Type (biology) - Types in Botany

Types in Botany

In botanical nomenclature, a type (typus, nomenclatural type), "is that element to which the name of a taxon is permanently attached." In botany a type is either a specimen or an illustration. A specimen is a real plant (or one or more parts of a plant or a lot of small plants), dead and kept safe, "curated", in a herbarium (or the equivalent for fungi). Examples of where an illustration may serve as a type are (this is not an exclusive listing):

• A detailed drawing, painting, etc., depicting the plant, from the early days of plant taxonomy. A dried plant was difficult to transport and hard to keep safe for the future; many specimens from the early days of botany have since been lost or damaged. Highly skilled botanical artists were sometimes employed by a botanist to make a faithful and detailed illustration. Some such illustrations have become the best record and have been chosen to serve as the type of a taxon.
• A detailed picture of something that can be seen only through a microscope. A tiny "plant" on a microscope slide makes for a poor type: the microscope slide may be lost or damaged, or it may be very difficult to find the "plant" in question among whatever else is on the microscope slide. An illustration makes for a much more reliable type (Art 37.5 of the Vienna Code, 2006).

Note that a type fixes only a name to a single representative of the taxon. A type does not determine the circumscription (therefore a taxon is independent of its type species or specimen) of the taxon. For example, the common dandelion is a controversial taxon: some botanists consider it to consist of over a hundred species, although most botanists regard it to be a single species. The type of the name Taraxacum officinale is the same whether the circumscription of the species includes all those small species (Taraxacum officinale is a "big" species) or whether the circumscription is limited to only one small species among the other hundred (Taraxacum officinale is a "small" species). In this case the name Taraxacum officinale is the same and the type of the name is the same, but the extent of what the name actually applies to varies strongly. Setting the circumscription of a taxon is done by a taxonomist in a publication.

Miscellaneous notes:

1. Only a species or an infraspecific taxon can have a type of its own. For most new taxa (published on or after 1 January 2007, article 37) at these ranks a type should not be an illustration.
2. A genus has the same type as that of one of its species (article 10).
3. A family has the same type as that of one of its genera (article 10).
4. The ICBN provides a listing of the various kinds of type (article 9), the most important of which is the holotype. Note that the word "type" appears in botanical literature as a part of several terms that have no status under the ICBN: for example a clonotype, an herbarium specimen vegetatively propagated from (and thus a clone of) the same plant from which a type specimen was made that is used for documenting the type collection.