Editing Linnaean taxonomy

{{short description|Rank based classification system for organisms}}
{{More citations needed|date=January 2019}}
[[File:Linné-Systema Naturae 1735.jpg|thumb|right|300px|The title page of ''Systema Naturae'', Leiden (1735)]]

'''Linnaean taxonomy''' can mean either of two related concepts:
# The particular form of [[Taxonomy (biology)|biological classification]] (taxonomy) set up by [[Carl Linnaeus]], as set forth in his ''[[Systema Naturae]]'' (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into ''classes'', and the classes divided 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 [[cladistics|cladistic]] systematics, which groups organisms into [[clade]]s. It is attributed to Linnaeus, although he neither invented the concept of ranked classification (it goes back to [[Plato]] and [[Aristotle]]) 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|''Giraffa camelopardalis'' Linnaeus, 1758]]; or a formal name in the accepted nomenclature (as opposed to a modernistic [[clade]] 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]]. 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 (biology)|priority]] over those of others.{{sfn|Polaszek|2010|p=1}} However, the impact he had on science was not because of the value of his taxonomy.

Linnaeus' kingdoms were in turn divided into ''[[Class (biology)|classes]]'', and they, in turn, into ''[[Order (biology)|orders]]'', ''[[genera]]'' (singular: ''genus''), and ''[[species]]'' (singular: ''species''), with an additional rank lower than species, though these do not precisely correspond to the use of these terms in modern taxonomy.{{sfn|Bihrmann|2021}}

=== Classification of plants ===

In ''Systema Naturae'' (1735), his classes and orders of plants, according to his ''Systema Sexuale'', were not intended to represent natural groups (as opposed to his [[ordo naturalis|''ordines naturales'']] in his ''[[Philosophia Botanica]]'') but only for use in identification. However, in 1737 he published ''Genera Plantarum'' in which he claimed that his classification of genera was a natural system.<ref>{{Cite journal |last1=Müller-Wille |first1=Staffan |last2=Reeds |first2=Karen |date=September 2007 |title=A translation of Carl Linnaeus's introduction to Genera plantarum (1737) |url=http://dx.doi.org/10.1016/j.shpsc.2007.06.003 |journal=Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences |volume=38 |issue=3 |pages=563–572 |doi=10.1016/j.shpsc.2007.06.003 |pmid=17893065 |issn=1369-8486|url-access=subscription }}</ref> His botanical classification and sexual system were used well in the nineteenth century.<ref>{{cite book|author=Comstock, J.L.|year=1837 |title= An introduction to the study of botany: including a treatise on vegetable physiology, and descriptions of the most common plants in the middle and northern states |publisher=Robinson, Pratt & Co.|url=https://books.google.com/books?id=QHnvAAAAMAAJ}}</ref> Within each class were several orders. This system is based on the number and arrangement of male ([[stamen]]s) and female ([[Gynoecium|pistil]]s) organs.{{sfn|Bremer|2007}}
[[File:SN-p837.jpg|thumb|270px|Key to the Sexual System (from the 10th, 1758, edition of the ''Systema Naturae'')]]
[[File:Kalmia latifolia Great Smoky.jpg|thumb|right|''[[Kalmia]]'' is classified according to  Linnaeus' sexual system in class Decandria, order Monogyna, because it has 10 [[stamen]]s and one [[pistil]]]]

