Principles and Rules of ICBN, IBC, The Hisory of ICBN

PLANT TAXONOMY
Welcome to
PRINCIPLES AND RULES ( ICN)
By
Dr. N. Sannigrahi, Associate Professor,
Department. Of Botany,
Nistarini College, Purulia, (W. B), India

A PLEASURE OF NATURALISTS TO KNOW THE PLANTS

RETROSPECTS OF ICBN
 Naming of the plants and it identification are the urge of all naturalists,
 Vernacular names are not widely accessible and not available to all plants,
 Common name do not provide sufficient desired information in this regard,
 The taxonomic hierarchy is not provided by the common as well as vernacular
names as assigned for plants from different time and places,
 Many common names may occur for the same species in the same language in
the same or different localities,
 Keeping all these disturbances in mind regarding plant naming, it becomes
essential to assign a particular name for a particular plant to make holistic and
easily accessible.,
 ICBN is the uniform domain that can address all the aforesaid issues.

ICN OR ICBN
 Linnaeus in 1737 & 1751 proposed the elementary rules of naming plants
in ‘ Philosophia Botanica’. Then in 1813, A.P.de Candolle set forth a
detailed rules regarding plants nomenclature in his Theories element ire de
la botanique. The same rules of Linnaeus, A.P.de Candolle and his son,
Alphonse de Candolle were later evolved into our present International
Code of Botanical Nomenclature (ICBN).
 Alphonse de Candolle convened the first International Botanical Congress
in 1867 in Paris called Paris Code attended by botanists from several
countries. They adopted a set of rules of plant nomenclature , most of
which were proposed by A. de Candolle. Subsequent meetings of ICBN
held in 1892 (Rochester code), 1905 (Vienna Code), 1907 (American
Code) and a general agreement came into the force on IBC at Cambridge.

IBC CHRONOLOGY
 Cambridge (1930)-”for the first time in botanical history, a code of
nomenclature came into being that was international in function as well as
in name”. This is called ICBN. Then from 1930, a number of IBC are being
held as per order for the adoption of rules and recommendations in Plants
taxonomy.
 1935- Amsterdam,
 1850-Stochholm,
 1954-Paris,
 1959-Montreal,
 1964-Edinburgh,
 1969- Seattle,
 1975-Leningrad,
 1981-Sydney,
 1987-Berlin,

IBC CHRONOLOGY
 1993-Tokyo,
 1999- St. Louis,
 2005-Vienna
 2011- Melbourne
 2017-Snenzhen,
 2024-Madrid
The IBC has the power to alter the ICN (International Code of
Nomenclature for algae, fungi, and plants, which was renamed from the
International Code of Botanical Nomenclature(ICBN) at the XVIII IBC.
Formally the power resides with the Plenary Session; in practice this
approves the decisions of the Nomenclature Section. The Nomenclature
Section meets before the actual Congress and deals with all proposals to
modify the Code: this includes ratifying recommendations from sub-
committees on conservation. To reduce the risk of a hasty decision the
Nomenclature Section adopts a 60% majority requirement for any change
not already recommended by a committee.

PRINCIPLES
 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.

RULES AND RECOMMENDATIONS OF ICBN
According to the ICBN(1983), the code “ are divided into Rules , set out in
Articles, and Recommendations”. As mention under point No. 4 of the
Preamble of 1983 ICBN” 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 can not be maintained”.
The rules and recommendations of ICBN apply to all organisms treated as
plants (including fungi but excluding bacteria), whether fossil or non-fossil.
Nomenclature of bacteria is governed by a separate code called
International Code of Bacterial Nomenclature (ICNB) and so as to
cultivated plants by ICNCP.
It is stated under point No. 10 of ICBN that the latest “edition of the Code
super codes all previous editions”

SOME IMPORTANT RULES
 1.Ranks and Endings of Taxa
 2. Principle of Priority,
 3. Type Method,
 4. Citation of Author
 5. Synonyms and related Definitions
 6. Names of Cultivated plants,
 7. Latin Diagnosis,
 8. Effective & Valid publication,
 9. Choice of Names when the Taxon Rank is Changed
 10.Choice of Names when same –rank Taxa are united,
 11. Retention of Names of Divided Taxa,
 12. Retention of Names of Taxa on Transference
 13. Rejection of Names
 14. Names of Different Taxa.

