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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.

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64-450: Subg. Chronosemium subg. Trifolium Clovers , also called trefoils , are plants of the genus Trifolium (from Latin tres  'three' and folium  'leaf'), consisting of about 300 species of flowering plants in the legume family Fabaceae originating in Europe. The genus has a cosmopolitan distribution with the highest diversity in

128-557: 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 ,

192-666: A crop, with negative effects on pollinators, but in the 1990s and 2010s, the cost of industrially-fixed nitrogen rose substantially, approximately doubling, and reviving interest in forage mixes that include clover. As the fixation process in energy-intensive, prices are closely tied to energy prices. The 21st century also took interest in clover as a countermeasure to fight the global pollinator decline . Several species of clover are extensively cultivated as fodder plants . The most widely cultivated clovers are white clover , Trifolium repens , and red clover , Trifolium pratense . Clover, either sown alone or in mixture with ryegrass , has for

256-536: A host-specific strain of bacteria known as rhizobia . This process has evolved multiple times within the legumes, as well as in other species found within the Rosid clade. Legume crops include beans , peas , and soybeans . Within legume root nodules, nitrogen gas (N 2 ) from the atmosphere is converted into ammonia (NH 3 ), which is then assimilated into amino acids (the building blocks of proteins), nucleotides (the building blocks of DNA and RNA as well as

320-643: 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

384-621: 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,

448-497: A long time formed a staple crop for silaging, for several reasons: it grows freely, shooting up again after repeated mowings; it produces an abundant crop; it is palatable to and nutritious for livestock ; it fixes nitrogen using symbiotic bacteria in its root nodules , reducing the need for synthetic fertilizers ; it grows in a great range of soils and climates ; and it is appropriate for either pasturage or green composting . In many areas, particularly on acidic soil , clover

512-409: 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

576-399: A single homeotic mutation. Legumes release organic compounds as secondary metabolites called flavonoids from their roots, which attract the rhizobia to them and which also activate nod genes in the bacteria to produce nod factors and initiate nodule formation. These nod factors initiate root hair curling . The curling begins with the very tip of the root hair curling around

640-459: A soft hairy plant with minute white or pale pink flowers and feathery sepals; Trifolium fragiferum , strawberry clover, with globose, rose-purple heads and swollen calyxes; Trifolium campestre , hop trefoil, on dry pastures and roadsides, the heads of pale yellow flowers suggesting miniature hops; and the somewhat similar Trifolium dubium , common in pastures and roadsides, with smaller heads and small yellow flowers turning dark brown. Clover

704-427: 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. ;

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768-466: A tendency to develop lateral roots in response to abscisic acid may enable the later evolution of root nodules. Some fungi produce nodular structures known as tuberculate ectomycorrhizae on the roots of their plant hosts. Suillus tomentosus , for example, produces these structures with its plant host lodgepole pine ( Pinus contorta var. latifolia ). These structures have, in turn, been shown to host nitrogen fixing bacteria , which contribute

832-455: 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

896-693: Is 63, set on August 2, 2023, by Yoshiharu Watanabe in Japan. The previous record holder, Shigeo Obara, had discovered an 18-leaf clover in 2002, a 21-leaf clover in 2008 and a 56-leaf clover in 2009, also in Japan. The first extensive classification of Trifolium had been done by Michael Zohary and David Heller, and it was subsequently released in 1984. They divided the genus into eight sections: Lotoidea, Paramesus, Mistyllus, Vesicamridula, Chronosemium, Trifolium, Trichoecephalum, and Involucrarium, with Lotoidea placed most basally . Within this classification system, Trifolium repens falls within section Lotoidea ,

960-596: 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

1024-437: Is foraged for by wildlife such as bears, game animals, and birds. Clover is edible by humans, although red clover should be avoided by pregnant women. The plant is a traditional Native American food, which is eaten both raw and after drying and smoking the roots. The seeds from the blossoms are used to make bread. It is also possible to make tea from the blossoms. Shamrock , the traditional Irish symbol, which according to legend

