Purple coneflower, black samson, red sunflower, comb flower, cock-up-hat, Indian head, and Missouri snakeroot are all common names for the same plant as defined by its Latin binomial, Echinacea purpurea (L.) Moench (Hobbs, 1994).

Another plant, also known locally in the U.S. Midwest as snakeroot, has a completely different Latin name: Parthenium integrifolium L. Confusion over the similar common names is thought to be the cause of exportation of Parthenium root as Echinacea purpurea root to Europe.

The substitution of Parthenium for Echinacea has raised doubt over which plant material was used in clinical trials conducted in Germany before 1986 (Awang and Kindack, 1991). Common names are not definitive, as demonstrated in the previous example.

Different plants may have the same common name, or the same plant may have different common names. Common names are given in the local language and often vary depending upon the region. In contrast, the scientific name, or Latin binomial, is a definitive name, and if used properly should eliminate confusion.

The name is composed of the taxonomic categories of genus and species followed by the name of the scientific authority, or authorities, who officially described the plant. Thus in the binomial for garlic, Allium sativum L., the “L.” at the end is an abbreviation for Linnaeus, the famous botanist of the 1700s.

Scientific names are based on guidelines laid down by the International Code of Botanical Nomenclature (ICBN). These rules were originally established in 1930 and are periodically revised (Greuter et al., 2000). According to the ICBN, the Latin binomial is accompanied by a published description and a “type” specimen upon which that description is based.

Although Latin names are definitive, they can be revised. All taxonomic revisions are conducted according to a detailed set of guidelines established by the ICBN. An old name can be replaced by a new one, or the definition of a name can be altered.

When the definition is altered, but the name remains the same, both authorities are listed after the binomial, with the previous authority listed in parentheses. As an example, we have the name for milk thistle, Silybum marianum (L.) Gaertn.

Latin names are commonly listed with the taxonomic family to which they belong. Milk thistle is in the sunflower family, or Asteraceae. Thus, the complete name for milk thistle is Silybum marianum (L.) Gaertn., Asteraceae.

The American Herbal Products Association (AHPA) has attempted to solve the confusion over common names by establishing definitive common names to be used in trade. In a publication titled Herbs of Commerce, AHPA has defined common trade names by pairing them with their Latin binomials (McGuffin et al., 2000).

The FDA, in its dietary supplement labeling regulations, has recognized the common names listed in Herbs of Commerce as official trade names (CFR 21 Part 101.36, 1997).