Taxonomy And International Code of Botanical Nomenclature Dr

Taxonomy And International Code of Botanical Nomenclature Dr. Harsh Manchanda Assistant Professor P. G. Govt. College for Girls Sector -11 Chandigarh

TAXONOMY Plant Taxonomy is a science that includes Identification, Nomenclature &Classification of plants. Taxonomy= ‘Taxis’+’Nomous’ Taxis means Arrangement & Nomous means Law or Rule. Thus , it means classification following certain rules or principles.

AIMS AND OBJECTIVES OF PLANT TAXONOMY 1. To identify and give scientific names to all the plants both existent or fossils. 2. To find out the similarities and differences between the plants identified and named. 3. To arrange the plants in a regular sequence. 4. To provide an inventory of plant taxa by means of flora.

5. To devise a natural system of classification and to assign proper status to group of plants 6. To find out the evolutionary history of a species and to find its relation with others. 7. To construct rules and regulations governing the method to name a species , genus or family.

NOMENCLATURE A System of naming plants and animals. The system of naming Plants on scientific basis is known as Plant Nomenclature.

COMMON NAMES The names given to plants on the basis of language of that locality in which the plants are growing are known as Common Names or Vernacular Names.

Why the common names are disadvantageous? 1. Only scientific names are universal, used the same world-wide; e. g. , Hibiscus- for China rose in English, Gurhal in Hindi & Jaba in Bengali. 2. Common names are not consistent. a) A taxon may have more than one common name b) One common name may refer to more than one taxon (e. g. , ”hemlock” for both Tsuga and for Conium maculatum). 3. Many of the organisms have no common name in any language. 4. Common names tell nothing about rank. 5. Common names are misleading.

SCIENTIFIC NAMES To overcome the problem raised by common names , botanists have given scientific names to all the known plants, for International communication. The language selected for this Naming was LATIN. Because: 1. This language is not being used by any country or nation at present. 2. Most of the European languages are derived from Latin. 3. It is considered to be a dead language.

BOTANICAL NOMENCLATURE Botanical nomenclature is the formal scientific naming of plants. In early attempts plants names were usually polynomials e. g. , Caryophyllum saxalitis, folis gramineus, umbellate corymbis. This cumbersome system was replaced by Binomial Nomenclature devised by Linnaeus in 1753 in Species Plantarum.

Carolus Linnaeus 1707 -1778

BINOMIAL NOMENCLATURE In this system , a botanical name consisted of two latinized words, a generic name followed by a specific epithet e. g. , the botanical name of Sunflower is Helianthus annuus. Here, Helianthus designates genus and annuus designates species of this genus.

GENERIC NAME Generic name is usually a noun and singular & may have different types of origin: (a) A genera may be named in honour of a botanist or horticulturist or may be a patron of botany e. g. , Linnaea in honour of Linnaeus (b)Some generic names are of poetic or mythological origin e. g. , Nymphaea denotes lovely water nymphs

SPECIFIC EPITHET The specific epithet is an adjective & may have several origins: (a) It may be in honour of a person e. g. , hookeri for Hooker (b) It may be derived from special characteristics of the plant e. g. , alba for white flowered plant

(c) It may be derived from a geographical location where the plant grows. (d) It may originate from an old common name. (e)It may be named arbitrarily. Generally, the specific epithet is of one word but if it has two words then a hyphon should be placed between them.

Sometimes nomenclature may be of TRINOMIAL or QUADRINOMIAL type. In trinomial the third epithet is of SUBSPECIES & in quadrinomial fourth epithet is of VARIETY.

INTERNATIONAL CODE OF BOTANICAL NOMENCLATURE [ICBN] In the nineteenth century it became increasingly clear that there was a need for rules to govern scientific nomenclature, and initiatives were taken to produce a body of laws. These were published in successively more sophisticated editions. For plants the key dates are 1867 (lois de la nomenclature botanique, ’Paris Code’), 1906 (International Rules of Botanical Nomenclature, 'Vienna Rules') , 1952 (International Code of Botanical Nomenclature, 'Stockholm Code) and 1994 (Tokyo Code)

ICBN The International Code of Botanical Nomenclature (ICBN) is the set of rules and recommendations dealing with the formal botanical names that are given to plants. Its intent is that each taxonomic group (“taxon", plural "taxa") of plants has only one correct name that is accepted worldwide.

