Diversity of organism of Class 9


To provide uniformity, and to avoid confusion, 12th International Congress at Leningrad in 1975, laid down certain principles that were published in 1978 in the form of International Code of Botanical Nomenclature (ICBN) and International Code of Zoological Nomenclature (ICZN). 

A scientific name consists of two words, first genus and second species. They should not have less than three letters and more than twelve letters.

  • The generic name is always written first, which is like a noun having its first letter in capital form. The generic name is always unique for a living organism and no two living organisms can have same generic name.

  • The specific name is written after the generic name, which is like an adjective having its first letter in small form. A botanical specific name may begin with a capital letter if it denotes a person or a place, e.g., PentoxylonShanii, TolypellaJwelli, etc. A species can be named only if it is assigned to a genus. The same specific name can be assigned to two genera but two species of the same genus cannot have the same specific name, e.g., Mangiferaindica, Holoptaleaindica (chilbil). It can be single or compound (e.g., Hibiscus rosa-sinensis).

  • The gender of the specific name follows the gender of the generic name, e.g., Mangiferaindica, Tamarindusindicus.

  • The biological or scientific name is always printed in italics whereas it is underlined while handwritten. This is done to make the scientific name distinct from the text. 

  • The two-word scientific names are generally followed by the name of the discoverer or author. The author’s name can be full or abbreviated form (i.e., Mangiferaindica L., Homo sapiensLinn.,Cycascircinalis Linnaeus) in roman script without a comma. Author’s name is not italicised. 

  • The names are generally derived from Latin language since Latin is a dead language and, therefore, it will not change in form or spelling with the passage of time. The names that are derived from languages other than Latin are latinized (e.g., Pinusroxburghii, Ricciahimalayensis, Spirogyraindica).

  • No names are recognized prior to those used by Linnaeus in 1758 in the 10th edition of SystemaNaturae.

  • When a species is transferred or revised, the name of the original author is retained but in parenthesis, e.g.,Syzygiumcumuni (Linn.) Skeels, Albizzialebbeck (Linn.) Benth.
  • In case an organism has been given more than one name, the earlier legitimate one is recognized to be valid (not prior to 1.5.1753 for plants or 1.8.1758 for animals). This is called law of priority.



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