1.
Precambrian
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The Precambrian is the earliest period of Earths history, set before the current Phanerozoic Eon. The Precambrian is a supereon that is subdivided into three eons of the time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 541 million years ago, the Precambrian accounts for 89% of geologic time. Relatively little is known about the Precambrian, despite it making up roughly seven-eighths of the Earths history, the Precambrian fossil record is poorer than that of the succeeding Phanerozoic, and fossils from that time are of limited biostratigraphic use. This is because many Precambrian rocks have been metamorphosed, obscuring their origins, while others have been destroyed by erosion. A stable crust was apparently in place by 4,412 Ma, the term Precambrian is recognized by the International Commission on Stratigraphy as a general term including the Archean and Proterozoic eons. It is still used by geologists and paleontologists for general discussions not requiring the more specific eon names and it was briefly called the Cryptozoic eon. A specific date for the origin of life has not been determined, carbon found in 3.8 billion year old rocks from islands off western Greenland may be of organic origin. Well-preserved microscopic fossils of bacteria older than 3.46 billion years have found in Western Australia. Probable fossils 100 million years older have been found in the same area, there is a fairly solid record of bacterial life throughout the remainder of the Precambrian. The oldest fossil evidence from that era of such complex life comes from the Lantian formation of the Ediacarian period, a very diverse collection of soft-bodied forms is found in a variety of locations worldwide and date to between 635 and 542 Ma. These are referred to as Ediacaran or Vendian biota, hard-shelled creatures appeared toward the end of that time span, marking the beginning of the Phanerozoic era. By the middle of the following Cambrian period, a diverse fauna is recorded in the Burgess Shale. The explosion in diversity of lifeforms during the early Cambrian is called the Cambrian explosion of life, while land seems to have been devoid of plants and animals, cyanobacteria and other microbes formed prokaryotic mats that covered terrestrial areas. Evidence of the details of plate motions and other activity in the Precambrian has been poorly preserved. It is generally believed that small proto-continents existed prior to 4280 Ma, the supercontinent, known as Rodinia, broke up around 750 Ma. A number of glacial periods have been identified going as far back as the Huronian epoch, one of the best studied is the Sturtian-Varangian glaciation, around 850–635 Ma, which may have brought glacial conditions all the way to the equator, resulting in a Snowball Earth. The atmosphere of the early Earth is not well understood, most geologists believe it was composed primarily of nitrogen, carbon dioxide, and other relatively inert gases, and was lacking in free oxygen
2.
Cambrian
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The Cambrian Period was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya and its subdivisions, and its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latinised form of Cymru, the Welsh name for Wales, as a result, our understanding of the Cambrian biology surpasses that of some later periods. The rapid diversification of lifeforms in the Cambrian, known as the Cambrian explosion, most of the continents were probably dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia, the seas were relatively warm, and polar ice was absent for much of the period. The United States Federal Geographic Data Committee uses a barred capital C ⟨Є⟩ character similar to the capital letter Ukrainian Ye ⟨Є⟩ to represent the Cambrian Period, the proper Unicode character is U+A792 Ꞓ LATIN CAPITAL LETTER C WITH BAR. Despite the long recognition of its distinction from younger Ordovician Period rocks and older Supereon Precambrian rocks, the base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. Pedum in Namibia, Spain and Newfoundland, and possibly, in the western USA, the stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, and probably in Spain. The Cambrian Period followed the Ediacaran Period and was followed by the Ordovician Period, the Cambrian is divided into four epochs and ten ages. Currently only two series and five stages are named and have a GSSP, because the international stratigraphic subdivision is not yet complete, many local subdivisions are still widely used. In some of these subdivisions the Cambrian is divided into three epochs with locally differing names – the Early Cambrian, Middle Cambrian and Furongian, rocks of these epochs are referred to as belonging to the Lower, Middle, or Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian, each of the local epochs is divided into several stages. The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago, the lower boundary of the Cambrian was originally held to represent the first appearance of complex life, represented by trilobites. The recognition of small shelly fossils before the first trilobites, and Ediacara biota substantially earlier and this formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago quickly gained favour, though the used to obtain this number are now considered to be unsuitable. A more precise date using modern radiometric dating yield a date of 541 ±0.3 million years ago, most continental land was clustered in the Southern Hemisphere at this time, but was drifting north. Large, high-velocity rotational movement of Gondwana appears to have occurred in the Early Cambrian, the sea levels fluctuated somewhat, suggesting there were ice ages, associated with pulses of expansion and contraction of a south polar ice cap. In Baltoscandia a Lower Cambrian transgression transformed large swathes of the Sub-Cambrian peneplain into a epicontinental sea, the Earth was generally cold during the early Cambrian, probably due to the ancient continent of Gondwana covering the South Pole and cutting off polar ocean currents
3.
