23-588: See List of Atriplex species Atriplex ( / ˈ æ t r ɪ p l ɛ k s / ) is a plant genus of about 250 species, known by the common names of saltbush and orache ( / ˈ ɒ r ɪ tʃ , - ə tʃ / ; also spelled orach ). It belongs to the subfamily Chenopodioideae of the family Amaranthaceae s.l. . The genus is quite variable and widely distributed. It includes many desert and seashore plants and halophytes , as well as plants of moist environments. The generic name originated in Latin and
46-666: A phylogenetic tree . In the taxonomical literature, sometimes the Latin form cladus (plural cladi ) is used rather than the English form. Clades are the fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over
69-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it
92-593: A characteristic leaf anatomy, known as kranz anatomy. The genus Atriplex was first formally described in 1753 by Carl Linnaeus in Species Plantarum . The genus name was used by Pliny for orach, or mountain spinach ( A. hortensis ). The genus evolved in Middle Miocene , the C 4 -photosynthesis pathway developed about 14.1–10.9 million years ago (mya), when the climate became increasingly dry. The genus diversified rapidly and spread over
115-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking
138-436: A few, scattered species, and the larger Atriplex clade, which is highly diverse and found around the world. After phylogenetic research, Kadereit et al. (2010) excluded Halimione as a distinct sister genus. The remaining Atriplex species were grouped into several clades. The following is a cladogram with estimated divergence times for the tribe Atripliceae. To infer the phylogeny, an ITS matrix composed of spacer ITS-1,
161-407: A perianth, but are enclosed by 2 leaf-like bracteoles , have a short style and 2 stigmas . After flowering, the bracteoles sometimes enlarge, thicken or become appendaged, enclosing the fruit but without adhering to it. The chromosome base number is x = 9, except for Atriplex lanfrancoi , which is x=10. A few Atriplex species are C 3 -plants , but most species are C 4 -plants , with
184-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on
207-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,
230-603: Is Atriplex hortensis . The name is derived from Ancient Greek ἀτράφαξυς ( atraphaxys ), "orach", itself a Pre-Greek substrate loanword. Atriplex is an extremely species-rich genus and comprises about 250-300 species, with new species still being discovered. An example includes Atriplex yeelirrie , formally described in 2015. Traditional taxonomy of Atripliceae based on morphological features has been controversial. Molecular studies have found that many genera are not true clades . One such study found that Atripliceae could be divided into two main clades, Archiatriplex , with
253-526: Is a list of Atriplex species accepted by the Plants of the World Online as at June 2022: Clade In biological phylogenetics , a clade (from Ancient Greek κλάδος (kládos) 'branch'), also known as a monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on
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#1732791617621276-499: Is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case,
299-476: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution
322-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed
345-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with
368-634: The 5.8S subunit, and spacer ITS-2 were amplified and sequenced for each specimen. Not all species in the genus Atriplex are presented in the cladogram (based on page 7 of ). This work suggested that the Americas were colonised by C4 Atriplex from Eurasia or Australia. Furthermore, that in the Americas Atriplex first appeared in South America, where two lineages underwent in situ diversification and evolved sympatrically. North America
391-445: The branches, rarely in opposite pairs, either sessile or on a petiole , and are sometimes deciduous. The leaf blade is variably shaped and may be entire, tooth or lobed. The flowers are borne in leaf axils or on the ends of branches, in spikes or spike-like panicles . The flowers are unisexual , some species monoecious , others dioecious . Male flowers have 3-5 perianth lobes and 3-5 stamens . Female flowers are usually lacking
414-520: The continents. The C 4 Atriplex colonized North America probably from Eurasia during the Middle/Late Miocene, about 9.8–8.8 mya, and later spread to South America. Australia was colonized twice by two C 4 lineages, one from Eurasia or America about 9.8–7.8 mya, and one from Central Asia about 6.3–4.8 mya. The last lineage diversified rapidly, and became the ancestor of most Australian Atriplex species. The type species ( lectotype )
437-546: The group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"
460-590: The last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of the relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade"
483-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of
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#1732791617621506-547: Was applied by Pliny the Elder to the edible oraches. The name saltbush derives from the fact that the plants retain salt in their leaves; they are able to grow in areas affected by soil salination . Species of plants in genus Atriplex are annual or perennial herbs, subshrubs , or shrubs. The plants are often covered with bladderlike hairs, that later collapse and form a silvery, scurfy or mealy surface, rarely with elongate trichomes . The leaves are arranged alternately along
529-1054: Was then colonised by Atriplex from South America, then one lineage later moved back to South America. Atriplex pentandra Atriplex hystrix Atriplex clivicola Atriplex taltalensis Atriplex vallenarensis Atriplex peruviana Atriplex leuca Atriplex philippii Atriplex myriophylla Atriplex chapinii Atriplex chizae Atriplex frigida Atriplex ameghinoi Atriplex monevidensis Atriplex pamparum Atriplex serenana Atriplex leucophylla Atriplex watsonii Atriplex acanthocarpa Atriplex polycarpa Atriplex canescens Atriplex phyllostegia Atriplex obovata Atriplex powellii Atriplex parishii Atriplex hymenelytra Atriplex parryi Atriplex lentiformis Atriplex undulata Atriplex patagonica Atriplex lithophila Atriplex atacamensis Atriplex braunii Atriplex oreophila Atriplex retusa Atriplex rusbyi List of Atriplex species The following
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