Naming Genus



Using Latin Names

by Marnie Flook and Dick Brooks

Rhododendron dauricum 'Arctic Pearl'
Picture by S & J Perkins
Rhododendron dauricum 'Arctic Pearl' in Salem, NH

Many beginning gardeners, and not a few expert ones, are uneasy, or even downright intimidated, when a colleague uses Latin names in discussing plants. They think such behavior is put on for the purpose of displaying the user's superior intellect, or even worse, for the purpose of showing up the listener's lack of knowledge. There is ready no reason for any feeling of inferiority, and we hope in this brief article to dispel the mystique which seems to surround the use of this unfamiliar tongue in a familiar context.

Latin was the international language of scientists and scholars when the present system of naming plants (and animals) began, in the middle 1700's. The formation of Latin names is now governed by the universally accepted International Code of Botanical Nomenclature.

Latin names of plants are precise, and can be understood by professional and amateur botanists and gardeners anywhere in the world. By use of its Latin name, a plant can be positively identified from among over 200,000 known plant species.

The species name consists of two parts: the generic name (genus: plural = genera) and the specific epithet. In writing, this two-part name is either italicized or underlined. Many familiar generic names are Latin or Greek words, such as Crocus, Anemone, Trillium, and Rhododendron. These words describe groups of plants that have similar characteristics. Sometimes the generic name honors a person, such as Jeffersonia for Thomas Jefferson, of Kalmia for Peter Kalm, a Finnish botanist of the eighteenth century. Sometimes the name describes the plant's appearance, such as Hemerocallis (Greek hemeros, a day, and kallos, beauty) or Rhododendron (Greek rhodon, rose, and dendron, a tree). Sometimes the name describes the plant's supposed medicinal qualities, such as Pulmonaria (Lungwort) or its imagined resemblance to parts of the body, such as Hepatica. whose lobed leaves are supposed to look like the liver (Greek hepar = liver). The name can also come from mythology, such as Narcissus or Andromeda.

Specific epithets often describe some aspect of the plant, such as its size (minus = small); color (luteum = yellow); habit of growth (arboreum = tree-like); leaf shape (orbiculare = round); or where it comes from (canadense = from Canada). The specific epithet can also commemorate a person, such as Rhododendron fortunei, after Robert Fortune, an Englishman who explored for plants in China in the mid-nineteenth century. Often the specific epithet helps to identify the plant and makes it easier to remember. An example is Linnaea borealis, the twinflower. The generic name commemorates Carl Linnaeus, whose binomial system of naming plants (genus plus specific epithet) is the one we use today. The specific epithet (borealis) means "of Northern regions", which is where this lovely little plant is found.

If a number of plants in the same genus are being discussed, the genus name is often abbreviated, after its initial use, for example: Rhododendron catawbiense, R. macrophyllum, and R. maximum.

Common names are confusing since one may refer to two or more different plants, depending on where you live and with whom you are talking. If you asked an English nursery to send you a 'blue-bell', you would receive Hyacinthoidese nonscriptus, a bulb in the lily family; a Scottish nursery would send you Campanula rotundifolia, the "Bluebell of Scotland". In the eastern US. you might receive Mertensia virginica, the "Virginia Bluebell". Conversely, one plant may be known under several different names, in different parts of the country. For example, here in New England we refer to our native Rhododendron maximum as the "Rosebay", but in the Southeastern states it is called "Great Laurel", and in that same region our native azaleas are often called "Wild Honeysuckle". In some cases, common names are identical to the Latin generic name, for instance Narcissus, Anemone, Magnolia, and Rhododendron.

Major plant genera, such as Primula, Campanula, and Rhododendron each contain many hundreds of species. It would be impossible to identify positively a particular plant in one of these groups without knowing its Latin name. There cannot be common English names for the thousands of plants which are found in all the countries of the world; where common names for these plants do exist, they may be in the local language or dialect, for example, for the Chinese Rhododendron praevernum "zao chun dujuan"

Often, horticulturally different or superior forms of plant species are given "fancy" names to distinguish them from other forms of the same species. These fancy names, or cultivar names, are not italicized or underlined. but rather are set off by single quotes, for example: Rhododendron yakushimanum 'Yaku Angel'.

Hybrids between different species may also be given fancy names: In the genus Rhododendron there are many thousands of hybrid cultivars so named. The naming of such plants is now governed by a different code, the International Code of Nomenclature of Cultivated Plants. Sometimes nursery catalogs and garden literature make the mistake of listing a hybrid cultivar as if it were a selected form of a species, for example: Rhododendron yakushimanum 'Yaku Princess'. Since this cultivar is a hybrid between 'King Tut' and R. yakushimanum the correct designation should be simply Rhododendron 'Yaku Princess'.

Once you begin reading about these plants, seeing them in gardens, and growing them in your own garden, you'll find that the Latin names become increasingly familiar, and you'll no longer feel inferior when talking about plants with your gardening friends. For further enlightenment on the subject you should read the excellent introduction to A. W. Smith's A Gardener's Book of Plant Names (Harper & Row, 1963).

Reprinted from Toronto Region Newsletter (RSC), November 1993 in the RSC Atlantic Rhododendron Society Newsletter, October 1997

[This article used with permission of Co-author Dick Brooks . Dick is past president of the American Rhododendron Society and a member of Massachusetts Chapter. Marnie belongs to the Greater Philadelphia Chapter]

Notice that in the caption of the image above Rhododendron is used to indicate the genus, dauricum is used to indicate the species, and 'Arctic Pearl' is used to indicate the cultivar name of the plant shown. This cultivar was selected and named for its white flowers. Most R. dauricum have lavender flowers in the wild.

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