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46-457: Elodea is a genus of eight species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog's-bit family ( Hydrocharitaceae ), Elodea is native to the Americas and is also widely used as aquarium vegetation and laboratory demonstrations of cellular activities. It lives in fresh water. An older name for this genus is Anacharis , which serves as

92-557: 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 ,

138-619: A common name in North America. The introduction of some species of Elodea into waterways in parts of Europe, Australia, Africa, Asia, and New Zealand has created a significant problem and it is now considered a noxious weed in these areas. Elodea canadensis , sometimes called American or Canadian water weed or pond weed, is widely known as the generic water weed. The use of these names causes it to be confused with similar-looking plants, like Brazilian elodea ( Egeria densa ) or hydrilla ( Hydrilla verticillata ). American water weed

184-621: A common origin, but which in fact do not. For example, Latin habēre and German haben both mean 'to have' and are phonetically similar. However, the words evolved from different Proto-Indo-European (PIE) roots: haben , like English have , comes from PIE *kh₂pyé- 'to grasp', and has the Latin cognate capere 'to seize, grasp, capture'. Habēre , on the other hand, is from PIE *gʰabʰ 'to give, to receive', and hence cognate with English give and German geben . Likewise, English much and Spanish mucho look similar and have

230-651: 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

276-628: 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,

322-409: 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

368-412: A similar meaning, but are not cognates: much is from Proto-Germanic *mikilaz < PIE *meǵ- and mucho is from Latin multum < PIE *mel- . A true cognate of much is the archaic Spanish maño 'big'. Cognates are distinguished from other kinds of relationships. An etymon , or ancestor word, is the ultimate source word from which one or more cognates derive. In other words, it

414-427: 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. ;

460-455: 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

506-479: Is also of economic importance as an attractive and easy to keep aquarium plant, although in the states of Alabama, New Hampshire, New York, and South Carolina it has been deemed Elodea densa an invasive species and is illegal to sell. Chemical methods are ineffective in eradicating Elodea – at best they only slow growth for a season or two. As Elodea spreads into new ecosystems, it experiences rapid growth for 5–6 years and then slows as soil nutrients are used up. Elodea

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552-413: Is an attractive aquarium plant and is a good substitute for Brazilian elodea. It can be used for science experiments in classrooms demonstrating how plants use carbon dioxide with the usage of bromothymol blue . The American water weed lives entirely underwater with the exception of small white flowers which bloom at the surface and are attached to the plant by delicate stalks. It produces winter buds from

598-612: 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

644-492: Is regular. Paradigms of conjugations or declensions, the correspondence of which cannot be generally due to chance, have often been used in cognacy assessment. However, beyond paradigms, morphosyntax is often excluded in the assessment of cognacy between words, mainly because structures are usually seen as more subject to borrowing. Still, very complex, non-trivial morphosyntactic structures can rarely take precedence over phonetic shapes to indicate cognates. For instance, Tangut ,

690-460: 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,

736-530: Is that through vegetative reproduction via fragments, mechanical removal methods can contribute to the spread of the plant. Torn fragments can be transported downstream or are introduced to new environments via attachment to boats and anchor chains. 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

782-474: 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

828-483: Is the source of related words in different languages. For example, the etymon of both Welsh ceffyl and Irish capall is the Proto-Celtic * kaballos (all meaning horse ). Descendants are words inherited across a language barrier, coming from a particular etymon in an ancestor language. For example, Russian мо́ре and Polish morze are both descendants of Proto-Slavic * moře (meaning sea ). A root

874-444: Is the source of related words within a single language (no language barrier is crossed). Similar to the distinction between etymon and root , a nuanced distinction can sometimes be made between a descendant and a derivative . A derivative is one of the words which have their source in a root word, and were at some time created from the root word using morphological constructs such as suffixes, prefixes, and slight changes to

920-583: Is threatening aquatic environments across Europe. Chemicals may be used in places that cause undue economic concerns, but very few aquatic herbicides are registered for aquatic use in the EU. Fluridone , the most commonly used aquatic herbicide is highly effective against Hydrilla, but only marginally effective against Elodea, especially at lower use rates. The plants can also be removed from lakes and rivers mechanically. They are extracted either by hand or by using rakes, chains, mowing boats or weed buckets. The problem

966-621: 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

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1012-824: 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;

