The latest, updated edition of the essential, authoritative reference for botanical, mycological, and phycological names.
The International Code of Nomenclature for algae, fungi, and plants, known as “the Code,” is the set of internationally agreed rules and recommendations that govern the naming of these organisms. Scientific naming has deep historical roots. Indeed, the system of naming organisms is one of the first truly global scientific standards. This essential reference originates in Alphonse de Candolle’s 1867 Lois de la nomenclature botanique. This 2025 edition of the Code, the Madrid Code, reflects the decisions made at the Twentieth International Botanical Congress, which met in Madrid, Spain, in July 2024. The congress debated 447 proposals to amend the Code and accepted important new rules, including a mechanism for voluntary registration of plant and algal names, clarifications for naming fossil taxa, the option to reject a new name if it is derogatory to a group of people, and the replacement of an epithet that was considered particularly offensive (revising to afra, afrorum, and afrum).
Preface
Key to renumbering between the Shenzhen Code and the Madrid Code
Important dates in the Code
Latin terms and their abbreviations used in the Code
Preamble
Division I. Principles
Principle I. Independence
Principle II. Types
Principle III. Priority
Principle IV. Single correct name
Principle V. Latin names
Principle VI. Retroactivity
Division II. Rules and Recommendations
Chapter I. Taxa and their ranks
Article
1. Taxa
Article
2. Ranks
Article
3. Principal ranks
Article
4. Secondary and further ranks
Article
5. Order of ranks
Chapter II. Status, typification, and priority of names
Section
1. Status definitions
Article 6
Section
2. Typification
Article
7. Typification in general
Article
8. Specimens and gatherings
Article
9. Categories and designation of types
Article
10. Typification of names above the rank of species
Section
3. Priority and status of names
Article
11. Priority of names
Article
12. Status of names
Section
4. Limitation of priority
Article
13. Nomenclatural starting-points
Article
14. Conserved names
[ Article
15. Sanctioned names see Article F.3]
Chapter III. Nomenclature of taxa according to their rank
Section
1. Names of taxa above the rank of family
Article
16. Names above the rank of family
Article
17. Names of orders and suborders
Section
2. Names of families, subfamilies, tribes, and subtribes
Article
18. Names of families
Article
19. Names of subfamilies, tribes, and subtribes
Section
3. Names of genera and subdivisions of genera
Article
20. Names of genera
Article
21. Names of subdivisions of genera
Article
22. Autonyms of subdivisions of genera
Section
4. Names of species
Article 23
Section
5. Names of taxa below the rank of species (infraspecific
taxa)
Article
24. Names of infraspecific taxa
Article
25. Sum of subordinate taxa
Article
26. Autonyms of infraspecific taxa
Article
27. Final epithet in names of infraspecific taxa
Section
6. Names of organisms in cultivation
Article 28
Chapter IV. Effective publication
Article
29. Definition and conditions of effective
publication
Article
30. Further conditions of effective publication
Article
31. Date of effective publication
Chapter V. Valid publication
Section
1. Valid publication in general
Article
32. General requirements for valid publication
Article
33. Date of valid publication
Article
34. Suppressed works
Article
35. Further requirements for valid publication
Article
36. Names not accepted by their authors, alternative
names
Article
37. Requirement of indication of rank
Section
2. Valid publication of names of new taxa
Article
38. Requirement of description, diagnosis, or
illustration with analysis
Article
39. Language of validating description or diagnosis
Article
40. Requirement of indication of type
Section
3. New combinations, names at new rank, and replacement
names
Article 41
Section
4. Registration of names and nomenclatural acts
Article 42
Section
5. Names in particular groups
Article
43. Names of fossil-taxa
Article
44. Names of algae
Article
45. Names in groups covered by other Codes
Chapter VI. Citation of names
Article
46. Author citations
Article
47. Names of altered taxa without exclusion of type
Article
48. Names of altered taxa with exclusion of type
Article
49. Parenthetical author citations
Article
50. Transfer between the hybrid and non-hybrid
category
General recommendations on citation [ Recommendations
50A50G]
Chapter VII. Rejection of names
Article
51. Limitation of rejection
Article
52. Nomenclaturally superfluous names
Article
53. Homonyms
Article
54. Inter-Code homonymy
Article
55. Limitation of illegitimacy
Article
56. Rejected names
Article
57. Names used for taxa not including their types
Article
58. Reuse of illegitimate names
[ Article
59. Names of fungi with a pleomorphic life cycle
see Article F.8]
Chapter VIII. Orthography and gender of names
Article
60. Orthography of names
Article
61. Orthographical variants of names
Article
62. Gender of names
Chapter F. Names of organisms treated as fungi (Maastricht version)
Section
1. Limitation of priority
Article F.1. Nomenclatural starting-point
Article F.2. Protected names
Article F.3. Sanctioned names
Section
2. Valid publication and typification of names
Article F.4. Misplaced rank-denoting terms
Article F.5. Registration of names and nomenclatural acts
Section
3. Rejection of names
Article F.6. Homonyms
Article F.7. Rejected names
Section
4. Names of fungi with a pleomorphic life cycle
Article F.8
Section
5. Orthography of names
Article F.9
Section
6. Author citations
Article F.10
Section
7. Recommendations on types that are living cultures
Recommendation F.11A
Chapter H. Names of hybrids
Article H.1. Indication of hybrids
Article H.2. Hybrid formulae
Article H.3. Names of nothotaxa
Article H.4. Circumscription of nothotaxa
Article H.5. Ranks of nothotaxa
Article H.6. Nothogeneric names and condensed formulae
Article H.7. Hybrids between subdivisions of genera
Article H.8. Parentage, nothogeneric names, and condensed
formulae
Article H.9. Valid publication of names of nothogenera and
their subdivisions
Article H.10. Valid publication of names of nothospecies and
infraspecific nothotaxa
Article H.11. Nothotaxa with parents belonging to different
higher-ranked taxa
Article H.12. Subordinate taxa within nothospecies
Division III. Provisions for governance of the Code
Provision
1. General provisions for governance of the Code
Provision
2. Proposals to amend the Code
Provision
3. Institutional votes
Provision
4. Nomenclature Section
Provision
5. Procedures and voting at the Nomenclature Section
Provision
6. After an International Botanical Congress
Provision
7. Permanent Nomenclature Committees [ Membership, Functions,
Procedural rules]
Provision
8. Provisions for governance of the Code relating solely to
names of organisms treated as fungi
Glossary. Definitions of terms used in this Code
Appendices IVII
Index of scientific names
Subject index
The members of the Editorial Committee of the Madrid Code are Nicholas J. Turland, Chair; John H. Wiersema, Secretary; Fred R. Barrie; Kanchi N. Gandhi; Julia Gravendyck; Werner Greuter; David L. Hawksworth; Patrick S. Herendeen; Ronell R. Klopper; Sandra Knapp; Wolf-Henning Kusber; De-Zhu Li; Tom W. May; Anna M. Monro; Jefferson Prado; Michelle J. Price; Gideon F. Smith; and Juan Carlos Zamora Señoret.
