Medicinal plants explored at Conservatory of Flowers

/ Rhett A. Butler

Plants have long been used by humans for treating a wide range of ills from childhood leukemia to hangovers. Indeed, many of the pharmaceuticals currently available to Western doctors have a long history of use as herbal remedies including quinine, opium, aspirin, and coca.

Medicinal plants explored at San Francisco Conservatory of Flowers

Medicinal powers of plants explored at San Francisco Conservatory of Flowers

Rhett A. Butler,

September 6, 2005

Kaiapo shaman in Brazil. Photo by Sue Wren

Plants have long been used by humans for treating a wide range of ills from childhood leukemia to hangovers. Indeed, many of the pharmaceuticals currently available to Western doctors have a long history of use as herbal remedies including quinine, opium, aspirin, and coca.

The use of plants for medicinal purposes is especially prevalent among indigenous peoples — the people of Southeast Asian forests used 6,500 species, while Northwest Amazonian forest dwellers used 1300 species for health purposes. Today the relationship between plants and people is increasingly being explored by pharmacologists in the development of new drugs. Ethnobotanists, the scientists who study these traditional uses of plants, are working with native healers and shamans in identifying prospects for drug development. The yield from these efforts can be quite good — a study in Samoa found that 86% of the plants used by local healers yielded biological activity in humans — and the potential from such collaboration is huge with approximately one half of the anti-cancer drugs developed since the 1960s having been derived from plants.

Why are plants a source of bioactive compounds

Through the rigorous process of natural selection, plant species have been perfecting various chemical defenses to ensure survival over millions of years of evolution, and are proving to be an increasingly valuable reservoir of compounds and extracts of substantial medicinal merit. These plants have synthesized compounds to protect against parasites, infections and herbivores, creating acutely powerful chemical templates with which pharmacologists can create new drugs.

…and why rainforest conservation is important

Due to their astonishing biodiversity, rainforests have the best potential for new plant-derived drugs. Seventy percent of the plants identified as having anti-cancer characteristics by the National Cancer Institute in the United States are found in tropical rainforests and 25 percent of the drugs used by Western medicine are derived from rainforest plants. And yet, despite all their promise, fewer than ten percent of tropical forest plant species have been examined for their chemical compounds and medicinal value. This leaves great potential for even more discovery, but also the potential for great loss as rainforests are felled around the globe and unstudied species are lost to extinction.

Perhaps more staggering than their boundless knowledge of medicinal plants, is how shamans and medicine men could have acquired such knowledge. There are over 100,000 plant species in tropical rainforests around the globe, how did indigenous peoples know what plants to use and combine especially when so many are either poisonous or have no effect when ingested. Many treatments combine a wide variety of completely unrelated innocuous plant ingredients to produce a dramatic effect. Some like curare of the Amazon are orally inactive, but when administered to muscle tissue are lethal.

No one knows how this knowledge was derived. Most say trial and error. Native forest dwellers say the knowledge was bestowed upon them by spirits of the rainforest. Whatever the mechanism, evidence from Amazonian natives suggests that indigenous knowledge of medicinal plants can develop over a relatively short period of time.

Display at the Conservatory of Flowers of medicines derived from plants

Ethnobotanists studying medicinal plant use by recently contacted tribes like the Waorani of Ecuador and the Yanomani of Brazil and Venezuela reported a relatively limited and highly selective use of medicinal plants. They had plants for treating fungal infections, insect and snake bites, dental ailments, parasites, pains and traumatic injuries. Their repertoire did not include plants to treat any Western diseases. In contrast, indigenous groups that have had a history of continuing contact with the outside world have hundreds of medicinal plants used for a wide range of conditions. It seems that after contact, in response to the introduction of Western diseases, these tribes accelerated their experimentation with medicinal plants. This notion contradicts the idea that indigenous knowledge of medicinal plants was accumulated slowly, over hundreds of years.

Further reading on indigenous use of plants

Anthropologist Wade Davis has written two books that explore both the indigenous knowledge of plants and the disappearing cultures of the world. One River touches on the history of ethnobotany in the Amazon along with a plethora of other topics, while Light at the Edge of the World: A Journey Through the Realm of Vanishing Cultures presents photographs and stories from his 30 years of exploring the planet’s most remote regions. After reading these works, you will probably come away with the understanding that it’s important to know what we’re losing before it’s gone.

These questions are becoming increasingly academic as rainforests around the world continue to fall — the Amazon alone has lost more than 200,000 miles of forest since the 1970s — and indigenous populations vanish or become assimilated, often by choice, into mainstream society. As youths from these communities leave their traditional societies, native cultures are forgotten and considerable knowledge about the processes for developing new medicinal recipes are lost forever.

With all this promise surrounding plants, if you live in the San Francisco Bay Area you can’t miss the “Nature’s Pharmacy: The Healing Power of Plants” exhibit at the Conservatory of Flowers in Golden Gate Park.

The Conservatory of Flowers of at Golden Gate Park

The special exhibit, on display through October 16, 2005, takes visitors on a fascinating journey to Africa, Asia, South and North America to explore medicinal plants, their many uses and the issues that surround them.

