Window on the World
In New York, Replanting Darwin's Fertile Ground For Thought

By Adrian Higgins
Washington Post Staff Writer
Saturday, May 3, 2008

NEW YORK Enter the New York Botanical Garden's Haupt Conservatory and you will see a pretty evocation of an English cottage garden. Foxgloves, delphiniums, wallflowers, roses, stocks and poppies form a sea of flowers before a partially re-created house facade. It looks thrillingly springlike from outside it, but if you go behind the set and look out from a window into this garden, the mood shifts from one of innocence to something cosmically important. This is the view, more or less, that Charles Darwin would have had of his own garden at Down House, 20 miles south of London. His worldview, really.

It was in the garden that he cemented his theory of evolution. Through close observation and imaginative experiments, he looked long and hard into flowers, which is to say, the sex life of plants, and demonstrated that these wondrous machines changed over time to permit the survival and spread of each species. Here, Darwin discovered "the notion that the flower is the organ of evolution," David Kohn says.

Kohn, 67, is a Darwin scholar and curator of a multifaceted exhibition at the botanical garden, which runs through July 20. He hopes the show will change our understanding of Darwin as a scientist, that our view of him will, well, evolve.

In his 20s, Darwin pondered the origin of species while on the five-year expedition of the H.M.S. Beagle. He collected fossils throughout South America, and in the Galapagos Islands discovered isolated species of finches. But it was not geology or ornithology that defined Darwin's personal scientific journey as much as his abiding interest in unlocking the secrets of his garden in Kent, on the southern fringe of London.

In the lean-to greenhouses he built, in wife Emma's flower garden and in outlying woodland and meadows, he would put to the test all the little ideas that added up to his earth-shattering theory of the origins of life.

It was here that we would have seen the guy who could peer into the tiny orifices of a cowslip flower and turn the universe on its head.

What strikes the horticulturists who helped put this show together is that however much they have been trained to observe plants, Darwin was looking harder. His handwriting and drawing were awful, but he had eyes like a hawk and the perseverance of a heron.

"He was just endlessly patient," says Margaret Falk, the associate vice president for horticulture who helped stage the garden re-creation, which includes re-creations of his botanical investigations. "Minute by minute, second by second -- what the plant was doing, what the insect was doing," Falk says.

In 1860, a year after "The Origin of Species" was published, Darwin began these plant experiments that produced six books to change the face of botany while providing the evidence for his theory that new species evolve through natural selection.

"Botany became the central focus of Darwin's research for the remaining 22 years of his life," Kohn writes in the show catalogue. By turning his domestic environment into a field station, he began the first efforts "to apply the principles of evolution to plants."

Gardeners take it for granted now that plants such as apple trees and blueberry bushes can pollinate their own flowers to produce fruit, but are more fruitful if bees deliver pollen from a neighbor.

Darwin found the answer in cowslips that grew in the fields around his home. He discovered that some plants had a short ovarian tube (or style), others had long styles that extended beyond the plants' own pollen-bearing anthers. This had to be an adaptation to prevent self-fertilization. And he then observed that cross-pollination produced more seeds.

He was also fascinated by carnivorous plants in the acid bogs of Ashdown Forest, 20 miles from his home. The tiny sundew plant is marked by hairs that end in balls (a little like a snail's extended eye) and are covered in sticky secretions. When an insect lands on it, the hairs converge to trap it, and it is then digested by enzymes. Darwin put some boiled egg white on the hairs to observe the phenomenon. Why would a plant adapt such a mechanism? The answer turned out to be that peat bogs are devoid of nutrients, but plants could live in them if they found another way to feed.

One of the exhibits in the conservatory is of vines -- passionflowers, jasmines, solanums -- good for showing how plants have adapted so that they can wander. Today, we take it for granted that plants are animated; we see it in the time-lapse photography of nature programs. But 150 years ago only a patient observer could discover the grasping gyrations of a tendril.

Darwin also conducted experiments in his greenhouse that revealed the ability of some plants to sleep, often by folding their leaves. He believed they did this to reduce heat loss at night.

Darwin sat on his theory for 20 years but was forced to publish it when an obscure naturalist, Alfred Russel Wallace, sent Darwin a paper in 1858 summarizing the same idea. In an exhibit of Darwin's letters, notebooks and specimens -- some original, some facsimiles -- Kohn points out a letter that Darwin wrote in 1857, outlining his theory, to the preeminent American botanist of the day, Asa Gray. This, in Kohn's view, established Darwin's primacy.

"I think of Darwin as the founding father of biodiversity, in his meadow," Kohn says. Darwin's ideas were quickly accepted by scientists around the globe, including those at the New York Botanical Garden, which opened in 1891.

"That's what we [continue to] study here," says Gregory Long, the botanical garden's president. "Plant systematics, and that's the study of the evolutionary history of plants. It really begins with Darwin."

Kohn has been studying Darwin and botany since he was a graduate student in the early 1970s and has come to see his subject as a man who was genial, brilliant, not as dissolute as a student as widely believed nor as reclusive in later years as supposed. He also sees a scientist who was ambitious, shrewd and patient. "He was concerned about [the theory] being stolen," Kohn says. "He was concerned about being wrong. Then, the idea itself is dangerous; it challenges religious and social understanding" of where we come from.

And, of course, it still does.

"The theory is supported by all the available data we have," says Dennis W. Stevenson, the botanical garden's vice president for laboratory science. "It's an important point because society says evolution is just a theory. But it's not an idea. It's a scientific theory that has stood up to many tests, including many done by Darwin himself."

Darwin's Garden: An Evolutionary Adventure is at the New York Botanical Garden. The re-creation of the garden runs through June 15. Another part of the show, in the botanical library, runs through July 20. An exhibit in the children's adventure garden runs through June 29. The exhibits are open 10 a.m.-6 p.m. Tuesday through Sunday. For more information, call 718-817-8700 or visit http://www.nybg.org.