Plant Nomenclature
International
Code of Botanical Nomenclature (ICBN) governs the naming of plants. Six
principles form the basis of the code:
1. Botanical nomenclature is independent of zoological nomenclature.
2. The application of names of taxonomic groups is determined by the means
of nomenclatural types, a specimen.
3. Nomenclature of taxonomic groups is based on priority of publication.
4. Each taxonomic group can have only one correct name, the earliest that
is in accordance with the rules (some exceptions).
5. Scientific names are latinized.
6. The rules are retroactive (some exceptions).
Two purposes of the ICBN:
I. Denote ranks of taxonomic groups, i.e. the hierarchy.
Kingdom
Phylum (Division) - phyta
Class - opsida, Subclass - idae
Order - ales
Family - aceae - except 8 conserved names
Genus
Species
II. Lay down the rules for naming plants within these groups.
One of the primary activities of taxonomy is the naming of new taxa as well
as the remodeling of old taxa. Frequently upon further study it is determined
that some taxa must be remodeled, i.e. divided, united, transferred, or changed
in rank.
1. Divided - make two taxa out of one.
2. United - combine two or more taxa into one.
3. Transferred - decide that one taxon belongs in another, e.g. a species
belongs in another genus.
4. Changed in rank - e.g. make a subspecies a species or vice versa.
Correct Name:
Each taxon can have only one correct name. A correct name must be legitimate
and validly published:
I. Legitimate name - is one in accordance with the rules.
II. Validly published name must be:
1. Effectively published, i.e. published in printed matter generally
available to botanists.
2. In the proper form for that taxon, e.g. family ending in -aceae, or
masculine or feminine ending of epithets.
3. Accompanied by a description or reference to a previously published
taxon.
4. Accompanied by a Latin description or reference to a previously
published taxon.
5. Nomenclatural type must be designated.
Place of publication:
For new world plants use Gray Herbarium Index. For other areas use Index
Kewensis.
Author citations:
See the online Index
to botanical authors for correct abbreviations of authors.
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.
The author's name stays with the particular taxon even if its rank is
changed. For example, if Arnica cordifolia Hook. is transferred to Senecio
by Smith the new name becomes Senecio cordifolia (Hook.) Smith, unless
that epithet already exists in Senecio.
Type specimens:
Nomenclatural Type - specimen of specific rank to which the name of the taxon
is permanently attached.
Some exceptions:
1. Valid publication of vascular plants starts on May 1, 1753,
with a few exceptions.
2. Principle of priority not binding above family rank.
3. Rules retroactive except Latin description required after Jan. 1, 1935.
Types of types:
1. Holotype - the one specimen used or designated by the author as the
nomenclatural type. As long as it is extant it automatically fixes the
application of the name.
2. Isotype - a duplicate (part of a single gathering made by a collector at
one time) of the holotype.
3. Lectotype - a specimen selected from the original material to serve as the
type when no holotype was designated or if it becomes missing.
4. Syntype - any one of two or more specimens cited by the original author
when no holotype was designated or any one of two or more specimens
simultaneously designated as types.
5. Neotype - 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.
Priority for selecting nomenclatural type:
Sometimes no holotype was designated or it is lost. In such a case a new type
must be selected. Listed below, in order of preference, are the sources which
should be considered.
- A. Lectotype
-
- 1. Isotype
- 2. Syntype
B. Neotype - only last resort if none of original material is extant.
Nyms:
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, e.g. if Senecio cordifolia Jones
already exists and we still want to transfer Arnica cordifolia Hook. to
the genus Senecio, the resulting name Senecio cordifolia (Hook.)
Your Name Here would be a homonym. We would therefore have to come up with a new
name Senecio whateverii Your Name Here.
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.) Your
Name Here an illegitimate tautonym.
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.
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