In this essay we will discuss about the nomenclature of plants. After reading this essay you will learn about:- 1. Meaning of Nomenclature 2. Types of Nomenclature 3. Rules.
Essay # 1. Meaning of Nomenclature:
The nomenclature may be defined simply as the system of naming of plants. After determination of a new taxon based on some important characteristics, it becomes essential to give a scientific name. The name of the taxon is given following the rules of International Code of Botanical Nomenclature (ICBN).
With the help of this procedure one can communicate his discovery to the world. So, many new plants may be known to the scientific world by the exploration of new areas. These plants are then included in the list of the existing flora. The rules of plant naming are constructed by the International Botanical Congress held at different intervals in different places.
Before the mid 18th century, botanical names were in the form of short descriptive phases i.e., polynomials. Thus the presently known plant Sida acuta Burm. f. was named by Plukenet as ‘Althaea coromandelina angustis prolongis foliis semine bicorneo’. Similarly, Strychnos nux-vomica L. was known as ‘Strychnos follies ovalis caule enerme’.
Similar type of naming is available in the earlier works of Linnaeus (1707-1778). This polynomial system serves as a label and the diagnosis of taxa. These two aspects later on proved to be contradictory and, therefore, Linnaeus separated them.
According to the review work of Choate (1912) on “Origin and evolution of the binomial system of nomenclature in Botany”, Caspar Bauhin (1560-1624) was the first to implement the binomial system, though he was not consistent in its use. Later on, this track was chosen by Carolus Linnaeus who used binomials for the plants described in his ‘Species Plantarum’ (1753) and later works.
Latin is used in biological nomenclature. But the ICBN gives one liberty of selecting names of taxa from any language or source but insists that they are deemed to be Latin.
Essay # 2. Types of Nomenclature:
Binomial Nomenclature:
The binomial nomenclature is the system where naming of plants consists of two words — a generic name and a specific name. The first one is the generic name and the second one is the specific name. Both the names together form a binary or binomial name.
In a binomial, only the generic name should start with capital letter and all others in small letters. After selecting the name of a particular plant, it must be added with the name of the author. If the author’s name is too long, it should be mentioned in abbreviated form. The names of the plants are written in Latin. The scientific name i.e., the Latin name of Paddy is Oryza sativa. The first name, Oryza is the generic name and the second name sativa is the specific name.
To complete the name, the author’s name in abbreviated form should be added at the end. So the complete scientific name of Paddy is Oryza sativa L. The L. indicates the name of Linnaeus, who has given the name.
Binomials should be typed in Italic type face or in case of handwriting both generic and specific epithet should be underlined separately.
Essay # 3. Rules for Nomenclature:
1. Scientific Names and Its Purpose:
Primitive man became interested in plants long back. The plants were useful to them for different aspects — medicines, food and so many other purposes. Same plants were available in different localities, different regions of a country and even in different countries.
But the same plants were called by different names in different places or the same name had been applied for several different plants. Sadly it can be said that no uniformity could be achieved regarding the naming of the plant. Thus the common names were different and restricted in some particular regions — either small or larger one.
For the above, botanists felt the requirement or need of uniform naming and to assign a single scientific name to a particular type of plant. Thus different types of plants have different scientific names used uniformly throughout the scientific world, e.g., paddy is called by different names in different regions of India, such as Dhan in West Bengal, Dhana in Orissa, Nellu in Tamil Nadu, Beeum in Andhra Pradesh, Chaul in Uttar Pradesh and Bihar etc. But the scientific name Oryza sativa is uniformly used throughout the scientific world.
2. Elementary Knowledge of “International Code of Botanical Nomenclature” (ICBN):
Caspar Bauhin (1560-1624) was the first to construct or design the binomial system. But this system was not harmonious in its use. After many years, it was Carolus Linnaeus who picked up the idea of Caspar Bauhin and used the binomial for all plants described in his Species Plantarum (1753) and later works.
