In botanical nomenclature, a taxon is usually assigned to a rank in a hierarchy. According to Art 3.1 of the ICBN the most important ranks of taxa are: kingdom, division or phylum, class, order, family, genus, and species. According to Art 4.1 the secondary ranks of taxa are tribe, section, series, variety and form. There is an inderminate number of ranks. The ICBN explicitly mentions: A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ... The International Code of Botanical Nomenclature is the set of rules according to which plants are given their formal botanical names (scientific names). ...

primary ranks

- - - secondary ranks

- - - - - - - further ranks

kingdom (regnum)

- - - - - - - subregnum

division or phylum (divisio, phylum)

- - - - - - - subdivisio or subphylum

class (classis)

- - - - - - - subclassis

order (ordo)

- - - - - - - subordo

family (familia)

- - - - - - - subfamilia

- - - tribe (tribus)

- - - - - - - subtribus

genus (genus)

- - - section (sectio)

- - - - - - - subsectio

- - - series (series)

- - - - - - - subseries

species (species)

- - - - - - - subspecies

- - - variety (varietas)

- - - - - - - subvarietas

- - - form (forma)

- - - - - - - subforma

The rules in the ICBN apply primarily to the ranks of family and below, and only to some extent to those above the rank of family. Also see descriptive botanical names. Descriptive botanical names: Art 16 of the ICBN rules that names above the rank of family may be either descriptive or based on the name of an included genus. ...

Taxa at the rank of genus and above get a botanical name in one part (unitary name); those at the rank of species and above (but below genus) get a botanical name in two parts (binary name); all taxa below the rank of species get a botanical name in three parts (ternary name). A botanical name is a formal name conforming to the ICBN. As with its zoological and bacterial equivalents it may also be called a scientific name. Botanical names may be in one part (genus and above), two parts (species) or three parts (below the rank of species). ... In botanical nomenclature, the ICBN prescribes a two-part name or binary name for any taxon below the rank of genus down to, and including the rank of species. ... In botanical nomenclature, the ICBN prescribes a three part name (ternary name) for any taxon below the rank of species. ...

For hybrids, getting a hybrid name, the same ranks apply, preceded by "notho", with nothogenus as the highest permitted rank. In botanical nomenclature, a hybrid may (or may not) be given a hybrid name. ...

See also

• rank (zoology)
• ICBN
• botanical name
• descriptive botanical names