The Naming of Plants
The Identification of Plants
The major service that is provided by a herbarium is the provision of the correct scientific name for any plant sample that is brought in for identification.
In order to do this the unknown specimen is matched against a correctly identified herbarium specimen. Herbarium specimens are ordered into a hierarchal system of classification; species (plural species), genus (plural genera) and family (plural families), so that the unknown specimen is systematically placed into a family, genus, species by a process of elimination.
This is not always an easy task, especially as a plant name may change as a result of new research that brings about a revision in the taxonomy and /or nomenclature of a species.
Name changes often necessitates the re-arrangement of the herbarium sheets / folders and even re-labeling them. Therefore it is necessary to update the collection from time to time to reflect revised names.
Taxonomists are responsible for the classification and naming of the plants.
A taxon (plural taxa) is a taxonomic group of plants of any rank, although it is more often applied to a species, such as Solanum lycopersicum (Tomato), rather than to a genus (Solanum) or to a family (e.g. Solanaceae).
Taxonomists are constantly improving our knowledge of the relationships between plant species. In doing this they may rename individual specimens, move species into different genera, and even change their relationships at family level.
They are allowed to do this by following very strict rules that must be adhered to in the naming of plants. These rules are set out in the International Code of Botanical Nomenclature. This involves describing each species, selecting a TYPE specimen and publishing in an acceptable print medium so that other taxonomists are informed about the new name.
Structure of Plant Names
The full name of each species of plant is binomial, that is, it consists of two words. the generic and the specific names. Species are grouped into genera. The genera are also grouped, this time into families.
The first name of a species is its generic name, the name of the genus to which it belongs (e.g. Lycopersicon). It always starts with a capital letter. The names of genera are Latin or Latinized nouns.
The second, the specific epithet, always starts with a common letter (e.g. esculentum - meaning 'edible'), and usually acts as an adjective.
After the generic and specific names is a personal name or its standard abbreviation. Thus Lycopersicon esculentum Mill. where Mill. is the abbreviaton for Miller.
Types
The proper name for a taxon is linked to a type. The type for a species, for example, is the actual specimen (sometimes a drawing) upon which the original description was based.
Type specimens are specially marked so that they can easily be found, and receive extra care in the herbarium.
The type specimen referred to above is called a holotype. If there are duplicates, part of the same collection, these are known as isotypes.
If the original material has got lost a subsequent author may designate a neotype to act as the type.
The Correct Name
The correct name for a species is normally the earliest name that is 'validly' and 'effectively' published according to the latest version of the Botanical Code.
All other names given to the species are known as synonyms, and in a check-list or taxonomic monograph it it important to list them, in descending order of time of publication - latest first, so that readers will be sure which plant is being discussed.
For example, Lycopersicon esculentum Mill. has the synonym Solanum lycopersicum L. (where L. stands for Linnaeus).
