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.
49-461: See text . Huperzia is a genus of lycophyte plants, sometimes known as the firmosses or fir clubmosses ; the Flora of North America calls them gemma fir-mosses . This genus was originally included in the related genus Lycopodium , from which it differs in having undifferentiated sporangial leaves, and the sporangia not formed into apical cones. The common name firmoss , used for some of
98-525: A handful of species in each of the spikemosses , other ferns, Gnetales , and cycads . The first important monograph on epiphytic plant ecology was written by A. F. W. Schimper ( Die epiphytische Vegetation Amerikas , 1888). Assemblages of large epiphytes occur most abundantly in moist tropical forests , but mosses and lichens occur as epiphytes in almost all biomes. In Europe there are no dedicated epiphytic plants using roots, but rich assemblages of mosses and lichens grow on trees in damp areas (mainly
147-651: 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
196-628: 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,
245-500: A one-genus or a three-genus division of the subfamily produced monophyletic taxa. The authors preferred the three-genus division, recognizing Huperzia , Phlegmariurus and Phylloglossum . Their preferred hypothesis for the relationships of the three genera was: Phylloglossum Huperzia Phlegmariurus The majority of the species formerly placed in a broadly defined Huperzia belong in Phlegmariurus . Earlier,
294-409: 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
343-425: A significant effect on the microenvironment of their host, and of ecosystems where they are abundant, as they hold water in the canopy and decrease water input to the soil. Some non-vascular epiphytes such as lichens and mosses are well known for their ability to take up water rapidly. Epiphytes create a significantly cooler and more moist environment in the host plant canopy, potentially greatly reducing water loss by
392-427: 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. ;
441-455: 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
490-399: Is a plant that spends only half of its life without the ground before the roots can reach or make contact with the ground. Orchids are a common example of holo-epiphytes and Strangler Figs are an example of hemi-epiphytes. Epiphytes are not connected to the soil, and consequently must get nutrients from other sources, such as fog, dew, rain and mist, or from nutrients being released from
539-612: 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
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#1732781177212588-457: Is not a plant may be called an epibiont . Epiphytes are usually found in the temperate zone (e.g., many mosses , liverworts , lichens , and algae ) or in the tropics (e.g., many ferns , cacti , orchids , and bromeliads ). Epiphyte species make good houseplants due to their minimal water and soil requirements. Epiphytes provide a rich and diverse habitat for other organisms including animals, fungi, bacteria, and myxomycetes . Epiphyte
637-616: Is one of the subdivisions of the Raunkiær system . The term epiphytic derives from the Greek epi- (meaning 'upon') and phyton (meaning 'plant'). Epiphytic plants are sometimes called "air plants" because they do not root in soil. However, that term is inaccurate, as there are many aquatic species of algae that are epiphytes on other aquatic plants (seaweeds or aquatic angiosperms ). The best-known epiphytic plants include mosses , orchids , and bromeliads such as Spanish moss (of
686-460: 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,
735-474: 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
784-501: The Flora of North America had also separated Huperzia from Phegmariurus . However, Phlegmariurus is difficult to separate morphologically, and others have preferred the one-genus division of the subfamily. The PPG I classification stated there were 25 species in the genus Huperzia . As of June 2024, World Ferns listed the following species, noting that "many species still need transfer into other split genera". The following hybrids have been described: As circumscribed in
833-621: 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
882-824: 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;
931-419: 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 ,
980-404: 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,
1029-552: The Arabian Peninsula and Western Asia. 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 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
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#17327811772121078-532: The PPG I classification, Huperzia is distributed in temperate, arctic and alpine habitats, including mountains in tropical Asia. Its species are terrestrial or grow on rocks. Phlegmariurus is epiphytic , and has a worldwide tropical distribution, so when Huperzia is defined broadly to include all three genera of the subfamily Huperzioideae, it has an almost worldwide distribution, absent mainly in North Africa,
1127-441: The apex of shoots, and migrate downwards inside the cortex of the stem to emerge at soil level. The unbranched gametophytes are not photosynthetic, but rather subterranean and mycorrhizal . The Flora of North America distinguishes Huperzia from the epiphytic tropical genus Phlegmariurus on the basis of differences such as the former's complex and specialized shoots, the gemmae and the branchlets on which they are borne, and
1176-442: 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
1225-411: The diversity and biomass of the ecosystem in which they occur, like any other organism. They are an important source of food for many species. Typically, the older parts of a plant will have more epiphytes growing on them. Epiphytes differ from parasites in that they grow on other plants for physical support and do not necessarily affect the host negatively. An organism that grows on another organism that