Ordovician
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The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. Lapworth recognized that the fauna in the disputed strata were different from those of either the Cambrian or the Silurian periods. It received international sanction in 1960, when it was adopted as a period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event considerably increased the diversity of life, fish, the worlds first true vertebrates, continued to evolve, and those with jaws may have first appeared late in the period. Life had yet to diversify on land, about 100 times as many meteorites struck the Earth during the Ordovician compared with today. The Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event and it lasted for about 42 million years and ended with the Ordovician–Silurian extinction event, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary slightly from those found in other sources and this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is highly significant and it correlates well with the occurrence of widespread graptolite, conodont, and trilobite species. The base of the Tremadocian allows scientists to relate these species not only to each other and this makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected an international system of subdivisions. There exist Baltoscandic, British, Siberian, North American, Australian, the Ordovician Period in Britain was traditionally broken into Early, Middle and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, the Floian corresponds to the lower Arenig, the Arenig continues until the early Darriwilian, subsuming the Dapingian. The Llanvirn occupies the rest of the Darriwilian, and terminates with it at the base of the Late Ordovician. The Sandbian represents the first half of the Caradoc, the Caradoc ends in the mid-Katian, during the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole, the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia
4.
Silurian
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The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period,419.2 Mya. As with other periods, the rock beds that define the periods start and end are well identified. The base of the Silurian is set at a major Ordovician-Silurian extinction event when 60% of marine species were wiped out, a significant evolutionary milestone during the Silurian was the diversification of jawed and bony fish. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian, the Silurian system was first identified by British geologist Sir Roderick Impey Murchison, who was examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s. He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick and this naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. As it was first identified, the Silurian series when traced farther afield quickly came to overlap Sedgwicks Cambrian sequence, however, charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was Gotlandian after the strata of the Baltic island of Gotland, the French geologist Joachim Barrande, building on Murchisons work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge. He divided the Silurian rocks of Bohemia into eight stages and his interpretation was questioned in 1854 by Edward Forbes, and the later stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils. The epoch is named for the town of Llandovery in Carmarthenshire, the Wenlock, which lasted from 433.4 ±1.5 to 427.4 ±2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in Shropshire, England, during the Wenlock, the oldest known tracheophytes of the genus Cooksonia, appear. The first terrestrial animals also appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ±1.5 to 423 ±2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, and it is named for the town of Ludlow in Shropshire, England. The Pridoli, lasting from 423 ±1.5 to 419.2 ±2.8 mya, is the final and it is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a field area. The high sea levels of the Silurian and the flat land resulted in a number of island chains. The southern continents remained united during this period, the melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity. The continents of Avalonia, Baltica, and Laurentia drifted together near the equator and this event is the Caledonian orogeny, a spate of mountain building that stretched from New York State through conjoined Europe and Greenland to Norway
5.