Display at the Conservatory of Flowers of medicines derived from plants

You can learn what makes peppers spicy and how ginkgo is being used to combat the early stages of Alzheimer’s disease. At the Conservatory you’ll learn that 1.8 billion people in Asia rely on herbal medicines while researchers in North America are studying the spiny devil’s club, a plant long-used for medicinal purposes by Native Americans, for the treatment of tuberculosis and diabetes.

Beyond the special exhibit, the Conservatory of Flowers has a lot of offer visitors including a storied history and several ongoing exhibits.

Long history

The Conservatory was originally destined not for San Francisco, but the rural Santa Clara estate of California’s then wealthiest man, James Lick. However he died before construction began and in 1877 a group of San Francisco businessmen purchased the Conservatory and donated it to the Park Commission. Built in 1878, the Conservatory was destroyed in a 1883 boiler fire just 4 years after it opened to the public. Its reconstruction was sponsored by Charles Crocker, the railroad baron, and soon thereafter the Conservatory became a fixture of Golden Gate Park. While the Conservatory survived the great 1906 earthquake and fire, it closed in 1933 due to “structural instability” and did not reopen until 1946. The Conservatory was forced to close again after a massive storm caused severe damage in 1995. It finally reopened again on September 20, 2003.

Ongoing exhibits

  • Lowland tropics

    Upon entering the Conservatory you are immediately met with a the warm humidity of the lowland tropics exhibit. Reminiscent of a tropical rain forest, this exhibit features a canopy of palms and other trees and is home to the Conservatory’s oldest and most valuable plants including a hundred-year-old Imperial Philodendron.

    Bromeliads in the highland tropics exhibit

    at the Conservatory of Flowers.

    Also on display are a number of commercially important plants including coffee, cacao, banana, and vanilla.

  • Highland tropics
    In the room to the right of the “lowland tropics” you’ll find the “highland tropics” room. Modeled after a tropical montane forest, this room is delicately planted with hundreds of orchids, bromeliads and other epiphytes. Mosses and ferns cover the stunted trees and you can almost imagine yourself in a Latin American cloud forest. The Conservatory of Flowers is one of only four institutions in the U.S. to feature a highland tropics display.

  • Aquatic plants

    One of the highlights of the Conservatory is the aquatic plant room which features a giant pool with cascades and fountains. In the pond you’ll find giant Amazon water lilies which may be up to six feet in diameter and can support the weight of a small children. The pond is surrounded by pots of colorful bromeliads and carnivorous pitcher plants which lure unsuspecting insects into their liquid-filled body cavity.

    Aquatic plants room

    at the Conservatory of Flowers.

  • Potted plants

    Amid the familiar plants ranging from giant hibiscus to orchidsyou will find oddities like the Madagascar palm (Pachypodium lamerei) and the bizarre Bat flower (Tacca chantrieri).

So if you find yourself in San Francisco this fall and have an interest in plants for their aesthetic value, historical significance, or economic importance then I highly recommend a visit to the Conservatory of Flowers in Golden Gate Park.

    The Conservatory is open Tuesday – Sunday, 9am – 4:30pm.

    Admission is $5.00 for Adults;

    $3.00 for Youth 12-17, Seniors 65 & over, and Students with ID;

    $1.50 for Children 5 – 11;

    FREE for Children 4 and under.

    You can learn more about the Conservatory of Flowers at their website ( or by calling the information line at 415-666-7001.

The Conservatory is located at:


    San Francisco Recreation and Park Department

    501 Stanyan Street, Golden Gate Park

    San Francisco, CA 94117

More pictures of the Conservatory of Flowers

The following is a press release from the Conservatory of Flowers announcing the “Nature’s Pharmacy: The Healing Power of Plants” exhibit earlier this year

    Wormwood, bitterleaf, spiny devil’s club – no, this isn’t the latest menu on Fear Factor. These are just some of the many thousands of plants that make their way from the world’s forests, fields and deserts into your medicine cabinet and onto the shelves of your local vitamin store. Plants and other natural products are included in the health care of eight out of 10 people alive today. Do they all work? Are they safe to use? Are we losing undiscovered medical miracles to world-wide deforestation?

    Nepenthes pitcher plant

    at the Conservatory of Flowers.

    In the new exhibition “Nature’s Pharmacy: The Healing Power of Plants” on view February 25 through October 16, 2005, the Conservatory of Flowers takes visitors on a virtual journey to Africa, Asia, South and North America to learn about medicinal plants, their many uses and the issues that surround them.

    Visitors enter the exhibition and are instantly immersed in the sights, sounds and scents of four culturally themed marketplaces. Here, amongst the stalls, they will be able to view living specimens of many healing plants and learn how some are cultivated and processed into medicines. Glossary cards are available to take on the “trip” to facilitate an understanding of the scientific terms used in the exhibition. An introductory video and four giant interactive models of important plants also help to create an intriguing and information-rich environment.