1058-820: The Paraguayan Guarani panambi , the Eastern Bolivian Guarani panapana , the Cocama and Omagua panama , and the Sirionó ana ana are cognates, derived from the Old Tupi panapana , 'butterfly', maintaining their original meaning in these Tupi languages . Cognates need not have the same meaning, as they may have undergone semantic change as the languages developed independently. For example English starve and Dutch sterven 'to die' or German sterben 'to die' all descend from

1104-404: 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,

1150-473: 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

1196-740: The Proto-Indo-European *nókʷts 'night'. The Indo-European languages have hundreds of such cognate sets, though few of them are as neat as this. The Arabic سلام salām , the Hebrew שלום ‎ shalom , the Assyrian Neo-Aramaic shlama and the Amharic selam 'peace' are cognates, derived from the Proto-Semitic *šalām- 'peace'. The Brazilian Portuguese panapanã , (flock of butterflies in flight),

1242-442: 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

1288-446: 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

1334-737: 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,

1380-432: 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

1426-532: The language of the Xixia Empire, and one Horpa language spoken today in Sichuan , Geshiza, both display a verbal alternation indicating tense, obeying the same morphosyntactic collocational restrictions. Even without regular phonetic correspondences between the stems of the two languages, the cognatic structures indicate secondary cognacy for the stems. False cognates are pairs of words that appear to have

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1472-633: 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,

1518-439: 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. Cognate In historical linguistics , cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language . Because language change can have radical effects on both

1564-403: 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

1610-428: 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

1656-532: The plants will grow in a wide range of conditions, from very shallow to deep water, and in many sediment types. It can even continue to grow uprooted, as floating fragments. It is found throughout temperate North America, where it is one of the most common aquatic plants. American water weed is an important part of lake ecosystems . It provides good habitat for many aquatic invertebrates and cover for young fish and amphibians. Waterfowl, especially ducks, as well as beaver, muskrat and aquatic turtles eat this plant. It

1702-541: 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

1748-983: The same Indo-European root are: night ( English ), Nacht ( German ), nacht ( Dutch , Frisian ), nag ( Afrikaans ), Naach ( Colognian ), natt ( Swedish , Norwegian ), nat ( Danish ), nátt ( Faroese ), nótt ( Icelandic ), noc ( Czech , Slovak , Polish ), ночь, noch ( Russian ), ноќ, noć ( Macedonian ), нощ, nosht ( Bulgarian ), ніч , nich ( Ukrainian ), ноч , noch / noč ( Belarusian ), noč ( Slovene ), noć ( Serbo-Croatian ), nakts ( Latvian ), naktis ( Lithuanian ), nos ( Welsh/Cymraeg ), νύξ, nyx ( Ancient Greek ), νύχτα / nychta ( Modern Greek ), nakt- ( Sanskrit ), natë ( Albanian ), nox , gen. sg. noctis ( Latin ), nuit ( French ), noche ( Spanish ), nochi ( Extremaduran ), nueche ( Asturian ), noite ( Portuguese and Galician ), notte ( Italian ), nit ( Catalan ), nuet/nit/nueit ( Aragonese ), nuèch / nuèit ( Occitan ) and noapte ( Romanian ). These all mean 'night' and derive from

1794-457: The same Proto-Germanic verb, *sterbaną 'to die'. Cognates also do not need to look or sound similar: English father , French père , and Armenian հայր ( hayr ) all descend directly from Proto-Indo-European *ph₂tḗr . An extreme case is Armenian երկու ( erku ) and English two , which descend from Proto-Indo-European *dwóh₁ ; the sound change *dw > erk in Armenian

1840-442: The sound and the meaning of a word, cognates may not be obvious, and it often takes rigorous study of historical sources and the application of the comparative method to establish whether lexemes are cognate. Cognates are distinguished from loanwords , where a word has been borrowed from another language. The English term cognate derives from Latin cognatus , meaning "blood relative". An example of cognates from

1886-497: 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,

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1932-412: 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

1978-569: The stem tips that overwinter on the lake bottom. It also often overwinters as an evergreen plant in mild climates. In the Autumn, leafy stalks will detach from the parent plant, float away, root, and start new plants. This is the American water weed's most important method of spreading, while seed production plays a relatively minor role. Silty sediments and water rich in nutrients favor the growth of American water weed in nutrient-rich lakes. However,

2024-403: 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

2070-576: 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

2116-429: 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

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