There is a need to standardize the naming of living organisms, such that a particular organism is known by the same name all over the world. A variety of nomenclatural methods are described below :
- Vernacular name: Names in local or common language are called vernacular names. So, many vernacular names exist for an organism in different languages. These may vary from place to place.
- Scientific names: These names were based on definite rules and criteria. These are of following types :
(i) Polynomial nomenclature
(ii) Trinomial nomenclature [both given in concept builder]
(iii) Binomial system of nomenclature:
- Swedish naturalist Carolus Linnaeus established binomial nomenclature though, it was first proposed by Casper Bauhin in his book PINAX.
- International Code of Nomenclature
Scientific names have been standardized through some international agencies, viz., International Code of Botanical Nomenclature (ICBN, 1961) and International Code of Zoological Nomenclature (ICZN, 1964), International Code for Nomenclature of Bacteria (ICNB), International Code of Nomenclature for Cultivated Plants (ICNCP) and currently being developed is International Committee for the Taxonomy of Viruses (ICTV).
- Rules for Binomial Nomenclature
ICBN and ICZN formulated certain rules and regulations for giving scientific names to all organisms. These rules are as follows :
- The valid name of an organism has two components, i.e., a generic name and a specific epithet. The generic name should begin with a capital letter and species name should begin with a small letter.
- Both the words in a biological name when handwritten are separately underlined or printed in italics to indicate their Latin origin.
- The name of the author should be written after the scientific name in Roman type with capital letter without any comma in between and is written in an abbreviated form, e.g., Homo sapiens Linn. is the complete scientific name for modern man. This shows that Linnaeus was the first scientist who named man as Homo sapiens.
- Scientific names should not contain less than three and more than twelve letters. Principle of priority: It is the most important of all the rules of ICBN. If first name given to the organism is valid (in terms of rules), that will be considered at the first preference. Any other valid name given after that will be considered as synonym. No names are recognised prior to those used by Linnaeus in 1758 in the 10th edition of Systema Naturae for animals and 1753 for plants.
- All the three words (generic name, species epithet and author citation) collectively form Binomial epithet.
- If a species name has two or more words in its name, a hyphen is put between these. Such names are compound specific names (e.g., Hibiscus rosa–sinensis).
Other scientific Methods of Nomenclature and additional Rules
(a) Polynomial nomenclature: This system was used before 1750. In this system, names of the plants are based upon morphological characters, e.g., Caryophyllum. The name given was “Caryophyllum saxatilis folis gramineus umbellatis corymbis” meaning it is caryophyllum growing on rocks having grass like leaves and umbellate corymb arrangement of flowers. But these names became lengthy and difficult to remember.
(b) Trinomial nomenclature : Proposed by Lamarck, it involves the use of three words for a name so that the names of subspecies (animals) or varieties (plants) can also be incorporated. For example, Brassica oleracea var. botrytis, Corvus splendens splendens.
Some examples of subspecies and varieties are given below:
Corvus splendens splendens – Indian crow
Gorilla gorilla gorilla – Gorilla (animal)
Brassica oleracea var. capitata – Cabbage
Acacia nilotica var. indica – Indian Babul
(c) Synonyms: In case two or more names are given, the oldest, i.e., the name given first is recognised as valid name and all other names are called synonyms. e.g, Albugo candida (= Cystopus candidus)
(d) Tautonyms : When generic and specific name are same, e.g., Rattus rattus. Tautonyms are not recognised by botanists.
(e) Autonyms: When species and subspecies or variety names are same, e.g., Corvous splendens splendens, Acacia nilotica nilotica.
(f) Homonyms: One name for two different plants. e.g., Prunus dulsi, (For both almond and plum)