The International Association for Plant Taxonomy is maintained by the International Association for Plant Taxonomy. Every individual plant can belong to multiple taxa but they are always part of a species. The code calls for the material on which a taxon is based, to be deposited and preserved in a herbarium.
Botanical nomenclature is independent of zoological and bacteriological nomenclature. There have been several versions of the code; the most recent is the 'St Louis code' and was adopted in 1999.