By Jean Ponzi
Dr. Peter H. Raven is now President Emeritus of Missouri Botanical Garden. The St. Louis Business Journal has honored him as a Sustainable Visionary in the publication’s 2010 Heroes of the Planet Awards.
Over the 40 years of his Garden leadership (13 of which I’ve also worked at the Garden), I’m honored to say Dr. Raven and I have grown a relationship that is mutually appreciative, frequently funny, always deeply committed to Green. We recently talked about how our species can – and must – learn some lessons from the world of plants.
Peter Raven: Human beings have always loved plants because they’re so beautiful and they enrich our lives in so many ways. In a 100,000 year old burial in Iraq there’s evidence that people who were alive at that time placed flowers on the grave of the deceased person, showing how much people have gotten from plants from the beginning. We have an ancient love affair with flowers, using them in our most important celebrations: engagements, weddings, birthdays, and parties of all kinds.
But if you dig into the situation more deeply, you see how plants in their communities control the orderly and moderated flow of water off hillsides, retaining topsoil, keeping communities functioning, capturing energy from the sun in the process of photosynthesis and converting a very small portion of it into chemical bonds that drive their own life processes and, indirectly, the life processes of everything that consumes them.
JP: You’re talking the most basic biology here, the Food Chain. Plants are the only living things that produce food – and they make it from sunlight!.
PR: Exactly. Through the food chain, all living things eat plants, or ultimately eat somebody who relied on plants, to survive.
And for two-thirds of all people in the world – mostly in the developing world – plants are their medicines as well as their food. These people gather plants and mix them together as they’ve done for thousands of years. So the 1.3 billion people living in China and the 1.1 billion in India – which is 2.4 billion of the world’s total population of 7.1 billion in those 2 counties alone – essentially use plants for their medicines.
For those of us who get our medicines from drug stores, about a quarter of the substances we use are obtained originally from plants, or may still be obtained directly from plants. Aspirin, for example. Salicylic acid is named after Salix, the Latin name for willow. We learned about aspirin observing how indigenous people chewed willow bark to relieve headaches and other pains.
Vinblastine and Vinchristine – which are powerful drugs against childhood leukemia and various forms of cancer – are extracted directly from Rosy Periwinkles, which are native only to Madagascar, but now occur all over the warmer part of the world, either as weeds or as garden plants. Taxol, an important medicine against ovarian and breast cancer, comes from Taxus, the yew tree.
So a quarter of our medicines, even if we go to the drug store, come directly from plants. Another quarter come from fungi and bacteria, such as the roughly 4,000 kinds of antibiotics that have been patented since the end of World War II. That’s half our medicines, patented after natural products.
Then we have our building materials – so many kinds of wood, bamboo, and so forth – and clothing materials like cotton and linen, and of course all the paper products we use every day. And we get many kinds of chemicals from plants, like Vitamin C and other vitamins, and different compounds plants manufacture, that are used industrially.
So if you consider how plants provide what are known as “environmental services” – their direct value to us – and the beauty and ways they enrich our lives – you see how plants are of fundamental importance to our lives, and have been since our first human ancestors appeared about two million years ago.
JP: That’s a long, diverse, essential web of relationships. Yet I don’t think people really see how much our lives are connected with plants.
PR: It’s very hard to realize our connection with plants, because we look at them and they just sit there, and it’s hard to realize they’re doing anything. We know how we depend on them to be beautiful. We always feel better when they’re in the room, but we can’t really see how completely we depend on them! Dick Wandersee of LSU talks about “plant blindness” – when you look at a living community you see animals, but not plants, let alone realizing how plants function.
JP: What’s the hardest message to get across about plants?
PR: That our life really depends on them! You can’t look at plants and feel that your life depends on them, even though it does. Of course it’s well known now that plants absorb and store carbon dioxide – so they provide a partial palliative against global warming, by storing CO2, the most common “greenhouse gas” manufactured by human beings.
But more fundamentally, the oxygen in our atmosphere originated through the process of photosynthesis in plants – algae and some kinds of bacteria over billions of years – and now oxygen constitutes 20% of our atmosphere, roughly, which is the kind of world into which we evolved and to which we’re adjusted.
A lot of people think food comes from grocery stores, not from plants, but we humans need to understand that we’re entirely dependent on the living world. One person calculated that the so-called “ecosystem services” – which would comprise everything I’ve talked about – would be worth about $37 trillion a year, the size of the whole human annual economic output. But on the other hand, if living ecosystem services didn’t exist we’d all be dead, so it’s kind of a false comparison.
JP: What one thing would you like to see human beings do differently, modeled on the plant world, that would be a truly fundamental, sustainable change? What would that function be?
PR: Plants form communities in which water balance is assured. And we should want to form communities in which water balance is assured.
Plants are bathed in a continuous stream of water that passes into the roots of the plants, goes up through the stems, out through the leaves and the aboveground parts. This operates perfectly if it’s undisturbed, but when we cut off plants then there are floods, erosion and lots of other problems – eventually even drought.
Plants left alone in a community form an equilibrium system in which water is flowing continuously, through which minerals and nutrients that plants get from the soil are recycling in the plants, and then the plants die and their nutrients return to the soil. They maintain a very balanced system. But the more we disturb or injure those natural systems, the more makeup we have to do to put them back together – more than we know how to do. Water flows through us and keeps us alive too, so we need to “take a leaf” from the natural know-how of plants – and apply what we learn.
JP: Thank you, Dr. Raven.
PR: You’re welcome. Now go thank a plant!
Learn more about sustainability and the world of plants by visiting Missouri Botanical Garden, in person and at www.mobot.org. Jean Ponzi is Green Resources Manager for the Garden’s EarthWays Center.