Philosophia Botanica - Binomial Nomenclature

Binomial Nomenclature

To understand the objectives of the Philosophia Botanica it is first necessary to appreciate the state of botanical nomenclature at the time of Linnaeus. In accordance with the provisions of the present-day International Code of Nomenclature for algae, fungi and plants the starting point for the scientific names of plants effectively dates back to the list of species enumerated in Linnaeus’s Species Plantarum, ed. 1, published 1 May 1753. The Species Plantarum was, for European scientists, a comprehensive global Flora for its day. Linnaeus had learned plant names as short descriptive phrases (polynomials) known as nomina specifica. Each time a new species was described the diagnostic phrase-names had to be adjusted, and lists of names, especially those including synonyms (alternative names for the same plant) became extremely unwieldy. Linnaeus’s solution was to associate with the generic name an additional single word, what he termed the nomen triviale (which he first introduced in the Philosophia Botanica), to designate a species. Linnaeus emphasized that this was simply a matter of convenience, it was not to replace the diagnostic nomen specificum. But over time the nomen triviale became the “real” name and the nomen specificum became the Latin “diagnosis” that must, according to the rules of the International Code of Nomenclature, accompany the description of all new plant species: it was that part of the plant description distinguishing that particular species from all others. Linnaeus did not invent the binomial system but he was the person who provided the theoretical framework that lead to its universal acceptance. The second word of the binomial, the nomen triviale as Linnaeus called it, is now known as the specific epithet and the two words, the generic name and specific epithet together make up the species name. The binomial expresses both resemblance and difference at the same time — resemblance and relationship through the generic name: difference and distinctness through the specific epithet.

Until 1753 polynomials served two functions, to provide: a) a simple designation (label) b) a means of distinguishing that entity from others (diagnosis). Linnaeus's major achievement was not binomial nomenclature itself, but the separation of the designatory and diagnostic functions of names, the advantage of this being noted in Philosophia Botanica principle §257. He did this by linking species names to descriptions and the concepts of other botanists as expressed in their literature — all set within a structural framework of carefully drafted rules. In this he was an exemplary proponent of the general encyclopaedic and systematizing effort of the 18th century.