In
botanical nomenclature
Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from taxonomy (biology), taxonomy. Plant taxonomy is concerned with grouping and classifying plants; Botany, botanical nomenclature then provides na ...
, a ''form'' (''forma'', plural ''formae'') is one of the "secondary"
taxonomic rank
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of or ...
s, below that of
variety, which in turn is below that of species; it is an
infraspecific taxon. If more than three ranks are listed in describing a taxon, the "classification" is being specified, but only three parts make up the "name" of the taxon: a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
name, a
specific epithet
In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...
, and an
infraspecific epithet.
The abbreviation "f." or the full "forma" should be put before the infraspecific epithet to indicate the rank. It is not italicised.
For example:
* ''
Acanthocalycium spiniflorum'' f. ''klimpelianum'' or
** ''Acanthocalycium spiniflorum'' forma ''klimpelianum'' (Weidlich & Werderm.) Donald
* ''
Crataegus aestivalis'' (Walter) Torr. & A.Gray var. ''cerasoides'' Sarg. f. ''luculenta'' Sarg. is a classification of a plant whose name is:
** ''Crataegus aestivalis'' (Walter) Torr. & A.Gray f. ''luculenta'' Sarg.
A form usually designates a group with a noticeable morphological deviation. The usual taxonomic practice is that the individuals classified within the form are not necessarily known to be closely related (they may not form a
clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
).
For instance, white-flowered plants of species that usually have coloured flowers can be grouped and named (e.g., as "f. ''alba''"). ''Formae apomicticae'' are sometimes named among plants that reproduce asexually, by
apomixis. There are theoretically countless numbers of forms based on minor genetic differences, and only a few that have particular significance are likely to be named.
See also
*
Form (zoology)
In zoology, the word "form" or "''forma''" (literally Latin for ''form'') is a strictly informal term that is sometimes used to describe organisms. Under the ''International Code of Zoological Nomenclature'' the term has no standing (it is not ac ...
*
Forma specialis, an informal rank used for a parasitic form adapted to a particular host
*
Trinomial nomenclature
*
Variety (botany)
*
Subvariety
*
Plant variety (disambiguation)
*
Cultivar
A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...
*
Hybrid (biology)
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two ...
*
Race (biology)
References
{{DEFAULTSORT:Form (Botany)
Form
Forma taxa