Later the Species Plantarum (1753) achieved much importance in Plant Taxonomy and the year of its publication is considered as the starting point of botanical nomenclature. The simple nomenclatural rules he considered in his publications Fundamenta Botanica (1736), Critica Botanica (1737) and Philosophia Botanica (1750).
Due to the subsequent activities of the botanists after Linnaeus, it was found that the total number of species of flowering plants is about 300,000, which is much more than 10,000 as reported by Linnaeus. It was found that the Linnaean rule is insufficient to govern plant nomenclature.
Later on, Augustin de Candolle published detail rules on plant nomenclature in Theorie elemaintaire de la botanique (1813). The confusion also arose among the taxonomists by the insufficient flow of message to the different comers of the world. Thereby same species was described by different names by different taxonomists from different corners of the world.
Due to this the number of plants recorded in Index Kewensis during 1753-1965 is 830,000 — much more than the actual existing specimens! The above happened due to multiple publication of about ⅓rd of the above specimens.
For the above, taxonomists felt the necessity of formulation of internationally accepted rules and regulations for the naming of plants.
As an organised effort, the first ‘International Botanical Congress’ was held in London in 1866, but nothing was settled there. In that conference Alphonse de Candolle (son of Augustin de Candolle) was entrusted to prepare a draft of the law of nomenclature. The second ‘International Botanical Congress’ was held in Paris in 1867.
In that conference Alphonse de Candolle proposed the laws of Botanical Nomenclature (Lois de la nomenclature botanique) which was accepted and adopted with some modifications as the guideline for nomenclature of vegetable kingdom. These rules are now known as Paris Code or de Candolle rules (1867) published in 1868.
Till date the Code has been periodically reviewed in different congress and subjected to addition, deletion and alteration. Subsequent meetings of the International Botanical Congress were held periodically in 1892 (Rochester Code), 1905 (Vienna Code), 1907 (American Code) and 1912 (Brussels Code), while in true sense the first ICBN was framed in the 6th Botanical Congress held in Cambridge (Cambridge Code) in 1930.
Saint Louis Code:
International Code of Botanical Nomenclature (ICBN) is a book of LAW, containing the Rules and Recommendations prescribed for naming plants in an international context and comprises of three divisions. Division I deals with six PRINCIPLES containing mandatory provisions which are inviolable and form the basis of the System of Nomenclature.
Division II deals with Rules and Recommendations the system of Nomenclature. Division III, on the other hand, outlines the procedures to be adopted if any of the Articles and Recommendations in Division II are proposed to be modified.
ICBN is a living document, revised and updated every 5 or 6 years by the Nomenclatural Session of the International Association for Plant Taxonomy (IAPT). The 16th International Code of Botanical Nomenclature (ICBN) was held at Saint Louis, Germany in 2000 under the Chairmanship of Prof. Werner Greuter.
This 16th ICBN is called Saint Louis Code. Although the Saint Louis Code, 2000 replaces the Tokyo Code (1994), it does not alter the basic structure of the hitherto published Codes.
The St. Louis Code has merely added some minor changes, clarified certain ambiguous terms like Epitype, and deleted some highly controversial provisions like REGISTRATION of new names, etc., added some new NOTES and EXAMPLES and in certain cases re-numbered the Articles, by bringing together Rules, such as those involving Typification, or deleted some duplicating examples, and clarified some ambiguous words here and there. The BASIC STRUCTURE of the CODE remains unaltered and thereby such steps ensure continuance of the ICBN as a universally acceptable document.
The ICBN of the Saint Louis Code (2000) comprises three Divisions:
Principles, Rules and Recommendations and Provisions for the governance of the code.
A. Division I. Principles:
This division provides 6 Principles which form the basis of the system of Botanical Nomenclature.
These are:
I. Botanical nomenclature is independent of zoological and bacteriological nomenclature. The Code applies equally to names of taxonomic groups treated as plants whether or not these groups were originally so treated.
