Q. What do you mean by Binomial system in binomial nomenclature?

In the previous sections we have outlined the concepts of binomial nomenclature at International level and the current principles. that we adopt today for naming the organisms. You should know that these have been evolved through a long historic process of refinement.

After having gone through the previous sections of this unit you must have understood that biological classification is centred on the primary groups of individual organisms, i.e. the species. Before the 17th century, learned biologists had no method of designating any species they wished to discuss except by writing descriptions. Thus we find "Mocking bird" was designated at that time in Latin phrase as "Turdus minor Cinero-albus non maculatus" (means, Thrush small grayish-white without spot, Similarly, a species of mint designated with the Latin phrase: "Prunella muguna flore albo" (i.e. pumella with the large white flower). These were polynomial names composed of several words in a series. These were cumbersome and often difficult to interpret. The first steps in developing modem nomenclature were those leading to binomial system of nomenclature. Binomial is a Latin term used to denote a combination of two words constituting a name also called binomen, binomial or binary. The system of naming species by means of a generic name plus a specific epithet (often termed trivial name)- is known as binomial system of nomenc1,ature. For example we can recollect the scientific name of sparrow i.e., Passer domestics Linn. In this binomial the first word (Passer) designates the genus to which the bird belongs and the second word (domestics) to a particular species of that genus. The two words in combination only constitute the species name of sparrow.

There is an obvious demerit in tagging specific epithet with the genus to form species name. With the transfer of a species to a different genus on taxonomists decision, its name is inevitably changed which in turn disturbs the free flow of information. To overcome the confusion so produced the code lays certain provisions which should be strictly observed. We can summarise the merits of binomial system as follows:,

1) It provides a summary of affinities for us which acts as an aid to the memory and provides basic information about organisms unknown to us;

2) If facilitates talking about groups of species that have certain features in common