Plant Names
Binomials
Common names of plants are frequently confusing, they may vary from region to region and from language to language. This problem, plus the fact that the Latin names in use by naturalists at the time were mostly short, descriptive phrases, led in 1753 to the Swedish naturalist Carl Linnaeus introducing a consistent Latin binomial, or two-word system, of plant naming. In such names the first name is the generic name, the second is the specific epithet. For example, the Swamp bloodwood, a tree of northern Australia, was first given the scientific name of Eucalyptus ptychocarpa F.Muell. Written in this form the name tells us that the Swamp bloodwood is a member of the genus Eucalyptus and has the specific name ptychocarpa. The "F.Muell." is the name of the person, in this case Ferdinand Mueller, who first validly named the species.
In scientific papers it is common practice to include the name of the author(s) of a name when it is first mentioned in the text. The authority is an abridged reference to the place and date of original publication of the name. This information is important to taxonomists concerned with ascertaining which names should be used for an organism.
The International Code of Botanical Nomenclature
The binomial naming system was readily accepted and today there are many Principles and Articles that govern the formal scientific naming of plants, these being set out in an International Code of Botanical Nomenclature, a work that is followed and regularly reviewed by plant taxonomists.
Theoretically, if there was agreement as to the classification of all plants, and if the Code was consistently interpreted there would be no name changes. This is far from reality. Names commonly change both as the result of previous non-compliance with the Code and as the result of taxonomic decisions. In the latter case it is common for botanists familiar with a group of plants to find that a current classification is not a good reflection of the circumscription and relationships of plant taxa (a taxonomic group such as a genus or species). For example, many botanists believe that the bloodwoods, commonly placed in the genus Eucalyptus, should be removed from that genus and placed in their own genus, Corymbia. Thus, Eucalyptus ptychocarpa F.Muell. is sometimes referred to as Corymbia ptychocarpa (F.Muell.) K.D.Hill & L.A.S.Johnson, in this example Hill & Johnson being the authors who first made what is referred to as a "new combination" under Corymbia.
Synonyms
With the exception of a few specified cases, providing there is taxonomic agreement with the circumscription, position and rank, a taxon can only have one correct name. All other names which apply to the taxon are termed synonyms (commonly abbreviated as "syn."). For example, if it is accepted that the genus Corymbia should be recognised, then the name Eucalyptus ptychocarpa is a synonym of C. ptychocarpa. Conversely, if this is not accepted then C. ptychocarpa is a synonym of E. ptychocarpa. Although there may be taxonomic dispute as to the genus in which it should be placed the circumscription of the species is not problematic and its name is fixed by the rulings of the Code.
If it is accepted that Corymbia ptychocarpa should be used in preference to E. ptychocarpa then the latter name is known as a nomenclatural (or homotypic) synonym, both names being based on the same type specimen, the type specimen being that material on which the name of a taxon, in this case a species, was first named.
Frequently the synonym is a taxonomic (or heterotypic) synonym, where the name is based on a type specimen which is different to the type specimen of the accepted name. For example, in 1837 when Robert Schomburgk found the plant we now know as Victoria amazonica (the giant water-lily from South America) he sent specimens to England where John Lindley used them to describe and validly name the species. Lindley believed that not only was the species new but that it was also generically distinct from the genus Euryale, naming the taxon Victoria regia after the then reigning Queen Victoria. Unbeknown to him, Eduard Poeppig had seen other material (not Schomburgk's specimen) of this species and had in 1832 validly named it Euryale amazonica. It was subsequently agreed that Lindley was correct in placing the species in the genus Victoria but, with Poeppig's species name being the earlier of the two, the combination Victoria amazonica (Poeppig) Sowerby was later published, the name E. amazonica becoming a nomenclatural synonym, the name V. regia becoming a taxonomic synonym.
Taxonomic Ranks
The above notes deal with generic and species names but there are a number of taxonomic ranks, the principal of which, in ascending order, are: species, genus, family, order, class and division. Family names, with the exception of a few accepted alternative names, terminate in the ending *aceae. (In the case of Corymbia ptychocarpa, it belongs to the family Myrtaceae). Various infraspecific names for naturally occurring entities are often applied, the most commonly used being subspecies (subsp.) and variety (var.) e.g. Corymbia ptychocarpa subsp. aptycha and Apium prostratum var. prostratum.
Cultivars
The naming of cultivars, types of plants that are used for agricultural, horticultural or forestry purposes, is governed by The International Code of Nomenclature for Cultivated Plants. Here the generic name or the binomial is followed by the cultivar name given in one of two ways, e.g. Grevillea 'Robyn Gordon' or Grevillea cv. Robyn Gordon, Grevillea alpina 'Grampians Gold' or Grevillea alpina cv. Grampians Gold.
P S Short
Northern Territory Herbarium
May 2002
