The system of naming the plants on a scientific basis is known as botanical nomenclature. Naming of the plants is useful in assigning their identity and relationship. Before the middle of the eighteenth century, the names of plants were commonly polynomials i.e. they were composed of several words in series constituting more or less the description of the plant. This can be illustrated with the example of Caryophyllum. The name given was Caryophyllum saxatilis folis gramineus umbellatis corymbis meaning Caryophyllum growing on rocks, having grass like leaves with umbellate corymbose inflorescence.
Since lengthy names are difficult to remember and use, attempts were made to shorten these names. Carolus Linnaeus suggested a system of binomial nomenclature. Although the binomial system was introduced by Gaspard Bauhin as early as 1623, it had properly been made use by Linnaeus in his book Species Plantarum.
In binomial nomenclature, every species is given a name of two words. For example, the binomial nomenclature of mango tree is Mangifera indica. Here the first word Mangifera refers to the genus and the second word indica to the species. The two words in combination comprise the name of the plant. Thus the binomial is a binary name. Hence, from the days of Linnaeus, two different kinds of plants could not have the same generic and specific names.
In 1930, the fifth International Botanical Congress was held at Cambridge, England to frame rules and regulations for naming plants. The twelfth meeting was held at Leningrad, USSR in July 1975. Based on the resolutions of this meeting, the current system of International Code of Botanical Nomenclature was adapted from 1978.
1. The generic name is a singular noun. The first letter of generic name is always written in capital. The specific epithet is an adjective and is always written with small letter. It is derived from many sources and may consist of one or two words. eg. Oryza sativa and Oldenlandia albo-nervia.
2. The name should be short, precise and easy to pronounce.
3. The binomials are printed in italics or underlined. The generic and specific epithets are underlined separately. eg. Abutilon neilgherrense or Abutilon neilgherrense
4. When new names are given to any plant, then the herbarium preparation of the same specimen with its original description is preserved in any recognized herbarium. This specimen is denoted as type specimen.
It is to be preserved on herbarium sheet.
5. The person who publishes the description of any plant for the first time or giving a new name to a plant is considered as author. The name of plant should bear the author's abbreviated name at the end of specific epithet. This is called author citation. Abbreviations were made for eminent taxonomists. The name Linnaeus was abbreviated to L. or Linn.,
Robert Brown to R.Br. and Sir Joseph Dalton Hooker to Hook. eg. Malva sylvestris Linn.
6. The original description of the plant should accompany the latin translation.
7. If naming the plant is from a source of error, it is regarded as ambiguous name. It is also called nomen ambiguum and is completely ignored from use.
8. If the generic and specific epithets are the same, it is called tautonym. eg. Sassafras sassafras. Such names are not accepted in the system of nomenclature.