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Let us learn about Nomenclature Plants. After reading this article you will learn about: 1. History of Nomenclature Plants 2. Common Names of the Nomenclature Plants 3. Botanical Names 4. International Rules 5. Main Points of the International Code 6. Advantages of Binomial System.
History of Nomenclature Plants:
The present day binomial system of nomenclature has a long evolutionary development. In near about 200 B.C. Cato in his monumental work ‘De Re Rustica’ used two names for plants, although he lacked the modern concept of genera and species. Later on the descriptive Greek nouns used for genera were translated into Latin, where it took the form of two words, i.e., binary generic names.
According to another tendency a descriptive phrase was given for the specific name. These methods resulted in the so called polynomials. In the middle of sixteenth century, Brunfels changed many binary generic names to single ones. A few years later Dodonaeus followed the binomial usage similar in principal to that of today’s binomial system of nomenclature.
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Gaspard Bauhin wrote his monumental work ‘Pinax’ in 1623, in which he has given a list of about 6,000 plants. He used the binomial system extensively to give names to the plants.
None of these workers could make a permanent impression upon the botanical world of that time and works of the writers of those days continued to appear having mixed usage— monomial, binomial, trinomial and polynomial.
In those times the names of the plants were composed of several words in a series, constituting more or less a description of the plants. In 1753 Linnaeus published his great work ‘Species Plantaruni where he employed the binomial system to name the plants in true sense.
Augustin de Candolle’s Theorie elementaire de la botanique published in 1813 provided the first significant work since the publications of Linnaeus on nomenclature and morphology of the plants. In this work for the first time, a complete and detailed set of rules on plant nomenclature was given.
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In 1821, Stendel’s Nomenclator botanicus was published, which comprised a list of the Latin names of all flowering plants known by then. The second edition of this work appeared in 1840. Nomenclature was used universally by the botanists, and formed the basis of the Index Kewensis.
Common Names of the Nomenclature Plants:
The plants have been provided with names by the different people of the different regions of the world in their own languages. These common or local names of the plants have their own weaknesses.
There are three main defects in common names:
(i) They may be quite indefinite, e.g., Pansy has been provided with fifty English names,
(ii) They are restricted to the people of one language or even one section of a country.
(iii) They are not regulated by any constituted authority. These common names give great trouble to a plant collector in a foreign country. There he feels the local names to be more difficult than the botanical names.
Botanical Names of the Nomenclature Plants:
At the present time each kind of plant is given a generic name followed by a specific name or epithet. The generic name is a noun, and the specific epithet is an adjective indicating which of the several members of the genus has been considered. The genus name is always capitalized.
The modern tendency is not to capitalize the specific name regardless of its derivation. Binomials are frequently descriptive of the plants and are usually derived from Greek or Latin, since these languages are internationally known by scholars. For example Coffea arabica Linn., stands for coffee; Ficus elastica Roxb., for India rubber, Helianthus annuus Linn., for sunflower, etc.
Binomials when written should always be underlined and when printed they must be in italicized type. The name or the abbreviated name of the scientist who first described the species follows the binomial-such as Coffea arabica Linn.; Mangifera Indica Linn.; Rosa alba Linn.; Santalum album Linn., etc. Linn., stands for the name of the great taxonomist Linnaeus; Albizia procera Benth. ; Aloe barbadensis Mill.; Kochia indica Wight; Mussaenda glabrala Hutch.; Solarium grandiflorum Ruiz and Pav., here each binomial is followed by the abbreviated name of the scientist who first described the species.
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Some binomials are followed by two names, the first of which is within the brackets, thus Albizia lebbeck (Linn.) Benth. The name within brackets is that of the person who first described the species. The name which follows the parenthesis is that of the person who is responsible for the currently recognized binomial.
Accordingly, Linnaeus described the plant for the first time and Bentham corrected the name later on. The other such examples are – Albizia chinensis (Osbeck) Merr.; Alocacia indica (Roxb.) Schott. Amorphophallus campanulatus (Roxb.) Blume ex Dene; Brassica juncea (Linn.) Czern. and Cors. var. Cuneifolia Roxb.; Butea monosperma (Lamk.) Taubert; Feronia limonia (Linn.) Swingle, etc.
The reason for such author citations aids the taxonomist in finding the original and subsequent descriptions of a plant when necessary, and to avoid confusion when different workers use the same binomial accidentally to name different species. To aid the taxonomist further, the year in which the plant was described is sometimes written after the author’s name following the binomial.
International Rules of Botanical Nomenclature:
In 1950, the seventh international botanical congress was held at Stockholm and the rules of nomenclature were the subject of lengthy and considered discussions. Many minor changes and refinements were legislated.
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Thereafter in 1956 the rules have been propounded by Lanjouw as the result of thorough study of many years.
They are as follows:
1. Long generic names with difficult pronunciation must be avoided;
2. A generic and a specific name is given to a perfectly named plant;
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3. The specific name must differentiate a plant from all allied species;
4. The species is not distinguished by its size;
5. The specific differences of a plant have no concern with the original place of the plant;
6. colour should not be treated as a specific difference;
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7. Each plant species must possess a generic name;
8. The generic name must be followed by a specific name;
9. The shorter specific name is always well and good.
The above Linnean principles are quite simple, the role of codifying such rules has been taken up by various International Congresses, which have clarified some rules, modified others, and when necessary have established new ones. In all these changes the main aim has been to produce a uniform system.