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.&nbsp;285–352{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/page/358106#page/297/mode/1up Hexandria monogynia i pp.&nbsp;285–352]}}
** Hexandria polygynia pp.&nbsp;342–343{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/page/358106#page/354/mode/1up Hexandria polyynia i pp.&nbsp;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, [[Ovary (plants)#Half-inferior ovary|perigynous]]
* Classis 13. Polyandria: flowers with many stamens, inserted on the [[Receptacle (botany)|receptacle]]
* Classis 14. Didynamia: flowers with 4 stamens, 2 long and 2 short
** Gymnospermia{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/3/mode/1up  ii pp.&nbsp;561–601]}}
** Angiospermia{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/44/mode/1up  ii pp.&nbsp;602–639]}}
* Classis 15. Tetradynamia: flowers with 6 stamens, 4 long and 2 short{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/82/mode/1up ii pp.&nbsp;640–672]}}
* Classis 16. Monadelphia; flowers with the anthers separate, but the filaments united, at least at the base
** Pentandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/115/mode/1up ii pp.&nbsp;673–675]}}
** Decandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/117/mode/1up ii pp.&nbsp;675–683]}}
** Polyandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/125/mode/1up ii pp.&nbsp;683–698]}}
* Classis 17. Diadelphia; flowers with the stamens united in two separate groups{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/141/mode/1up ii pp.&nbsp;699–781]}}
** Hexandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/3/mode/1up ii pp.&nbsp;699–701]}}
** Octandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/3/mode/1up ii pp.&nbsp;701–706]}}
** Decandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/3/mode/1up ii pp.&nbsp;706–781]}}
* Classis 18. Polyadelphia; flowers with the stamens united in several separate groups{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/224/mode/1up ii pp.&nbsp;782–788]}}
** Pentandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/224/mode/1up ii p.&nbsp;782]}}
** Icosandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/224/mode/1up ii pp.&nbsp;782–783]}}
** Polyandria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/225/mode/1up ii pp.&nbsp;783–788]}}
* Classis 19. Syngenesia; flowers with stamens united by their anthers{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/231/mode/1up ii pp.&nbsp;789–938]}}
** Polygamia aequalis{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/231/mode/1up ii pp.&nbsp;789–845]}}
** Polygamia superba{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/287/mode/1up ii pp.&nbsp;845–904]}}
** Polygamia frustranea{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/346/mode/1up ii pp.&nbsp;904–919]}}
** Polygamia necessaria{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/361/mode/1up ii pp.&nbsp;919–927]}}
** Monogamia{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/370/mode/1up ii pp.&nbsp;928–938]}}
* Classis 20. Gynandria; flowers with the stamens united to the pistils{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/381/mode/1up ii pp.&nbsp;939–]}}
* Classis 21. Monoecia: [[monoecious]] plants
* Classis 22. Dioecia: [[dioecious]] plants
* Classis 23. Polygamia: [[Plant sexual morphology#Plant population|polygamodioecious]] plants
* Classis 24. Cryptogamia: the "flowerless" plants, including [[fern]]s, [[fungus|fungi]], [[algae]], and [[bryophyte]]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.<ref>{{cite web|title=Linnaeus Sexual System|url=http://cronklab.wikidot.com/linnaeus-sexual-system|website=CronkLab|publisher=Biodiversity Research Centre, University of British Columbia|access-date=26 January 2015|ref={{harvid|Linnaeus Sexual System|2015}}}}
</ref> Index to genera p.&nbsp;1201{{sfn|Linnaeus|1753|loc=[https://www.biodiversitylibrary.org/item/13830#page/643/mode/1up Index generum p.&nbsp;1201]}}

By contrast his ''ordines naturales'' numbered 69, from Piperitae to Vagae.

=== Classification for animals ===
[[File:Linnaeus - Regnum Animale (1735).png|thumb|400px|The 1735 classification of 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 in the 10th edition of Systema Naturae|Mammalia]] (mammals)
* Classis 2. [[Aves in the 10th edition of Systema Naturae|Aves]] (birds)
* Classis 3. [[Amphibia in the 10th edition of Systema Naturae|Amphibia]] (amphibians)
* Classis 4. [[Pisces in the 10th edition of Systema Naturae|Pisces]] (fishes)
* Classis 5. [[Insecta in the 10th edition of Systema Naturae|Insecta]] (arthropods)
* Classis 6. [[Vermes in the 10th edition of Systema Naturae|Vermes]] (worms)

=== Classification for minerals ===
His taxonomy of [[mineral]]s has long since been 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 ==
{{Main|Taxonomy (biology)}}

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]] name and a second term, which together uniquely identify each [[species]] of organism within a kingdom. For example, the [[human]] 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]]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 [[Systematics|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 code]]s.

