In botanical nomenclature, variety is a taxonomic rank below that of species and subspecies, but above that of form. As such, it gets a three-part infraspecific name. It is sometimes recommended that the subspecies rank should be used to recognize geographic distinctiveness, whereas the variety rank is appropriate if the taxon is seen throughout the geographic range of the species.
Example
The pincushion cactus, Escobaria vivipara Buxb., is a wide-ranging variable species occurring from Canada to Mexico, and found throughout New Mexico below about. Nine varieties have been described. Where the varieties of the pincushioncactus meet, they intergrade. The variety Escobaria vivipara var. arizonica is from Arizona, while Escobaria vivipara var. neo-mexicana is from New Mexico.
Definitions
The term is defined in different ways by different authors. However, the International Code of Nomenclature for Cultivated Plants, while recognizing that the word "variety" is often used to denote "cultivar", does not accept this usage. Variety is defined in the code as follows: "Variety the category in the botanical nomenclatural hierarchy between species and form ". However the code acknowledges the other usage as follows: "term used in some national and international legislation for a clearly distinguishable taxon below the rank of species; generally, in legislative texts, a term equivalent to cultivar. See also: cultivar and variety ". A variety will have an appearance distinct from other varieties, but will hybridize freely with those other varieties.
In zoological nomenclature, the only allowed rank below that of species is that of subspecies. A name that was published before 1961 as that of a variety is taken to be the name of a subspecies. A name published after 1960 as that of a variety does not formally exist. In zoology, forms and morphs are used informally if needed, but are unregulated by the ICZN.
In bacteriological nomenclature, "variety" is not allowed, but names published as varieties before 1992 are taken to be published as subspecies.
In viticulture nomenclature, what is referred to as "grape varieties" are in reality cultivars according to usage in the International Code of Nomenclature for Cultivated Plants or "plant varieties" in the legalsense rather than botanical taxonomy varieties, since they are propagated by cuttings and have properties that are not stable under sexual reproduction. However, usage of the term variety is so entrenched in viticulture that a change to cultivar is unlikely.