The 1956 edition of the code gives detailed instructions on the steps to be taken when any change appears necessary. Such a change is first proposed to the various nomenclature committees elected by the International Botanical Congress and these committees make their recommendations on the subject in preliminary way.
The recommendations are then submitted to a vote by post from all the members of the International Association for Plant Taxonomy, from the authors themselves, and from the members of the committees.
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During the International Botanical Congress all officially enrolled members of the Section cast their final vote. After the inception of the journal ‘Taxon’, every change that has been proposed is fully discussed in the journal before any decision is taken on the subject. Any proposal for a change receives full consideration before it is put up for confirmation or rejection during the session of the congress.
It is to be noted that during the last three or four International Botanical Congresses there have been but few changes, except perhaps in the rearrangement of the code and in some less important points of nomenclature.
Main Points of the International Code for Nomenclature Plants:
The code is divided into three parts:
(i) Principles,
(ii) Rules and
(iii) Recommendations.
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In addition there are few interesting appendices. The principles are basic points on which the code is based. They do not give detailed rules about nomenclature, but show the main ideas that have guided the compilers of the Code, and should be kept in view by any botanist attempting to publish a new taxon.
According to this section of the code, every taxon or group of plants can bear only one correct name and vice versa a name could be applied to one group of plants. The rules give detailed prescriptions on all the points connected with the naming of plants. The recommendations are practical applications of the rules.
Some More Important Rules:
1. The rank of taxa:
In the 1956 edition of the code, the word ‘taxon’ has been introduced for the first time, to signify “taxonomic groups of any rank” (Article 1). The rank of species is basic; one or more species make up a genus; one or more genera make up a family, one or more families form an order, one or more orders make up a class, one or more classes make up a division-, several divisions make up the Vegetable Kingdom.
It is to be noted that the Code does not recognize “Natural Order”, a term often used in older books for the modem equivalent of “family” of the code.
The code has special provisions for the naming of the various taxa. The names of families must ordinarily end in – aceae, those of orders in – ales, and both should be treated as feminine plural nouns. Accordingly it is wrong to say, e.g., “The Amaranthaceae consists often genera.
” The correct way is to say, “The Amaranthaceae consist of ten genera” or the Papilionaceae are a family of the Leguminosae, which include two other families, Caesalpiniaceae and Mimosaceae.” Names of sub-families, e.g., Amaranthoideae; of tribes, e.g., Amarantheae; of sub-tribes, e.g., Amaranthinae, are all plural names and should be treated like the name of the family in this respect.
2. The type method:
This is a modification introduced in the code. According to Principle II, “The application of name of taxonomic groups is determined by means of nomenclatural types.” This means that when a species is described as new, the author must indicate which is the type of specimen on which the new species is based.
In the case of species, the type is an individual specimen, which is the type specimen on which the new species is based. In the small herbaceous plants all mounted on one herbarium sheet, the whole sheet may be marked as the type. When a specimen cannot be preserved, an illustration or figure or a description may be a type. The type of a genus is a species; that of a family is a genus.
In the nomenclature of types, several terms are used which are as follows:
The type or holotype is the one element chosen by the author as the nomenclatural type. An isotype is a duplicate of the type or holotype, e.g., if several branches of a tree are collected at the same time, one specimen may be chosen as the type, the rest are isotypes.
Similarly, if a number of small herbaceous plants are collected at the same time, all belonging to the same new species, one may be selected as the holotype, the rest are isotypes. If they are mounted on the same herbarium sheet, they may be all part of the holotype (Article, 10).
A ‘paratype’ is a “specimen cited with the original description other than the holotype or isotype(s).” A paratype usually is a specimen from a collection other than the type on which the description of the new taxon has been based. Thus, there can be only one sheet of holotype, whereas a number of sheets of isotypes and paratypes.
When an author describes a new species and cites two or more specimens, they become the syntypes, if none of them individually has been designated the type or if more than one has been so designated.
“A lectotype is a specimen or other element selected from the original material to serve as nomenclatural type when the holotype was not designated at the time of publication or for so long as it is missing.” When two or more specimens have been designated as types by the author, they become syntypes, and one must be chosen as a lectotype.
However, when all the material, on which the description of a new species was based, is missing, then a neo-type must be selected, and the selection once made must be followed by subsequent taxonomists. This seems to be the case with many of the new taxa described by Roxburgh (1814), for which no actual specimen was either designated or preserved.
The fixing of the type specimen for a species or of the type in general for taxa below the rank of order is considered so important in the Code that Article 35 prescribes that “publication on or after January 1, 1958, of the name of a new taxon of recent plants of the rank of order or below is valid only when the nomenclatural type is indicated.” (Santapau, 1959)
3. Priority:
With a few exceptions, where alternative names are permitted, each taxon of plants can bear only one correct name; “the correct name is the earliest legitimate one validly published; except in cases of limitation of priority by conservation.”