Species can be placed in a [[taxonomic rank|ranked]] [[hierarchy]], starting with either ''[[Domain (biology)|domains]]'' or ''kingdoms''. Domains are divided into [[Kingdom (biology)|kingdoms]]. Kingdoms are divided into ''[[phylum|phyla]]'' (singular: ''phylum'') — for [[animal]]s; the term ''division'', used for [[plant]]s and [[fungi]], 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 ''[[Class (biology)|classes]]'', and they, in turn, into ''[[Order (biology)|orders]]'', ''[[Family (biology)|families]]'', ''[[genus|genera]]'' (singular: ''genus''), and ''[[species]]'' (singular: ''species''). There are ranks below species: in zoology, ''subspecies'' (but see ''[[form (zoology)|form]]'' or ''[[morph (zoology)|morph]]''); in botany, ''variety'' (varietas) and ''form'' (forma), etc.

Groups of organisms at any of these ranks are called ''taxa'' (singular: ''[[taxon]]'') 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]] and [[phylogenetic nomenclature]] has led to a different way of looking at evolution (expressed in many nested [[clade]]s) and this sometimes leads to a desire for more ranks. An example of such complexity is the [[Mammal classification#McKenna.2FBell classification|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]] as the mechanism of biological diversity and species formation, following the 1859 publication of Charles Darwin's ''[[On the Origin of Species]]''. 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 taxon|extant]] and [[extinction|extinct]] 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]], 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 [[monophyly|monophyletic]] (including all descendants) such as genus ''[[Homo]]'', or [[paraphyly|paraphyletic]] (excluding some descendants), such as genus ''[[Australopithecus]]''.

Originally, Linnaeus established three kingdoms in his scheme, namely for [[Plant]]s, [[Animal]]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 [[prokaryote]]s (i.e., bacteria); [[Protist]]a, for protozoans and most algae; and [[fungus|Fungi]].  This five-kingdom scheme is still far from the [[phylogenetics|phylogenetic]] ideal and has largely been supplanted in modern taxonomic work by a division into three domains: [[Bacterium|Bacteria]] and [[Archaea]], which contain the prokaryotes, and [[Eukaryote|Eukaryota]], comprising the remaining forms. These arrangements should not be seen as definitive. They are based on the [[genome]]s of the organisms; as knowledge on this increases, classifications will change.<ref>{{cite journal|author1=Embley, T. A.  |author2=Martin, W. |name-list-style=amp|date=2006 |title=Eukaryotic evolution, changes and challenges. |journal=Nature |volume=440 |issue=7084 |pages=623–630 |doi=10.1038/nature04546 |pmid=16572163 |s2cid=4396543 |url=http://www.nature.com/scitable/content/eukaryotic-evolution-changes-and-challenges-13997647|url-access=subscription }}</ref>

Representing presumptive evolutionary relationships within the framework of Linnaean taxonomy is sometimes seen as problematic, especially given the wide acceptance of [[cladistic]] methodology and numerous [[molecular phylogenetic|molecular phylogenies]] that have challenged long-accepted classifications. Therefore, some systematists have proposed a [[PhyloCode]] to replace it.

== See also ==
* [[History of plant systematics]]
* [[Linnaean Herbarium]]
* [[Phylogenetic tree]]&nbsp;– 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 ==
{{reflist|30em}}

