8 Main Rules of Nomenclature | Plants

The following points highlight the eight main rules of nomenclature. The rules are: 1. Nomenclatural Type 2. Rule of Priority 3. Names of Taxa 4. Effective and Valid Publication 5. Retention of Specific and Infra-specific Epithets 6. Rejection of Names 7. Splitting of a Genus 8. Synonym and Basionym.

Nomenclature: Rule # 1. Nomenclatural Type:

The nomenclatural type is that constituent element (a spec­imen, or a description or a figure) of a taxon to which the name is permanently at­tached. This need not be the most typical or representative element but is the original material on which the description of the taxon is based.

Following kinds of types are recognised:

(a) Holotype:

Specimen or other element designated by the author or used by him as the nomenclatural type.

(b) Isotype:

This is a duplicate of the holotype.

(c) Syntype:

When more than one specimen are cited by the author without mentioning which is the holotype, each specimen is designated as a Syntype.

(d) Paratype:

Specimens cited along with the holotype are designated as Para- types.

(e) Lectotype:

This is a substitute of the holotype when that is lost and is to be selected from the isotypes. When no holotype was designated by the author a speci­men from the original material is selected to be the Lectotype.

(f) Neotype:

When all original materials are missing a Neotype is selected from other materials.

(g) Topotype:

Specimen of a species collected at the same locality as the holo­type.

Nomenclature: Rule # 2. Rule of Priority:

In the case of a family or a taxon below the rank of a family the earliest legitimate name should be considered as valid (or correct). For this purpose 1st May 1753 is taken as the earliest date for all plants excepting the Fungi, some Algae, and the Musci other than the Sphagnaceae.

This means the names appearing in Linnaeus’s Species Plantarum are the earliest names for the purpose of consideration of the Rule of Priority; those published earlier are not to be given priority.

Nomenclature: Rule # 3. Names of Taxa:

The name of a species is a binary combination consisting of the name of the genus followed by a single specific epithet. The name of a genus is a subs­tantive in the singular number. The specific epithet is an adjective and is of the same gender as the generic name, or is a noun in apposition to the generic name. The specific epithet must not exactly repeat the generic name.

The name of an infra-specific taxon is a combination of the name of a species and an infra-specific epithet connected by a term denoting its rank. The name of a genus or of a taxa of higher rank is spelt with a capital initial letter.

All specific and infra-specific epithets should be written with a small initial letter. Formerly it was the custom to spell the epithets with a capital initial letter where the epithets were derived from the names of persons, or were vernacular names, or were former generic names. This is not followed at present.

The name of a family is derived from the name of the genus which is the type for the family. The name of a subfamily, a tribe or a sub-tribe is derived from the name of the type-genus belonging to that subfamily, tribe or sub-tribe.

Endings of the names of taxa above the rank of genus should be in the manner noted below:

Order —”ales” (e.g. Rosales)

Suborder —”ineae” (e.g. Rosineae)

Family —”aceae” (e.g. Rosaceae)

Subfamily —”oideae” (e.g. Rosoideae)

Tribe —”eac”

Subtribe —”inae”

A few family-names although not complying with the above rules are treated as valid because of long usage as such.

These are noted below with their alternative names:

Palmae (Arecaceae from Areca)

Gramineae (Poaceae from Poa)

Cruciferae (Brassicaceae from Brassica)

Leguminosae (Fabaceae from Faba)

Guttiferae (Clusiaceao from Clusia)

Umbelliferae Apiaceae from Apium)

Labiatae (Lamiaceae front Lamium)

Compositae (Asteraceae from Aster).

Nomenclature: Rule # 4. Effective and Valid Publication:

Any printed matter when widely circulated is re­garded as effectively published. It is sufficient, if the printed matter is distributed at least to the botanical institutions with libraries accessible to botanists generally. The date of effective publication is the date on which the printed matter became available.

Valid publication of a name of new taxon is necessary to have it effectively published, to have a correct form and to be accompanied by a description or diagnosis or a reference to a previously published description. For the name of a new taxon to be valid it is necessary that the description or the diagnosis should be in Latin.

Those published earlier to 1st Jan. 1935 are considered valid even if the description or diagnosis were not in Latin. In the case of Algae the date has been fixed as 1st Jan. 1958 instead of 1st Jan. 1935, In the case of recent Algae, the Latin description or diagnosis of a new taxon must be accompanied by an illustration or figure.

Publication of a new name of the rank of family or below on or after 1st January, 1958 is not considered valid if the type is not indicated.

The name of a taxon below the rank of a genus is not validly published unless the name of the genus or species to which it is assigned is validly published.

He who first validly published the name of a taxon is the author of that name. It is necessary to cite the name of the author after the name of the taxon.

Nomenclature: Rule # 5. Retention of Specific and Infra-specific Epithets:

When a species is transferred to another genus without change of rank the specific epithet must be retained. If the name of a genus is changed being illegitimate, the binary combinations for all the species under that genus should be changed also and in doing so the new generic name should be used retaining the older specific epithets.

This rule applies equally to infra-specific taxa. A specific epithet is not illegitimate merely because it was originally published under an illegitimate generic name; it is to be taken into consideration for purpose of priority.

Nomenclature: Rule # 6. Rejection of Names:

A name is to be rejected if it is used in different senses and for that reason has become a source of error. A name is to be rejected if it is based on a type consisting of two or more entirely discordant elements. A name is to be rejected also if it is based on a monstrosity.

Nomenclature: Rule # 7. Splitting of a Genus:

When a genus is divided into 2 or more genera the original generic name must be retained for one of the smaller genera which includes the type species of the undivided genus. This rule applies equally to cases of division of species.

Nomenclature: Rule # 8. Synonym and Basionym:

All names of a taxon other than the valid names are synonyms of that taxon. When the name of a species or of an infra-specific taxon is changed the synonym of which the epithet is to be taken for the valid name, is Basionym for that taxon.