International Code of Nomenclature (ICN) for Algae, Fungi & Plants

The International Code of Nomenclature for algae, fungi, and plants (ICN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all those "traditionally treated as algae, fungi, or plants. It was formerly called the International Code of Botanical Nomenclature (ICBN); the name was changed at the International Botanical Congress in Melbourne in July 2011 as part of the Melbourne Code which replaces the Vienna Code of 2005. As with previous codes, it takes effect as soon as ratified by the congress (on Saturday 23 July 2011), but the documentation of the code in its final form takes some time to prepare after the congress. Preliminary wording of some of the articles with the most significant changes has been published in September 2011.

The name of the Code is partly capitalized and partly not. The lower-case for "algae, fungi, and plants" indicates that these terms are not formal names of clades, but indicate groups of organisms that were historically known by these names and traditionally studied by phycologists, mycologists, and botanists. This includes blue-green algae (Cyanobacteria); fungi, including chytrids, oomycetes, and slime moulds; photosynthetic protists and taxonomically related non-photosynthetic groups. There are special provisions in the ICN for some of these groups, as there are for fossils.

The ICN can only be changed by an International Botanical Congress (IBC), with the International Association for Plant Taxonomy providing the supporting infrastructure. Each new edition supersedes the earlier editions and is retroactive back to 1753, except where different starting dates are specified.

For the naming of cultivated plants there is a separate code, the International Code of Nomenclature for Cultivated Plants, which gives rules and recommendations that supplement the ICN.

Principles

• Botanical nomenclature is independent of zoological, bacteriological, and viral nomenclature (see Nomenclature codes).
• A botanical name is fixed to a taxon by a type. This is almost invariably dried plant material and is usually deposited and preserved in a herbarium, although it may also be an image or a preserved culture. Some type collections can be viewed online at the websites of the herbaria in question.
• A guiding principle in botanical nomenclature is priority, the first publication of a name for a taxon. The formal starting date for purposes of priority is 1 May 1753, the publication of Species Plantarum by Linnaeus. However, to avoid undesirable (destabilizing) effects of strict enforcement of priority, conservation of family, genus, and species names is possible.
• The intent of the Code is that each taxonomic group ("taxon", plural "taxa") of plants has only one correct name that is accepted worldwide, provided that it has the same circumscription, position and rank. The value of a scientific name is that it is an identifier; it is not necessarily of descriptive value.
• Names of taxa are treated as Latin.
• The rules of nomenclature are retroactive unless there is an explicit statement that this does not apply.

History
The rules governing botanical nomenclature have a long and tumultuous history, dating back to dissatisfaction with rules that were established in 1843 to govern zoological nomenclature. The first set of international rules was the Lois de la nomenclature botanique ("Laws of botanical nomenclature") that was adopted as the "best guide to follow for botanical nomenclature" at an "International Botanical Congress" convened in Paris in 1867. Unlike modern codes, it was not enforced. It was organized as six sections with 68 articles in total.

Multiple attempts to bring more "expedient" or more equitable practice to botanical nomenclature resulted in several competing codes, which finally reached a compromise with the 1930 congress In the meantime, the second edition of the international rules followed the Vienna congress in 1905. These rules were published as the Regles internationales de la Nomenclature botanique adoptees par le Congres International de Botanique de Vienne 1905 (or in English, International rules of Botanical Nomenclature adopted by the International Botanical Conference of Vienna 1905). Informally they are referred to as the Vienna Rules (not to be confused with the Vienna Code of 2006).

Some but not all subsequent meetings of the International Botanical Congress have produced revised versions of these Rules, later called the International Code of Botanical Nomenclature. Some important versions are listed below.

Year of adoption
Informal name

1905
Vienna Rules

1935
Cambridge Rules

1952
Stockholm Code

1969
Seattle Code

1975
Leningrad Code

1981
Sydney Code

1987
Berlin Code

1993
Tokyo Code

1999
St Louis Code, The Black Code

2005
Vienna Code

2012
Melbourne Code

The Nomenclature Section held just before the 18th International Botanical Congress in Melbourne, Australia in July 2011 saw sweeping changes to the way scientists name new plants, algae, and fungi.

• For the first time in history the Code now permits electronic-only publication of names of new taxa; no longer will it be a requirement to deposit some paper copies in libraries.
• The requirement for a Latin validating diagnosis or description was changed to allow either English or Latin for these essential components of the publication of a new name.
• "One fungus, one name" and "one fossil, one name" are important changes for fungi and for fossils; the concepts of anamorph and teleomorph (for fungi) as well as morphotaxa (for fossils) have been eliminated.
• As an experiment with "registration of names", new fungal descriptions will require the use of an identifier from "a recognized repository"; there are two recognized repositories so far, Index Fungorum and MycoBank.
• The title of the Code was broadened to make explicit that it applies not only to plants, but also to algae and fungi.

International Code of Botanical Nomenclature (ICBN) »

International Code of Nomenclature for Cultivated Plants (ICNCP) »

Some References on Binomial Nomenclature

• McNeill, J.; Barrie, F. R.; Buck, W. R. et al., eds. (2012), International Code of Nomenclature for algae, fungi, and plants (Melbourne Code), Adopted by the Eighteenth International Botanical Congress Melbourne, Australia, July 2011 (electronic ed.)
• Knapp, S.; McNeill, J.; Turland, N.J. (2011). "Changes to publication requirements made at the XVIII International Botanical Congress in Melbourne - what does e-publication mean for you?". PhytoKeys 6 (0): 5-11.
• Nicolson, D.H. (1991). "A History of Botanical Nomenclature". Annals of the Missouri Botanical Garden 78 (1): 33-56.
• Alphonse Pyramus de Candolle (1868). Laws of Botanical Nomenclature adopted by the International Botanical Congress held at Paris in August 1867; together with an Historical Introduction and Commentary by Alphonse de Candolle, Translated from the French. translated by Hugh Algernon Weddell. London: L. Reeve and Co.
• Miller JS, Funk VA, Wagner WL, Barrie F, Hoch PC, Herendeen P (2011). "Outcomes of the 2011 Botanical Nomenclature Section at the XVIII International Botanical Congress". PhytoKeys 5: 1-3.
• John McNeill, 2011. Important decisions of the Nomenclature Section of the XVIII International Botanical Congress, Melbourne, 18-22 July 2011.
• Botanists finally ditch Latin and paper, enter 21st century, Hannah Waters, Scientific American blog, December 28, 2011.