21.1. The name of a subdivision of a genus is a combination of a generic name and a subdivisional epithet. A connecting term (subgenus, sectio, series, etc.) is used to denote the rank.
21.2. The epithet is either of the same form as a generic name, or a noun in the genitive plural, or a plural adjective agreeing in gender with the generic name, but not a noun in the genitive singular. It is written with an initial capital letter (see Art. 32.7 and 60.2).
21.3. The epithet in the name of a subdivision of a genus is not to be formed from the name of the genus to which it belongs by adding the prefix Eu- (see also Art. 22.2).
21.4. The use of a binary combination instead of a subdivisional epithet is not admissible. Contrary to Art. 32.1(c), names so constructed are validly published but are to be altered to the proper form without change of author citation or date of publication.
21A.1. When it is desired to indicate the name of a subdivision of the genus to which a particular species belongs in connection with the generic name and specific epithet, the subdivisional epithet should be placed in parentheses between the two; when desirable, the subdivisional rank may also be indicated.
21B.1. Recommendations made for forming the name of a genus (Rec. 20A) apply equally to an epithet of a subdivision of a genus, unless Rec. 21B.2-4 recommend otherwise.
21B.2. The epithet in the name of a subgenus or section is preferably a noun, that in the name of a subsection or lower subdivision of a genus preferably a plural adjective.
21B.3. Authors, when proposing new epithets for names of subdivisions of genera, should avoid those in the form of a noun when other co-ordinate subdivisions of the same genus have them in the form of a plural adjective, and vice-versa. They should also avoid, when proposing an epithet for a name of a subdivision of a genus, one already used for a subdivision of a closely related genus, or one which is identical with the name of such a genus.
21B.4. When a section or a subgenus is raised to the rank of genus, or the inverse change occurs, the original name or epithet should be retained unless the resulting name would be contrary to this Code.
(c) 2006, by International Association for Plant Taxonomy. This page last updated 13.03.2007 .