International Code of Nomenclature for algae, fungi, and plants

thumb|270px|[[Carl Linnaeus's garden at Uppsala, Sweden.]]

The International Code of Nomenclature for algae, fungi, and plants (ICN or ICNafp) 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 replaced the Vienna Code of 2005.

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 fungi the Code was revised by the San Juan Chapter F in 2018.

The 18th edition, the Madrid Code, was published in July 2025. It incorporates decisions made by the Twentieth IBC held in Madrid, Spain, in July 2024.

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.

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. The first set of international rules was the ("Laws of botanical nomenclature") that was adopted as the "best guide to follow for botanical nomenclature" Unlike modern Codes, it contained recommendations for naming to serve as the basis for discussions on the controversial points of nomenclature, rather than obligatory rules for validly published and legitimate names within the Code.
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 (Article 39).
"One fungus, one name" and "one fossil, one name" are important changes; the concepts of anamorph and teleomorph (for fungi) and morphotaxa (for fossils) have been eliminated.
As an experiment with "registration of names", new fungal descriptions require the use of an identifier from "a recognized repository"; there are three recognized repositories, Index Fungorum, MycoBank, and Fungal Names.

Versions

All the versions are listed below.

{| class="wikitable"

! Year of publication !! Informal name

|1867||Laws of botanical nomenclature

|1883||Laws of botanical nomenclature, ed. 2

|1906||Vienna Rules

|1912||Brussels Rules

|1935||Cambridge Rules

|1950||Amsterdam Code

|1952||Stockholm Code

|1956||Paris Code

|1961||Montreal Code

|1966||Edinburgh Code

|1972||Seattle Code

|1978||Leningrad Code

|1983||Sydney Code

|1988||Berlin Code

|1994||Tokyo Code

|2000||St Louis Code

|2006||Vienna Code

|2012||Melbourne Code

|2018||Shenzhen Code

|2025

|Madrid Code (current)

International Code of Nomenclature for algae, fungi, and plants

Principles

Versions

See also

References