== Bibliography ==<!-- Zoosystema28:165. Zootaxa1519:27. -->
{{refbegin|30em}}
;Books
* {{cite book|last1=Fara|first1=Patricia|author-link=Patricia Fara|title=Sex, Botany and Empire: The Story of Carl Linnaeus and Joseph Banks|date=2003 |publisher=Icon Books |location=Cambridge |isbn=9781840464443 |url=https://books.google.com/books?id=TtmhBQAAQBAJ |ref=none}}
* {{cite book |editor-last1=Frängsmyr |editor-first1=Tore |title=Linnaeus: The Man and His Work |date=1994 |origyear=1983, [[University of California Press]]|edition=revised|publisher=Science History Publications/USA |location=Canton, MA, USA|isbn=978-0-88135-154-5 |url=https://books.google.com/books?id=5kVCAQAAIAAJ| oclc=30154266 |ref=none}}{{link note|note=Original edition available [https://archive.org/details/linnaeusmanhiswo0000unse/mode/2up here] at [[Internet Archive]]}}
* {{cite book |url= https://www.biodiversitylibrary.org/bibliography/669|last=Linnaeus |first=C. |author-link=Carl Linnaeus|title=Species Plantarum | year=1753 |publisher=Laurentii Salvii|location=Stockholm}}
* {{cite book |last1=Polaszek |first1=Andrew |title=Systema Naturae 250 - The Linnaean Ark |date= 2010 |publisher=[[CRC Press]] |location=Boca Raton, FL|isbn=978-1-4200-9502-9 |url=https://books.google.com/books?id=ReWP31_IJSIC |oclc=237886102}}
* [[Richard Dawkins|Dawkins, Richard]]. 2004. ''[[The Ancestor's Tale]]: A Pilgrimage to the Dawn of Life''. Boston: Houghton Mifflin. {{ISBN|0-618-00583-8}}
* Ereshefsky, Marc. 2000. ''The Poverty of the Linnaean Hierarchy: A Philosophical Study of Biological Taxonomy''. Cambridge: Cambridge University Press.
* [[Stephen Jay Gould|Gould, Stephen Jay]]. 1989. ''[[Wonderful Life (book)|Wonderful Life]]: The Burgess Shale and the Nature of History''. W. W. Norton & Co. {{ISBN|0-393-02705-8}}
* Pavord, Anna. ''The Naming of Names: The Search for Order in the World of Plants''. Bloomsbury. {{ISBN|0-7475-7952-0}}
;Articles
* {{cite journal |last1=Bremer |first1=Birgitta |title=Linnaeus' sexual system and flowering plant phylogeny |journal=Nordic Journal of Botany |date=April 2007 |volume=25 |issue=1–2 |pages=5–6 |doi=10.1111/j.0107-055X.2007.00098_12.x|doi-access=free }}
* {{cite journal|last1=George|first1=Sam|author-link1=Samantha George|title='Not Strictly Proper For A Female Pen': Eighteenth-Century Poetry and the Sexuality of Botany|journal=Comparative Critical Studies|date=June 2005|volume=2 |issue=2|pages=191–210 |doi=10.3366/ccs.2005.2.2.191 |ref=none}}
;Websites
* {{cite web |last1=Bihrmann |title=Taxonomy, Carl Linnaeus' system 1753 |url=http://www.bihrmann.com/caudiciforms/div/tax-LIN.asp |website=Birhmann's Caudiciforms |access-date=29 October 2021 |date=2021}}
{{refend}}

== External links ==
* [http://www.bgbm.org/iapt/nomenclature/code/SaintLouis/0000St.Luistitle.htm International Code of Botanical Nomenclature] (Saint Louis Code), Electronic version
* [http://www.iapt-taxon.org/nomen/main.php International Code of Nomenclature for algae, fungi, and plants] (Melbourne Code, 2011), Electronic version
* [https://web.archive.org/web/20150801154338/http://iczn.org/ ICZN website], for zoological nomenclature
* [https://web.archive.org/web/20090524144249/http://www.iczn.org/iczn/index.jsp Text of the ICZN], Electronic version
* [http://www.zoobank.org ZooBank: The World Register of Animal Names]
* [http://www.the-icsp.org/ International Committee on Systematics of Prokaryotes] for bacteria
* [https://web.archive.org/web/20090524144249/http://www.iczn.org/iczn/index.jsp International Code of Zoological Nomenclature. 4th Edition. By the International Union of Biological Sciences]
* [https://www.ncbi.nlm.nih.gov/ICTVdb/ ICTVdB website], for virus nomenclature by the International Union of Microbiological Societies
* [http://tolweb.org Tree of Life]
* [https://web.archive.org/web/20061211145046/http://www.finitesite.com/dandelion/Linnaeus.HTML European Species Names in Linnaean, Czech, English, German and French]

{{List of systems of plant taxonomy}}
{{Carl Linnaeus}}

[[Category:Carl Linnaeus|Taxonomy]]
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