1088-522: Is short-lived because of a combination of insect pests, diseases and nutrient balance; this is known as "clover sickness". When crop rotations are managed so that clover does not recur at intervals shorter than eight years, it grows with much of its pristine vigor. Clovers are most efficiently pollinated by bumblebees , which have declined as a result of agricultural intensification. Honeybees can also pollinate clover, and beekeepers are often in heavy demand from farmers with clover pastures. Farmers reap

1152-460: 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,

1216-474: 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

1280-424: Is the most widely studied type of nodule, but the details are quite different in nodules of peanut and relatives and some other important crops such as lupins where the nodule is formed following direct infection of rhizobia through the epidermis and where infection threads are never formed. Nodules grow around the root, forming a collar-like structure. In these nodules and in the peanut type the central infected tissue

1344-429: Is uniform, lacking the uninfected ells seen in nodules of soybean and many indeterminate types such as peas and clovers. Actinorhizal-type nodules are markedly different structures found in non-legumes. In this type, cells derived from the root cortex form the infected tissue, and the prenodule becomes part of the mature nodule. Despite this seemingly major difference, it is possible to produce such nodules in legumes by

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1408-621: 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

1472-799: 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;

1536-451: The Rhizobium . Within the root tip, a small tube called the infection thread forms, which provides a pathway for the Rhizobium to travel into the root epidermal cells as the root hair continues to curl. Partial curling can even be achieved by nod factor alone. This was demonstrated by the isolation of nod factors and their application to parts of the root hair. The root hairs curled in

1600-432: The legume family – Fabaceae  – with taxa such as kudzu , clovers , soybeans , alfalfa , lupines , peanuts , and rooibos . They contain symbiotic bacteria called rhizobia within the nodules, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants, and this helps to fertilize

1664-404: 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,

1728-500: The root cortex ; they are then surrounded by a plant-derived symbiosome membrane and differentiate into bacteroids that fix nitrogen . Effective nodulation takes place approximately four weeks after crop planting , with the size, and shape of the nodules dependent on the crop. Crops such as soybeans, or peanuts will have larger nodules than forage legumes such as red clover, or alfalfa, since their nitrogen needs are higher. The number of nodules, and their internal color, will indicate

1792-427: The soil . The great majority of legumes have this association, but a few genera (e.g., Styphnolobium ) do not. In many traditional farming practices, fields are rotated through various types of crops, which usually includes one consisting mainly or entirely of a leguminous crop such as clover, in order to take advantage of this. Although by far the majority of plants able to form nitrogen-fixing root nodules are in

1856-469: 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

1920-605: The axils of lateral or adventitious roots and are formed following infection via cracks where these roots emerge and not using root hairs . Their internal structure is quite different from those of the soybean type of nodule. Indeterminate nodules are found in the majority of legumes from all three sub-families, whether in temperate regions or in the tropics. They can be seen in Faboideae legumes such as Pisum (pea), Medicago (alfalfa), Trifolium (clover), and Vicia (vetch) and all mimosoid legumes such as acacia s,

1984-522: The basal position of Lotoidea , because they were ancestral. Aside from considering this section basal, they did not propose relationships between other sections. Since then, molecular data has both questioned and confirmed the proposed phylogeny from Zohary and Heller. A genus-wide molecular study has since proposed a new classification system, made up of two subgenera, Chronosemium and Trifolium. This recent reclassification further divides subgenus Trifolium into eight sections. The molecular data supports

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2048-442: 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

2112-400: The benefits of increased reseeding that occurs with increased bee activity, which means that future clover yields remain abundant. Beekeepers benefit from the clover bloom, as clover is one of the main nectar sources for honeybees . Trifolium repens , white or Dutch clover, is a perennial abundant in meadows and good pastures. The flowers are white or pinkish, becoming brown and deflexed as

