Order ( Latin : ordo ) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy . It is classified between family and class . In biological classification , the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes . An immediately higher rank, superorder , is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families.
29-575: Boraginales is an order of flowering plants in the asterid clade, with a total of about 125 genera and 2,700 species. Different taxonomic treatments either include only a single family, the Boraginaceae , or divide it into up to eleven families. Its herbs, shrubs, trees and lianas (vines) have a worldwide distribution. The classification of plants now known as Boraginales dates to the Genera plantarum (1789) when Antoine Laurent de Jussieu named
58-461: A cohors (plural cohortes ). Some of the plant families still retain the names of Linnaean "natural orders" or even the names of pre-Linnaean natural groups recognized by Linnaeus as orders in his natural classification (e.g. Palmae or Labiatae ). Such names are known as descriptive family names. In the field of zoology , the Linnaean orders were used more consistently. That is,
87-602: A common ancestor ) or paraphyletic (excluding some descendants), these concepts do not apply to monotypic taxa because they contain only a single member. Monotypic taxa are part of a broader challenge in biological classification known as aphyly – situations where evolutionary relationships are poorly supported by evidence. This includes both monotypic groups and cases where traditional groupings are found to be artificial. Understanding how monotypic taxa fit into this bigger picture helps identify areas needing further research. The German lichenologist Robert Lücking suggests that
116-510: A phylogenetic study of DNA sequences of selected genes , Boraginales was resolved as sister to Lamiales sensu APG, but that result had only 65% maximum likelihood bootstrap support . In the 2016 APG IV system Boraginales is an order with only one family Boraginaceae, which includes the former family Codonaceae . At the time of the APG IV consensus there was insufficient support to further divide this monophyletic group further. ( For
145-509: A capital letter. For some groups of organisms, their orders may follow consistent naming schemes . Orders of plants , fungi , and algae use the suffix -ales (e.g. Dictyotales ). Orders of birds and fishes use the Latin suffix -iformes meaning 'having the form of' (e.g. Passeriformes ), but orders of mammals and invertebrates are not so consistent (e.g. Artiodactyla , Actiniaria , Primates ). For some clades covered by
174-734: A complete discussion of the history of the taxonomy of Boraginales, see BWG (2016) ) Following the publication of APG IV, a collaborative group along similar lines to the APG, the Boraginales Working Group, has published an alternative taxonomy based on the phylogenetic relationships within the Boraginaceae s.l. . This classification split the order into eleven families, including: Boraginaceae s.s. or s.str. , Cordiaceae , Ehretiaceae , Heliotropiaceae , and Hydrophyllaceae. A number of these were monogeneric . Boraginaceae
203-441: A distinct definition to maintain logical structure. Otherwise, the different taxonomic ranks become effectively identical, which creates problems for organizing biological diversity in a hierarchical system. When taxonomists identify a monotypic taxon, this often reflects uncertainty about its relationships rather than true evolutionary isolation . This uncertainty is evident in many cases across different species. For instance,
232-570: A distinct rank of biological classification having its own distinctive name (and not just called a higher genus ( genus summum )) was first introduced by the German botanist Augustus Quirinus Rivinus in his classification of plants that appeared in a series of treatises in the 1690s. Carl Linnaeus was the first to apply it consistently to the division of all three kingdoms of nature (then minerals , plants , and animals ) in his Systema Naturae (1735, 1st. Ed.). For plants, Linnaeus' orders in
261-557: A family, Lennoaceae , but it is now known that they form a clade that is nested within Ehretiaceae. Some studies have indicated that Hydrophyllaceae is paraphyletic if the tribe Nameae is included within it, but further studies will be needed to resolve this issue. The inclusion of the genus Hoplestigma in Boraginales was occasionally doubted until it was strongly confirmed in a cladistic study in 2014. Hoplestigma
290-399: A group of plants Boragineae, to include the genus Borago , now the type genus . However, since the first valid description was by Friedrich von Berchtold and Jan Svatopluk Presl (1820), the botanical authority is given as Juss. ex Bercht. & J.Presl, where the ex refers to the prior authority of Jussieu. Lindley (1853) changed the name to the modern Boraginaceae. Jussieu divided
319-423: Is a genus in the special case where a genus and a single species are simultaneously described. Monotypic taxa present several important theoretical challenges in biological classification . One key issue is known as "Gregg's Paradox": if a single species is the only member of multiple hierarchical levels (for example, being the only species in its genus, which is the only genus in its family), then each level needs
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#1732790464236348-419: Is determined by a taxonomist , as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with
377-462: Is hard to characterize morphologically if it includes the genera Codon and Wellstedia . Codon was long regarded as an unusual member of Hydrophyllaceae , but in 1998, a molecular phylogenetic study showed that it is closer to Boraginaceae, and both Codon and Wellstedia have been allocated to their own families, Codonaceae and Wellstediaceae . The achlorophyllous holoparasites Lennoa and Pholisma were once regarded as
406-407: Is particularly associated with island species. Among 25 documented extinct monotypic genera studied, 22 occurred on islands, with flightless animals being particularly vulnerable to human impacts. Just as the term monotypic is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within
435-699: Is the closest relative of Cordiaceae and it has been recommended that the latter be expanded to include it. Hydrolea was thought to belong in Hydrophyllaceae for more than a century after it was placed there by Asa Gray , but it is now known to belong in the order Solanales as sister to Sphenoclea . Pteleocarpa was long regarded as an anomaly , and was usually placed in Boraginales, but with considerable doubt. The molecular evidence strongly supports it as sister to Gelsemiaceae , and that family has been expanded to include it. Order (biology) What does and does not belong to each order
