The Weight of a Petal: The Value of Botanical Gardens
By H. Bruce Rinker
Gardens, as landscapes with scattered trees and copses interspersed with open spaces or bodies of water, widely appeal to our aesthetic sense and our need to perceive an organized natural world. Such settings may even appeal to a genetic memory of humanity's remote origins on the African savanna. Undoubtedly, flowers and the near-infinite diversity of their fruits influenced the survival of early hominids and the skill of modern humans to inhabit every corner of the planet.7 Flowering plants originated during the Cretaceous Period, nearly 100 million years ago when Africa and South America were still connected to each other. The dramatic co-evolution of flowering plants and their insect pollinators colored the face of the planet and set the stage for the emergence of our vision-dominated ancestors millions of years later. Loren Eiseley, late anthropologist from the University of Pennsylvania, exclaimed, "the weight of a petal changed the face of the world and made it ours."4
What are botanical gardens?
Some people have the mistaken impression that botanical gardens are parks devoid of play, something like 19th century museums where plants bear labels with unpronounceable names. Modern botanical gardens, however, are global treasures in an age of ecological crisis. Today numbering more than 2000 gardens worldwide, they are places devoted to the culture, study, and exhibition of documented collections of living plants.12,13 Further, they:
- are committed to developing, documenting, verifying, maintaining, sharing, propagating, and disseminating their plant collections -- a description offered by the American Association of Botanical Gardens and Arboreta (AABGA)11
- serve as reference centers for plant identification, cultivar registration, nomenclature, and plant exploration
- and, for some threatened species, have become the last hope for their precarious survival
Simply put, modern botanical gardens are scholarly places for the research and conservation of plants.
The western tradition of botanical gardens
Botanical gardens can be traced to human beginnings and are found in all cultures, past and present. In the western world, gardens went through a metamorphosis:
Medicinal Gardens: 16th and 17th centuries
The early European institutions were medicinal gardens, also called physics gardens or gardens of simples (such as Florence's Giardino dei Semplici), whose principle role was to provide material for medical faculties in Italy, France, and other western countries. The earliest medicinal gardens in Europe were all established in the 16th and 17th centuries: Pisa (1543), Zurich (1560), Paris (1597), Oxford (1621), Berlin (1679), and others.9,11
Colonial Gardens: 17th and 18th centuries
Later on, governments created tropical botanical gardens as instruments of colonial expansion and commercial development.2 The celebrated 18th century Calcutta Botanical Garden and Royal Botanic Gardens Pamplemousses in Mauritius come to mind.
Linnaean Gardens: 18th and 19th centuries
Gradually, a strict utilitarian display gave way to a comprehensive study of plants. Based on the work of Carolus Linnaeus (1707-1778),15 the father of modern taxonomy, gardens were laid out to show plant relationships. Live and preserved material poured into the botanical gardens of Europe, especially from the New World, to be exhibited, studied, and identified. As taxonomy gained in prominence, botanical gardens emphasized their herbaria, laboratories, and libraries over their living collections, on which little research was then undertaken.
Civic Gardens: 19th and 20th centuries
Municipal gardens were founded in the 19th and 20th centuries (e.g., Missouri Botanical Garden in 1859) that advanced the horticultural aspects of their living collections.
Specialist Gardens: 20th and 21st centuries
Specialist gardens, such as experimental stations and orchid gardens, emerged in the 20th century that highlighted research on particular plant groups. Floristic explorations and taxonomic studies, especially in remote tropical locations, allowed botanical gardens to expand their living and preserved collections. It also allowed them to advance as leading research centers for plant conservation.
Sanctuary Gardens: 20th and 21st centuries
Today, much of the responsibility for the genetic protection of threatened species, along with ex situ protection of plants with economic and ecological importance, rests with botanical gardens. For instance, the Marie Selby Botanical Gardens in Sarasota, Florida propagates a handful of species that are listed as no longer existing in the wild: Anthurium leuconeurum (Araceae) from Chiapas, Mexico; Epidendrum ilense (Orchidaceae) from the Pinchincha Province in Ecuador; Platycerium grande (Polypodiaceae) from Mt. Banahau in the Philippines; and others. These species may depend upon the horticultural and scientific support of trained staff members at the Gardens for their survival. Botanical gardens have become flagships of our international botanical efforts in the service of science and humanity during an age of unparalleled ecological crisis.2
Stewardship in an age of crisis
Botanists have identified more than 400,000 species of plants worldwide.5 However,
- approximately 34,000 are threatened at present6
- two-thirds of the world's plant species are in danger of extinction during the course of the 21st century3
- of the 20,000 known plant species in the United States, more than 200 had already vanished by the end of the 20th century; and another 600 to 700 are in imminent jeopardy10
These plant species are in jeopardy because of a burgeoning human population that then affects proximate causes such as deforestation, habitat loss, the spread of invasive species, and agricultural expansion.3,6 Given the deplorable rates of deforestation throughout the tropics, where most of the planet's biodiversity is located, we stand to lose thousands of plant species worldwide in the next few decades unless we make a concerted and collaborative effort to conserve them.