1.RANKS AND ENDINGS OF TAXA
 The system of classification provides a hierarchical arrangement of the
ranks and this is very much necessary to know the assignment status of
the given taxa. Generally, there are about seven main obligatory ranks of
taxa are used in order to designate them and each one is identified by the
particular suffix used as the endings of the each taxa. The obligatory
ranks are as below:
 Kingdom, ( regnum), Division ( Diviso), Class (classis), Order (ordo),
family(familia), Genus (genus) and Species ( species). The suffixes are
used as stated below.
 Division- Phyta,
 Sub-division- phytina,
 Class- opsida,
 Sub-class- opsidae,
 Order-ales,
 Suborder- ineae
 Family- aceae

RANK AT THE LEVEL OF GENUS & SPECIES
As per previous information is concerned about the endings of the rank of the
taxa, different suffixes are used to designate them. The question arises how the
name of the genus and species are designed and whether do they follow any
strict rule in this regard for naming them? The answer lies in the understanding
of the genus and species name determined as stated below:
A. Generic name:
i. Commemoration of a person- The names may be dedicated to great
personalities in different fields as stated below:
Bauhinia from Bauhin, Darwinia from Darwin, Victoria from the Queen
Victoria of England, Washingtonia from George Washington. When the names
are used for genus, it takes famine form and some rules are followed in this
regard. Like Otto becomes Otto etc.

RANK AT THE LEVEL OF GENUS & SPECIES
 ii. Based on place- some places may be associated with genus like
Caucasis from Caucasus in Russia, Salvador from EL Salvador,
Arabis from Arabia, Siberia from Siberia of Russia etc.
 iii. Based on important character- Zanthoxylum from yellow
wood, Hepatica from Liver-like, Hygrophila form Marshy habit,
Trifolium from Trifoliate leaves etc.
 Aboriginal names- Without alternation of ending in genus, the
name has been designed as stated below:
 Narcissus- a Greek name of daffodils after the name of Greek god,
 Ginkgo- a Chinese name,
 Vanda- Sanskrit word,
 Sasa- a Japanese original name,
 Putranjiva- a mythological name etc

SPECIES NAME
 All the epithet usually starts with small letter and it may derive from any or
compound arbitrarily.
 Name of a person: Wallachia from Wallchi, Hookari for Hooker etc (If it is
becomes genitive or possessive form, it becomes capital).
 Formed by a place- indica from India, kasmiriansis from Kashmir, etc.
 Based on character- alba or albus or album for white, cultivated species as
sativa , cordifolia for cordate leaves.
 Noun in apposition- Some epithets may have their own gender as they are noun
in apposition, in nominative case .Pyrus malus is based on Greek name malus
for common people.
 Some other specific epithets are rara (rare), vulgaris (common), autmnalis (
autumn), ethnic or superstitious denotations like religiosa , serpentina etc.

PRINCIPLE OF PRIORITY
 (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 comprehensive, the correct name is the earliest rightful
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 Linnaeus. The principle that
superiority is fixed by the date of valid publication is known as Principle of

 i. Correct name of the species Nymphaea nouchali Burm. F., 1768. other three
names of the genus Nymphaea are
 Nymphaea malabarica., 1798
 N. stellate Willd., 1799
 N. acutiloba., 1824
 ii.Correct name for Zea is selected as per rule of priority
 Zea mays L., 1753
 Z.curagua Molina, 1782
 Z,japonica von Houtte, 1886
 Z. indurata Sturter., 1885

 3. When two or more names appear simultaneously for a species, both the
names are combined, the first author to take the naming process. The generic
name Thea L. and Camellia L. are published simultaneously on 01.05.1753. In
1818, Sweet combined and the genus get the name Camellia. He treated Thewa
as synonym.
 LIMITATION TO THE PRINCIPLE OF PRIORITY
 1. The principle of priority came to existence after publication of Species
plantarum of Linnaeus in 01.05.1753. This is called starting date. Other plant
groups including seed plants, pteridophytes, Sphagnaceae, Hepaticae, most
Algae, and Fungi , Slime moulds and lichens were published in 01.05.1753,
Mosses on 01.01.1801, Fungi on 31.12.1801, Fossils 31.12.1820. The
publication before dates for species group are omitted. Starting dates for
suprageneric names was set a Vienna Congress on 04.08.1789.

