Tree Buyers Beware: Use the Scientific Name

Two years ago, when a friend emailed that he planned to add a new tree to his garden, I asked if I could help and take photographs of the process, images I would use in a magazine piece on selecting and planting trees. He agreed and we decided on a planting date in early May.

He asked my advice on what kind of tree he should plant, keeping in mind that it would be a focal point in his garden. We discussed several options and he decided on a red maple, a native tree with tolerance for the wet soil it would experience in early spring and a tree that would exhibit outstanding ornamental character throughout the year, including red flowers in early spring, before the leaves appear, and outstanding fall foliage color.

On the appointed morning, before my arrival, my friend drove his pickup to the local garden center to pick up a red maple for his garden. He had called earlier, telling one of the nursery workers what he wanted, and they had it ready to load. Within the hour he was back home, ready to plant. I arrived just as he pulled in and was pleased to see that he had purchased the perfect tree for my photographs. It was a foot or so longer that the truck bed and about two inches in trunk caliper, the best size to plant (it takes much longer for larger caliper trees to become established in the garden).

Before my friend could get out of his truck, I was looking at the label on the tree, a white plastic nursery tag containing both the scientific name and common name of the tree: “Acer platanoides, Norway Maple”. “Damn!” I said, too loud. “If you bought a native red maple, the tag should read, “Acer rubrum”! This tree is a Norway maple, an invasive species, and probably the variety with dark red leaves in the summer. Nurserymen have given this purple-leaved beast the nickname “red maple”, but this is an invasive plant native to Europe, not Maine!

We took the tree back to the nursery and traded it in for a native red maple of similar size. On the way back to his home, my friend commented, “You know, I would have planted that tree if you had not been here. It would have been a month or two from now before I suspected something was wrong.”

This story is not an isolated example of mistaken identity. I have seen European mountain ash (Sorbus aucuparia) sold as Sorbus decora, the showy mountain ash, a New England native, an error created by the use of only the common name. Ask any nurseryman or garden center worker for a showy mountain ash and you’re going home with S. aucuparia. Sadly, S. decora is as scarce as hens’ teeth in the nursery industry, even though it is a superior tree in terms of ornamental character and disease resistance.

Tree buyers beware! You cannot assume that the employees at the nursery know what you have in mind when you ask for a plant using a common name. A little knowledge of the scientific names of plants is a valuable tool, as necessary as the digging spade.

This cultivar of  white ash,  Fraxinus americana 'Autumn Purple', has much better autumn foliage color than the species.

This cultivar of white ash, Fraxinus americana ‘Autumn Purple’, has much better autumn foliage color than the species.

Let’s begin with the species name. Every plant has a unique binomial (two-word name), such as “Acer rubrum”. “Acer” is the genus name, the first letter always capitalized, while “rubrum”, the specific epithet, is always lower case. The species name for red maple is Acer rubrum, and, like all species names, italicized or underlined when written. While at least two maples share the common name of “red maple”, only one unique species has the scientific name of Acer rubrum.

Specific epithets often tell us something about the plant. The epithet “rubrum” means “red” and, in the case of Acer rubrum, refers to the color of the flower. The epithet “alatus” means “winged”, “borealis” means “from the north”, “gracilis” means “graceful”, and so on through literally thousands of possibilities. An extensive list of specific epithets can be found at: http://tomclothier.hort.net/page37.html.

'Hokie Pink', a cultivar of summersweet clethra (Clethra alnifolia), differs from the species in being much shorter and more compact with pink flowers instead of white.

‘Hokie Pink’, a cultivar of summersweet clethra (Clethra alnifolia), differs from the species in being much shorter and more compact with pink flowers instead of white.

Other specific epithets are latinized forms of places, often the location where the plant was first found. For example, the specific epithet “florida”, as in Cornus florida (flowering dogwood), refers to the location of its initial discovery as a unique species. In fact, the botanist who discovers a new plant is given the honor of naming it, thus many specific epithets are latinized forms of the discoverer’s last name. The epithet sargentii, for example, is a specific epithet used to honor Charles Sprague Sargent, first director of the Arnold Arboretum (1872). Several plants bearing his name, such as the Sargent crabapple (Malus sargentii), were discovered by Sargent while exploring Japan in 1892.

Similar species are grouped in the same genus. For example, all 128 know maple species are in the genus Acer. Gardeners owe this elegant invention of plant nomenclature to the Swedish botanist Carl Linnaeus who, in 1753 published Species Plantarum. (He made a similar contribution to animal nomenclature with the publication of Systema Naturae in 1758.) Before Linnaeus, botanical names were long, often beautiful descriptive phrases written in Latin. For example, the common briar rose was variously known as “Rosa sylvestris inodora seu canina” (odorless woodland dog rose) or “Rosa sylvestris alba cum rubore, folio glabro” (pinkish white woodland rose with hairless leaves). It is easy to see how such a system would eventually become too cumbersome as more and more species were discovered. The binomial system developed by Linnaeus, in use now for 262 years, greatly simplified the task of naming organisms. Each new discovery is given a simple two-word name. The common briar rose is now R. canina. (Note that once a writer spells out the name of a genus, such as Rosa, the genus name can then be written using only the first letter, such as R., unless the discussion includes another genus that also starts with that letter.)

The cultivar of red maple, 'October Glory' is my favorite.

The cultivar of red maple, ‘October Glory’ is my favorite.

Gardeners should also understand the use of cultivated variety names (or “cultivar” names). Horticulturally, the cultivar name, for those plants that have one, is the most important part of the plant’s identity. As the name implies, a cultivar is a group of cultivated plants, i.e. plants that do not occur in nature, and it is distinguished from the species by a specific character, such as size, habit, leaf color, flower color, cold tolerance, etc. The distinguishing characteristic(s) must be retained in future generations through vegetative propagation (cuttings, grafting, tissue culture). As an example, there are at least 60 cultivars of Acer rubrum, including ‘October Glory’, selected for its outstanding deep red fall foliage. Note that cultivar names are always capitalized and enclosed in single quotation marks. A cultivar’s name is decided by the horticulturist who develops it.

This cultivar of our native winterberry (Ilex verticillata), 'Winter Red', has larger and redder berries that the species.

This cultivar of our native winterberry (Ilex verticillata), ‘Winter Red’, has larger and redder berries that the species.

Yes, plant nomenclature can seem tedious, and nearly impossible to absorb in one reading. And even when you have a command of scientific names, it is so much easier to resort to common names. Thankfully, use of the simple two-word binomial is all that is necessary to avoid confusion. Without this understanding, the gardener is apt to meet the same fate as my friend, or worse.

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About Reeser Manley

I was born in Laramie Wyoming but moved to the southeast at an early age. I was educated through my B.S. in Biology in the Columbus, Georgia area, then crossed the Chattahoochee River to earn my M.S. in Botany at Auburn University. For the next ten years, I worked as Horticultural Manager for the George W. Park Seed Co. in Greenwood, S.C. At 40 years of age, I decided to return to graduate school and in 1994, I earned a Ph.D. in Horticultural Science from Washington State University, Pullman, Washington. Fast forward through 10 years at university (7 at UMaine, Orono) and you find me teaching high school science in Eastport, Maine, the edge of the world, and writing a weekly garden column for the Bangor Daily News. My new book, The New England Gardener's Year, a Month-by-Month Guide for Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, and Upstate New York”, will be published later this year by Cadent Publishing. You can learn more about the book by visiting its Facebook page: http://www.facebook.com/pages/The-New-England-Gardeners-Year/187285218055676.)