II. The application of names of taxonomic group is determined by means of nomenclatural type.
III. The nomenclature of taxonomic group is based on the priority of publication.
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.
V. Scientific names of taxonomic groups are treated as Latin, regardless of their derivation.
VI. The Rules of Nomenclature are retroactive unless expressly limited.
B. Division II. Rules and Recommendations:
This division contains the Rules distributed in 62 Articles and Recommendations. The names which contravene (contradict) any one or more of the above Rules are illegitimate. Recommendations deal with subsidiary points. The object is to bring about greater uniformity in Nomenclature.
Names contrary (contradictory) to Recommendations need not be rejected, but are not examples of the following:
C. Division III. Provisions for the Governance of the Code:
The provisions for modifications are mentioned in 7 Appendices.
These are:
I. Names of hybrids and some special categories.
II A. Nomina familiarum algorum, fungorum, pteridophytorum et fossilium conservanda et rejieienda.
II B. Nomina familiarum bryophytorum et spermatopytorum conservenda.
III A. Nomina generica conservanda et rejicienda.
III B. Nomina specifica conservanda et rejicienda.
IV. Nomina utique rejicienda.
V. Opera utique oppressa.
There are FIVE Appendices split up into several sub-appendices and also INDEXES to Appendices II—IV, as also subject Index and, finally, Index of scientific names. Thus, while the CODE proper comprising of all the three Divisions, is covered by 104 pages, the APPENDICES and INDEXES spread over 370 pages form the bulk of the CODE.
Of the 62 Articles, Arts. 3, 4 and 5 deal with the sequence of the RANKS of taxa, whose relative sequence cannot be altered. Effective and valid publication of a name are covered by Arts 29-31 and Arts. 32-45 and Art. 61 or H. 9 respectively.
Arts. 7-10 deal with problems of TYPIFICATION; Arts. 11-12, with the question of PRIORITY of a validly published name, whereas Arts. 13-15 outline the limitations of the Principle of Priority. Art. 14 provides guidelines for CONSERVATION OF NAMES, to by-pass disadvantages that may accrue because of strict application of the RULES OF PRIORITY.
The single largest of the changes made in the St. Louis Code concerns TYPIFICATION. Art. 8.2 defines that a specimen is a gathering, or part of a gathering of a single species or infraspecific taxon, made at one time, mounted on a Herbarium sheet or is preserved in a box, packet, jar or as microscopic slide and therefore, none of such a part- mounting can be selected as a lectotype.
In the St. Louis Code, entries of all conserved generic names, within each major group, are printed alphabetically, abandoning the former system of numerical classification of the obsolete Dalla Torre and Harms system. Instructions to review/revise the list of conserved family names of Spermatophyta, abandoning A. L. Jussieu and accepting Adanson as the starting point date of family- names and introducing numerous other changes of authorship and date of publication, based on J. E. Reveal’s list of suggested changes, a less dependable compilation, have been accepted in the St. Louis Code (2000). Citation of Berchfold and J. Presl, as authors of family names, were modified, because the word rad they used refers to orders, not to families (celed).
The Nomenclatural Session at St. Louis denied registration of newly proposed names and refused to discuss even the question of protection of NAMES IN CURRENT USE (NCU) and all suggestions for harmonised terminology in biological nomenclature (Biocode), so painstaking laboured upon over two decades, by the host of nomenclaturalists under the leadership of Prof. Werner Greuter, were rejected.
And, all traces of registration of Botanical names found mentioned in the TOKYO Code were deleted and the entire procedure adopted in the Nomenclature Session at St. Louis to conduct the Proceedings of the session, is considered, by Greuter, as “unprecedented”. A series of proposals to bring harmony between the RULES governing ICBN, ICZN, Bacterial Code and the Viral Nomenclature, were all sidestepped.
