• Nomenclature is giving distinct scientific names to various structures including living organisms for their identification.
• The names are of two types - vernacular (common name) and scientific names.
• The vernacular names are based on some peculiarity of the organisms, e.g., Kandali (a plant having spines).
• Scientific names are distinct and specific, they have particular spellings which are not changed.

TYPES OF NOMENCLATURE

Three types of nomenclature are polynomial, binomial and trinomial.

POLYNOMIAL SYSTEM

According to this system, name of any plant consists of many words.

For e.g., Caryophyllum saxatilis folis  gramineus umbellatus corymbia which means Caryophyllum growing on rocks, having grass like leaves and umbellate corymb flowers.

BINOMIAL SYSTEM

• Carolus Linnaeus used this nomenclature system for the first time and proposed scientific name of all the plants and animals. He is the founder of binomial system.
• Linnaeus proposed scientific name of plants in his book "Species plantarum".
• In binomial nomenclature, each scientific name has 2 components - generic name (genus) and specific name (species). E.g., Solanum tuberosum (potato), Mangifera indica (mango)
• The name indicates relationship of a species with others present in the same genus.

TRINOMIAL SYSTEM

• This system was proposed by Huxley and Stricklandt.
• According to this system, name of any plant or species is composed of three names-
  • Generic name
  • Specific name
  • Subspecific name (Name of variety)
• When members of any species have large variations then trinomial system is used. On the basis of dissimilarities, this species is classified into sub-species.

Eg. Brassica oleracea var. botrytis (Cauliflower)

Brassica oleracea var. capitata (Cabbage)

Brassica oleracea var. caulorapa (Knol-Khol)

ICBN - INTERNATIONAL CODE OF BOTANICAL NOMENCLATURE

• Collection of rules regarding scientific - nomenclature of plants is known as ICBN.
• ICBN was firstly proposed by Sprague, Hitchcock, Green (1930).
• ICBN was first accepted in 1961.

MAIN RULES OF ICBN

• According to binomial system name of any species consists of two names.

• E.g.,  Solanum   tuberosum (Potato)

     ↓                              ↓

  Generic name     Specific name

• In plant nomenclature (ICBN), tautonyms are not valid i.e. generic name and specific name should not be same in
  plants  E.g., Mangifera mangifera

• But tautonyms are valid for animal nomenclature

  (ICZN-International Code of Zoological Nomenclature)
  E.g., Naja naja (Indian cobra), Rattus rattus (Rat)

• Length of generic name or specific name should not be less than 3 letters and not more than 12 letters E.g., Mangifera indica.

• Exception : Riccia pathankot ensis - More than 12 letters

• First letter of generic name should be in capital letter and first letter of specific name should be in small letter, E.g., Mangifera indica.
• When written with free hand or typed, then generic name and specific name should be separately underlined. But during printing, name should be italicized.
• Name of scientist (who proposed nomenclature) should be written in short after the specific name

• E.g., Mangifera indica Lin.

• Name of scientist should be neither underlined nor written in italics, but written in roman letters (simple alphabets).
• If any scientist has proposed wrong name then his name should be written in bracket and the scientist who corrected the name should be written after the bracket.

• E.g., Tsuga canadensis (Lin.) Salisbury

  Notes:- Linnaeus named this plant as Pinus canadensis.

• The ICBN recognises several kinds or types, depending on the way in which a type of specimen is selected.
• Type specimen (Herbarium Sheet) of newly discovered plant should be placed in herbarium (Dry garden).
• Standard size of herbarium sheet is 11.5 × 16.5 inches.
• Type specimen (herbarium sheet) are of different types
  • Holotype : Herbarium sheet on which the first description of plant is based.
  • Lectotype : In case of holotype is lost, second herbarium sheet prepared from the original plant is called lectotype.
  • Neotype : In case holotype and original plant is lost then herbarium sheet prepared from some other plant of same species is called neotype.
  • Syntype : In case holotype and original plant is lost then many herbarium sheet prepared from many plants of same species is called syntype.
  • Isotype : It is duplicate of holotype. In presence of holotype a second herbarium sheet prepared from the original plant is called isotype.
  • Paratype : Additional herbarium sheet used in the first description of plant is called paratype. It is prepared from some other plant of same species having some variations.