In this article we will discuss about International Code of Botanical Nomenclature (ICBN).
Name is the means of reference to all living and non-living things. Any object known to human being is given a name to describe and communicate ideas about it. The name may be different in different languages and at different places. The art of naming the object is known as Nomenclature. And when it comes to naming of plants it is called Botanical nomenclature.
The process of naming plants based on international rules proposed by botanists to ensure a stable and universal uniform system is called Botanical nomenclature.
Common name is the same of the plant in a particularly area or locality given by the people of that particular area. Such names vary from place to place and language to language. It is vulnerable. In India the name changes even with the dilect.
To overcome the problems of common names, scientists suggested name in such a way that it is accepted in the world and is used internationally. But again, the problem remains the same, i.e., the language which is not universal. So the botanists agreed to lay down certain rules and conditions. The main suggestion was that the language of the name should be Latin.
It is because:
(a) The language is not a national language of any country at present.
(b) European languages derived from Latin only.
(c) Past European scholars learnt their subjects in Latin. A lot of previous botanical literature is written in Latin only.
During 1600 to 1850 AD Europe, particularly Greece, had dominated the world of science. The language was Latin but the script was Roman.
Binomial Nomenclature:
Linnaeus for the first time proposed that every living being has bionomial name, i.e., a name with two epithets. One is generic and the other is specific epithet. If an organism has a variety also, then the name becomes trinomial.
Linnaeus proposed some rules for generic names of plants in Fundamental Botanica (1736) and Critica Botanica (1737). A.P.de Candolle for the first time proposed rules for nomenclature of plants which are passed by International Botanical Congress at Paris (1867).
For the first time it was a Swedish Naturalist Carolus Linnaeus who started naming plants in 1753 as Binomial names. It was published in his book “Species plantarum”.
The generic name is always a noun showing colour, name or adjective, e.g., Sarracenia named after a scientist Michel Sarracin. Species is always an adjective, e.g., for white flower, it is alba., for edible one it is sativa, black colour-nigrum etc.
These names are not used always. Species may be a Pronoun, e.g., americana, indica, benghalensis, etc. It may be shape of a leaf (character of plant), e.g., sagittifolia, name of other scientist to whom the plant is dedicated, e.g., Sahnii etc.
Before the middle of 18th century, plant names were generally polynomial consisting of several words in a series. Linnaeus proposed the elementary rules in Philosophia Botanica in 1751.
In 1813 A.P.de Candolle proposed details of the rules regarding plant nomenclature in Theorie elementaire de la botanique. Alphonse de Candolle son of A.P.de Candolle after a long time convened an assembly of botanists of the world to present a new set of rules. Candolle convened the first International Botanical Congress at Paris in 1867.
Linneaus to Tourneforte to A.P.de Candolle made Laws of Botanical Nomenclature. In 1867 it was put before Paris Botanical Congress with principles of priority as Basic code with no exception.
Earlier to this in 1787 Tourneforte laid 7 laws:
i. Plants of one genus must have same generic name.
ii. Plants of different genera must have different generic name.
iii. If two plants have same name then it should be banished from one place.
iv. He who establishes a new genus should give a name.
v. Polynomials are invalid.
vi. Generic name based on plant character should be encouraged.
vii. Technical term in place of generic name is invalid.
(A) Paris Code (1867):
The first International Botanical Congress was held at Paris in August 1867. About 150 American and European Botanists were invited to make laws for Botanical Nomenclature (Lois de la nomenclature botanique). The laws were called Paris code, as they were adopted at French capital.
According to this code, the starting-point, for all nomenclature was fixed with Linnaeus. The rule of Priority was considered as basic for valid publication, author citation was very important. Paris code has many inherent defects. After some years the American and British Botanists deviated from the rides and started following a new rule called Kew Rule.
(B) Rochester Code (1892):
N.L. Brittan headed the Botanical Congress at Rochester, New York, USA in 1892. The Paris code was modified and with new recommendations, it was called as Rochester Code.
Some important recommendations were:
(i) Strict adherence to Principles of Priority.
(ii) Name and date of publication for interpretation of priority.
(iii) Acceptance of alternate binomials from employment of the principles of priority even in case of tautonyms.
(iv) Establishment of the type concept to ascertain the correct application of names.
(C) Vienna Code (1905):
The third International Botanical Congress was held at Vienna in June 1905. In this congress, it was established that Linnaeus Species Plantarum (1753) is the starting point for naming vascular plants. Nomina genera conservenda by which generic names having a wide use would be conserved over earlier but less well known names. Tautonyms are banned and the names of new taxa be accompanied by Latin diagnosis.