All these developments led Dr. Werner Greuter (Chairman) and Dr. David L. Hawks- worth (Secretary), to lament and nickname the Saint Louis Code, 2000 AD (printed with a black jacket cover) as the BLACK CODE, after naming the Tokyo Code as the PURPLE CODE.
The 17th International Botanical Congress was held in Vienna in 2005.
Phylocode:
The Phylocode is an unofficial code of biological nomenclature in relation to phylogenetic relationship. Phylocode advocates abolition of ranks, but this would have undesirable consequences for biodiversity studies.
Because classifications are utilitarian, they should be worked out by the systematists and users of classifications. In defence, one may assume that the Phylocode is defined “by Law” rather than “by people”. But what role should it play in taxonomy is still to be worked out.
3. Ranks of Taxa:
The taxa (sing, taxon) indicate the ‘taxonomic groups of any rank’ as mention in Art. 1 of the code. The rank of species is the basic unit and the successive higher taxa are genus, family, order, class, division and kingdom. Thus species is included under a genus, genus under a family, family under an order and so on.
The code also provides that the name of each taxon of different rank should end with specific manner. Name of the different taxa with their specific ending along with examples are given in Table 4.1.
The botanists are authorised to develop additional categories with the addition of a prefix ‘sub’ to the next higher categories. This can be exemplified as suborder, subfamily etc.
The name of specimens is mentioned in binomials but in intraspecific categories trinomials are used with their own epithets added with the respective species to which they belong, e.g., Brassica campestris var. dichotoma Watt (Kalisarson); B. campestris var. toria Duth. (Indian rape or Toria); B. oleracea var. capitata L. (Cabbage); B. oleracea var. botrytis (Cauliflower); Anisomeles indica var. albiflora (Hassk.) Backer.
4. Rules of Priority:
Many more names are published for plant taxon than the actual number available in the world flora. The above fact indicates that several names are given for the same taxon. To avoid such confusion it becomes essential to eliminate the duplication and to decide which one will be selected for a taxon out of several published names.
To avoid such problem, certain provisions are there in the code. According to the Principles of Priority (Arts.11 and 12), each family or taxon of lower rank with particular circumscription, position and rank can bear only one correct name. The first validly published name of a taxon becomes its valid name.
If other names are subsequently published for a particular taxon, those will be considered as synonyms. The botanists have agreed with the opinion that for the flowering plants the starting point shall be from Species Plantarum of Carolus Linnaeus, published in 1st May, 1753.
(i) Thus there should be only one valid name for a particular plant, but it may have many synonyms. For the above, date of publication have to be mentioned for each name.
(ii) This rule is not applicable to the names of taxa above the rank of family.
Some examples of the validity of the genus is given below:
A. Valid Generic Name – Xyris:
1. The name ‘Xyris’ was published by Carolus Linnaeus in Species Plantarum (1753).
2. The same plant was named as ‘Schismaxow’ published by Steudel in Bot. Zeitung 14, 1856.
So the priority should be given to Xyris as it was published earlier than Schismaxow.
B. Valid Generic Name – Mondo:
1. The name Mondo was given by Adanson in 1 763.
2. The same plant was named as Ophiopogon by Kerl Gawl in 1807.
So the name Mondo was retained as a valid name.
C. Valid Generic Name – Polygala:
1. The name Polygala was given by Linnaeus in 1753.
2. Later on, the same plant was named as Poligala Neck (1768), Polygaloides Agosti (1770) and Phylax Nor. (1790) are the synonyms.
5. Alternative Names:
The name of the family should end with the suffix ‘aceae’ added with the legitimate name of a genus included in the family, e.g., Magnoliaceae from Magnolia, Ranunculaceae from Ranunculus, etc.
Some exceptions are also permitted at the family level. The alternative names are permitted to be used for eight (8) families, those which do not end with ‘aceae’. The new names are given according to the name of type genus of the particular family. The old names are also treated as valid, as such, because of long usages.
