In biology, the phrase type genus is used differently depending on the nomenclatural Code that applies:
- In zoological nomenclature, a type genus is "The nominal genus that is the name-bearing type of a nominal family-group taxon."
- In botanical nomenclature, the phrase "type genus" is used, unofficially, as a term of convenience. In the ICBN this phrase has no status. Although the code also uses type specimens for ranks up to family (all ranks must bear the name of the genus in which their types are placed), but does not refer to the genus containing that type as a "Type genus". Names above the rank of family are not under any nomenclatural restriction according to the ICBN, except where it comes to their endings.
- Example: The sentence "Faba is the type genus of the family Fabaceae" is another way of saying that the family name Fabaceae is based on the generic name Faba. Note that this should not be taken as an indication that there is an actual genus Faba, or that there are species whose name starts with Faba.