Devonian
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The Devonian is a geologic period and system of the Paleozoic, spanning 60 million years from the end of the Silurian,419.2 million years ago, to the beginning of the Carboniferous,358.9 Mya. It is named after Devon, England, where rocks from this period were first studied, the first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents, by the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. Various terrestrial arthropods also became well-established, Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fish. The first ray-finned and lobe-finned bony fish appeared, while the placodermi began dominating almost every aquatic environment. The ancestors of all four-limbed vertebrates began adapting to walking on land, as their strong pectoral, in the oceans, primitive sharks became more numerous than in the Silurian and Late Ordovician. The first ammonites, species of molluscs, appeared, trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction which started about 375 million years ago severely affected marine life, killing off all placodermi, and all trilobites, save for a few species of the order Proetida. The palaeogeography was dominated by the supercontinent of Gondwana to the south, the continent of Siberia to the north, while the rock beds that define the start and end of the Devonian period are well identified, the exact dates are uncertain. According to the International Commission on Stratigraphy, the Devonian extends from the end of the Silurian 419.2 Mya, another common term is Age of the Fishes, referring to the evolution of several major groups of fish that took place during the period. Older literature on the Anglo-Welsh basin divides it into the Downtonian, Dittonian, Breconian and Farlovian stages, in the Late Devonian, by contrast, arid conditions were less prevalent across the world and temperate climates were more common. The Devonian Period is formally broken into Early, Middle and Late subdivisions, the rocks corresponding to those epochs are referred to as belonging to the Lower, Middle and Upper parts of the Devonian System. Early Devonian The Early Devonian lasted from 419.2 ±2.8 to 393.3 ±2.5 and began with the Lochkovian stage, which lasted until the Pragian. It spanned from 410.8 ±2.8 to 407.6 ±2.5, and was followed by the Emsian, which lasted until the Middle Devonian began,393. 3±2.7 million years ago. Middle Devonian The Middle Devonian comprised two subdivisions, first the Eifelian, which gave way to the Givetian 387. 7±2.7 million years ago. Late Devonian Finally, the Late Devonian started with the Frasnian,382.7 ±2.8 to 372.2 ±2.5, during which the first forests took shape on land. The first tetrapods appeared in the record in the ensuing Famennian subdivision. This lasted until the end of the Devonian,358. 9±2.5 million years ago, the Devonian was a relatively warm period, and probably lacked any glaciers
6.
Carboniferous
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The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period 358.9 million years ago, to the beginning of the Permian Period,298.9 Mya. The name Carboniferous means coal-bearing and derives from the Latin words carbō and ferō, and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the system names to be employed. The Carboniferous is often treated in North America as two periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial life was established by the Carboniferous period. Amphibians were the dominant land vertebrates, of one branch would eventually evolve into amniotes. Arthropods were also common, and many were much larger than those of today. Vast swaths of forest covered the land, which would eventually be laid down, the atmospheric content of oxygen also reached their highest levels in geological history during the period, 35% compared with 21% today, allowing terrestrial invertebrates to evolve to great size. A major marine and terrestrial extinction event, the Carboniferous rainforest collapse, occurred in the middle of the period, the later half of the period experienced glaciations, low sea level, and mountain building as the continents collided to form Pangaea. In the United States the Carboniferous is usually broken into Mississippian and Pennsylvanian subperiods, the Silesian is roughly contemporaneous with the late Mississippian Serpukhovian plus the Pennsylvanian. In Britain the Dinantian is traditionally known as the Carboniferous Limestone, the Namurian as the Millstone Grit, and the Westphalian as the Coal Measures and Pennant Sandstone. There was also a drop in south polar temperatures, southern Gondwanaland was glaciated throughout the period and these conditions apparently had little effect in the deep tropics, where lush swamps, later to become coal, flourished to within 30 degrees of the northernmost glaciers. Mid-Carboniferous, a drop in sea level precipitated a major extinction, one that hit crinoids. This sea level drop and the unconformity in North America separate the Mississippian subperiod from the Pennsylvanian subperiod. This happened about 323 million years ago, at the onset of the Permo-Carboniferous Glaciation, the Carboniferous was a time of active mountain-building, as the supercontinent Pangaea came together. The southern continents remained tied together in the supercontinent Gondwana, which collided with North America–Europe along the present line of eastern North America, in the same time frame, much of present eastern Eurasian plate welded itself to Europe along the line of the Ural mountains. Most of the Mesozoic supercontinent of Pangea was now assembled, although North China, the Late Carboniferous Pangaea was shaped like an O. There were two major oceans in the Carboniferous—Panthalassa and Paleo-Tethys, which was inside the O in the Carboniferous Pangaea, other minor oceans were shrinking and eventually closed - Rheic Ocean, the small, shallow Ural Ocean and Proto-Tethys Ocean
7.