2176-597: The corolla fades. Trifolium hybridum , alsike or Swedish clover, is a perennial which was introduced early in the 19th century and has now become naturalized in Britain. The flowers are white or rosy, and resemble those of Trifolium repens . Trifolium medium , meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, has potential for interbreeding with T. pratense to produce perennial crop plants. Other species are: Trifolium arvense , hare's-foot trefoil; found in fields and dry pastures,

2240-414: The direction of the application, demonstrating the action of a root hair attempting to curl around a bacterium. Even application on lateral roots caused curling. This demonstrated that it is the nod factor itself, not the bacterium that causes the stimulation of the curling. When the nod factor is sensed by the root, a number of biochemical and morphological changes happen: cell division is triggered in

2304-461: The few nodulated caesalpinioid legumes such as partridge pea . They earned the name "indeterminate" because they maintain an active apical meristem that produces new cells for growth over the life of the nodule. This results in the nodule having a generally cylindrical shape, which may be extensively branched. Because they are actively growing, indeterminate nodules manifest zones which demarcate different stages of development/symbiosis: This

2368-825: The first lineage to branch off; thus, the ability to fix nitrogen may be plesiomorphic and subsequently lost in most descendants of the original nitrogen-fixing plant; however, it may be that the basic genetic and physiological requirements were present in an incipient state in the last common ancestors of all these plants, but only evolved to full function in some of them: Betulaceae : Alnus (alders) Cannabaceae : Trema Casuarinaceae : ...... Coriariaceae : Coriaria Datiscaceae : Datisca Elaeagnaceae : ...... Myricaceae : ...... Rhamnaceae : ...... Rosaceae : Two main types of nodule have been described in legumes: determinate and indeterminate. Determinate nodules are found on certain tribes of tropical legume such as those of

2432-446: 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

2496-453: The genera Glycine (soybean), Phaseolus (common bean), and Vigna . and on some temperate legumes such as Lotus . These determinate nodules lose meristematic activity shortly after initiation, thus growth is due to cell expansion resulting in mature nodules which are spherical in shape. Another type of determinate nodule is found in a wide range of herbs, shrubs and trees, such as Arachis ( peanut ). These are always associated with

2560-727: 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,

2624-432: 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

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2688-404: The important energy molecule ATP ), and other cellular constituents such as vitamins , flavones , and hormones . Their ability to fix gaseous nitrogen makes legumes an ideal agricultural organism as their requirement for nitrogen fertilizer is reduced. Indeed, high nitrogen content blocks nodule development as there is no benefit for the plant of forming the symbiosis. The energy for splitting

2752-419: The largest and least heterogeneous section. Lotoidea contains species from America, Africa, and Eurasia, considered a clade because of their inflorescence shape, floral structure, and legume that protrudes from the calyx. However, these traits are not unique to the section, and are shared with many other species in other sections. Zohary and Heller argued that the presence of these traits in other sections proved

2816-628: 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,

2880-530: The legume family Fabaceae , there are a few exceptions: The ability to fix nitrogen is far from universally present in these families. For instance, of 122 genera in the Rosaceae , only 4 genera are capable of fixing nitrogen. All these families belong to the orders Cucurbitales , Fagales , and Rosales , which together with the Fabales form a nitrogen-fixing clade (NFC) of eurosids . In this clade, Fabales were

2944-411: 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. Root nodules Root nodules are found on the roots of plants , primarily legumes , that form a symbiosis with nitrogen-fixing bacteria . Under nitrogen -limiting conditions, capable plants form a symbiotic relationship with

3008-608: The loss of AON receptor kinase activity, suggesting that nodule growth and root development are functionally linked. Investigations into the mechanisms of nodule formation showed that the ENOD40 gene, coding for a 12–13 amino acid protein [41], is up-regulated during nodule formation [3]. Root nodules apparently have evolved three times within the Fabaceae but are rare outside that family. The propensity of these plants to develop root nodules seems to relate to their root structure. In particular,

