In botanical nomenclature, a ''form'' (''forma'', plural ''formae'') is one of the "secondary"

taxonomic rank In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system consists of species, genus, family, order, class, phylum, kingdom, domain. While ...

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 ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

name, a specific epithet, 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 ''Acanthocalycium'' is a genus of cactus consisting of several species from Argentina. The taxon name comes from Greek ''akantha'' (meaning ''prickly'') and ''kalyx'' (meaning ''buds''), which refers to the spines on the floral tubes. These plan ...

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 A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...

). 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.

References

{{DEFAULTSORT:Form (Botany)

Form Form is the shape, visual appearance, or configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to write or enter data * ...

Plant taxonomy Forma taxa

See also

References