ICBN.pdf

This is prepared for the undergraduate students of Botany

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TAXONOMY GFGC YELAHANKA P B Mallikharjuna,PhD
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PLANT NOMENCLATURE
Plant nomenclature is an important aspect of Taxonomy. The naming of plants
based on certain rules is proposed by the International Botanical Society(IBS) over a
period of time is called Plant Nomenclature. These names are usually termed as the
botanical names or the scientific names. These are evolved as the Binomials from the
Polynomials and the Vernaculars through the ages.
BINOMIAL NOMENCLATURE
The method of giving scientific names to plants, animals and microbes with the
name consisting of two parts is binomial nomenclature (ICBN, Art.23.1) Therefore, the
scientific names of organisms are always binomials.
Ex. 1. Mangifera indica (plant)
2. Homo sapiens (Human being)
3. Mus musculus (animal, mouse) &
4. Escherichia coli (microbe, bacterium)
Naming the organisms become essential mainly for three reasons
 To remember the particular organism, we studied
 To communicate the same with the others, and
 To maintain the scientific documentation.
Giving names to organisms is in practice since time immemorial. However, the names used
in earlier days are vernacular names in local languages and such names have many
defects. For example;
1. They do not remain same throughout the world,
2. They tend to change from place to place and from language to language,
3. In some instances, a common name is applied to different plants and the same
plant may be called by different names, and
4. Common names are not available to all kinds of plants.
Therefore, there was a necessity to give scientific names. However, the first
introduced scientific names were Polynomials. These were lengthier, descriptive and
difficult to remember. For example, Gravellia robusta grandiflora australiana. Later
the binomial system is proposed, where the name is consisted only of two parts. The
first part of the name is the genus name and the second part is the species name or
specific epithet. This binomial system was actually proposed for the first time by
“Casper Bauhin”( 1623), but he did not make its application compulsory. Later, it was
Linnaeus (1753), a Swedish botanist, who adopted the binomial nomenclature in his
“Species plantarum, 1753”, and hence the credit gone to Linnaeus. Therefore, 1
st
May

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1753 is regarded as the beginning date of the scientific names of all living beings
including plants. Latin is the chosen language for scientific names.
Certain rules are to be followed while giving the binomials. The first letter of the
genus should be capital and the first letter of the species should be a small letter. For
example, Mangifera indica & Cocos nucifera etc. Whenever, these names are hand-
written or type written they are to be underlined. The names should be in Latin language
or if the names are derived from any other source, they are to be Latinised. The genus
name always be a noun, the species name will be an adjective, and hence it usually reveals
of a character or home of the place. For example, Solanum nigrum (nigrum-black),
Mangifera indica (Indica-India). The scientific names usually followed by the name of
the author in abbreviation form, who validly published it for the first time.
Example: Mangifera indica L. (L-Linnaeus).
ICBN
International code of botanical nomenclature (ICBN) or the Code is the premier
constituent body of the International Botanical Society/Congress. Its main objective is
to look after the plant nomenclature of both extant and extinct taxa. The first code
was held in Paris, France (1867) under the guidance of A.P. de Condolle. The basis for
the code has been drawn from de Condolle's “Theorie Elementiare de la Botanique” and
also from the Linnaeus’ “Critica Botanica”, “Fundamenta Botanica” and “Philosophia
Botanica”. Since then for every 6 years, the International Botanical Congress (IBC)
meeting was held to discuss the various aspects of nomenclature and publishing its
proceedings as the Code. The latest edition of Code i.e., 19
th
edition was held in Shenzen,
China (2017) recently and which supersedes all previous editions.
The Code/ICBN is mainly consisting of the preamble and three divisions as follows

THE PREAMBLE
Botany requires a precise and simple system of nomenclature used by Botanists all over
the world.

