Part of a figure from Richard Waller's collection showing the dichotomous choices for species identification through leaf-ordering. (Credit: American Journal of Botany)


In the days before smart phones and laptops put Google, Bing and other Internet search engines within fingertips' reach, no method of identification was more vital to aspiring scientists than the dichotomous key.

Worldwide go-to popularity of the dichotomous key, a sequential series of binary either/or observations that allows users to cancel out option after option until their targeted specimen is identified, has long been attributed to French naturalist Jean-Baptiste Lamarck for his publication of the first edition of Flore Francaise in 1778. However, new evidence recently uncovered by Dr. Lawrence Griffing, an associate professor of biology at Texas A&M University, suggests that Lamarck's version may not be the original.

That distinction, says Griffing, could very well belong to a lesser-known English businessman named Richard Waller who designed his own dichotomous format nearly 100 years earlier using a series of detailed color images, as opposed to words, Lamarck's eventual framework of choice.

Griffing, an expert in structure and biochemical organization of cells and membrane trafficking and a member of the Texas A&M Department of Biology faculty since 1985, says the purpose of Waller's collection of illustrations had been a mystery to scientists for the past 320 years. However, after close examination, Griffing has determined they served as a "proof of concept" for a style of dichotomous key still used in modern biological sciences. His findings are explained in a recent publication of the American Journal of Botany, accessible through the United States National Library of Medicine's www.pubmed.gov.

"Waller came up with this identification system that's almost as sophisticated as any identification keys we have today," says Griffing, a member of the American Society of Plant Biologists. "What struck me was that Waller wanted to represent things with pictures rather than words. I think in terms of describing natural objects and species, it was relatively new."

The origins of the dichotomous classification style can be traced back nearly 100 years before Waller's invention to influential French humanist Peter Ramus, who used a yes/no format to prove philosophical arguments. The use of Ramist dichotomies soon made their way into early field guides to describe plants and their properties.

Waller, however, became the first to use visual aids for such a purpose. Rather than a tool for classification, Waller envisioned one for identification that would be usable and easily understood, even by a non-educated, lay audience.

Yet how could such a revolutionary contribution to botanical knowledge manage to escape recognition? Unfortunate sign of the times, Griffing explains.

In addition to being an enterprising businessman, Waller was the secretary of London's Royal Society -- a prestigious fellowship of the world's most eminent scientists and the oldest scientific academy still in existence -- and saw fit to share his idea with his colleagues. Given that most work by the Royal Society in those days was aimed at an expert audience, Griffing says a visual dichotomous model, especially one for novices, would have been viewed as such an atypical concept that it would have carried little if any weight with Waller's peers.

"People may not have recognized the value of his work at the time," Griffing adds. "When you're 100 years ahead of everyone else, it's easy to be ignored."

Griffing's own fascination with the history of the dichotomous key began in 2006, when a casual conversation with his wife, Dr. Margaret Ezell, a distinguished professor of English at Texas A&M, led to discussion about a publication she had written early in her career nearly 30 years prior. It was on Waller and a series of watercolors he had produced in the 1688 that were housed in the Library and Archives of the Royal Society. Given her husband's profound interest in plant biology, Ezell thought Griffing might be interested in seeing the artwork.

At her suggestion, he examined the drawings firsthand at the Royal Society while on sabbatical in Oxford studying the inner workings of plant cells. To his growing amazement, Griffing found a collection of 42 watercolor illustrations representing 65 different plant species, still as vibrantly pigmented as the day they were first painted despite their advanced age and sketched with precision right down to every filament, petal and seed. The astounding detail of each image must have taken considerable time, and Griffing became curious as to why Waller would have made the effort to draw them in the first place.

Griffing's curiosity led him to begin researching Waller's past. Recalling that his wife's paper contained a reference to a letter from Waller to John Ray, the most preeminent natural scientist of the time, Griffing traced down their correspondence in an 18th century volume of notes kept by the Royal Society.

"I was looking at Waller's letter and realized he was basically describing a dichotomous key," he recalls.

