Genus ( / ˈ dʒ iː n ə s / ; pl. : genera / ˈ dʒ ɛ n ər ə / ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses . In binomial nomenclature , the genus name forms the first part of the binomial species name for each species within the genus.
43-475: See text. Polygonum is a genus of about 130 species of flowering plants in the buckwheat and knotweed family Polygonaceae . Common names include knotweed and knotgrass (though the common names may refer more broadly to plants from Polygonaceae ). In the Middle English glossary of herbs Alphita ( c. 1400–1425), it was known as ars-smerte . There have been various opinions about how broadly
86-557: A species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in the nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,
129-447: A functional pistil . The flowers are arranged in a raceme . The tepals of the flowers are dry and paper-like when mature. The flowers have short styles with partially fused stigmas forming a "head". The fruits are achenes with three sharp edges. The genus Fallopia was first described by Michel Adanson in 1763. He distinguished it from Polygonum and other genera he placed in his family "Persicariae". Adanson did not explain
172-643: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as
215-621: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,
258-424: A membranous ochrea (a sheath around the stem nodes). The flowers are usually bisexual , rarely unisexual , and have five (occasionally four) tepals , the outer being slightly different from the inner ones. There are usually four to six stamens and three (rarely two) styles . The fruit is three-sided. The genus Polygonum was first described by Carl Linnaeus in 1754. The genus name is usually said to be from
301-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for
344-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;
387-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and
430-596: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms
473-614: Is native to temperate and subtropical regions of the Northern Hemisphere , but species have been introduced elsewhere. The genus includes species forming vines and shrubs . Species of Fallopia grow as vines , lianas , shrubs or subshrubs. Unlike species of the related genus Duma , they do not have thorn-like tips to their branches. Nectaries are present outside the flowers (extrafloral). Plants usually have bisexual flowers. More rarely they may be dioecious , each plant only having flowers with either functional stamens or
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#1732847809299516-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,
559-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with
602-552: The Greek πολυ- ( poly -, 'many') and γόνυ ( gonu , 'knee' or 'joint'), in reference to the swollen jointed stem. However, long before Linnaeus, the name was used in Greek and Latin for a plant used medically. Discussing the plant he knew as polygonum in 1655, Matthias Martinius referred to Scribonius Largus (who wrote a list of prescriptions around 47 AD) and gave an alternative etymology, based on γόνος ( gonos , 'offspring', 'seed'),
645-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to
688-799: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;
731-450: The larvae of some Lepidoptera species – see list. Most species are considered weeds in Europe and North America. When the genus is defined narrowly, Polygonum species are annual or perennial herbaceous plants , rarely shrubby , with much branched stems. The leaves are arranged alternately, usually less than 2 cm (0.8 in) long, with a length greater than the width. They have
774-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,
817-469: The French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or the scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of
860-523: The World Online accepted 12 species. Many species at one time placed in Fallopia have been moved to other genera in the subfamily Polygonoideae . Some synonyms are listed below. Crosses between Japanese knotweed and giant knotweed have occurred where the two species grow in close proximity. The hybrid, × Reyllopia conollyana (J.P.Bailey) Galasso ( Reynoutria japonica × Fallopia baldschuanica )
903-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of
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#1732847809299946-521: The circumscription of the genus. A number of species that had been included in Polygonum have been moved into several other genera, including Bistorta , Fagopyrum , Fallopia , Koenigia , Persicaria and Reynoutria . Other genera, such as Polygonella , have been subsumed into Polygonum . As of February 2019, Plants of the World Online accepted 129 species. Many species formerly placed in Polygonum have been moved to other genera in
989-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this
1032-727: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,
1075-489: The genus Reynoutria in a broadly defined Polygonum , as did Bentham and Hooker in 1880. When the genus Fallopia was recognized, as was generally the case from the 1970s onwards, Reynoutria was sometimes included and sometimes not. Thus the Flora of North America in 2005 included Reynoutria in Fallopia , whereas the Flora of China in 2003 separated the two genera. Subsequent molecular phylogenetic studies have confirmed
1118-524: The genus should be defined. For example, buckwheat ( Fagopyrum esculentum ) has sometimes been included in the genus as Polygonum fagopyrum . Former genera such as Polygonella have been subsumed into Polygonum ; other genera have been split off. The genus primarily grows in northern temperate regions. The species are very diverse, ranging from prostrate herbaceous annual plants to erect herbaceous perennial plants . Polygonum species are occasionally eaten by humans, and are used as food plants by
1161-676: The genus. Molecular phylogenetic studies, particularly in the 21st century, have led to major changes. Clarifying the circumscription of genera split from Polygonum was described in 2015 as "still ongoing". Polygonum is placed in the tribe Polygoneae of the subfamily Polygonoideae . Within the tribe, it is most closely related to the genera Duma and Atraphaxis , forming the so-called "DAP clade". Knorringia Polygonum ciliinode (syn. Fallopia ciliinodis ) Duma Atraphaxis Polygonum Reynoutria Muehlenbeckia Fallopia s.s. Between 65 and 300 species have been recognised at various times, depending on
1204-432: The idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of the same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but
1247-628: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,
1290-420: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Fallopia Fallopia is a genus of about 12 species of flowering plants in the buckwheat family , often included in a wider treatment of the related genus Polygonum in the past, and previously including Reynoutria . The genus
1333-542: The meaning of the name then being the Latin foecundus , i.e. 'fecund', 'with many offspring'. The Flora of North America says that a derivation meaning 'many seeds' is the "grammatically correct interpretation". Many members of the family Polygonaceae that are now placed in separate genera were at one time or other placed in Polygonum , including species of Fagopyrum , Fallopia , Persicaria and Reynoutria , and older sources frequently use much wider definitions of
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1376-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus
1419-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this
1462-489: The origin of the name. It is said to be named after the Italian botanist Gabriele Falloppio , known as Fallopius in Latin. He was the superintendent of the botanical garden at Padua and an acclaimed anatomist, being considered a founder of modern anatomy . The status of the genus has varied considerably over time, and its taxonomic history is complicated. For example, Meissner in 1856 placed both Adanson's Fallopia and
1505-526: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for
1548-485: The separation of Fallopia from other related genera. Fallopia is placed in the tribe Polygoneae of the subfamily Polygonoideae . Within the tribe, it is most closely related to the genera Reynoutria and Muehlenbeckia , forming the so-called "RMF clade". Knorringia Polygonum ciliinode (syn. Fallopia ciliinodis ) Duma Atraphaxis Polygonum Reynoutria Muehlenbeckia Fallopia s.s. As of March 2019 , Plants of
1591-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,
1634-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being
1677-579: The subfamily Polygonoideae . Some synonyms are listed below. Several species can be eaten cooked, for example during famines. The species Polygonum cognatum , known locally as "madimak", is regularly consumed in central parts of Turkey. In The Man Who Laughs Victor Hugo wrote of the Comprachicos (child-buyers) who created artificial dwarfs, formed "by anointing babies' spines with the grease of bats, moles and dormice" and using drugs such as "dwarf elder, knotgrass, and daisy juice". The idea of such use
1720-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for
1763-566: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up
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1806-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in
1849-452: Was also known to Shakespeare , as Beatrice K. Otto pointed out, quoting A Midsummer Night's Dream : Get you gone, dwarf; You minimus, of hindering knot-grass made; Genus The composition of a genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including
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