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AIM OF THE CODE:
1. It aims at the provisions of a stable method of naming taxonomic groups, avoiding
or rejecting the use of names, which may cause error or ambiguity.
2. Further, it aims at the avoidance of the useless creation of new names.
Division I - Principles: these will form the basis of the system of botanical
nomenclature and has six Principles, namely,
 Principle I: Botanical nomenclature is independent of zoological and bacteriological
nomenclatures. Further, the code applies equally to names of taxonomic groups
treated as plants whether or not these groups were originally so treated.
 Principle II: The application of names of taxonomic groups is determined by means
of nomenclature types.
 Principle III: The nomenclature of a taxonomic group is based upon the priority of
publication.
 Principle IV: Each taxonomic group with a particular circumscription, position and
rank can bear only one correct name, the earliest that is in accordance with the
rules, except in specified cases.
 Principle V: Scientific names of taxonomic groups are treated as Latin regardless
of their derivation.
 Principle VI: The rules of nomenclature are retroactive unless expressly limited.
Division II - Rules and Recommendations: The detail provisions of the code are divided
into Rules in the form of Articles (62) and which are binding. The main objective of rules
is to put the nomenclature of the past into order and to provide the same for the future.
Whereas, Recommendations are subsidiary points and which are non-binding but
to be preferred. The main objective is to bring about greater uniformity and clarity
especially in future nomenclature.
This division included 7 Chapters, 16 Sections and 62 Articles.
o Chapter I deals with taxa and their ranks (Art 1-5)
o Chapter II deals with typification (Art. 6-10) and rule of priority (Art. 11-15)
o Chapter III deals with nomenclature of taxa according to their ranks (Art.16-28)
o Chapter IV deals with Effective and Valid publication (Art. 29-50)
o Chapter V deals with rejection of names (Art. 51-58)
o Chapter VI deals with the names of fungi with pleomorphic life cycle (Art 59), &
o Chapter VII deals with the Orthography and gender of names (Art: 60-62)
Division III: Includes provisions regulating the governance of the code. It has five
appendices namely;
 Appendix I: names of hybrids

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 Appendix IIA/B: Nomina familiarum conservanda (Family names conserved)
 Appendix IIIA/B: Nomina generica/specifica conservanda et rejicienda (The
rejected names of the genera/species are conserved)
 Appendix IV: Nomina utique rejicienda (rejected in favour of a particular
conserved name, and combinations based on a suppressed name)
 Appendix V: opera utique oppressa (Rejection of names)

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RULE OF PRIORITY
According to the Code /ICBN rule,” Each family or taxon of lower rank with a
particular circumscription, position and rank can bear only one correct name. And, it is
the earliest legitimate one which is validly published with the same rank (Art 11).
Further, the name of a taxon has no status under this code unless it is validly published
(Art 12)”. The date of valid publication is 1
st
May 1753 of Linnaeus ‘Species plantarum’.
For instance, when there are several names for a taxon, the earliest name, which
is validly published, is regarded as the correct name. Thus, the rule of priority gives
stability to the plant nomenclature.
Ex: Cleome gynandra Linn (1753)
Cleome pentaphylla Linn (1762)
Gynandropsis pentaphylla DC (1824)
The above three names are existing for a single taxon. Of these, the earliest one i.e.,
Cleome gynandra is valid and legitimate name according to the the priority. While the
other two are synonyms and these are conserved in the appendix IIIB of the Code (
Nomina specifica conservanda et rejicienda). Finally, the application of both conserved
and rejected names, are determined by the nomenclature type (Art 14).
Effective and Valid publication
According to the Code/ICBN, the author to make it, as a correct or legitimate
name must effectively and validly published the scientific name of a given taxon.
In general, effective publication deals with standards applicable to the media. In which
the names are published and not to the names themselves (Article 29). Whereas, valid
publication deals with standards applicable to the names themselves (Article 32 – 45).
There are four general criteria for publication of a name,
1. The name must be effectively published. That means it must be published in a
journal commonly available to botanists such as Rheedea (at national level) or
TAXON or Systematic Botany (at international level).

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2. The name must be published in the correct form, i.e., properly Latinised, with
rank indicated (Ex. as “sp.nov” or “gen.nov”). Such a name in correct form is known
as the admissible name.
3. The name must be published with a Latin description or diagnosis or with a
reference to such. The diagnosis maybe a brief account. For instance, listing how
the new taxon is different from a similar, related taxon.
4. A nomenclatural type must be indicated.
Finally, the term “PROTOLOGUE” is “everything associated with a name at its valid
publication i.e., description or diagnosis, illustrations, references, synonyms,
geographical data, citation of specimens, discussion and comments”. A full citation of a
scientific name may include the authorship and the journal, volume, page numbers and
data of publication. For ex: A complete citation for the new species (sp.nov). Cited as:
Perityle vigilans Spellenb & A. Powell, Syst. Bot.15: 252.1990.