(D) American Code (1907):
The botanist proposed Rochester Code were dissatisfied with Vienna Code and refused to accept it in 1907. They modified the Rochester code to American Code. American code does not subscribe to the principle of Nomina generica conservenda or the requirement of Latin diagnosis. It accepts type concept. In American Code, a binomial cannot be used again for a plant in any way if it has been employed previously for another plant.
(E) Brussels Code (1912):
Fourth International Botanical Congress was held at Brussels in 1910. This code accepts different starting points for priority of names of non-vascular plants. It recognises the type concept and classification of Pharseology of the Vienna rules.
(F) Cambridge Code (1935):
The difference between Vienna code and American code was removed at the fifth Botanical Congress held at Cambridge (1930).
The provisions suggested in this code are as follows:
(i) Type concept should be persued.
(ii) A list of Nomina generica conservenda should be provided.
(iii) Tautonyms should be discarded.
(iv) Latin diagnosis of plants is necessary after January 1, 1932.
(G) Amsterdam Code (1947):
Sixth International Botanical Congress was held at Amsterdam in 1935. In this a major change in the rules was made, i.e., from January 1, 1935, names of new groups of recent plants, (except Bacteria) are to be considered as validity published only when they have a Latin diagnosis.
(H) Stockholm Code (1952):
The 7th International Botanical Congress was held at Stockholm in 1952. For the first time word “Taxon” was introduced to designate any taxonomic group or entity.
(I) Paris Code (1956):
8th International Botanical Congress was again held in Paris in July 1954. Here, the rule of compulsion of Latin diagnosis was scraped out and it was decided that it should be published in English, French and German languages. Preamble and Principles of the code were separated from the Rules and Recommendations. Nomina Generica Conservenda et rejecienda was amended and supplemented.
(J) Montreal Code (1961):
9th International Botanical Congress met at Montreal in August 1959, where a committee was appointed to study the question of conservation of family names. Nomina familiarum conservanda for Angiospermae was introduced. The code also asserted the naming of fossil plants should also follow the same lines as those of recent ones.
(K) Edinburgh Code (1966):
In the 10th Botanical Congress held at Edinburgh in August 1964, the report of committee was presented. According to it, for family names the starting point should be A.L.de Jussieu’s Genera Plantarum (1789).
Some of the spelling of a few families were changed, (e.g., Capparaceae for Capparidaceae and Cannabaceae for Cannabinaceae) in the list of Nomina familiarum Conservenda. A new committee was formed to work upon the preparation of Glossary of technical terms which was called An Annotated Glossary of Botanical Nomenclature.
(L) Seattle Code (1972):
11th International Botanical Congress met at Seattle in August 1969. The code was published in 1972 by F.A. Stafleu. Seattle Code includes the tautonymous designations of taxa between genus and species and below it. Code introduced a new word Autonym, i.e., automatically established names.
(M) Leningrad Code (1978):
12th International Botanical Congress was held at Leningrad in July 1975. The outcomes were published in 1978. It included minor changes, e.g., concept of organ genera was eliminated for fossil plants. The code does not apply for bacteria. Principles of automatic typification was extended to the names of taxa above family rank, etc.
(N) Sydney Code (1983):
13th Botanical Congress was held at Sydney in August 1981 and the outcomes were published in 1983.
(O) Berlin Code (1988):
14th International Botanical Congress was held at Berlin 1986 and the outcomes were published in 1988. Nomina Specifica Conservenda was introduced in the congress. Articles 66 and 67 were removed. In this two species names Triticum aestivum Linn, and Lycopersicon esculentum P. Miller were conserved against the rules of priority as these names were used widely and it was thought that if the names were changed confusion might arise.
(P) Tokyo Code (1994):
15th International Botanical Congress met at Yokohama in Japan in 1993. The code was translated into Chinese, French, German, Italian, Japanese, Russian and Slovak.
(Q) St. Louis Code (1999):
16th International Botanical Congress was held at St. Louis, Missouri in 1999. This code is also available in many languages. The code is divided into Rules, Articles, and Recommendations. Rules are set up to put the nomenclature of the past into order and to provide space for the future.
Recommendations deal with subsidiary points. According to it in future the names not following the recommended ones be rejected. Rules and Recommendations apply for all living and fossil organisms and fungi but do not include Bacteria. For Bacteria International Code of Nomenclature of Bacteria (ICNB) was proposed separately.
