Linnaean taxonomy
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Linnaean taxonomy can mean either of two related concepts: # The particular form of biological classification (taxonomy) set up by
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature ...
, as set forth in his ''
Systema Naturae ' (originally in Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around pr ...
'' (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into ''classes'', and they, in turn, into lower ranks in a hierarchical order. # A term for rank-based classification of organisms, in general. That is, taxonomy in the traditional sense of the word: rank-based scientific classification. This term is especially used as opposed to
cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, ...
systematics, which groups organisms into
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 te ...
s. It is attributed to Linnaeus, although he neither invented the concept of ranked classification (it goes back to
Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first instit ...
and
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ...
) nor gave it its present form. In fact, it does not have an exact present form, as "Linnaean taxonomy" as such does not really exist: it is a collective (abstracting) term for what actually are several separate fields, which use similar approaches. Linnaean name also has two meanings: depending on the context, it may either refer to a formal name given by Linnaeus (personally), such as ''Giraffa camelopardalis'' Linnaeus, 1758, or a formal name in the accepted nomenclature (as opposed to a modernistic
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 te ...
name).


The taxonomy of Linnaeus

In his ''Imperium Naturae'', Linnaeus established three kingdoms, namely ''Regnum Animale'', ''Regnum Vegetabile'' and ''Regnum Lapideum''. This approach, the Animal, Vegetable and Mineral Kingdoms, survives today in the popular mind, notably in the form of the parlour game question: "Is it animal, vegetable or mineral?". The work of Linnaeus had a huge impact on science; it was indispensable as a foundation for biological nomenclature, now regulated by the
nomenclature codes Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or science ...
. Two of his works, the first edition of the '' Species Plantarum'' (1753) for plants and the tenth edition of the ''Systema Naturae'' (1758), are accepted as part of the starting points of nomenclature; his binomials (names for species) and generic names take priority over those of others. However, the impact he had on science was not because of the value of his taxonomy. Linnaeus' kingdoms were in turn divided into '' classes'', and they, in turn, into '' orders'', '' genera'' (singular: ''genus''), and ''
species In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that ...
'' (singular: ''species''), with an additional rank lower than species, though these do not precisely correspond to the use of these terms in modern taxonomy.


Classification of plants

His classes and orders of plants, according to his ''Systema Sexuale'', were never intended to represent natural groups (as opposed to his ''ordines naturales'' in his '' Philosophia Botanica'') but only for use in identification. They were used for that purpose well into the nineteenth century. Within each class were several orders. This system is based on the number and arrangement of male (
stamen The stamen ( plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division An ...
s) and female (
pistil Gynoecium (; ) is most commonly used as a collective term for the parts of a flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The bi ...
s) organs. The Linnaean classes for plants, in the Sexual System, were (page numbers refer to ''Species plantarum''): * Classis 1. Monandria: flowers with 1 stamen * Classis 2. Diandria: flowers with 2 stamens * Classis 3. Triandria: flowers with 3 stamens * Classis 4. Tetrandria: flowers with 4 stamens * Classis 5. Pentandria: flowers with 5 stamens * Classis 6. Hexandria: flowers with 6 stamens ** Hexandria monogynia pp. 285–352 ** Hexandria polygynia pp. 342–343 * Classis 7. Heptandria: flowers with 7 stamens * Classis 8. Octandria: flowers with 8 stamens * Classis 9. Enneandria: flowers with 9 stamens * Classis 10. Decandria: flowers with 10 stamens * Classis 11. Dodecandria: flowers with 11 to 19 stamens * Classis 12. Icosandria: flowers with 20 (or more) stamens, perigynous * Classis 13. Polyandria: flowers with many stamens, inserted on the receptacle * Classis 14. Didynamia: flowers with 4 stamens, 2 long and 2 short ** Gymnospermia ** Angiospermia * Classis 15. Tetradynamia: flowers with 6 stamens, 4 long and 2 short * Classis 16. Monadelphia; flowers with the anthers separate, but the filaments united, at least at the base ** Pentandria ** Decandria ** Polyandria * Classis 17. Diadelphia; flowers with the stamens united in two separate groups ** Hexandria ** Octandria ** Decandria * Classis 18. Polyadelphia; flowers with the stamens united in several separate groups ** Pentandria ** Icosandria ** Polyandria * Classis 19. Syngenesia; flowers with stamens united by their anthers ** Polygamia aequalis ** Polygamia superba ** Polygamia frustranea ** Polygamia necessaria ** Monogamia * Classis 20. Gynandria; flowers with the stamens united to the pistils * Classis 21. Monoecia: monoecious plants * Classis 22. Dioecia:
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduct ...
plants * Classis 23. Polygamia: polygamodioecious plants * Classis 24. Cryptogamia: the "flowerless" plants, including ferns,
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored a ...
,
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organism In biology Biology is the scientific study of life. It is a natural science with a broad scope but has seve ...
, and
bryophyte The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants ( embryophytes): the liverworts, hornworts and moss Mosses are small, non-vascular flower A flower, sometimes known as a blo ...
s The classes based on the number of stamens were then subdivided by the number of pistils, e.g. ''Hexandria monogynia'' with six stamens and one pistil. Index to genera p. 1201 By contrast his ''ordines naturales'' numbered 69, from Piperitae to Vagae.


