The scientific names of botanical taxa are regulated by the International Code of Nomenclature for algae, fungi, and plants (ICN).
glabrum, the name of a subvariety of the species Astrophytum myriostigma (bishop's hat cactus).
[6] Names that use these connecting terms are now deprecated (though still legal), but they have an importance because they can be basionyms of current species.
The commonest cases use "β" and "b"; examples mentioned in the ICN are Cynoglossum cheirifolium β Anchusa (lanata)[7] and Polyporus fomentarius β applanatus[8] whilst other examples (coming from the fungus database Index Fungorum) are Agaricus plexipes b fuliginaria[9] and Peziza capula ß cernua.
[10] The ICN allows the possibility that a validly published name could have no defined rank and uses "[unranked]" as the connecting term in such cases.
[13] For a proposed infraspecific name to be legitimate it must be in accordance with all the rules of the ICN.
[16] As an example, consider Poa secunda J.Presl, whose type specimen is in the Wisconsin State Herbarium.
juncifolia (in other words, if there is a single type specimen whose classification is Poa secunda subsp.
If two infraspecific taxa which have different types are accidentally given the same epithet, then a homonym has been created.
This nomenclature only governs one infraspecific rank, the subspecies, but allows a number of infrasubspecific subdivisions to be used.
Such names are regulated by the International Code of Nomenclature for Cultivated Plants (ICNCP).