Presently, the rules and recommendations of St. Louis code which were proposed by Greuter in 1999 are in practice.
The seventeenth International Botanical Congress met at Vienna in 2005 but its code is not published as yet.
Principles of International Code of Botanical Nomenclature, (ICBN):
I. Botanical nomenclature is independent of zoological nomenclature. The code applies equally to names of taxonomic groups treated as plants whether or not these groups were originally so treated (Plants do not include Bacteria).
II. Application of names of taxonomic groups is determined by means of nomenclature types.
III. The nomenclature of a taxonomic group is based upon priority of publication.
IV. Each taxonomic group with a particular circumscription, position, and route can bear only one correct name, the earliest that is in accordance with the rules, except in specific cases.
V. Scientific names of taxonomic groups are treated as Latin regardless of their derivation.
VI. The rules of nomenclature are retroactive unless expressly limited.
The Principles were laid down in 1983.
Preamble of ICBN 1983:
1. Botany requires a precise and simple system of nomenclature used by Botanists in all countries, dealing, on the one hand, with the terms which denote the ranks of taxonomic groups or units, and on the other hand with the scientific names which are applied to the individual taxonomic groups of plants.
The purpose of giving a name to a taxonomic group is not to indicate its character or history, but to supply a means of referring it and to indicate its taxonomic rank. The code aims at the provision of a stable method of naming taxonomic groups, avoiding and rejecting the use of names which may cause error or ambiguity or throw science into confusion. It avoids the useless creation of names.
2. The Principles form the basis of the system of Botanical Nomenclature.
3. The detailed provisions are divided into Rules and Recommendations. Examples are added to the rules and the 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 clearness, 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 modification of this code from its last decisions.
7. The Rules and Recommendations apply to all organisms treated as plants (except Bacteria), whether fossil or non-fossil. Nomenclature of Bacteria is governed by the ICNB. Special provisions are needed for certain groups of plants. The International Code of Nomenclature of cultivated plants (1980) was adopted by the International Commission for the Nomenclature of Cultivated Plants; provisions for the names of hybrids appear in Appendix I.
8. The only proper reason for changing a name is either a more profound knowledge of the facts resulting from adequate taxonomic study or the necessity of giving up nomenclature that is contrary to the rules.
9. In the absence of a relevant rule or where the consequences of rules are doubtful, established custom is followed.
10. This edition of the code supersedes all previous editions.
Division III. Governance of the Code:
1. The code may be modified only by action of a plenary session of an International Botanical Congress on resolution moved by the nomenclature section of the congress.
2. Permanent Nomenclature Committees are established under the auspices of the International Association for Plant Taxonomy. Members are elected by an International Botanical Congress. The Committees have power to co-opt and to establish sub-committees.
3. The Bureau of Nomenclature of International Botanical Congress its officers are:
(a) The president,
(b) The recorder,
(c) The rapporteur-general, and
(d) The vice-rapporteur.
4. The voting on nomenclature proposals is of two kinds:
(a) Preliminary guiding mail vote
(b) Final and binding vote at the nomenclature section of the International Botanical Congress.
Some Important Rules and Recommendations:
1. All those plants which belong to one genus must be designed by the source generic name (Rule 213).
2. All those plants which belong to different genera must be designated by different generic names (Rule 214)
3. He who establishes a new genus should give it a name (Rule 218).
4. Those generic names are best which show essential characters of plants or its appearance (Rule 240).
5. Generic names one and a half foot long or difficult to pronounce or unpleasant are to be avoided (Rule 249).
6. The specific name must distinguish a plant from all its relatives (Rule 257).
7. Size does not distinguish species (Rule 260).
8. The original place of plant does not give specific difference (Rule 264).
9. A generic name must be applied to each species (Rule 284).
10. The specific name should always follow the generic name (Rule 285).
In accordance with the ICBN some traditional names of the families are changed to their alternate names as:
Compositae is now known as Asterceae.
Gramineae is now known as Poaceae.
Labiatae is now called as Lamiaceae.
Palmae is now called as Arecaceae.
Umbelliferae is now known as Apiaceae.
A unique exception to article 52 of the code is that the name Leguminosae is sanctioned only as long as it includes all three subfamilies Papilionoideae, Caesalpinoideae and Mimosoideae. If the subsfamilies are upgraded to family status the Papilionaceae shall be called Fabaceae.
Author Citation:
A name cannot be complete without an author’s name. The author’s name is abbreviated, e.g., Linneaus is abbreviated as Linn or L, Benthm as Benth; Hooker as Hook, Roxburgh as Roxb, Lamark as Lamk etc.
