Binomial Nomenclature

A formal scientific system of naming species by giving each a name composed of two parts (‘bi' = two).

The first part is the generic name (i.e. the genus), whilst the second part is called the specific epithet (i.e. the species), which uniquely identifies the individual plant.

For precision, the name of the author who named and described the species is included after the plant name. The name of the author is often abbreviated. For example, L. is used to denote Carl Linnaeus.

There is a convention in the naming and writing the first and second part of a plant name. The generic name is a noun (i.e. a thing); whilst the specific epithet is an adjective (a qualifying word which is added to a noun).

A generic name may be named after a person who first discovered and described a plant, or in honour of a person; for example, Fuchsia after Leonard Fuchs (1501 - 1566), Hosta after Nicolaus Host (1761 - 1834), or Alstroemeria after Claes (Claus) Alstroemer (1736 - 1794).

These rules are set by the International Code of Nomenclature for algae, fungi and plants (ICN); until 2011 this was the International Code of Botanical Nomenclature (ICBN).

For cultivars the rules are set by the International Code of Nomenclature for Cultivated Plants (ICNCP).

The naming of animals is undertaken by the International Code of Zoological Nomenclature (ICZN).

The grass plant Perennial Ryegrass has the genus name Lolium and the specific epithet perenne (which unsurprisingly means perennial); together the species is identified as Lolium perenne.

This term might also be referred to by other names, such as Binomial name, Binomial classification, Scientific Latin name, Latin name, nomenclature, or Botanical name if the organism is a plant.

Writing botanical names
The rules are given in the 2018 ICN Shenzhen code
• Generic name: the first letter is a capital letter, with the rest being lower case, italicised, e.g. Taxus.
• Specific epithet: all lower case, italicised, e.g. baccata.
• Species is the binary combination of genus and specific epithet, e.g. Taxus baccata.
• Variety: These are lower case and italised but are preceded by the letters var. which is not italicised. e.g. Taxus baccata var. variegata

• Cultivar (The rules are given in the International Code of Nomenclature for Cultivated Plants (ICNCP, Cultivated Plant Code, Ninth Edition, 2016)).
A cultivar name is not italicised and is also enclosed in single quotation marks (e.g. 'Manhattan'). The abbreviation of cultivar to cv has not been formally used since 1996.
The minimum requirement when writing a cultivar name is either:
o the Genus and the cultivar name; or
o if the plant has an unambiguous common name then this can be used with the cultivar name.
An example of the minimum requirement: Erysimum 'Winter Orchid', or Wallflower 'Winter Orchid', with both ways being acceptable.