The old name, new names (mentioned in parenthesis) and the type genus is given below:
When Papilionaceae (Fabaceae; Type, Faba Mill.) are regarded as a family distinct from the remainder of the Leguminosae, the name Papilionaceae is conserved against Leguminosae.
When the Papilionaceae are included in the family Leguminosae as a subfamily, the name Papilionoideae may be used as an alternative to Faboideae.
6. Effective and Valid Publication:
The condition for effective and valid publication have been mentioned in Articles 29-45 of the Code.
Publication regarding new name of a plant with taxon is effective only when the printed matter is distributed (through gift, exchange or sale) to the general public (particularly botanist) or at least to botanical institution with libraries accessible to botanists generally with the consequent said matter published in the recognised periodicals or journals concerning botany.
The publication is not effected by communication of new names in local newspaper, gardens open to the public, public meeting etc. The date of effective publication is the date of availability of printed matters.
The publication of name of new taxa is considered as valid only when it will fulfill the following conditions:
1. Publication must be effective.
2. It must be accompanied by a description of a taxon or by a reference to a previously and effectively published description.
3. The new name, if published after 1.1.1953, must have clear indication of the rank of the taxon.
4. It must be accompanied by a Latin diagnosis or reference to a previously and effectively published Latin diagnosis.
5. The name of a new taxon of the rank of family or below must be indicated by nomenclatural type if published on or after 1.1.1958.
7. How Names are Given:
Botanical names are given by the following procedures:
Name of Genera:
i. Latinisation of common plant names from any other language, e.g., Ravenala from Madagascan, Nelumbo from Ceylonese.
ii. Commemoration of some botanist or patron of Botany, e.g., Hookerea, Jacobinia, Gerardiana, Caesalpinia, etc.
iii. Combination of two or more Greek or Latin words, e.g., Hygrophyla (marsh loving), Acanthospermum (spiny fruits), Asterocantha (spreading spine), Polygala (more milk), etc.
Name of Species:
i. Based on habitat of plant, e.g., aquatica or aquatilis (grows in water), montanus (grows on mountains), arvensis (grows on cultivated land) etc.
ii. Based on the names of locality or country, e.g., indica (India), mexicana (Mexico), americana (America), zeylanica (Ceylon), sinensis (China) etc.
iii. Formed from a noun with a suffix indicating relationship, e.g., portulacastrum (like Portulaca), boerhavifolia (leaves like Boerhavia), etc.
iv. Based on the name of some honourable persons, e.g., hookeriana, griffithii, roxburghii, wallichii, etc.
v. The specific epithet should agree with the gender of the generic name. In Latin, there are three genders: masculine, feminine and neuter gender.
These are:
a. Masculine gender, e.g., japonicus, albus, etc.
b. Feminine gender, e.g., japonica, alba, etc.
c. Neuter gender, e.g., japonicum, album etc.
Similarly, above procedure is followed in generic name with some exceptions: e.g., Fagus, Pyrus, Quercus etc. ends with us but are feminine.
8. Author‘s Citation:
A. The name of a taxon should append the name of the author or authors who first published validly. This helps the taxonomists to verify the dates of publication. Commonly the names are used in abbreviated forms, e.g.,
i. Vitex Linn.
ii. Vitex trifolia Linn.
iii. Vitex trifolia var. simplicifolia Cham.
B. When a taxon of a lower rank is altered in a rank by retaining its older name, the name of the earlier author must be mentioned in parenthesis, followed by the name of the author who altered it.
This is called double citation, e.g.;
i. Citrus aurantium var. grandis L., when promoted to the rank of species by Osbeck ; the new name of the plant becomes Citrus grandis (L.) Osbeck.
C. Similarly, the above rule is applied when a subdivision of a genus or a species is transferred or placed to another genus, e.g.,
i. When Oxalis sensitivum L. was transferred to the genus Biophytum by A. de Candolle, it becomes Biophytum sensitivum (L.) DC.
ii. When Antirrhinum spurium L. was transferred to the genus Linaria by Miller, it becomes Linaria spuria (L.) Mill.