According to Article 46 the indications of name of a taxon are to be accurate and complete. It is necessary to cite the name of the author who first validly published the name. If the author’s name is too long it should be abbreviated. e.g., Hibisus L., Indigofera grandulosa var. Syskessi Baker, Solarium nigrum Linn etc.
According to Article 49 when a genus or taxon of a lower rank is altered in upper rank but retains its name or epithet, the author who first published this as a legitimate name or epithet must be cited in parentheses; followed by the name of the author was effected the alternation e.g., Citrus auranium var. grandis L; when raised to rank of species it become Citrus grandis (L) Obseck. Here L is the first author and Osbeck altered it.
Similarly, when a subdivision of a genus or a species is transferred to another genus or placed under another generic name (Article 54 and 55), it will be written as:
(i) Saponaria section vaccaria DC when transferred to Gypsophila, it becju.es Gypsophila sec. vaccaria (DC) Godr.
(ii) Limonia aurantifolia Christm, when transferred to Citrus it becomes Citrus aurantifolia (Christm) Swingle.
In case of infraspecific changes it is, Alysicapus nummularifolius DC when reduced to variety it becomes Alysicarpus viginalis var. nummularifolius (DC) Baker.
The names of two authors are linked by ex. when the first author proposed a name but was validly published only by second author, the first author failing to satisfy all requirements of the code, e.g.,
Cerasus cornuta Wall ex. Royle. When two or more authors publish a new species their names are linked by et, e.g., Delphinium viscosum Hook.F. et Thomson. When the first author publishes a new species or name in a publication of another author, in is used, e.g., Carex kashmirensis Clarke in Hook. F, it means Clarke published the new species in Hooker’s Flora of British India.
The names of two authors are linked using emend (emendavit) or person making amendment or correction in the diagnosis or circumscription of a taxon without altering the type, e.g., Phyllanthus Linn, emend. Mull.
When a name was already suggested but it is before 1753, i.e., the starting of binomial system, the name of the author will be put in brackets ([ ]), e.g., Lupinus [Tourne] Linn, here Tournefort suggested the name in 1719, i.e., before 1753 (Species Plantarum).
In the citation of infraspecific taxon both authorities are called as Acasia nelotica (Linn) Del. ssp indica (Benth). In case of autonym, the infraspecific epithet does not bear author’s name since it is based on same type as the species, e.g., Acacia nelotica (Linn.) Del. ssp nelotica.
Publication of Names:
The name of a Taxon should fulfill certain requirements before its effective publication, e.g.,
(1) Formulation:
It should indicate.
(a) sp. nov (species nova) for a new species
(b) Comb, nov (combination nova) for change in the epithet of basionym The name of the original author should be kept in Parantheses.
(c) nom. nov (Nomen novum) when the original name is completely replaced.
(2) Latin diagnosis:
Name of New Taxa should have a Latin diagnosis, i.e., translation of all features in Latin language.
(3) Typification:
Holotype should be designated. The name of new Taxon is valid only when the type of the name is mentioned after January 1, 1990. The name of the taxon whose type is a specimen or unpublished illustration; the herbarium or institution in which the type is conserved must be specified.
(4) After January 1, 1996 the name of new taxon of fossil should be accompanied by a Latin or English description of character.
Article 32, 1-2 or Tokyo Code (ICBN) is amended as new names of plants and Fungi will have to be registered in order to be validly published after January 1, 2000.
Rejection of Names:
The rules for rejection of names are:
(i) Nomen nudunm (nom. nud):
Name without description, without typification and Latin diagnosis etc. is rejected.
(ii) Tautonym:
Botanical nomenclature does not allow tautonym (repetition of generic name), e.g., Malus malus. Repetetion of specific epithet in infra specific epithet does not constitute tautonym.
(iii) Later homonym:
If a name which is already existing is given to another taxa once again then the later homonym is rejected.
(iv) Nomen ambiguum (nom. ambig):
The name is rejected if it is used in different sense by different authors.
(v) Nomen confusum (nom. confus):
The name should not be confusing.
(vi) Nomen dubium (non. dub):
Dubious name i.e., with uncertain applications is also rejected.
Types of Taxon:
Names of different taxonomic groups are based on the type method.
The principles and articles of the ICBN provide that all taxonomic groups will be based on nomenclatural types, meaning thereby that all names are permanently attached with some taxon or specimen designated as type. For species (and infraspecific taxa) the type is a specimen or in some circumstances only an illustration. The name of the first author should be attached.