 2. The principle of priority is applied only upto family level.
 3. A correct name for a taxon is chosen considering names and epithets
available at that rank. Other wise , a suitable name is selected taking epithet
from another rank.
 4. Nomina conservanda are to be used as correct names replacing the earlier
legitimate names, earlier legitimate name is rejected treated as nomina rejicinda.
The family name Theaceae D. Don , 1825 is conserved in place of
Ternstromiaceae Mirbe, 1813. The genus Sesbania Scop., 1777 is conserved in
place of Sesban Adans., 1763 and Agati Adan., 1763.
 Thus, the above limitations are considered as far as the conservation of the
names at the different rank and categories.

TYPIFICATION/TYPE METHOD
 Typification is a methodology by which a certain representative of the group is
the source of the name for the same group. This is called nomenclatural type. A
type of a particular genus is a species so as to a particular family is a genus.
Type of a particular genus is species as Poa pratensis for Poa. A single type
specimen is designated and it is generally treated as Holotype. The holotype
should be kept in a permanent herbarium and conserved properly. Publication
on or after January 1, 12958 of the name of a new taxon of the rank of the genus
or below is valid when the same type name is indicated Publication of name of
a new taxon of genus or below after January 1, 1990 should carry either the
word ‘typus’ or ‘holotypus’. Publication of names on or after January 1, 2007
requires a specimen as a type but in case of microscopic algae and fungi where
preservation of the specimen is technically difficult, illustration is accepted as
type.

 ICN’s second principle states that a specimen must be associated with the
scientific name known as nomenclatural type. A nomenclatural type is either a
specimen or may be an illustration. Example: Herbarium sheet for vascular
plants. There are different nomenclatural types.
 Holotype : A specimen or illustration originally cited by the author in
protologue. It is a definitive reference source for identity. Citation of holotype
and submission of it is one of the criteria for valid publication of a botanical
name.
 Isotype: Duplicate specimen of the holotype collected from same population
by same person on same date with same field number. They are the reliable
duplicates of holotype and may be distributed to various herbaria of various
regions.
 Lectotype: Specimen selected from original material serves as a type, when no
holotype was designated at the time of publications or if holotype is missing or
destroyed.
 Syntype: When more than one specimen cited by the author in the protologue
without designating holotype.

 Neotype: Specimen derived from non-original collection selected
as the type, when original specimen is missing or destroyed.
 Paratype: Specimen cited in the protologue is other than
holotype, isotype or syntype.
 Epitype: Specimen or illustration serves as an interpretive type,
when holotype, neotype or lectotype is ambiguous.
 Thus, the type concept is the most important issue that to be
addressed in case of the developing the different type of
taxonomic problems. The different rules and regulations as framed
by ICBN is very important in this regard. Thus, addressing a
taxonomic problem with the adi of the element is very essential in
this regard.

REJECTION OF NAMES
Illegitimate names are not accepted because they do not obey any
botanical nomenclature. A legitimate name is also not rejected and it is
rejected due to the following reasons as mentioned below:
1. Tautonym - When the generic name and the specific epithet are same,
it is called tautonym. In botanical nomenclature, tautonym is completely
not in un use Sometimes, naming involves tautony which is accepted as
Sesbania seshan. Repetition of a specific epithet in an intraspecific
epithet does not constitute a legitimate autonym(Acacia nilotica ssp.
nilotica).
2.Nomen nudum (nom.nud): A taxon without association of proper
description is called nom. nud. In 1812, Wallich published many names
without proper description in his catalogues in Wall.cal and those were
nomen nudum. But if the same species named properly by another
author , the new names remain valid. For example, Quercus dilatata
wall., nom.nud, but rejected and replaced by Quercus himalayan
Bahadur, 1972.

REJECTION OF NAMES
3.Lain Diagnosis- The scientific name is subject to rejection when it is not
effectively published , not formulated , lacking typification and the diagnosis of
the element without in Latin language.
4. Later isonym- sometimes by coincidence, two same names , based on same types
come independently at different times by different authors, the name of the
earlier author stands among the ‘Isonymes’. The name is published with the
original place of valid publication. Baker (1992) and Christensen (1905)
independently published the taxon, Alsophila kalbrengeri as a substitute of A.
podophylla Baker (19812). A. kalbrengeri is being a later isonym, is rejected.
5. Nomen superfluum (nom. superfl.)- A superficial published name becomes
illegitimate and it must be rejected. It indicates that the name is out of the rule
of the code. In 11790, Physkium nastas Lour., was transferred to the genus
Vallisneria without natus.In 1826, de Jessieu named it Vallisneria physakium
Juss., that becomes superfluous. Subsequently, the species in 1974 was properly
named as Vallisneria natas (Lour.) Hara.