Permian
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The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, turtles, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks, echinoderms, and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, fungi, arthropods, the period saw a massive desert covering the interior of Pangaea
8.
Triassic
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The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, however, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early, Middle, and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed. Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, thus, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods, prosauropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact. At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ginkgophyta, ferns, horsetails
9.
Jurassic
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The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic, Middle, and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, Middle, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, India, South America, Japan, Australasia. As the Jurassic proceeded, larger and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
10.
Cretaceous
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The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 Mya. It is the last period of the Mesozoic Era, the Cretaceous Period is usually abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, during this time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, the name Cretaceous was derived from Latin creta, meaning chalk. The Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series, in older literature the Cretaceous is sometimes divided into three series, Neocomian, Gallic and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide, in many parts of the world, alternative local subdivisions are still in use. As with other geologic periods, the rock beds of the Cretaceous are well identified. No great extinction or burst of diversity separates the Cretaceous from the Jurassic and this layer has been dated at 66.043 Ma. A140 Ma age for the Jurassic-Cretaceous boundary instead of the usually accepted 145 Ma was proposed in 2014 based on a study of Vaca Muerta Formation in Neuquén Basin. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a first step toward formally changing the age in the International Union of Geological Sciences, due to the high sea level there was extensive space for such sedimentation. Because of the young age and great thickness of the system. Chalk is a type characteristic for the Cretaceous. It consists of coccoliths, microscopically small calcite skeletons of coccolithophores, the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not easily consolidated and the Chalk Group still consists of sediments in many places. The group also has other limestones and arenites, among the fossils it contains are sea urchins, belemnites, ammonites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls
11.
Paleogene
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The Paleogene is a geologic period and system that spans 43 million years from the end of the Cretaceous Period 66 million years ago to the beginning of the Neogene Period 23.03 Mya. It is the beginning of the Cenozoic Era of the present Phanerozoic Eon and this period consists of the Paleocene, Eocene and Oligocene epochs. The terms Paleogene System and lower Tertiary System are applied to the rocks deposited during the Paleogene Period. By dividing the Tertiary Period into two periods instead of directly into five epochs, the periods are more comparable to the duration of periods of the preceding Mesozoic and Paleozoic Eras. The trend was caused by the formation of the Antarctic Circumpolar Current. During the Paleogene, the continued to drift closer to their current positions. India was in the process of colliding with Asia, subsequently forming the Himalayas, the Atlantic Ocean continued to widen by a few centimeters each year. Africa was moving north to meet with Europe and form the Mediterranean, inland seas retreated from North America early in the period. Australia had also separated from Antarctica and was drifting towards Southeast Asia, mammals began a rapid diversification during this period. Some of these mammals would evolve into forms that would dominate the land, while others would become capable of living in marine, specialized terrestrial. Those that took to the oceans became modern cetaceans, while those that took to the trees became primates, the group to which humans belong. Birds, which were well established by the end of the Cretaceous. In comparison to birds and mammals, most other branches of life remained unchanged during this period. As the Earth cooled, tropical plants became less numerous and were now restricted to equatorial regions, deciduous plants, which could survive through the seasonal climates the world was now experiencing, became more common. The Paleogene is notable in the context of offshore oil drilling, and especially in Gulf of Mexico oil exploration and these rock formations represent the current cutting edge of deep-water oil discovery. Lower Tertiary explorations to date include, Kaskida Oil Field Tiber Oil Field Jack 2 Paleogene Microfossils, 180+ images of Foraminifera
12.
