How new plant species get their names

Scientists count 1.4 million different names for plants on Earth. But botanists estimate there are just 300,000 existing species. That means there’s a veritable Tower of Babel of plant names are kicking around.

So what happened?

In some cases it was a matter of scientists “discovering” slightly different variants of the same species; in others it was owing to new descriptions of wide-ranging species in geographically diverse locations; then there have been changes in scientific understanding of relationships between species; and finally, there’s plain old human error.

Kanchi Gandhi to the rescue.

The senior nomenclatural registrar is part of a small community of global experts toiling in relative obscurity to bring order from the chaos and ensure that when botanists talk to each other about a plant, they can be confident they’re talking about the same one.

“I think Kanchi is really outstanding in being one of the few nomenclaturists left in the world who understands — and referees — the ‘rules’ when it comes to naming new species of plants,” said Michael Dosmann, keeper of the living collections at Arnold Arboretum. “It really is a labor of love and often is too in-the-weeds or bureaucratic for a majority of botanists to get as proficient as Kanchi is.”

The job, Dosmann said, includes not only ensuring that newly discovered plants are named properly, but also serving as something of a global taxonomic cop tossing out names that don’t follow guidelines, sending botanists flush with the excitement of new discovery back to the keyboard for another try.

In fairness to those with naming “fails” to their credit, the rules that have sprung up since Carl Linnaeus’ “Species Plantarum” in the mid-18th century first described a plant using two Latin names are complex. Gandhi keeps in his Harvard Herbarium office the 203-page “International Code of Nomenclature for algae, fungi, and plants” — known as “The Shenzhen Code” for the city where this latest version of guidelines was adopted in 2018.

Two hundred and three pages may seem an excessive number of rules — they deal largely with technical things like, say, the proper way to convert an individual’s name into a Latin or Greek scientific one (discoverers often name new species after themselves, loved ones, or mentors). Gandhi notes, however, that the principles not only keep everyone on the same page regardless of native language or culture, but also result in names that are more than mere monikers. They provide information such as other plant relatives of a species and, in some instances, can note where it was found, the name and gender of the discoverer, or a striking characteristic.

Before Linnaeus established his system, plants were known by what are called polynomials: long names made up of multiple descriptive terms. Before “Species Plantarum” was published, just 5,000 plants were described, Gandhi said, and talented botanists memorized them all.

Linnaeus’ innovation, first applied to plants and later to animals, was to create a two-part name, today given in either Latin or Greek. The first designates the broader group to which the plant belongs, called a genus, and the second names the plant itself as a species.

Over the centuries since, scientists have created more than a million additional names, creating enough confusion that international collaborations of scientists arose to police the situation and write the first naming guidelines — the ancestor of today’s Shenzhen Code — more than a century ago, Gandhi said.

Today, nomenclature is regulated by the International Association for Plant Taxonomy, based in Bratislava, Slovakia, on whose Committee for Vascular Plants Gandhi sits. The committee works to ensure scientists everywhere use the same standards. It also wrestles with knotty issues such as renaming plants. One recent drama involved three Chinese botanists proposing to change the scientific name of the apple tree from Malus pumila to Malus domestica. Malus pumila was the older name and otherwise met naming guidelines, so Gandhi voted against the change, a sentiment that initially carried the day. The proposers didn’t give up, however, and on their second try, narrowly succeeded — against Gandhi’s vote.

“M. pumila had priority and was widely used,” Gandhi said. “They [committee members] wanted the problem to go away. I was unhappy, but you have to go with the majority.”

Gandhi got his start in plant nomenclature on the job. He grew up in India and got a master’s degree in botany from Bangalore University in 1970. He was steered to collecting, classification, and nomenclature in his first job, surveying rainforest plants in his home state of Karnataka for a collaborative project between Indian scientists and the Smithsonian Institution. Gandhi said Dan Nicolson, the Smithsonian’s project director, became a mentor and taught him the basics of plant nomenclature.