“A rose is a rose is a rose,” according to Gertrude Stein. “A rose by any other name would smell as sweet,” Shakespeare wrote a few centuries earlier.

Neither writer was really talking about the flower. Still, botanically speaking, those statements remain true because rose is a common name, developed by people in conversation rather than by the botanists who meet every six years for the International Botanical Congress to determine the proper scientific names for plants, using Latin as its language.

While common names work for most gardeners, common names often mean different things in different parts of the world. A dogwood in China is not the same thing as a dogwood in Maine.

Researchers, however, need to know they are talking about the same plant, so a precise system of names is required.

Although naming systems existed earlier, the current system of taxonomy, or the naming of plants, dates back to Carl Linnaeus, who lived from 1707 to 1778.

“He grouped them as people brought plants to him, mostly according to their reproductive structure,” Lois Berg Stack said in January before she retired a long career as an ornamental horticulture specialist with the University of Maine Extension. “Take a rose and an apple and a geum and a pear. You might not think when you look at them that they are much alike. But if you look at the flower and fruit, you can notice that they are pretty closely related.”

A geum, by the way, is a herbaceous perennial that resembles a buttercup with ruffles.

There were bound to be mistakes. Linnaeus did not travel around the world in order to classify plants, rather he looked at the plants he encountered himself in Europe or those he was shown. Also, microscopes improved over time, so once botanists could see those plants better, the botanical names of some plants reflected new knowledge.

And then came DNA analysis. We read about it most often when it involves people – whether for finding criminals or determining ancestry. But the same science applies to plants.

“Every once in a while there comes an enormous breakthrough that breaks the system and causes people to rethink things, and that is what is happening now with DNA analysis,” Stack said.

Once scientists have looked at plant DNA, they can determine without any doubt how plants are related to each other, and which plants preceded others in lineage. Since there are thousands of plants, it will take time and money to do DNA research on all of them, Stack said.

People often get upset about plant name changes. It reminds me of what happened when Pluto was removed from the list of planets in our solar system. Pluto still exists, just like it always did. The scientists did not kill Pluto. They just changed what they called it – today it’s classified as a dwarf planet.

Stack said that whenever she was teaching a class and mentioned that a plant’s botanical name had changed, her students would roll their eyes – frustrated that they would have to remember new names.

But in at least one case, the nonscientists stopped a name change.

Bryan Peterson, an assistant professor of environmental horticulture at the University of Maine, said the International Botanical Congress – which will meet later this year in China – restored the name “chrysanthemum” to the popular mum, loved for its blossoms in fall.

The name chrysanthemum was first given to a wildflower in Europe, and Linnaeus added garden mums to its group.

“In the 1960s, a botanist realized that garden mums were not that closely related to (the original wildflower) chrysanthemum, and garden mums were changed to a new genus, Dendranthema,” Peterson said.

Every nation except The Netherlands (where Linnaeus, who was Swedish, did much of his work) rejected the change. Eventually, the Botanical Congress made an exception to its rule and gave the European wildflower the name Glebionis coronaria, and mums were again chrysanthemums.

Peterson noted that the Botanical Congress divided dogwoods, Cornus, into four groups when it last met in Australia in 2011. Coastal Maine Botanical Gardens in Boothbay was quick to adopt the new names on its garden labels, even though the change has met with some resistance. The garden made its choice after consulting Arthur Haines, a Mainer and expert in taxonomy who wrote “Flora Novae Angliae,” the scientific manual for identifying plants in New England.

Although I find the name-changing practice interesting, it won’t affect home gardeners. If you want a red-twig dogwood to provide some winter interest, you will be able to plant it no matter what you call it – its common name, its original Latin name Cornus sericea or its more recent Latin name Swida sericea. Catalogs will have the common name, often followed by one or both of the Latin names.

I talked with Peterson at the Maine Landscape and Nursery Association meeting in January, and he made one comment – in jest – that I think we all believe in our hearts.

“The right names are the ones from when I first started learning botany,” he said. “I just have to get used to the others.”

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at 767-2297 or at: [email protected]