Neogene
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The Neogene is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.03 million years ago to the beginning of the present Quaternary Period 2.58 Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene, some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. During this period, mammals and birds continued to evolve into modern forms. Early hominids, the ancestors of humans, appeared in Africa near the end of the period, some continental movement took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the ocean currents from the Pacific to the Atlantic ocean. The global climate cooled considerably over the course of the Neogene, the terms Neogene System and upper Tertiary System describe the rocks deposited during the Neogene Period. The continents in the Neogene were very close to their current positions, the Isthmus of Panama formed, connecting North and South America. The Indian subcontinent continued to collide with Asia, forming the Himalayas, sea levels fell, creating land bridges between Africa and Eurasia and between Eurasia and North America. The global climate became seasonal and continued an overall drying and cooling trend which began at the start of the Paleogene. The ice caps on both poles began to grow and thicken, and by the end of the period the first of a series of glaciations of the current Ice Age began, marine and continental flora and fauna have a modern appearance. The reptile group Choristodera became extinct in the part of the period. Mammals and birds continued to be the dominant terrestrial vertebrates, the first hominids, the ancestors of humans, appeared in Africa and spread into Eurasia. In response to the cooler, seasonal climate, tropical plant species gave way to deciduous ones, grasses therefore greatly diversified, and herbivorous mammals evolved alongside it, creating the many grazing animals of today such as horses, antelope, and bison. The Neogene traditionally ended at the end of the Pliocene Epoch, just before the definition of the beginning of the Quaternary Period. However, there was a movement amongst geologists to also include ongoing geological time in the Neogene, by dividing the Cenozoic Era into three periods instead of seven epochs, the periods are more closely comparable to the duration of periods in the Mesozoic and Paleozoic eras. The International Commission on Stratigraphy once proposed that the Quaternary be considered a sub-era of the Neogene, with a date of 2.58 Ma. In the 2004 proposal of the ICS, the Neogene would have consisted of the Miocene and Pliocene epochs, thus the Neogene Period ends bounding the succeeding Quaternary Period at 2.58 Mya. Digital Atlas of Neogene Life for the Southeastern United States — by San Jose State University via Web Archive
13.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
14.
Plant
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Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
15.
Flowering plant
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The flowering plants, also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants, with 416 families, approx. 13,164 known genera and a total of c.295,383 known species, etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant. The term angiosperm comes from the Greek composite word meaning enclosed seeds, the ancestors of flowering plants diverged from gymnosperms in the Triassic Period, during the range 245 to 202 million years ago, and the first flowering plants are known from 160 mya. They diversified extensively during the Lower Cretaceous, became widespread by 120 mya, angiosperms differ from other seed plants in several ways, described in the table. These distinguishing characteristics taken together have made the angiosperms the most diverse and numerous land plants, the amount and complexity of tissue-formation in flowering plants exceeds that of gymnosperms. The vascular bundles of the stem are arranged such that the xylem and phloem form concentric rings, in the dicotyledons, the bundles in the very young stem are arranged in an open ring, separating a central pith from an outer cortex. In each bundle, separating the xylem and phloem, is a layer of meristem or active formative tissue known as cambium, the soft phloem becomes crushed, but the hard wood persists and forms the bulk of the stem and branches of the woody perennial. Among the monocotyledons, the bundles are more numerous in the stem and are scattered through the ground tissue. They contain no cambium and once formed the stem increases in diameter only in exceptional cases, the characteristic feature of angiosperms is the flower. Flowers show remarkable variation in form and elaboration, and provide the most trustworthy external characteristics for establishing relationships among angiosperm species, the function of the flower is to ensure fertilization of the ovule and development of fruit containing seeds. The floral apparatus may arise terminally on a shoot or from the axil of a leaf, occasionally, as in violets, a flower arises singly in the axil of an ordinary foliage-leaf. There are two kinds of cells produced by flowers. Microspores, which divide to become pollen grains, are the male cells and are borne in the stamens. The female cells called megaspores, which divide to become the egg cell, are contained in the ovule. The flower may consist only of parts, as in willow. Usually, other structures are present and serve to protect the sporophylls, the individual members of these surrounding structures are known as sepals and petals. The outer series is usually green and leaf-like, and functions to protect the rest of the flower, the inner series is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators, attraction is effected by color, scent, and nectar, which may be secreted in some part of the flower
16.
