Binomial system was originally introduced by Gaspard Bauhin or Casper Bauhin (1560- 1624) in his ‘Pinax Theatri Botanici’ (1623) commonly known as ‘Pinax’.
Linnaeus did not devise the binomial system, he used it consistently for the first time.
Structure a binomial:

Now note that in the above example:
-
First two words connstitute the binomial.
-
First word of the binnomial is the ‘genus name’ (in above example ‘Annona’). First letter of a genus name is always caitalized.
-
Second word of a binomial is the ‘specific epithet’, NOT THE ‘SPECIES NAME’. Specific epithet always begins with a small letter, irrespective of being a proper noun or common noun.
-
Genus name and Specific epithet together connstitute the ‘species name”.
-
Binomial is followed by the ‘author name’, name of the taxonomist who first proposed the binomial. Author’s name is usually abbreviated. For example, L. or Linn. is an abbreviation of Linnaeus. In this case both abbreviations are allowed but in a particular article, paper, or review only one abbreviation must be used consistently.
-
Then comes publication/reference. It is complete reference (Title of publication, volume, number if given, page number and year) to the work in which a binomial was first published. In this example, the binomial Annona squamosa published by Linnaeus on page 537 of his famous book ‘Species Plantarum’ in the year 1753.
-
In handwritten matter, genus name and specific epithet are invariably underscored separately. In printed matter they must be italicized.