Plant nomenclature is the formal system for assigning names to plants, providing a common language for communication across the globe. This organized system is governed by the International Code of Nomenclature for algae, fungi, and plants, which establishes the rules for creating and applying scientific names. The primary function of botanical nomenclature is to ensure that every recognized plant species has one unique, universally accepted name. This standard framework allows botanists, horticulturists, and researchers worldwide to communicate accurately about specific plant materials.
The Problem with Common Names
Relying on common names for plants often creates significant confusion, making accurate identification nearly impossible. A single common name can frequently be applied to multiple, sometimes unrelated, species, leading to misidentification in gardens and scientific discourse. For instance, the name “lily” is used for true lilies (Lilium) but also for daylilies (Hemerocallis), which belong to a different family entirely. Conversely, a single species can have numerous common names depending on the region, language, or culture. One example is Arctostaphylos uva-ursi, which may be known as Bearberry, Kinnikinick, or Mountain Box. This lack of standardization means that a conversation about a plant using only its common name provides no guarantee that all parties are discussing the same organism.
The Two-Part System: Genus and Species
The solution to the ambiguity of common names is the system of binomial nomenclature, established by Carl Linnaeus in the 18th century. This system gives every unique species a formal scientific name consisting of two parts derived from Latin or Greek. The first part is the Genus name, which is always capitalized and functions much like a surname, grouping closely related species together. The second part is the specific epithet, which is never capitalized and acts as a descriptive modifier to distinguish the species within its genus. Together, the Genus and the specific epithet form the unique species name, which is always written in italics or underlined if handwritten. For example, the scientific name for a white oak is Quercus alba, where Quercus is the genus and alba is the specific epithet. Once a Genus name has been fully spelled out, it can be abbreviated to its first letter in subsequent mentions, such as writing Q. alba.
Deciphering the Meaning of Scientific Names
Scientific names are intentionally descriptive, offering clues about the plant’s characteristics, origin, or history. The Latin and Greek roots used for the specific epithets often translate to physical descriptions of the plant’s color, size, or form. For instance, the epithet rubrum indicates a red feature, while gigantea or maximus suggests a large size. Terms like microphylla mean “small-leaved,” and florida refers to a plant that is free-flowering or from the state of Florida. The name may also encode geographic origin, with australis meaning southern and japonica indicating the plant originated in Japan. Some names are dedicated to botanists or explorers, typically ending in the letter -i for a man or -ae for a woman, such as Magnolia sargentiana honoring a person named Sargent.
Naming Plants Below the Species Level
Plant names often extend beyond the species level to account for natural variations and human-cultivated selections. Natural populations that show consistent differences, often related to geographic isolation, are designated as subspecies (subsp. or ssp.). A further natural subdivision is the variety (var.), which represents a naturally occurring variation within a species. These subordinate ranks are written in lowercase and italicized, following the species name. Cultivars, or “cultivated varieties,” are the most common sub-species designation encountered by gardeners, representing plants selected and maintained by humans for specific desirable traits. A cultivar name is placed within single quotation marks, is not italicized, and each word begins with a capital letter. For example, a specific type of red maple is correctly written as Acer rubrum ‘October Glory’.