Conservation is not always synonymous with preservation. Conservation implies wise management. Preservation means to put aside. Preservation can be a conservation strategy, however, for a natural resource that is rare, nonrenewable, or irreplaceable. For example, authorities for a national forest may decide to protect an old-growth stand from hunting, logging, and other extractive uses because of its overall value for posterity. Conservation, then, is an umbrella term that widely encompasses use and nonuse of natural resources, depending upon our management strategy. Ideally, that strategy should be based on four considerations:1
- What ecosystem service is provided by the resource?
- What is the economic benefit of the resource?
- What is the aesthetic value of the resource?
- What is the ethical value of the resource?
Easily overlooked are free services provided by nature, such as:
- clean air and water
- nitrogen cycling
- erosion control
- climate stability
It is near-to-impossible to place a dollar value on these benefits, and attempts to replace them with human technologies have fallen short. Mangroves are superior to seawalls, protecting our shorelines from wave erosion and acting as a resilient living barrier during hurricanes. Bacteria return nitrogen gas from our atmosphere to all other living things, where it is essential for the construction of proteins. No invention has been able to imitate that ancient global function. These services have immeasurable value for all living things on the planet.
Many plants provide us with food, shelter, fuel, clothing, and medicines. Indigenous peoples face this reality on a daily basis. People in the United States and other affluent countries may think they live removed from local ecosystems, but no one escapes from nature entirely. As a global species, we gain our sustenance from our surroundings. For example:
- fully 50% of our medicines are derived from plants
- 25% of all prescription drugs have their origins in tropical forests
The cinchona tree of the eastern Andean tropical forest yields the anti-malarial drug, quinine. The rosy periwinkle from Madagascar produces scores of different alkaloids, two of which led to major breakthroughs in cancer treatment. In addition to their medicinal value, plants provide us with numerous other economic benefits: food products, building materials, paper, ornamentation, fuelwood, green gas, even pest control (e.g., the use of the carnivorous plant, Utricularia, to trap aquatic insect pests in ponds). Life on the planet, much of it unexplored, represents a cornucopia of natural resources for humanity. Aesthetic value
In addition to deriving our livelihood directly and indirectly from the planet's rich biodiversity, we also value species richness for
- scientific research
- and primal companionship
Early exploration of the tropical rainforest canopy yielded new kinds of organisms and new ecological processes unknown to us. Fishermen, hunters, skiers, golfers, pet owners, and boatmen all value the outdoors for their sports and livelihoods. And who can say how the faithful of major world religions have been affected by the natural world in which their credos emerged?
What is the moral basis for conserving our natural resources, especially the more diminutive, not-so-glamorous species such as bacteria, mosses, and worms? Some scientists argue that morality is the most valid reason for our management strategies, obligating us to do everything possible to prevent human-caused extinction everywhere on the planet. For many scientists, in situ preservation of species is the first commandment of conservation. As Aldo Leopold wrote in his A Sand County Almanac, "To keep every cog and wheel is the first precaution of intelligent tinkering."8
Education and environmental ethics
Education and ethics are components of a vital formula for our survival on an ancient, but latterly threatened, planet. Already botanists have documented relentless threats facing the tropics and their plant stocks. Recent data from the latest IUCN Red List of Threatened Species, released in September 2000 by the International Union for the Conservation of Nature, indicate that the global extinction crisis is worse than previously believed:14
- Not only has the magnitude of risk increased with forest areas shrinking around the world, but the capacity of remaining forests to maintain biodiversity also appears to be diminishing significantly.
- Plant species are declining most rapidly in Central and South America, historically important areas for many botanical gardens, as well as in Central and West Africa, and Southeast Asia.
- Some plants are no longer found in the wild. Botanists have catalogued and preserved many species of orchids and bromeliads that, because of tropical habitat destruction, may now exist only in greenhouses.
- In short, the plants forming the basis of botanical gardens' core mission and ethics are under serious threat around the globe. A solid commitment to education and ethics could stem this appalling trend, launching botanical gardens as leaders in ecological stewardship.
Conclusion: the weight of a petal
Many modern botanical gardens started in far different times. Twenty-five years ago the threats to tropical systems were not as widely documented as they are now. Then we had barely begun our explorations in the world's treetops. Today we sense the imminent collapse of entire ecosystems, including many vital habitats for threatened plant species. The early mission of botanical gardens prioritized the exploration and cataloguing of the wealth of tropical rainforest flora that formed the basis of their plant collections. Today exploration and collection of species are increasingly limited by international regulations and botanical gardens are expanding the scope of their mission to be relevant in the next 25 years.
Botanists now recognize unequivocally the temporal/spatial ecological connections operating within plant communities. We no longer simply focus on collections of rare and unusual species but also include in situ and ex situ conservation of their ecological associates. Thanks to pioneering efforts during the last 25 years in many remote regions, especially the canopies of tropical rainforests, we now realize how little is known about the diversity and ecological richness of the world's plants -- and how much effort is needed to conserve them. Botanical gardens can change the world as flagship institutions for research and education about the plant kingdom. Plants represent the basis of most life on the planet. Like the weight of a petal, a handful of botanical gardens across the globe can help us steward earth's green mantle and, thereby, insure our own survival in an age of ecological crisis.