D. Similar rules are applied during intra-specific transfer or change of rank, e.g.,
i. When Sesbania aegyptiaca var. picta Prain was transferred to Sesbania sesban by Santapau, it becomes Sesbania sesban var picta (Prain) Santapau.
E. When the name is published by two authors, their names must be linked with et or by an ampersand (&), e.g.,
i. Didymopanax gleasonii Britton et Wilson (or Britton & Wilson).
F. When the name is published by more than three authors, the name must be appended by the first author and is followed by et al., e.g.,
i. Streptomyces albo-niger Hesseltine et al.
G. When an author who suggested the name but published validly by other author or to an author who published the name before the starting point of the group; the name of the latter author should be connected with the name of the author who validly published the name by an ex, e.g.,
i. Allmannia nodiflora R. Br. ex Hook. f.
ii. Acalypha racemosa Wall, ex Baill.
iii. Arenaria uligenosa schleich. ex Schlechtend.
H. During citing the name of a taxon of garden origin, the name must be ascribed to hort (hortulanorum) and ex. should be added before the name of the author who published it. e.g.,
i. Gresneria donklarii hort. ex. Hook.
9. Retention and Choice of Names:
Some rules adopted from time to time by different congresses are mentioned below:
A. When a genus is divided into two or more genera, the original name is to retain for the one which includes the type species, e.g.,
i. The genus Dicera J. R. et. G. Forster (1776) was divided by Rafinesque (1838) into two genera Misipus and Skidanthera and did not follow the rule and consequently the name Dicera was retained as one of the genera and kept for the part of Dicera based on lectotype Dicera dentata.
B. When a species or intra-specific taxa is divided, it will also follow the above procedure, viz.
i. The Heliotropium indicum Linn. is divided into two species. The part which includes the type retains the name Heliotropium indicum L. and the other one as H. keralense Manilal et Sivarajan.
C. When a genus or a species is transferred to another genus or another generic name of the same species, the legitimate name have to be retained.
i. The Melochia cordata Burm. f. when transferred to the genus Sida becomes Sida cordata (Burm. f.) Borssum Waalkes.
ii. When Antirrhinum spurium L. was transferred to the genus Linaria by Miller, it becomes Linaria spuria (L.) Mill.
D. When two or more taxa of the same rank are combined, the oldest legitimate epithet should be retained, unless it contravenes other provisions of the Code.
i. K. Schumann combined 3 genera Sloanea L. (1753), Echinocarpus Bl. (1825) and Phoenicosperma Miq. (1865), adopted the oldest one Sloanea L.
ii. When Sida rhombifolia Linn. (1753) and S. rhomboidea Roxb. ex Flem. (1810) are combined, it becomes accepted as Sida rhombifolia Linn.
E. The autonym will get the priority over names of the same date that automatically established it (Art. 57.3 of Sydney Code), e.g.,
i. When Heracleum sibiricum Linn. (1753) included H. sibiricum subsp. lecokii (Godron & Gren.) Nyman (1879), the subsp. sibiricum (1879) automatically established at the same time.
The abbreviated names of the different authors and their full names are:
BSP. = Britton, Sterns and Poggenberg;
Carr. = Carriere;
DC. = A. P. de Candolle;
A. DC. = Alphonse de Candolle;
HBK. = Humboldt, Bonpland and Kunth;
Hook. = William Hooker;
Hook. f. = Sir J. D. Hooker (son of William Hooker), f. represents the Latin word filius, son;
Koch. = Karl Koch;
L. or Linn. = Carolus Linnaeus;
Marsh. = Humphrey Marshall;
Mill. = Miller;
R. Br. = Robert Brown;
R&P = Ruiz Lopez and Pavon;
T&G = Torrey and Gray;
Willd. = Carl Willdenow;
Wm. Br. = William Brown;
W & K = Waldtein and Kitaibel etc.
