THE BINOMIAL SYSTEM OF CLASSIFICATION
The scientific or botanical name of a plant is the means by which we give it its unique place in the scientific and biological world. Begun by Carolus Linneaus, a Swedish botanist, in the eighteenth century, this name is binomial (has two parts), consisting of genus and species, both of which are expressed in Latin. The genus or generic name is a noun which usually names some aspect of a plant, such as Coffea, the Latinized form of the Arabic word for beverage, kahwah. The species or specific name is usually an adjective that describes the genus. In the case of coffee, the species is arabica, indicating that the plant was thought to originate in Arabia. The coffee plant botanical name, Coffea arabica, refers to only one plant and cannot be confused with any other. Its botanical name is unique to that particular plant the world over.
The botanical name is often followed by a letter or letters which stand for the botanist who named that plant. The coffee plant's complete botanical name is Coffea arabica L., the L. standing for Linneaus. If the original botanical name of a plant is later changed, the original classifier is still noted in parentheses. Other often used abbreviations are Sarg. for Charles Sprague Sargent, founder of Harvard University's Arnold Arboretum; Lam. for Jean Baptiste Lamarck, French evolutionist and botanist; and Audub. for John James Audubon, ornithologist, naturalist, and painter. (Interestingly, this convention of naming the discoverer is not found in the naming of animals.) Sometimes the Family name is included, which groups the genera. It can usually be distinguished by its ending--"eae."
Linneaus's book Species Plantarum (The Species of Plants), published in 1753, continues to influence the naming of plants today. It is the starting point for checking whether a name has been used previously to insure that each plant is given a unique name. The earliest name for a plant is usually the official name should a dispute arise.
WHAT THE NAMES MEANThe genus and species names often tell something about the plant. They can describe the appearance of the plant, reflect the common name of the plant, indicate a chemical present in the plant, tell how the plant tastes or smells, or describe how the plant grows. The genus or species name can honor someone, a botanist, a person in power, someone historically prominent. The name can reflect the country or origin of a plant.
For example, Erythroxylum coca, the plant from which we derive cocaine, is named after erythro meaning red and xylo meaning wood, literally "red stem." (Coca, the species name, is the common name of the plant.) The jaborandi tree Pilocarpus jaborandi has a genus name which indicates that the alkaloid pilocarpine can be extracted from the plant. The species name jaborandi means "one who makes saliva or one who spits," referring to the use of the plant as an expectorant.
Plant classification can be painstakingly difficult. Plant species can resemble one another quite closely; plants can sometimes interbreed within species or across species, producing hybrids and varieties that complicate classification. A case in point is the cinchona tree, a plant instrumental in world history as a result of its alkaloid derivative, quinine, which helped to reduce the incidence of the terrible disease malaria. The cinchona tree, with its many species and hybrids and varieties within species, has resisted absolute classification. It's ambivalent ways have left botanists puzzled as to the exact number of species which exist. In fact, one species grouping of cinchona has been labeled 'Cinchona officinalis.' Officinalis (meaning 'of the workshop') is a common species name used for many medicinal plants, particularly, it seems, under the trying circumstances of difficult taxonomy.