal plants. I love learning about them. And yet there's something -- kind of a little voice in my head -- that kind of asks me, to what extent do we want to conserve and value these plants because they have human use value?

STELLAAnd to what extent do we want to conserve them because they just have a right to exist, kind of fellow inhabitants and beings of this planet? And how do you balance that kind of within your own research and your own work? And does that ever kind of bother you?

NNAMDIThat's like a fundamental philosophical question, and I'd like to hear both Holly and Mark address it.

SHIMIZUWell, I am very pro almost all plants, and so I value them, not only because of their potential for medicine, their use as medicine but also just for plants, for being plants. Even this argument about native versus exotic can get very intense. But there are a lot of people who will say, even the pioneer plants that are not native, they fulfill a great need. I, for one, love dandelions, and they're very helpful. So in my world, I value both, and so I don't have that divide. I wonder what Mark feels about that.

PLOTKINI think that in all of our personal lives, when it comes to the environment, we need to be both altruistic and selfish. Altruistic, we need to protect the planet because we live here because it should speak to us. Driving through Rock Creek Park, to me, is a sublime experience. And if you paved it over and turned it into high-end condominiums, something in the world would be lost. So conservation has to, first and foremost, be an ethical spiritual exercise.

PLOTKINRemember that the Endangered Species Act was not saved by anarchistic, democratic, left-wing tree huggers like myself. It was saved by the Christian coalition who came to Capitol Hill with placards that said, species: God made them. We protect them. And God bless them for doing that. However, I think we need to be conservationists because we're all basically inherently selfish creatures. My father died of cancer. My two grandmothers died of diabetes. I want new treatments.

PLOTKINI want cures for those diseases. And I know that there's leads out there for both of those in Mother Nature.

NNAMDIStella, thank you so much for your call. That leads me on to Nick in Beltsville, Md. Nick, you're on the air. Go ahead, please.

NICKYes. Actually, yeah, I've heard a couple of comments that tie right into what my question was -- which I can take the answer off the air -- was in that are their -- in your guests' travels for their job in the past, have they seen any spirituality that can then be associated to any effects that the community might feel...

NNAMDINick, we’ve only got a few minutes left in this program. This is something that Mark and Holly can talk about, literally, for hours. But, you said you would take your answer off the air?

NICKYes. Yeah, just so they can -- if they can comment briefly on -- if they found any connection, you know, spiritually, with using plants as -- for medicinal purpose.

NNAMDIGo ahead, Mr. Shaman.

PLOTKINI can do it in a single line. An anthropologist once wrote, the white man goes into his church and talks about Jesus. The Indian goes into his teepee, ingests peyote and talks to Jesus.

NNAMDIThere's a huge spiritual element to all of this. Holly.

SHIMIZUWell, I will address more the experience of being in a garden or being in nature, that that is a very spiritual experience. It promotes health and well-being. There are nine senses that we experience when we're in these environments that are very important to being in the moment, a sense of reflection and a connection to the earth.

NNAMDIWhat are the three additional senses? Most of us are only aware of six. You mentioned nine.

SHIMIZUWell, there's one, which is called proprioception, which is kind of having a sense of what your body is doing within the environment. It's unconsciously knowing where your feet are, where your hands are. That is something that is a sense we experience in gardens. There's a Japanese garden designer named Hoichi Kurisu, and he designs fabulous gardens where they're designed for all of these nine senses, so the additional ones are connection to the earth, sense of reflection and a sense of being in the moment.

NNAMDISo there are, in fact, nine senses.

SHIMIZUNine.

NNAMDIThank you very much. It's an education every time Holly Shimizu or the real Mark Plotkin joins us on this broadcast. Here is Eric in Kensington, Md. Eric, you're on the air. Go ahead, please.

ERICOh, good afternoon, Kojo, and to your guests. Great show. I just am going to relate my experience. I am married to a lovely Peruvian woman, and, as such, we spend a lot of time in Peru and, personally, in the Amazon. I can remember on one of my first visits, visiting family and friends of hers, who have a lodge in and around -- Mark might be familiar with Pucallpa, if he's been in the Peruvian Amazon.