4. Tautonyms:
“The name of a species is a binary combination consisting of the name of the genus followed by a single specific epithet” (Article, 23). The Code gives to authors very great latitude in the selection of names, always provided that the specific name has not been used previously in the genus.
There is one case, however, which is specifically condemned as illegitimate and that is the use of tautonyms, i.e., when the specific name repeats unaltered the generic name, e.g., Malus malus Britt. This method is accepted in zoological nomenclature, where such names are coined, e.g., Turdus turdus or Corvus corvus, etc.
In botanical nomenclature, however, this is condemned. Art., 70(4). Thus, doubts have arisen about the validity of such names as Sesbania sesban or Samanea saman, etc.
Some authors have expressed strongly against such names, while on the other hand, Merrill (1912, 1916) accepts them as valid on the ground that a tautonym is only a name that repeats unaltered the generic name, and the names mentioned above do not repeat the generic name in full. Thus, such names can be taken as valid until a further, International Botanical Congress decides the matter.
5. Names of families:
The name of a family is a plural adjective and is formed by adding the suffix-aceae to the stem of a legitimate name of an included genus, e.g., Rosaceae from Rosa, Linaceae from Linum and Cucurbitaceae from Cucurbita.
The new names of the following eight families are:
Palmae = Arecaceae
Gramineae = Poaceae
Cruciferae = Brassicaceae
Leguminosae = Fabaceae
Gutti ferae = Clusiaceae
Umbelliferae = Apiaceae
Labiatae = Lamiaceae
Compositae = Asteraceae
6. Names of infra-specific taxa:
There is one case where repetition of the names is not only allowed, but ordered. Article 26 prescribes that the name of an infra-specific taxon (i.e., subspecies, variety or form) must be the same as that of the higher taxon, if the lower taxon includes the type of the higher one.
Thus, if a species is divided into varieties, the one that contains the type of the species must be called by the same name as the species and not var., genuina or var., typica (Art., 71), as often used to be called before.
For example, Carissa congesta Wt., of Khandala on the Western Ghats has two varieties:
(i) The typical plant, var., congesta (without name of author after the variety) and (ii) Var., albida Sant.
If the species has been divided into sub-species, varieties, forms, etc., then a plant is called Carissa congesta Wt., subsp., congesta, var., congesta, f., congesta, if the type of each higher rank is included in the lower division, the name Andropogon sorghum subsp., halepensis (L) Hackel var., halepensis is legitimate since the subspecies and the variety have the same type and the epithet must be repeated under (Art., 26; Art. 27, Santapau).
7. Effective and valid publication of new taxa:
Publication is effective when one can expect that the general botanical public may come to know of the publication (Santapau). According to Art., 29, publication is effective only when printed matter is distributed to the general public or atleast to botanical institutions with libraries accessible to botanists.
It is not effective by communication of a new names at a public meeting such as during the annual session of the Indian Science Congress, nor by placing of names in collections or gardens open to the public as for instance by labelling one’s specimens and placing them in public herbaria, where visitors may see the names. The date of the effective publication is the date on which the printed matter became available.
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The following are the conditions attached to the publication of new taxa for validity.
1. Publication must be effective.
2. There must be a description of the new taxon, or a reference to a previously and effectively published description.
3. A combination is not validly published unless the author actually makes it (Art., 32).
4. Publication must be done in Latin (Art., 34) or with reference to a previously published Latin description.
5. When all the conditions for valid publication are not fulfilled at one and the same time, publication becomes valid when the last condition has been fulfilled. Thus, a publication is invalid if a botanist forgets to indicate the type of his new taxa, but it becomes valid when the type of the taxon has been indicated. The date of such publication will be when the type was indicated.
8. Changes in name when taxa are divided fused or altered:
When a genus is divided into two or more genera, or a species is split into two or more species, the original generic or specific name must be retained for the new taxon containing the type; this applies also to infra-specific taxa.
When a section of a genus or species is transferred to another genus or species without alteration in rank, the original name must be retained whenever possible.
When the rank of a genus or infra-generic taxon is changed, the correct name or epithet is the earliest legitimate one available in the new rank.
When taxa of the same rank are united into one, the oldest legitimate name must be used for the new combined taxon, if the names are of the same date, the author who first unites them has the right to choose one of the names and his choice must be followed by subsequent botanists.
9. Form and spelling of names:
As per Code, authors have full liberty to coin their names. Authors are recommended not to make such names too long, nor too difficult to pronounce. In any case such names should be treated as Latin names.
When the name is actually taken from the Latin language, it retains the original gender and spelling. When the name is taken from the vernaculars, the author assigns a gender to it, and this must be followed by subsequent botanists. Names of genera and higher taxa are written with a capital initial letter. Specific names should be written with a small initial letter.
Advantages of Binomial System of Nomenclature Plants:
The binomials are more definite and precise than the common names. They are usually derived from Greek or Latin, since these languages are internationally known by scholars. They are frequently descriptive of the organism or plants. They and the taxonomists in finding the original and subsequent descriptions which indicate the systematic relationships.