REJECTION OF NAMES
6. Nomen ambiguum ( nom. ambig.)- sometimes a name is used by the different
authors in different sense, and a persistent error is produced, the name is subject
to rejection. As an example, Rosa villosa L. is a source error due to its use for
different species. Hence , it is rejected.
7. Nomen confusum( nom. confus.)- In this case, it becomes difficult to select a
satisfactory lectotype among two or more conflicting species. For example, in
the genus Actinotinus the characters are derived from two genera Viburnum and
Asculus where the insertion of inflorescence in the former and the terminal bud
latter., So, the name Aconitus for the taxon was abandoned.
8. Nomen dubium (nom.dub.)- When the placement of a taxon is doubtful to
which it should be published, the name of the taxon is rejected. In 1753,
Linnaeus named Rhinanthus crista-galli L for a group of several varieties and
subsequently he rejected his own concept and used separate names for the
varieties discarding R. crista-galli. Though the name continued for considerable
period by authors, finally in 1939 Schwarz treated under nomen.dubium.

NAME OF THE HYBRIDS
Hybrids plants may be cross between the two elements at the
different level. It may be either nothogenus and nothospecies.The
hybrid between the two species is expressed by putting a cross
between the species is expressed by putting a cross between the
species which is called hybrid formula as stated below.
i. Salix aurita X S. caprea
ii. Agrostis X Polypogon
iii. Agrostis stolonifera X Polypogon monspeliensis.
There are some rules showing the position of the species in a
hybrid formula.
Species in a formula put in alphabetical order,
Generally Female is kept first using specific sign to denote it.
If the sequence is not followed, reason must be acknowledged.

NAME OF THE HYBRIDS
Hybrid may be interspecific of intergeneric, interspecific involves
two species under same genus but intergeneric involves two
different genera. A binary name is assigned to the interspecfic
hybrid or notho-species putting X before the specific epithet. The
hybrid should be self-perpetuating and or reproductively isolated.
The following examples can beautify the event.
i. Rosa X odorata ( Interspecific) derived from Rosa chinensis X
R. gigantea.
ii. Salix X capreola (Interspecific) derived from Salix aurita and
Salix caprea.
The variants of interspecific hybrids are named as nothosubspecies
and nothovarities , e.g. Salix rubens nothovar. basfordiana.

NAME OF THE HYBRIDS
In intergeneric cross, the naming of the hybrid follows the following rules as
stated below:
i. A cross between Triticum & Secale that produces a intergeneric hybrid ,
named as xTriticosecale and in case of xAndropogon it is Agrostis x Polypogon
and in xPaeonia from Pyrus and Cynodon.
The name of the nothogenus derived from the combination of the two.
Sometimes, intergeneric naming includes four or more genera to produce an
intergeneric hybrid. The hybrid carries a cross sign immediately before it and it
should be more than eight syllables. The condensed formula xPotinara is the
outcome of 4 genera- Brassavola x Cattleya x Laelia x Sophrontitis. The hybrid
genus end with – ara derived from the person who produced the hybrid or so.

NAME OF THE HYBRIDS
When the nothogeneic name is formed out of three genera, the name does not
contain eight syllables .But it consists of whole or first part of one followed by
the whole, or any part of the second followed by the whole or the last part of the
third followed by the one or more connecting vowels. The nothogenic name of
the trigenic hybrid may be named as tetragenic hybrid if the above pattern is not
accepted i.e. from personal name to which added the termination –ara.
Nothogenic hybrid of 3 genera:
Xsopholaeliocattleyaya, it is derived from (xSophronitis x Laelia x Cattleya).
Two species involved in graft are demarcated by plus sign, e.g. Hibiscus rosa-
sinensis+ and H.syricus +---

THANK YOU VERY MUCH
 References:
 1.A text Book of Plant Systematics- C. Mohanty
 2.A text Book of Botany- Hait, Bhattacharya & Ghosh
 3. Plant taxonomy- O.P. Sharma,
 4. Advanced Plant Taxonomy- A.K. Mondal
 5.Studies in Botany- Mitra, Guha & Choudhury
 6.College Botany- Kar & Ganguly
 7.Google for Images,
 8.Different websites for reference reading sources.
 Disclaimer: This PPT has been designed and developed for enriching the free
knowledge domain in the field of plant sciences without keeping any financial
interest.

Principles and Rules of ICBN, IBC, The Hisory of ICBN

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