1. Botany requires a precise and simple system of nomenclature used by botanists in all countries, dealing on the one hand with the terms that denote the ranks of taxonomic groups or units, and on the other hand with the scientific names that are applied to the individual taxonomic groups of plants1. The purpose of giving a name to a taxonomic group is not to indicate its characters or history, but to supply a means of referring to it and to indicate its taxonomic rank. This Code aims at the provision of a stable method of naming taxonomic groups, avoiding and rejecting the use of names that may cause error or ambiguity or throw science into confusion. Next in importance is the avoidance of the useless creation of names. Other considerations, such as absolute grammatical correctness, regularity or euphony of names, more or less prevailing custom, regard for persons, etc., notwithstanding their undeniable importance, are relatively accessory.

2. The Principles form the basis of the system of botanical nomenclature.

3. The detailed Provisions are divided into Rules, set out in the Articles, and Recommendations. Examples (Ex.) are added to the rules and recommendations to illustrate them.

4. The object of the Rules is to put the nomenclature of the past into order and to provide for that of the future; names contrary to a rule cannot be maintained.

5. The Recommendations deal with subsidiary points, their object being to bring about greater uniformity and clarity, especially in future nomenclature; names contrary to a recommendation cannot, on that account, be rejected, but they are not examples to be followed.

6. The provisions regulating the governance of this Code form its last division.

7. The rules and recommendations apply to all organisms traditionally treated as plants, whether fossil2 or non-fossil, e.g., blue-green algae (Cyanobacteria)3; fungi, including chytrids, oomycetes, and slime moulds; photosynthetic protists and taxonomically related non-photosynthetic groups. Provisions for the names of hybrids appear in App. I.

8. The International code of nomenclature for cultivated plants is prepared under the authority of the International Commission for the Nomenclature of Cultivated Plants and deals with the use and formation of names for special plant categories in agricultural, forestry, and horticultural nomenclature.

9. The only proper reasons for changing a name are either a more profound knowledge of the facts resulting from adequate taxonomic study or the necessity of giving up a nomenclature that is contrary to the rules.

10. In the absence of a relevant rule or where the consequences of rules are doubtful, established custom is followed.

11. This edition of the Code supersedes all previous editions.

footnote 1. In this Code, unless otherwise indicated, the word “plant” means any organism traditionally studied by botanists (see Pre. 7).

footnote 2. In this Code, the term “fossil” is applied to a taxon when its name is based on a fossil type and the term “non-fossil” is applied to a taxon when its name is based on a non-fossil type (see Art. 13.3).

footnote 3. For the nomenclature of other prokaryotic groups, see the International code of nomenclature of bacteria (Bacteriological Code)