A taxon (plural taxa), or taxonomic unit, is a name designating an organism or group of organisms. A taxon is assigned a rank and can be placed at a particular level in a systematic hierarchy reflecting evolutionary relationships. This article needs additional references or sources for verification. ...

A distinction is to be made between taxa/taxonomy and classification/systematics. The former refers to biological names and the rules of naming. The latter refers to rank ordering of taxa according to presumptive evolutionary (phylogenetic) relationships.

A broad scheme of ranks in hierarchical order:

Domain

Kingdom

Phylum or Division

Class

Order

Family

Genus

Species

Note: "Phylum" applies formally to any biologial domain but traditionally it was always used of animals whereas "Division" was traditionally often used of plants, fungi etc. In biology, a domain (also superregnum, superkingdom, or empire) is the top-level grouping of organisms in scientific classification, higher than a kingdom. ... Ernst Haeckels presentation of a three-kingdom system (Plantae, Protista, Animalia) in his 1866 Generelle Morphologie der Organismen). ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... This article discusses categorisations of organisms. ... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ... In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... The hierarchy of scientific classification In biological classification, family (Latin: familia, plural familiae) is a rank, or a taxon in that rank. ... For other uses, see Genus (disambiguation). ... The hierarchy of scientific classification. ... Look up domain in Wiktionary, the free dictionary. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Subkingdom/Phyla Chytridiomycota Blastocladiomycota Neocallimastigomycota Glomeromycota Zygomycota Dikarya (inc. ...

A simple mnemonic phrase to remember the order is "Dignified Kings Play Chess On Fine Green Silk"; another, highly expedient example is "King Philip's Class Orders the Family Genus to Speak". Not to be confused with pneumonic. ... Chess is a recreational and competitive game for two players. ...

A prefix is used to indicate a ranking of lesser importance. The prefix super- indicates a rank above, the prefix sub- indicates a rank below. In zoology the prefix infra- indicates a rank below sub-. For instance:

Superclass

Class

Subclass

Infraclass

Rank is relative, and restricted to a particular systematic schema. For example, liverworts have been grouped, in various systems of classification, as a family, order, or a class. The use of a narrow set of ranks is challenged by users of cladistics; for example, the mere 10 ranks traditionally used between animal families (governed by the ICZN) and animal phyla (usually the highest relevant rank in taxonomic work) often cannot adequately represent the evolutionary history as more about a lineage's phylogeny becomes known. In addition, the class rank is quite often not an evolutionary but a phenetical and paraphyletic group and as opposed to those ranks governed by the ICZN, can usually not be made monophyletic by exchanging the taxa contained therein. This has given rise to phylogenetic taxonomy and the ongoing development of the PhyloCode, which is to govern the application of taxa to clades. Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... A class is the rank in the scientific classification of organisms in biology below Phylum and above Order. ... In biology, a subclass is one level below a class. ... In taxonomy, an infraclass is a further subdivision of a biological subclass. ... ... It has been suggested that Clade be merged into this article or section. ... The International Code of Zoological Nomenclature (ICZN) is a set of rules in zoology that have one fundamental aim: to provide the maximum universality and continuity in classifying all animals according to taxonomic judgment. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... In biology, phenetics, also known as numerical taxonomy, is an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e. ... Types of Clade (Note: Stem-based is now branch-based, to avoid confusion with the term stem group which means total clade minus crown clade.) The PhyloCode is a developing draft for a formal set of rules governing phylogenetic nomenclature. ... A clade is a term belonging to the discipline of cladistics. ...

See also

• Alpha taxonomy
• Cladistics
• ICBN
• ICZN
• Rank (botany)
• Rank (zoology)
• Segregate (taxonomy)

Taxonomy, sometimes alpha taxonomy, is the science of finding, describing and naming organisms, thus giving rise to taxa. ... It has been suggested that Clade be merged into this article or section. ... The International Code of Botanical Nomenclature is the set of rules according to which plants are given their formal botanical names (scientific names). ... The International Code of Zoological Nomenclature (ICZN) is a set of rules in zoology that have one fundamental aim: to provide the maximum universality and continuity in classifying all animals according to taxonomic judgment. ... In botanical nomenclature, a taxon is usually assigned to a rank in a hierarchy. ... In zoology, a taxon is usually assigned to a rank in a hierarchy. ... In Taxonomy, a segregate, or a segregate taxon is a created when a taxon is divided into several more specific taxa. ...