Definition of Binomial Nomenclature | Rules and Examples


Plants and animals are given common names by the people. These names differ from country to country and region to region. For example, the Argvad plant has other common names such as gurmala, golden shower, amaltas, and purging cassia. Similarly, one common name might be used to refer to two different organisms e.g., a blackbird name can be used crow as well as a raven.

Common names have no scientific basis and do not follow any naming system. So, they are confusing and cannot be used internationally. To overcome this confusion, in the 18th century, Swedish botanist Carolus Linnaeus devised a system of giving two names to each organism. 

Instead of using common names, he used specific characteristics of the organism to generate scientific names. He published a list of scientific names of plants and animals in 1753 and 1758, respectively. This system devised by Linnaeus was later called binomial nomenclature.

Definition of binomial nomenclature

Binomial is made up of two words “bi” means “two” and “nominal” means “names”. While “nomenclature” means “system of choosing the names for things”.

In other words, binomial nomenclature is a systematic method of naming living creatures by giving a name made of two terms. The first term represents the genus, while the second term indicates the species of the organism. Latin words are used for this purpose, but words from other languages can also be used.

definition of binomial nomenclature
Binomial nomenclature.

Nomenclature codes

Biologists from all over the world observe a uniform collection of rules for the naming of species. Over time, these rules become nomenclature codes. The nomenclature codes make sure to give a name to each living thing and that name is internationally acknowledged. These codes are:

  • The International Code of Zoological Nomenclature (ICZN) gives names to the animals.
  • The International Code of Nomenclature for algae, fungi, and plants (ICNafp) deals with plants including cyanobacteria.
  • The International Code of Nomenclature of Bacteria (ICNB) gives names to bacteria along with Archaea.
  • The International Committee on Taxonomy of Viruses (ICTV) determines names and taxa of Virus.

Rules of binomial nomenclature

There are some binomial nomenclature rules which need to be followed while writing the scientific name of an organism.

  • Binomial names are originated from Latin.
  • The binomial names are typed in italics e.g., Allium cepa, Homo sapiens. If handwritten, a binomial name should be underlined e.g., Allium cepa, Homo sapiens.
  • The genus or first name always starts with a capital letter, while species or second name is always written in small letters.
  • Generally, the binomial name is written in full. However, if several species belonging to the same genus are written or listed then the full name of the genus is written only once and the latter abbreviation letter is used followed by a full stop e.g., Allium cepa, A. sativum, A. tricoccum, and A. ursinum.

Benefits of binomial nomenclature

There are many benefits of using binomial nomenclature such as:

  • It is globally recognized. If a person on one end of the earth writes a research paper on a specific organism by using binomial nomenclature, the other person from the other end of the earth can easily understand it.
  • Binomial nomenclature provides a unique name to each organism, which makes it reliable and easy to use.
  • Binomial names are shorter, specific, and easy to use.

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