binomial [ bahy-NOH-mee-uhl ] nomenclature [ NOH-muhn-kley-cher ]: a system of naming a plant or animal that consists of two terms: the first identifies its genus and the second identifies the species by descriptive epithet
botanical [ buh–TAN-i-kuhl ] nomenclature [ NOH-muhn-kley-cher ]: the systematic or scientific naming of plants
The systematic naming of plants dates back to 1753 when Carl Linnaeus, the “father of modern taxonomy,” published Species Plantarum, which used binomial nomenclature—two terms, the genus and an epithet—to denote a species. This began the transition towards a worldwide standardized system of botanical nomenclature. About 200 years later, the International Code of Botanical Nonmenclature (ICBN) and the International Code of Nomenclature for Cultivated Plants (ICNCP) were established. They laid out the rules, which are followed today, for naming plants.
The examples below illustrate the basic format for naming species, varieties, cultivars, and hybrids, including which words to capitalize or italicize.
- Species names are Latin with the genus first and the epithet second: Rudbeckia fulgida. This is referred to as binomial nomenclature. The Latin name is italicized (in print) or underlined (if handwritten). The first letter of the genus is capitalized; epithet is lowercase.
- Variety names follow the abbreviation var. (preferred) or v. inserted after the species Latin name: Rudbeckia fulgida var. sullivantii
- Cultivar names follow the Latin taxonomic treatment surrounded by single quotes (preferred) or preceded by the abbreviation cv. ~Coreopsis verticillata ‘Moonbeam’ ~Rudbeckia fulgida var. sullivantii ‘Goldsturm’ ~Quercus nigra × Quercus coccinea ‘Fire Water’ [Sometimes cultivars are sold by a brand name/trademark, which may be used in addition to the cultivar name with or without parentheses: Betula nigra ‘Cully’ (also sold as HERITAGE®) or Quercus phellos ‘QPSTA’ P.P.#13,677 Hightower®.]
- Hybrid names are indicated by the genus followed by an x and then the hybrid name: Quercus × heterophylla. The parents of a hybrid are denoted by their Latin names with an x in between: Quercus phellos × Q. rubra [When a genus is repeated in a sequence, repetitions may use just the first letter capitalized followed by a period.]
Left to right: Species Rudbeckia fulgida Variety Rudbeckia fulgida var. sullivantii Cultivar Rudbeckia fulgida var. sullivantii ‘Goldsturm’ Hybrid Quercus × heterophylla.
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