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 species names. Scientific naming has deep historical roots. Indeed, the system of naming organisms is the first truly global scientific standard, predating even standard calendars and units of measurement. This essential reference originates in publications like Alphonse de Candolle's 1867 Lois de la Nomenclature Botanique. This 2025 edition of the Code, the Madrid Code, reflects the decisions of the Twentieth International Botanical Congress, which met in Madrid, Spain, in July 2024. The Congress debated 433 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 possibility to reject a new name if it is derogatory to a group of people, and replacing 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 50A–50G] 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 I–VII 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.