In his letter, Waller explained a novel concept -- a floral manual consisting of a series of images with the purpose of identification. Ray, who was also a member of the Royal Society, already had a well-respected guide circulating in the scientific community he had published in 1686 called Historia Plantarum that contained Ramist-style classification tables for sorting out different plant species. Waller wanted to design visuals for Ray's tables, ensuring that even someone with no knowledge of plants whatsoever could determine their identity. Even though the term for it had not yet been created, Griffing says Waller in fact was proposing what was essentially an illustrated dichotomous key.

Ray's formal response to Waller, as recorded by Waller himself in notes from a Royal Society meeting in 1688, was unfavorable. He dismissed Waller's concept, believing words provided a much more precise description than pictures.

Undeterred, Waller created an image-based identification key of his own composed of a series of tables, each with their own descending dichotomies, which he would continue to develop during the next 25 years. He presented his dichotomous key to his Royal Society peers on five different occasions, hoping to garner support, but each time, his work invoked skeptical responses. According to records, one colleague labeled Waller's work "peculiar" in 1689.

After his death in 1714, Waller's collection endured several generations of inheritance. Although some of the watercolors were sold at auctions, a good portion eventually made it to Royal Society archives, where Griffing says they still harbor unanswered questions -- a big one being whether or not Waller's prototype for a visual dichotomous key ever achieved publication. Griffing's evidence-based answer? Perhaps.

"There is a copper-plate etching in Waller's documents, which is how it would have been published in those times and then hand-colored for publication," he says. "The fact that we have this artifact is an indication. Waller made at least that engraving, and if other copper plates were made, we just don't know."

Whether or not it was ever made public, Griffing says Waller's dichotomous key was on a completely different plane from Ray's verbal classification key. It was more extensive, identifying plants right down to the species level, which Ray's did not. It was also more accurate: Waller had grouped the cornflower, at the time known as the blue bottle flower, with the knapweed. Ray, on the other hand, had put them in widely separate categories, when in fact biologists now know they are different species of the same genus.

Certainly, Waller was ahead of his time, as evidenced by the structural format he used for his visual dichotomous key -- the precursor to what is known today as linear leaf-ordering of hierarchical clusters, widely used in many molecular biology circles to examine genes of similar function from gene microarrays. For instance, a popular gene expression search engine called Genevestigator uses a leaf-order cluster.

Griffing currently is completing work on a book, Imaging Life, due to be released this fall, which will discuss the significance of images and how they are often unfairly judged for their aesthetic attributes rather than their significance to science. Waller, along with his intricately detailed artwork, will be featured as an example of how visual aids can be a powerful source of knowledge.

"One of the things people need to get away from when learning about imaging is simply getting a thrill out of it for its color or gloss," he notes. "What you should really see is the data, and I think that's why a lot of Waller's work got ignored. They're beautiful watercolors, but people didn't know the scientific context for them."

Today, hand-drawing has given way to digital imaging with microscopes, ultrasound and magnetic resonance, equipping scientists with perception unachievable with the human eye. Before this technology existed, however, early scientists had only illustrations to supplement their research and yet, they still were able to make significant findings. In Waller's case, Griffing notes, he was able to depict through drawings what botanists now understand are intricate differences between many herbal species.

Griffing marvels at just how much they were able to accomplish and understand with only basic material, describing it as nothing short of amazing in his upcoming book.

"They would have these really high levels of insights," Griffing adds. "I'm merely putting into modern terms what had been discovered a long time ago. Often times, all we're doing in science is rediscovering what people have discovered before us."

To read Griffing's paper on Waller, visit http://www.ncbi.nlm.nih.gov/pubmed/22074776.

To see some of Waller's watercolors, visit the Royal Society's Turning the Pages online gallery collection.


Contact: Chris Jarvis, (979) 845-7246 or cjarvis@science.tamu.edu or Dr. Lawrence Griffing, (979) 845-6493 or griffing@neo.tamu.edu

Jarvis Chris

  • Combing for Clues

    Dr. Lawrence Griffing, from his research perch on the porch of the British Library, studying their holdings using his iPad.

  • Dr. Lawrence Griffing

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