464-528: The International Code of Zoological Nomenclature , several additional classifications are sometimes used, although not all of these are officially recognized. In their 1997 classification of mammals , McKenna and Bell used two extra levels between superorder and order: grandorder and mirorder . Michael Novacek (1986) inserted them at the same position. Michael Benton (2005) inserted them between superorder and magnorder instead. This position
493-815: The Systema Naturae and the Species Plantarum were strictly artificial, introduced to subdivide the artificial classes into more comprehensible smaller groups. When the word ordo was first consistently used for natural units of plants, in 19th-century works such as the Prodromus Systematis Naturalis Regni Vegetabilis of Augustin Pyramus de Candolle and the Genera Plantarum of Bentham & Hooker, it indicated taxa that are now given
522-565: The Boragineae into five groups. Since then Boraginaceae has been treated either as a large family with several subfamilies, or as a smaller family with several closely related families. The family had been included in a number of higher order taxa, but in 1926 Hutchinson erected a new order, Boraginales, to include the Boraginaceae. Although Boraginales was included in a number of taxonomic classifications including Dahlgren (1980), Takhtajan (1997) and Kubitzki (2016) as an order , it
551-745: The common application of the term monotypic is frequently misleading, "since each taxon by definition contains exactly one type and is hence "monotypic", regardless of the total number of units", and suggests using "monospecific" for a genus with a single species, and "monotaxonomic" for a taxon containing only one unit. Species in monotypic genera tend to be more threatened with extinction than average species. Studies have found this pattern particularly pronounced in amphibians , where about 6.56% of monotypic genera are critically endangered , compared to birds and mammals where around 4.54% and 4.02% of monotypic genera face critical endangerment respectively. Studies have found that extinction of monotypic genera
580-400: The diatom Licmophora juergensii is placed in a monotypic genus because scientists have not yet found clear evidence of its relationships to other species. Some taxonomists argue against monotypic taxa because they reduce the information content of biological classifications. As taxonomists Backlund and Bremer explain in their critique, "'Monotypic' taxa do not provide any information about
609-708: The orders in the zoology part of the Systema Naturae refer to natural groups. Some of his ordinal names are still in use, e.g. Lepidoptera (moths and butterflies) and Diptera (flies, mosquitoes, midges, and gnats). In virology , the International Committee on Taxonomy of Viruses 's virus classification includes fifteen taxomomic ranks to be applied for viruses , viroids and satellite nucleic acids : realm , subrealm , kingdom , subkingdom, phylum , subphylum , class, subclass, order, suborder, family, subfamily , genus, subgenus , and species. There are currently fourteen viral orders, each ending in
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#1732790464236638-564: The precursor of the currently used International Code of Nomenclature for algae, fungi, and plants . In the first international Rules of botanical nomenclature from the International Botanical Congress of 1905, the word family ( familia ) was assigned to the rank indicated by the French famille , while order ( ordo ) was reserved for a higher rank, for what in the 19th century had often been named
667-502: The rank of family (see ordo naturalis , ' natural order '). In French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille (plural: familles ) was used as a French equivalent for this Latin ordo . This equivalence was explicitly stated in the Alphonse Pyramus de Candolle 's Lois de la nomenclature botanique (1868),
696-405: The relationships of the immediately subordinate taxon". When monotypic taxa are sister to a single larger group, they might be merged into that group; however, when they are sister to multiple other groups, they may need to remain separate to maintain a natural classification. From a cladistic perspective, which focuses on shared derived characteristics to determine evolutionary relationships,
725-403: The suffix -virales . Monogeneric In biology , a monotypic taxon is a taxonomic group ( taxon ) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera , the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature , a monotypic genus
754-403: The theoretical status of monotypic taxa is complex. Some argue they can only be justified when relationships cannot be resolved through synapomorphies (shared derived characteristics); otherwise, they would necessarily exclude related species and thus be paraphyletic. However, others contend that while most taxonomic groups can be classified as either monophyletic (containing all descendants of
783-526: The traditionally recognized families Hydrophyllaceae and Lennoaceae based on recent molecular phylogenies that show that Boraginaceae, as traditionally defined, is paraphyletic over these two families. APG III included Boraginaceae in the Euasterid I ( lamiid ) clade but this family was otherwise unplaced ; its precise relationship to other families in the Euasterid I group remained unclear. In
812-418: Was adopted by Systema Naturae 2000 and others. In botany , the ranks of subclass and suborder are secondary ranks pre-defined as respectively above and below the rank of order. Any number of further ranks can be used as long as they are clearly defined. The superorder rank is commonly used, with the ending -anae that was initiated by Armen Takhtajan 's publications from 1966 onwards. The order as
841-573: Was not recognized in either of two major systems , the Cronquist system and the APG system . In the Cronquist system , Boraginaceae (including Cordiaceae , Ehretiaceae , and Heliotropiaceae ) and Lennoaceae were placed in the order Lamiales , while the related Hydrophyllaceae was placed in Solanales . The APG system took a broad view of Boraginaceae (Boraginaceae s.l. ), including within it
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