1274-446: 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
1323-737: 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,
1372-489: The genus Phlegmariurus . Huperzia is left with about 25 species, although not all have been formally transferred to other genera. Other sources recognize only Huperzia , which then has about 340 species. The sporophytes of this genus have unbranched shoots that are generally upright and round in cross section. Horizontal stems are absent. The leaves are not borne in distinct ranks, and are usually somewhat lanceolate in shape. In some species, they vary in size according to
1421-417: The genus Tillandsia ), but epiphytes may be found in every major group of the plant kingdom. Eighty-nine percent of (or about 24,000) terrestrial epiphyte species are flowering plants . The second largest group are the leptosporangiate ferns , with about 2,800 species (10% of epiphytes). About one-third of all fern species are epiphytes. The third largest group is clubmosses , with 190 species, followed by
1470-422: The ground rooted plants by decomposition or leaching, and dinitrogen fixation. Epiphytic plants attached to their hosts high in the canopy have an advantage over herbs restricted to the ground where there is less light and herbivores may be more active. Epiphytic plants are also important to certain animals that may live in their water reservoirs, such as some types of frogs and arthropods . Epiphytes can have
1519-882: The host through transpiration. CAM metabolism , a water-preserving metabolism present among various plant taxa , is particularly relevant to epiphytic communities. For example, it is estimated that among epiphytic orchids, as many as 50% are likely to use it. Other relevant epiphytic families which display such metabolism are Bromeliacee (e.g. in genera Aechmea and Tillandsia ), Cactaceae (e.g. in Rhipsalis and Epiphyllum ) and Apocynaceae (e.g. in Hoya and Dischidia ). The ecology of epiphytes in marine environments differs from those in terrestrial ecosystems. Epiphytes in marine systems are species of algae, bacteria, fungi, sponges, bryozoans, ascidians, protozoa, crustaceans, molluscs and any other sessile organism that grows on
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1568-633: 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,
1617-525: 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. Epiphyte An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phorophytes . Epiphytes take part in nutrient cycles and add to both
1666-403: 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
1715-428: 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
1764-483: The north temperate species, refers to their superficial resemblance to branches of fir ( Abies ), a conifer . As of 2020, two very different circumscriptions of the genus were in use. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Huperzia is one of three genera in the subfamily Huperzioideae of the family Lycopodiaceae . Most species in the subfamily are placed in
1813-541: 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
1862-470: 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 the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or
1911-408: 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 a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in
1960-414: The season in which they grow. Branchlets bearing gemmae – bud-like structures by which the plant reproduces asexually – occur among the leaves. The gemmae are triangular, with eight leaves in a constant pattern: four flattened into a plane and two large lateral leaves. The sporangia are kidney-shaped (reniform), occurring at the base of a leaf that is either unmodified or reduced. The roots are produced near
2009-497: 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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2058-412: 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
2107-416: The surface of a plant, typically seagrasses or algae. Settlement of epiphytic species is influenced by a number of factors including light, temperature, currents, nutrients, and trophic interactions. Algae are the most common group of epiphytes in marine systems. Photosynthetic epiphytes account for a large amount of the photosynthesis in systems in which they occur. This is typically between 20 and 60% of
2156-403: 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
2205-416: The total primary production of the ecosystem. They are a general group of organisms and are highly diverse, providing food for a great number of fauna. Snail and nudibranch species are two common grazers of epiphytes. Epiphyte species composition and the amount of epiphytes can be indicative of changes in the environment. Recent increases in epiphyte abundance have been linked to excessive nitrogen put into
2254-486: The unbranched gametophytes. The genus Huperzia was created by Johann Jakob Bernhardi in 1801. Bernhardi separated Huperzia from Lycopodium . The type species is Lycopodium selago which became Huperzia selago . In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Huperzia is placed in the subfamily Huperzioideae of the family Lycopodiaceae . A phylogenetic study in 2016, employing both molecular and morphological data, concluded that either
2303-576: 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
2352-429: 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
2401-405: The western coastal fringe), and the common polypody fern grows epiphytically along branches. Rarely, grass, small bushes or small trees may grow in suspended soils up trees (typically in a rot-hole). Epiphytes however, can generally be categorized into holo-epiphytes or hemi-epiphytes. A holo-epiphyte is a plant that spends its whole life cycle without contact with the ground and a hemi-epiphyte
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