The formal, scientific naming of plants and certain groups of algae and fungi is known as botanical nomenclature. Botanical nomenclature is closely linked with plant taxonomy.
The conventions of botanical nomenclature were established by Carl von Linné (better known by his Latinised name Carolus Linnaeus, 1707–1778) when he published Species Plantarum in 1753. Linnaeus described every species he knew using a two-part name (binomial) and a concise description. The value of the binomial system is its economy and universality: the same name is used, regardless of language differences.
A binomial (species name) comprises a genus name (such as Banksia or Eucalyptus; plural genera), and a species epithet or descriptor (e.g. 'serrata' or 'camaldulensis'). The genus is always capitalised and the species epithet is in lower case; both are italicised, e.g. Banksia serrata, Eucalyptus camaldulensis. Binomials can come from any language, but are always treated according to the grammatical rules of Latin. Genus and species names often describe a feature of the plant, or designate a person or a place. For example:
- Eucalyptus is derived from the Greek eu- 'well' and kályptos 'covered', referring to the covering of the unopened flower buds.
- Banksia is named in honour of Joseph Banks, the botanist who accompanied Captain James Cook on his first voyage.
- Pomaderris buchanensis (a species described by RBG Botanist Neville Walsh in 2008) is confined to rocky banks of the Snowy River near Buchan in East Gippsland, Victoria.
In scientific literature, binomials also include an author or authority, denoting the person who originally described the taxon. For example, Banksia serrata L.f. was described by Linnaeus' son, Carl Linnaeus (1741–1783; L.f. is an abbreviation of Linnaeus filius, meaning 'son of Linnaeus').
Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi and plants (ICN). One of the principles of the ICN is that the application of the name of a taxon is determined by means of a nomenclatural type. A type specimen is the herbarium specimen to which the name of a taxon is permanently attached. For example, the type for Banksia serrata was collected by Joseph Banks and Daniel Solander in Botany Bay in 1770, a specimen of which is held in the National Herbarium of Victoria at Royal Botanic Gardens Victoria. A type is not necessarily the first collection of a taxon, nor the most typical or representative example of the taxon.
Since 1 January 1958, to validly publish a name for a new taxon, the author must specify the type in the original publication. For names published prior to 1958, the ICN includes provisions to deal with names to which no types were assigned, or names to which multiple types were assigned. As such, there are numerous categories of types, including holotype, isotype, lectotype, isolectotype and syntype.
Royal Botanic Gardens Victoria's Australian collection contains almost 20,000 types of names of flowering plants, gymnosperms (conifers) and pteridophytes (ferns) and another 2,000 types of names of fungi, lichens, bryophytes (mosses, liverworts and hornworts) and algae. Royal Botanic Gardens Victoria's foreign collections contain an as yet unknown number of types (potentially more than 10,000), many of which are from Otto Sonder's herbarium.