ERICAnd our guide, one of his employees is a Shipibo Indian and the local group's shaman. And he basically took us on a medicinal tour of the jungle. And I was just amazed at the immense, I should say, nature's medicine cabinet, and -- which he pointed out how many plants, flowers. In fact, if you look closer, you would find a pattern that might be similar to a certain part of the human body, which that particular bark, tea, poultice could be used.

ERICAnd at that time, my wife, who was suffering from a migraine, he picked a berry and crushed it and had her eat it, and her migraine went away for a couple of hours. So I just -- I think -- show my...

NNAMDIYou are describing the apprenticeship of our guest here, Mark Plotkin. Mark, care to comment on that, please?

PLOTKINWell, from a scientific perspective, this makes no sense whatsoever, but it sometimes works. And there is a magnolia in Mexico that the Aztecs used for heart problems, and the fruit is shaped like a heart, and it has shown some effectiveness in the lab. So sometimes this so-called doctrine of signatures does lead us to new and interesting chemicals, and...

NNAMDIWell, we find this interest -- and, Eric, thank you very much for your call -- and people get very enthusiastic, but what should people be aware of when they're using plants or spices medicinally? There are a lot of claims in the world of herbal remedies people might come across. I heard this prevents cancer, and they run to the Internet to learn more. But, obviously, not all of the sources are reliable.

SHIMIZUNo. What I really encourage people to do is you've got to do your own studying. There's some great online resources, but you've got to be very particular. MedlinePlus is the NIH library of medicine. There are some great scientific sources where you can find good information. Study the current research and check your sources because you cannot take a lot of these modern claims. We know that a lot of them are absolute rubbish.

SHIMIZUBut I wanted to mention briefly the nutmeg. A lot of these plants are powerful, as Mark pointed out, and, in large doses, can be dangerous. Bay leaf, for example, we use that in our cooking. We use one leaf. Now, if you ate a lot of bay leaves, that would be trouble. They're actually used to repel roaches. So, you know, you don't -- quantity is a very important part of using these plants, and they are powerful.

PLOTKINI agree with everything Holly said. And like, you know, they say in real estate, location, location, location. In some cases, with medicinal plants, it's dosage, dosage, dosage. And you read every couple of years about how ephedra is bad for you because somebody took it, and they freaked out. Well, you know, when they used to -- they used to do these marijuana studies, and they'd give a mouse a piece of hashish the size of a table, and it would run on a wheel.

PLOTKINYeah, I understand. So, you know, do your homework. Make sure you're getting good stuff. Make sure you're not buying contaminated herbs. Better to grow your own when you can. And don't think because one tablet is good for you that four is going to be a lot better.

NNAMDIAnd I -- I'm running out of time very quickly, but I do have to have you talk about this very briefly, Mark. We're talking of plants, not pills, but we do know that a lot of people are using many of these herbs and natural remedies as supplements. What should people be aware of in terms of how supplements are regulated?

PLOTKINJust like Holly said, plants are powerful, and you shouldn't go to your doctor and ask her for a prescription and then go home and start taking plants that you bought off the Internet. Powerful chemicals are powerful chemicals. And one of the things that -- one of the ways our system does fall down is we're really not very good at figuring how drugs interact with each other, much less how drugs interact with plants, which, in their own right, are drugs.

PLOTKINSo we live in challenging, exciting and times where you have to do your own homework and you have to take charge of your own health care and well-being wherever possible.

NNAMDIAnd verify, verify, verify. Mark Plotkin is an ethnobotanist and president of the Amazon Conservation Team, which works with indigenous peoples of the Amazon to protect the culture and the land. He's also the author of "Medicine Quest: In Search of Nature's Healing Secrets" and "Tales of a Shaman's Apprentice." Mark Plotkin, great to see you again.

PLOTKINMy pleasure, Kojo.

NNAMDIHolly Shimizu is the executive director of the U.S. Botanic Garden. Holly, always a pleasure.

SHIMIZUOh, great. Thank you for having me.

NNAMDIAnd thank you all for listening. I'm Kojo Nnamdi.