Classification for animals

Only in the Animal Kingdom is the higher taxonomy of Linnaeus still more or less recognizable and some of these names are still in use, but usually not quite for the same groups. He divided the Animal Kingdom into six classes, in the tenth edition, of 1758, these were: * Classis 1. Mammalia (mammals) * Classis 2.
Aves Birds are a group of warm-blooded vertebrate Vertebrates () comprise all animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, ...
(birds) * Classis 3. Amphibia (amphibians) * Classis 4. Pisces * Classis 5. Insecta * Classis 6. Vermes


Classification for minerals

His taxonomy of
mineral In geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly ove ...
s has long since dropped from use. In the tenth edition, 1758, of the ''Systema Naturae'', the Linnaean classes were: * Classis 1. Petræ * Classis 2. Mineræ * Classis 3. Fossilia * Classis 4. Vitamentra


Rank-based scientific classification

This rank-based method of classifying living organisms was originally popularized by (and much later named for) Linnaeus, although it has changed considerably since his time. The greatest innovation of Linnaeus, and still the most important aspect of this system, is the general use of binomial nomenclature, the combination of a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as virus A virus is a submicroscopic infectious agent that replicates only inside the living cells of an o ...
name and a second term, which together uniquely identify each
species In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that ...
of organism within a kingdom. For example, the
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cult ...
species is uniquely identified within the animal kingdom by the name ''Homo sapiens''. No other species of animal can have this same binomen (the technical term for a binomial in the case of animals). Prior to Linnaean taxonomy, animals were classified according to their mode of movement. Linnaeus's use of binomial nomenclature was anticipated by the theory of definition used in Scholasticism. Scholastic logicians and philosophers of nature defined the species human, for example, as ''Animal rationalis'', where ''animal'' was considered a genus and ''rationalis'' (Latin for "rational") the characteristic distinguishing humans from all other animals. Treating ''animal'' as the immediate genus of the species human, horse, etc. is of little practical use to the biological taxonomist, however. Accordingly, Linnaeus's classification treats ''animal'' as a class including many genera (subordinated to the animal "kingdom" via intermediary classes such as "orders"), and treats ''homo'' as the genus of a species ''Homo sapiens'', with ''sapiens'' (Latin for "knowing" or "understanding") playing a differentiating role analogous to that played, in the Scholastic system, by ''rationalis'' (the word ''homo'', Latin for "human being", was used by the Scholastics to denote a species, not a genus). A strength of Linnaean taxonomy is that it can be used to organize the different kinds of living
organism In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cell ...
s, simply and practically. Every species can be given a unique (and, one hopes, stable) name, as compared with common names that are often neither unique nor consistent from place to place and language to language. This uniqueness and stability are, of course, a result of the acceptance by working systematists (biologists specializing in taxonomy), not merely of the binomial names themselves, but of the rules governing the use of these names, which are laid down in formal nomenclature codes. Species can be placed in a ranked
hierarchy A hierarchy (from Ancient Greek, Greek: , from , 'president of sacred rites') is an arrangement of items (objects, names, values, categories, etc.) that are represented as being "above", "below", or "at the same level as" one another. Hierarchy i ...
, starting with either '' domains'' or ''kingdoms''. Domains are divided into kingdoms. Kingdoms are divided into '' phyla'' (singular: ''phylum'') — for
animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...
s; the term ''division'', used for
plant Plants are predominantly photosynthetic eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota o ...
s and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored a ...
, is equivalent to the rank of phylum (and the current International Code of Botanical Nomenclature allows the use of either term). Phyla (or divisions) are divided into '' classes'', and they, in turn, into '' orders'', '' families'', '' genera'' (singular: ''genus''), and ''
species In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that ...
'' (singular: ''species''). There are ranks below species: in zoology, ''subspecies'' (but see '' form'' or '' morph''); in botany, ''variety'' (varietas) and ''form'' (forma), etc. Groups of organisms at any of these ranks are called ''taxa'' (singular: ''
taxon In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that ...
'') or ''taxonomic groups''. The Linnaean system has proven robust and it remains the only extant working classification system at present that enjoys universal scientific acceptance. However, although the number of ranks is unlimited, in practice any classification becomes more cumbersome the more ranks are added. Among the later subdivisions that have arisen are such entities as phyla, families, and tribes, as well as any number of ranks with prefixes (superfamilies, subfamilies, etc.). The use of newer taxonomic tools such as
cladistics Cladistics (; ) is an approach to biological classification in which organism In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it toge ...
and
phylogenetic nomenclature Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', whi ...
has led to a different way of looking at evolution (expressed in many nested
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 te ...
s) and this sometimes leads to a desire for more ranks. An example of such complexity is the scheme for mammals proposed by McKenna and Bell.


