Plant nomenclature is the formal scientific naming of plants and has a long history dating back, in Europe, to the ancient Greek scholars, such as Theophrastus, known as the ‘Father of Botany’ (371-287 BCE) and Dioscorides (40-90AD). During Mediaeval times Latin was adopted as the universal scientific language and so plant names in new botanical works were then written in Latin, and earlier works were translated into Latin.

For scientific purposes, names need to be unique to a plant, but the only way to be more precise at that time was to use a more detailed description as a name. These early descriptive phrase names were concise descriptions of what the plant looked like, with the emphasis being on what made the plant look different from others similar to it, or made it, in some way, noteworthy, such as its smell.  Often this meant a lengthy name – for example mistletoe was known scientifically as Viscum foliis lanceolatis obtusis, caule dichotomo, spicis axillaribus (viscum with blunt, lanceolate leaves, dichotomous stem and axillary spikes). These phrase names had evolved arbitrarily over time and so were inconsistently applied and highly variable in length, making classification and accurate communication of plant knowledge difficult, which in turn meant that it could be difficult for botanists to know exactly which plant another botanist was referring to unless an author was known. Confusion was further compounded by variable abbreviations and spellings.

Various attempts were made to make plant names more usable. For instance, the Swiss botanist Gaspard (or Caspar) Bauhin described about 6,000 plants in his Pinax theatri botanici (1623) in which he used descriptive names reduced down to as few words as possible. These phrase names, now called polynomials, persisted through to the 1700s. The Swedish botanist Carl Linnaeus, when ambitiously embarking on cataloguing all the plants then known, (approximately 7,700 of them) found that dealing with such a large number of unwieldy and inconsistent names required a workable system for his catalogue, and so his method was to reduce each plant name to just two words; the first word to indicate the group of plants (genus) and the second to differentiate the particular kind within the group (species) – for example, Viscum album, Fagus sylvatica. In doing so, he was improving on Bauhin’s system which had given the appearance of a two-part name for some plants. In Linnaeus’ format however, names were not assigned by just using a word from the plant’s description as Bauhin had done, but assigned an arbitrary name with a view to creating a memorable name, and so created names based on where the plant was to be found growing or in honour of a particular person, as well using a notable word from the description. This binomial system of using two-part names created a unique identifying name for each plant. Linnaeus proposed some elementary rules for plant naming in his Philosophia botanica of 1751, but it was in his Species Plantarum (1753) that the consistent use of this practical binomial system was first published. This would later prove to be the starting point for our plant naming today.

Plant knowledge was continually expanding, fuelled in part by European botanical exploration, with hundreds of new species new to science being discovered. It became increasingly obvious that some way to govern plant names was needed, not only in order to bring uniformity and clarity to existing plant names but to provide rules for the future naming of plants. Attempts to refine the rules of Linnaeus notably included that by the French botanist A.P. de Candolle who proposed rules for plant nomenclature in his Theorie elementaire de la botanique (1813), which included the principle of priority of publication; the oldest published name taking precedence. Later, in 1867, his son, Alphonse de Candolle presented a set of rules to a botanical meeting in Paris which were adopted and published as the first Code of Nomenclature, Lois de la Nomenclature Botanique (1868).

However it was not until 1905 that the first binding nomenclatural rules were established. The International Botanical Congress held in Vienna took the important step of agreeing the  further improved the previous attempt and the International Code of Botanical Nomenclature (ICBN) was agreed, which formally setting out internationally agreed rules and recommendations to govern plant naming and,notably, setting the formal starting date of plant nomenclature as 1^st May 1753, the publication date of Linnaeus’ Species Plantarum. The format of binomial plant names written in Latin within a stable, international method for scientific plant naming was finally established. Past plant names could be brought in line with all future plant names and standardised plant names would become recognisable worldwide.

While Linnaeus’ names from 1753 form the basis to our current plant naming, continuing advances in plant taxonomy have necessitated the publication of successive revisions. The current system requires the International Botanical Congress to meet regularly to update the Code, in order that it reflects accepted botanical changes arising from research.  As such, the International Code for Botanical Nomenclature has now been replaced by the International Code of Nomenclature for algae, fungi and plants (ICN), to reflect the separation of bacteria and prokaryotes from fungi, algae and plants, with separate newer codes to govern the scientific naming of bacteria and prokaryotes. Plant names are governed by the Code (ICN), and they are maintained through databases such as the International Plant Names Index (IPNI).

Of note to horticulturalists, further rules, specifically to govern the naming of cultivars, are contained in the International Code of Nomenclature for Cultivated Plants (ICNCP) also known as the Cultivated Plant Code. The ICNCP is supplementary to the ICN, was first published in 1953 and is also regularly updated.