Principles of ICBN I. Botanical nomenclature is independent of zoological nomenclature. II. The application of names of taxonomic groups is determined by means of nomenclatural types. III. The nomenclature of a taxonomic group is based upon priority of publication.

Principles of ICBN IV. Each taxonomic group (e. g. , family or genus or species) 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.

RULES OF ICBN Basic Rules The complete scientific name includes genus and species, the name of the scientist who first described the species and the year. By convention that the genus and species are written in italics (or, where that is not possible, underlined). The generic name is always capitalized & the species name is not.

The first letter of the genus is capitalized; the first letter of specific epithet usually is not. EXAMPLES: Dianthus caryophyllus L. Rosa cinnamomea Dianthus caryophyllus or Dianthus caryophyllus “L. ” stands for Linnaeus, who is the authority who first named this plant. When related species in a genus are in a list, it is acceptable after the first species to list them by the first letter of the genus. EXAMPLE: Dianthus caryophyllus, D. chinensis, D. giganteus

If we know the genus (eg. Dianthus) but do not know or do not want to specify the species we can indicate the plant name as follows: EXAMPLE: Dianthus sp. Or if plural --- Dianthus spp.

TAXONOMIC RANKS Taxon is a taxonomic group of plants of any rank e. g. , Hibiscus (genus) is a taxon, Malvaceae (family) is a taxon. The rules of nomenclature prescribe the categories for plant classification. These categories or taxa constitute the unit s of classification. The basic unit of classification is species.

A typical Linnaean hierarchy has seven taxa represented as follows:

The extended Linnaean hierarchy may consist of the following taxonomic ranks:

Categories below the rank of species are: Subspecies Varieties Sub-varieties Forma Clone .

Major Rank Endings Phylum [Division] Subphylum [Subdivision] Class Subclass Super-order Order Suborder Family Subfamily Tribe Subtribe -phyta -phytina -opsida -idae -anae, [-iflorae] -ales -ineae -aceae -oideae -inae

In accordance to ICBN, some traditional names of the families are changed to their alternate names as (New) Apiaceae = Asteraceae = Poaceae = (Traditional) Umbelliferae Compositae Graminae Lamiaceae Arecaceae = Labiatae = Palmae Cruciferae = Brassicaceae

TYPE CONCEPT The naming of taxonomic group is determined by means of nomenclatural types, where a nomenclatural type is thatelement, to which the name of a taxon is permanently attached, either as a correct name or as a synonym.

Some of the imp. Nomenclatural types are: 1. Holotype – A holotype is the one specimen or illustration used by the author, or designated by the author as the nomenclatural type. As long as a holotype is extant, it fixes the application of the name concerned. 2. Isotype- An isotype is any duplicate of the holotype; it is always a specimen.

3. Lectotype – It is a specimen selected from the original material to serve as the type when no holotype was designated or if it becomes missing. 4. Syntype – A syntype is any one of two or more specimens cited by the original author when no holotype was designated. 5. Neotype – It is a specimen selected to serve as the type as long as all of the material on which the name of the taxon was based is missing.

6. Paratype: A paratype is a specimen cited with the original description other than the holotype or syntype. 7. Topotype: It refers to the specimen collected from the same locality.

8. Epitype- An epitype is a specimen or illustration selected to serve as an interpretative type when the holotype, lectotype, or previously designated neotype, or all original material associated with a validly published name, is demonstrably ambiguous and cannot be critically identified for purposes of the precise application of the name of a taxon. When an epitype is designated, the holotype, lectotype, or neotype that the epitype supports must be explicitly cited

EFFECTIVE AND VALID PUBLICATION 1) Name must be effectively published 2) Name must be published in the correct form, properly Latinized with the correct rank ending. 3) Name must be published with a Latin description or diagnosis or with a reference to such. [Vernacular description typically included]. 4) Nomenclatural type must be indicated (for genus and below).