Alternatives

Over time, understanding of the relationships between living things has changed. Linnaeus could only base his scheme on the structural similarities of the different organisms. The greatest change was the widespread acceptance of
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the ...
as the mechanism of biological diversity and species formation, following the 1859 publication of Charles Darwin's ''
On the Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life''),The book's full original title was ''On the Origin of Species by Me ...
''. It then became generally understood that classifications ought to reflect the phylogeny of organisms, their descent by evolution. This led to evolutionary taxonomy, where the various extant and
extinct Extinction is the termination of a kind of organism In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coheren ...
are linked together to construct a phylogeny. This is largely what is meant by the term 'Linnaean taxonomy' when used in a modern context. In
cladistics Cladistics (; ) is an approach to biological classification in which organism In biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it toge ...
, originating in the work of Willi Hennig, 1950 onwards, each taxon is grouped so as to include the common ancestor of the group's members (and thus to avoid phylogeny). Such taxa may be either
monophyletic In cladistics for a group of organisms, monophyly is the condition of being 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 anc ...
(including all descendants) such as genus ''
Homo ''Homo'' () is the genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as virus A virus is a submicroscopic infectious agent that replicates only in ...
'', or paraphyletic (excluding some descendants), such as genus '' Australopithecus''. Originally, Linnaeus established three kingdoms in his scheme, namely for
Plant Plants are predominantly photosynthetic eukaryote Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota o ...
s,
Animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...
s and an additional group for minerals, which has long since been abandoned. Since then, various life forms have been moved into three new kingdoms: Monera, for prokaryotes (i.e., bacteria); Protista, for protozoans and most algae; and
Fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored a ...
. This five kingdom scheme is still far from the phylogenetic ideal and has largely been supplanted in modern taxonomic work by a division into three domains:
Bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were a ...
and
Archaea Archaea ( ; singular archaeon ) is a domain of single-celled organisms. These microorganisms lack cell nuclei and are therefore prokaryotes. Archaea were initially classified as bacteria Bacteria (; singular: bacterium) are ubiq ...
, which contain the prokaryotes, and
Eukaryota Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the ...
, comprising the remaining forms. These arrangements should not be seen as definitive. They are based on the genomes of the organisms; as knowledge on this increases, classifications will change. Representing presumptive evolutionary relationships within the framework of Linnaean taxonomy is sometimes seen as problematic, especially given the wide acceptance of
cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, ...
methodology and numerous molecular phylogenies that have challenged long-accepted classifications. Therefore, some systematists have proposed a PhyloCode to replace it.


See also

* History of plant systematics *
Phylogenetic tree A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree In botany, a tree is a perennial plant with an elongated ...
 – a way to express insights into evolutionary relationships * Zoology mnemonic for a list of mnemonic sentences used to help people remember the list of Linnaean ranks.


References


Bibliography

;Books * * * * * Dawkins, Richard. 2004. '' The Ancestor's Tale: A Pilgrimage to the Dawn of Life''. Boston: Houghton Mifflin. * Ereshefsky, Marc. 2000. ''The Poverty of the Linnaean Hierarchy: A Philosophical Study of Biological Taxonomy''. Cambridge: Cambridge University Press. * Gould, Stephen Jay. 1989. '' Wonderful Life: The Burgess Shale and the Nature of History''. W. W. Norton & Co. * Pavord, Anna. ''The Naming of Names: The Search for Order in the World of Plants''. Bloomsbury. ;Articles * * ;Websites *


External links


International Code of Botanical Nomenclature
(Saint Louis Code), Electronic version
International Code of Nomenclature for algae, fungi, and plants
(Melbourne Code, 2011), Electronic version
ICZN website
for zoological nomenclature
Text of the ICZN
Electronic version
ZooBank: The World Register of Animal Names

International Committee on Systematics of Prokaryotes
for bacteria
International Code of Zoological Nomenclature. 4th Edition. By the International Union of Biological Sciences

ICTVdB website
for virus nomenclature by the International Union of Microbiological Societies
Tree of Life

European Species Names in Linnaean, Czech, English, German and French
{{Carl Linnaeus Taxonomy Taxonomy (biology) Biological nomenclature Botanical nomenclature Zoological nomenclature Swedish inventions