10. Rejection of Names:
A legitimate name is one in accordance with the Rules of Botanical Nomenclature, while those which do not satisfy the rules are known as illegitimate names. A synonym is a rejected name due to misapplication or difference in taxonomic judgement. Some rules have been framed for the rejection of names.
These are:
i. Superfluous Name:
The name which is given to a taxon when already some name is present in existence is called superfluous name. The superfluous name must be rejected. The Chrysophyllum sericeum Salisb. (1796) is superfluous, because this taxon already has a name C. cainito L.
ii. Basionym:
It is a specific or infraspecific epithet which has priority and is retained when transferred to a new or different taxon. viz. Desmodium ochroleucum Curtis includes Meibomia ochroleuca (Curtis) Kuntze, where the latter is a legitimate name based on the same type in which basionym ochroleuca is correctly retained.
iii. Homonym:
The homonym must be rejected. (It is the same name given to other taxon). The Astragalus rhizanthus Boiss (1843) is a homonym of Astragalus rhizanthus Royle (1835) and it should be rejected.
iv. Tautonyms:
The tautonym must be rejected. (When the specific epithet repeats exactly the generic name is called tautonyms). Malus malus, Linaria linaria are the tautonyms.
v. Nomen Nudum:
The names, those are published without any description, called nomina nuda. They are rejected unless and until published with proper description.
vi. If the name is based on discordant elements and monstrosities should be rejected.
vii. If the name is used in different senses and has become a persistent source of error should be rejected.
viii. If the naming does not follow the rules of nomenclature should be rejected.
11. Typification:
The names of taxa in the rank of family or a lower rank i.e., genus and species are determined by means of nomenclatural types.
A nomenclatural type is that element of a taxon to which the name of a taxon is permanently attached (either as correct name or as a synonym). The nomenclatural type of a species is an individual herbarium specimen mounted on a sheet. It is that element with which the name is permanently attached.
For small herbs, the type consists of more than one individual mounted on a sheet. Careful preservation is essential as they are the records of the present and the past. If a specimen cannot be preserved in dried form it should be recorded by diagnostic drawing, photographs and proper description. The type of a family is a genus and that of a genus is a species.
The following terms are commonly used in the nomenclature of types:
A. Holotype:
It is the one specimen or other element used by the author or designated by him as the nomenclatural type.
B. Isotype:
It is a duplicate copy of the holotype. It is always a specimen. During collection, several plants or several branches of a plant are collected. At that time one is selected as a holotype and the rest are considered as isotypes.
C. Lectotype:
A lectotype is a specimen or other element selected from the original material to serve as nomenclatural type when no holotype was designated at the time of publication or as long as it is missing.
D. Syntype:
If the author does not designate a single holotype from the multiple collections and has used all or more than one specimen then the specimens are called syntypes.
E. Neotype:
A neotype is a specimen or other element selected to serve as nomenclatural type as long as all of the material on which the name of the taxon was based is missing.
F. Paratype:
It is a specimen other than an isotype or a syntype cited by the author while describing a taxon. (Where the author has cited two or more specimens as types, the remaining specimens are designated as paratype and not syntype. However, when no holotype was designated there will also be no paratype because all the cited specimens will be syntypes.)
After the publication of Sydney Code (1983), the above concept of nomenclatural type has now been extended to the names of taxa of higher ranks when the names are ultimately based on generic names.
The genera which typify the alternate specific names should be taken as types of the respective family names which are not based on generic names, e.g., the genus Faba is the type genus of the family Leguminosae (alternate name Fabaceae), Aster that of Compositae (alternate name Asteraceae) and similarly with other six families having alternate names.
The type can be defined as an element on which the original valid description of a taxon is based. The type is simply a nomenclatural concept. The types are the materials to which the respective names always remain attached.