AUTHOR CITATION 1. Joint authors - If only two, both should be cited, e. g. Smith & Jones, or Smith et Jones, if more than two then Smith et al. 2. Name proposal - Sometimes one author proposes but doesn't validly publish the name him/herself. In this case the one who proposed it is listed first followed by ex and the author who validly published it. Ex means validly published by. For example, . Arenaria rossii R. Br. ex Richards. 1823.

3. Publication in anothers work - Sometimes one person supplies the new name for publication in anothers work, e. g. many floras. He/she should get credit so cited as Smith in Jones, or if shortened Smith. 4. Abbreviated names: Usually the names are cited in abbreviated forms but never underlined or italicized e. g. , Vitex Linn. , V. trifolia Linn. etc.

5. Double Citation: If a genus or taxon of lower rank is altered in rank or position, but retains its name or epithet, the name of the author who first published the name or epithet (basionym) must be cited in parenthesis folowed by the name of author who effected the change e. g. , Leucaena latisiliqua (Linn. ) Gillis (1974). . Basionym: Mimosa latisiliqua.

RULE OF PRIORITY Law of Priority says that if a genus or species has been accidentally given two names, only the earlier one is valid. The later name becomes a "junior synonym”. Polygala L. (1753) , Poligalia Neck. (1768), Polygaloides Agosti (1770).

REJECTION OF NAMES 1. Synonym - a rejected name due to misapplication or difference in taxonomic judgment. 2. Basionym - a specific epithet or infraspecific epithet that has priority and is retained when transferred to a new or different taxon, e. g. Arnica cordifolia Hook. if transferred to Senecio by Smith becomes Senecio cordifolia (Hook. ) Smith. The type specimen for Senecio cordifolia is actually that of Arnica cordifolia.

3. Homonym - one of two or more identical names based on different types, only one of which can be legitimate i. e. identical names can not be applied to different taxa. 4. Tautonym - an illegitimate binomial in which the generic name and specific epithet are the same, e. g. if transfer Arnica cordifolia Hook. to the genus Cordifolia would make Cordifolia cordifolia (Hook. )

5. Autonym - an automatically created name for infrageneric or infraspecific taxa, e. g. Arnica subgenus Arnica or Arnica cordifolia Hook. subspecies cordifolia. Not genuina or typicus. 6. Nomen nudum- It is a name that does not fulfill the criteria set by ICBN.

RETENTION OF NAMES Of Taxa which are divided When a genus/species is divided into two or more genera/spp. The original name must be retained for the type species. E. g. , Lychnis dioica was divided by Miller into 2 species which were named as L. dioica L. emend Mill. And L. alba Miller.

RETENTION OF NAMES Of Taxa on Transference If a species is transferred to another genus without change of rank, its original name must be retained if a species with that name does not exist in other genus. The name of original author is bracketed followed by the name of second author. For example, Hydrocotyle asiatica L. when transferred to genus Centella was named as Centella asiatica (Linn. ) Urban.

CHOICE OF NAMES Following are the criteria for the choice of name of a taxon: 1. When the taxon rank is changed, for e. g. , a species becomes a genus, the earliest legitimate name in its new rank is its correct name. 2. When 2 or more taxa of the same rank are united into one, e. g. , two or more genera are united , the oldest legitimate name of these taxa should be retained as the name of united taxon.

TAXONOMY AS A SYNTHETIC DISCIPLINE Taxonomy provides a classification based on evolutionary relationships. But the goal of attaining a truly natural system of classification remains unfulfilled. So , it is essential to have a comprehensive knowledge of the taxa from various aspects and various branches of botany. Therefore , various aspects of botany like anatomy, embryology, phyto-chemistry and the newly developed techniques of molecular biology and new aspects of taxonomy i. e. numerical taxonomy are include under taxonomy and thus, taxonomy has now become a synthetic discipline. Thank you