    First stop Africa, where visitors learn about Barbados aloe (also known as aloe vera), a plant whose medicinal properties were recognized at least 3,500 years ago by the ancient Egyptians. The gel extracted from its pulpy leaves is now used world wide as a topical treatment for burns and skin disorders as well as a health drink. Visitors can also take a close up look at an over-sized calabar bean pod. The calabar bean is the source of physostigmine, which relieves the symptoms of glaucoma. It’s also being studied for the treatment of Alzheimer’s disease. But one man’s medicine is another man’s poison. This helpful plant was traditionally used as a deadly test of guilt or innocence in Nigeria. The accused was forced to drink a poison made from the beans. If he survived, he was proven innocent. If not, well…the punishment was obviously built into the test.

    Red flowered bromeliad

    at the Conservatory of Flowers.

    Next, visitors cross the Atlantic to North America to learn a lesson in sustainability with the story of the Pacific yew tree. The cancer-fighting drug paclitaxel (Taxol®) was originally isolated in the bark of this tree, but harvesting it meant killing the whole tree, and the supply couldn’t meet the demand for the drug. Researchers quickly found an alternative, extracting a similar chemical from the leaves and twigs of living European yews. Recently, more advances have been made as drug manufacturers have begun producing plant cell cultures from which they can extract the paclitaxel, saving native habitat and significantly reducing waste. Visitors are also introduced to some of the many plants Native Americans have used medicinally for hundreds of years including spiny devil’s club. A large model shows the parts of this beneficial plant in detail and illustrates how remedies were derived from each for such things as colds, coughs and bronchitis.

    Then it’s on to Asia where herbal medicines have been the mainstay of treatment for thousands of years. In China, more than 1 billion people rely on such things as ginkgo to delay mental deterioration and dong quai for balancing the female hormone system. Cultivating some plants, however, can reap a bushel of trouble too. Asia is the source of most of the world’s legal and illicit supply of opium. Sap from opium poppies is processed into important painkillers such as morphine, codeine and noscapine. But the poppy fields of Afghanistan are the source for 75% of the illegal opium from which heroin is derived.

    Highland forest room

    at the Conservatory of Flowers.

    Back across the Pacific, visitors enter South America where the destruction of the rain forest is endangering more than parrots and jaguars. Less than twenty percent of the 250,000 known plant species have been investigated medicinally. As the forest is cleared, we could be losing the cure for diabetes, cancer, HIV/AIDS or other diseases. One such revolutionary cure in the past was quinine, derived from the bark of cinchona. This important alkaloid became one of the most important treatments for malaria worldwide. Visitors also learn the benefits of the common chili pepper, used traditionally to soothe upset stomachs and even as a salve for arthritis. Working with models of four common peppers, visitors rank their heat according to the amount of the capsaicin compound in each.

    To complement the exhibition, the Conservatory of Flowers will offer a series of lectures in spring 2005 by some of the nation’s leading researchers of medicinal plants including Mark Plotkin, a renowned ethnobotanist hailed by Time Magazine in 1999 as an environmental “Hero for the Planet” and Karyn Sanders, herbalist and host of KPFA’s “Herbal Highway”. For more information about “Nature’s Pharmacy: The Healing Power of Plants,” related public programs and the Conservatory of Flowers itself, the public should visit or call (415) 666-7001.


    The Conservatory of Flowers is a spectacular living museum of rare and beautiful tropical plants under glass. From Borneo to Bolivia, the 1,500 species of plants at the Conservatory represent unusual flora from more than 50 countries around the world. Immersive displays in five galleries include the lowland tropics, highland tropics, aquatic plants, potted plants and special exhibits. Opened in 1879, the wood and glass greenhouse is the oldest existing conservatory in North America and has attracted millions of visitors to Golden Gate Park since it first opened its doors. It is designated as a city, state and national historic landmark and was one of the 100 most endangered sites of the World Monuments Fund.

More pictures of the Conservatory of Flowers

Further reading

  • Anti-HIV compounds from the rainforest Calanolide A was isolated from a Borneo tree species by the National Cancer Institute (NCI). In vitro studies have shown Calanolide A, a non-nucleoside reverse transcript inhibitor “to be active against HIV-1, including strains resistant to AZT, Nevirapine, and other nucleoside reverse transcriptase inhibitors.” Researchers are grateful that Calanolide A even came into existence. Calanolide A is derived from Calophyllum lanigerum var austrocoriaceum, an exceedingly rare species that has virtually disappeared from the wild. Samples were last collected from a specimen at the Singapore Botanical Garden.
  • Shamans and Robots: Bridging the Past and Future of Ethnobotany and Bioprospecting A look at trends in ethnobotany and bioprospecting in seeking new ways to address human health conditions.
  • Bioprospecting in Panama Coiba, an island 12 miles off the coast of Panama and once a notorious penal colony, may be hiding big secrets in its reefs, among them, a possible cure for malaria.
  • Medicinal drugs from the rainforest

    Increasingly, rainforest plants and to a lesser extent, rainforest animals, are the source of compounds useful for medicinal purposes.


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