TYPIFICATION
(Type Method)
According to the Code/ICBN (Article 7-10), the application of names to
taxonomic groups is governed by nomenclatural types. This rule previously applicable to
the rank of family or below. However, now it is extended to the names of taxa of higher
ranks when the names are ultimately based on generic names.
Nomenclature type: it is the representative element of a taxon. When any author
publishes the account of species, the original plant on which the description is based, is
deposited in any standard Herbarium (like Kew Herbarium). This type specimen becomes
the nomenclatural type of that specimen and is associated ever with the specific name
given on its basis.
Type specimen: is the one that is ultimately associated with the name of a taxon.
The type for a genus is a species, for a family it is a genus, and for an order, it is a
family.
Examples:
 Ex: Rosa indica (Species) Rosa (Genus) Rosaceae (Family)  Rosales (Order)
 Magnolia grandiflora (Species)  Magnolia (Genus)Magnoliaceae
(Family)Magnoliales (Order)
There are several types of nomenclatural types existing, such as
 Holotype
 Isotype
 Syntype
 Paratype

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 Lectotype
 Neotype

1. HOLOTYPE: is the type specimen or other element used or designated by the
author in the original publication as the main nomenclatural type. At present, it is
essential that a holotype designated for a newly described species be deposited
in a national herbarium like the Central National Herbarium (CAL), Calcutta of the
BSI.
2. ISOTYPE: is the duplicate specimen of a holotype. There are plants forming part
of the same gathering as the holotype and gathered at the same time. In the
absence of holotype, isotype will serve as the nomenclatural type.
3. SYNTYPE: is one or two or more specimens studied and cited by the author, when
the holotype is not designated by him.
4. PARATYPE: is a specimen cited with the original description in addition to the
holotype. When the author fails to designate a holotype or the holotype is missing,
a lectotype or neotype is selected to serve as a nomenclatural type.
5. LECTOTYPE: is a specimen selected from those cited by the author with the
original description.
6. NEOTYPE: is selected only when all the original specimens collected and cited by
the author missing.
For example: Impatiens thomsonii Hook.f., is a member of the family
Balsaminaceae and its description is given in the Flora of British India. The author
(J D Hooker) has cited three specimens on which the description was based on.
1. Collected by Thomson from Piti and Kunawar.
2. Collected by Strach. and Wint. from the Kouman and Garhwall hills.
3. Collected by JD Hooker from Sikkim.
Hooker stated that specimen 3 of the above is the nomenclatural type (i.e.,
Holotype). Specimens 1 and 2 are the Paratype. If Hooker had not designated the 3
rd

specimen as holotype, then all three were Syntypes. One of these syntypes can serve as
a Lectotype, if the type holotype is missing. If all 3 specimens are destroyed for some
reason, then the 4
th
specimen (Collected by Wallich from Sikkim,) which does not find
mention in Hookers description, will be treated as a Neotype.

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Additional Information:
o Basionym is a technical term used in the scientific name of organisms. Basionym
means the 'original name'. The term is primarily used in botanical nomenclature,
and is regulated by the ICBN (Art.6.10). The term 'basionym' is used to indicate
which name was the original, validly published name of the taxon. For instance,
when the binomial name of a species has been changed, the earliest name is the
basionym. For example, the basionym of the name Picea abies is Pinus abies. The
species was originally named Pinus abies by Carolus Linnaeus; later on, botanist
Karsten decided this species should not be grouped in the same genus Pinus as
the pines, but in a separate genus, so he transferred it to the genus Picea.
o Autonym: The automatically established name of a subdivision of a genus or of
an infraspecific taxon that includes the type of the adopted, legitimate name of
the genus or species, respectively. Its final epithet repeats unaltered the
generic name or specific epithet and is not followed by an author citation (Art.
22.1 and 26.1). Autonyms need not be effectively published nor comply with the
provisions for valid publication (Art. 32.1), they are automatically established,
at any given rank, by the first instance of valid publication at that rank of a
name of a subdivision of a genus under a legitimate generic name or of a name
of an infraspecific taxon under a legitimate species name (Art. 22.3 and 26.3).
o Isonym: The same name based on the same type, published independently at
different times perhaps by different authors. Note: only the earliest isonym
has nomenclatural status (Art. 6 Note 2; but see Art. 14.14).
o Homonym: A name spelled exactly like another name published for a taxon at
the same rank based on a different type (Art. 53.1). Note: names of subdivisions
of the same genus or of infraspecific taxa within the same species that are
based on different types and have the same final epithet are homonyms, even if
they differ in rank (Art. 53.3), because the rank-denoting term is not part of
the name (Art. 21 Note 1 and Art. 24 Note 2) (see also confusingly similar
names).
o Tautonym. A binary designation in which the specific epithet exactly repeats
the generic name (Art. 23.4), usually not applicable to plants but common in
animals, Ex. Bubo bubo (owl)
o Nothospecies: A hybrid species (Art. 3.2).
Source: https://www.iapt-taxon.org/nomen/pages/main/glossary.html