3072-632: The monophyletic nature of three sections proposed by Zohary and Heller ( Tripholium, Paramesus, and Trichoecepalum ), but not of Lotoidea (members of this section have since been reclassified into five other sections). Other molecular studies, although smaller, support the need to reorganize Lotoidea. 291 species of Trifolium are accepted: 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

3136-403: 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

3200-428: 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

3264-489: The nitrogen gas in the nodule comes from sugar that is translocated from the leaf (a product of photosynthesis ). Malate as a breakdown product of sucrose is the direct carbon source for the bacteroid. Nitrogen fixation in the nodule is very oxygen sensitive. Legume nodules harbor an iron containing protein called leghaemoglobin , closely related to animal myoglobin , to facilitate the diffusion of oxygen gas used in respiration. Plants that contribute to N2 fixation include

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3328-526: 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

3392-686: The rarer it is; see four-leaf clover ), with stipules adnate to the leaf-stalk, and heads or dense spikes of small red, purple, white, or yellow flowers; the small, few-seeded pods are enclosed in the calyx . Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago ( alfalfa or Calvary clover ). As legumes , clovers fix nitrogen using symbiotic bacteria in their root nodules , and are used as an alternative or supplement to synthetic nitrogen fertilizers . They are also valuable food source for grazing livestock and bees. The domestication of clover caused substantial increases in agricultural productivity. Clover

3456-428: The root to create the nodule, and the root hair growth is redirected to curl around the bacteria multiple times until it fully encapsulates one or more bacteria. The bacteria encapsulated divide multiple times, forming a microcolony . From this microcolony, the bacteria enter the developing nodule through the infection thread, which grows through the root hair into the basal part of the epidermis cell, and onwards into

3520-501: The rural landscape; adding clover made livestock feed more nutritious. Honey production also rose drastically, and clover remained the main nectar source for bees until the mid-twentieth century. Clover was carried around the world as a crop by European colonists , and some clover species became invasive in some areas. Imports of guano and the development of the Haber-Bosch process in the 20th century substantially displaced clover as

3584-497: 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,

3648-412: 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

3712-937: The status of nitrogen fixation in the plant. Nodulation is controlled by a variety of processes, both external (heat, acidic soils, drought, nitrate) and internal (autoregulation of nodulation, ethylene). Autoregulation of nodulation controls nodule numbers per plant through a systemic process involving the leaf. Leaf tissue senses the early nodulation events in the root through an unknown chemical signal, then restricts further nodule development in newly developing root tissue. The Leucine rich repeat (LRR) receptor kinases (NARK in soybean ( Glycine max ); HAR1 in Lotus japonicus , SUNN in Medicago truncatula ) are essential for autoregulation of nodulation (AON). Mutation leading to loss of function in these AON receptor kinases leads to supernodulation or hypernodulation. Often root growth abnormalities accompany

3776-403: 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

3840-455: The temperate Northern Hemisphere , but many species also occur in South America and Africa , including at high altitudes on mountains in the tropics. They are small annual , biennial , or short-lived perennial herbaceous plants, typically growing up to 30 cm (12 in) tall. The leaves are trifoliate (rarely, they have four or more leaflets; the more leaflets the leaf has,

3904-566: 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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3968-429: 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

4032-573: Was coined by Saint Patrick for the Holy Trinity , is commonly associated with clover, although alternatively sometimes with the various species within the genus Oxalis , which are also trifoliate. Clovers occasionally have four leaflets, instead of the usual three. These four-leaf clovers , like other rarities, are considered lucky. Clovers can also have five, six, or more leaflets, but these are rarer still. The clover's outer leaf structure varies in physical orientation. The record for most leaflets

4096-520: Was first domesticated in Spain in around the year 1000. During European urbanization, crop rotations involving clover became essential for replacing the fixed nitrogen exported to cities as food. Increased soil nitrogen levels from the spreading use of clover were one of the main reasons why European agricultural production in 1880 was about 275% of the production in 1750. Fields of clover, used as forage and newly-invented silage , became an important part of

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