Name of the taxa above the level of species, i.e., section, subgenus, genus, tribe, and family etc., are based on the name of immediately next lower taxon on which the group was originally based, i.e., Lamiaceae was based on genus Lamium. Orchidaceae was based on genus Orchis etc.
When a new species is described, the author of new species has one or more specimen having characters are distinctive enough to be segregated into new species.
Different Kinds of Types:
(i) Holotype:
Single specimen, may be whole plant or a part of it with which the name of taxon is permanently attached, is known as holotype.
(ii) Isotype or Cotype:
Fragments from the same plant from which the Holotype is made or plants with same field number are isotypes.
(iii) Paratype:
Specimen other than holotype and Isotype is called Paratype. The specimen may bear a different field number as it is collected from different localities by different collectors.
(iv) Syntype:
The specimen which is the basis of new taxon when no holotype is designated by author is known as syntype. If author studies collection from different localities and by different collectors and decides to establish a new species, labels all of them as types, all these specimen become syntype.
(v) Lectotype:
It is type chosen to serve as Holotype, when either an earlier designated holotype was lost or destroyed or Holotype was never designated and from the Isotype, Paratype or Syntype a specimen is chosen by a specialist to serve as the type.
(vi) Neotype:
If Holotype, Isotype, Paratype or Syntype are lost or not available a Neotype is selected from other specimens, to serve as Type. Some taxonomists call it Standard Specimen.
(vii) Topotype:
When no original type material is available and a specimen is collected from type locality is chosen to serve as type it is called Topytype.
(viii) Epitype:
Specimen is selected to serve as an interpretive type when the holotype, lectotype, Neotype etc. could not effectively be identified to name the taxon, it is called Epitype.
Principles of Priority:
Principles of Priority are concerned with the selection of a single correct name of taxonomic group. Only legitimate names should be retained while the illegitimate names should be rejected.
According to article 11-12 rules for priority are:
(i) Each family or taxon of lower rank with a particular circumscription, position and rank can bear only one correct name (Art. 11).
(ii) For any taxon from family to genus inclusive, the correct name is the earliest legitimate one, validly published with the same rank (Art. 11).
(iii) A name of a taxon has no status under this code unless it is a validly published (Art. 12).
(iv) The application of both conserved and rejected names is determined by nomenclatural type (Art. 14).
(v) “When a name proposed for conservation has been provisionally approved by the general committee, botanists are authorized to retain it pending the decision of a later International Botanical Congress”.
Valid Publication of names is usually considered beginning in May 1753, the date of publication of Species plantarum vol. I by Linneaus.
With many names of a taxon, the valid will be the earliest name which is regarded as correct name. Rule of Priority provides stability to his name.
The principle that seniority is fixed by the date of valid publication is known as Principle of Priority.
Example 1:
Nymphea nouchali Burm F. 1768; N. Pubescence Willd 1799 and N.torus Hook T; 1872 are names of the same species but if rule of Priority is applied the first name is the correct name and other two are synonyms.
Example 2:
Loureiro described a plant and named it Physkium nataus in 1790. A.L.de Jussieu transferred it in genus Vallisneria in 1828. He instead of nutans gave the specific name as V. physkium. It is superfluous name. Graebner (1912) described the same plants as V.gigantee and Miki (1934) named as V.asiatica. Harg while studying Asiatic species confirmed that all these names are synonymous.
There is no legitimate combination based on Physikium natans (Leru) existed. He made V.natans Hara in 1974. The correct name of the specimen is now the recent name, but it is based on earliest basionym, others will be synonym. V.gigantea and V.asiatica will be known as nomenclatural synonyms or homotypic synonyms. V.gigantea and V.asiatica are the names based on separate types. Such synonyms are known as taxonomic synonyms or heterotypic synonyms.
Limitations of Principles of Priority:
1. Starting dates:
Principles of Priority starts with the Species Plantarum of Linnaeus published on 1-5-1753.
2. Limited only upto family ranks:
This principle does not apply over family rank.
3. The corrected name should not be outside the rank. Only when a correct name in the taxon is not available, a combination with other rank is allowed.
4. The application of Principles of Priority resulted in numerous name changes. To avoid it a list of conserved generic and family names has been prepared and Published in the code with some changes. Such Nomina conservanda (non. cons) are to be used as correct name replacing earlier legitimate name, e.g., Sesbania scop, 1777 is the conserved genus as against Sesban adam 1763 and Agati adam 1763.