Ranunculales
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Ranunculales is an order of flowering plants. Of necessity it contains the family Ranunculaceae, the buttercup family, Ranunculales belongs to a paraphyletic group known as the basal eudicots. It is the most basal clade in this group, in other words, widely known members include poppies, barberries, and buttercups. Historically the term Ranales was used to include the Ranunculaceae and related families, as described by Bentham and this became replaced with Ranunculales by Melchior in 1964. The Cronquist system also recognised the order, but placed it in the subclass Magnoliidae, the Cronquist circumscription of Ranunculales is now known to be polyphyletic. Sabiaceae is in a clade of basal eudicots separate from Ranunculales, coriariaceae is now placed in the order Cucurbitales. The Angiosperm Phylogeny Group recognized seven families in Ranunculales in their APG III system, in the preceding APG II system, they offered the option of three segregate families as shown below. Order Ranunculales family Berberidaceae family Circaeasteraceae family Eupteleaceae family Lardizabalaceae family Menispermaceae family Papaveraceae family Ranunculaceae Note, under this definition, well-known members of Ranunculales include buttercups, clematis, columbines, delphiniums, and poppies. A phylogeny of Ranunculales was published in 2009, based on phylogenetic analysis of DNA sequences. The authors of this paper revised the subfamilies and tribes of the order and this is reflected in the subsequent revision of the APG, APG IV. The analysis revealed that the order consisted of three clades, Eupteleaceae, Papaveraceae and a clade, considered to be the core Ranuculales. The phylogeny of the families is shown in the cladogram, a recently discovered fossil has been recognized as a member of this order. Leefructus mirus shows fully developed leaves, stem and flower that are similar in structure to those of the modern buttercups. The fossil is dated to 125 million years old and it not only proves that Ranunculales is an ancient group of eudicots, the structure of the plant and its age may lead to a new approach regarding the field that studies the evolution of flowering plants. The fact that Leefructus shows a structure similar to modern ranunculids suggests that this group of eudicots may have developed earlier than the age of the fossil
17.
Proteales
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Proteales is the botanical name of an order of flowering plants consisting of two families. The Proteales have been recognized by almost all taxonomists, the Angiosperm Phylogeny Website, however, suggests the addition of Sabiaceae, which was not placed in an order in the eudicots in the APG III system, would be sensible. The APG IV system of 2016 added family Sabiaceae to the order, well-known members of the Proteales include the proteas of South Africa, the banksias and macadamias of Australia, the London plane, and the sacred lotus. The origins of the order are clearly ancient, with evidence of diversification in the mid-Cretaceous, of interest are the current family distributions, with the Proteaceae a mostly Southern Hemisphere family, while the Platanaceae and Nelumbonaceae are Northern Hemisphere plants. It used this circumscription, order Proteales family Proteaceae
18.
Trochodendraceae
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Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a species found in south east Asia. The two living species both have secondary xylem without vessel elements, which is rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention, deciduous or evergreen trees, up to 20–30 m, sometimes with umbrella-shaped branches. Idioblasts present, large, branched, sclerenchymatous in Trochodendron and secretory in Tetracentron, terminal Inflorescence in erect, aggregated racemiforms or defined, axillary, multi-floral amentoid spikes with the flower in whorls of 4. Bracts and bracteoles present or absent, perfect flowers, actinomorphic or dissymmetric, yellowish. Reduced, very thin perianth, of 4 tepals in 2 decussate whorls, androecium of 4 decussate stamens in pairs of 40-70 in a spiral, non-versatile, basifixed, tetrasporangial, latrorso, apiculate anthers, dehiscence along 2 longitudinal valves in the theca. Fruit in ventricidal or slightly loculicidal capsule or an aggregate of dorsally and ventrally dehiscent semicarpical follicles, with basal and external styles. Small, flattened, tapered seeds, 3–4 mm in length, with lateral, apical, chalazal wings, with thin testa, with abundant, oily and proteinaceous endosperm, small embryo, with 2 cotyledons. Pollen in small, granular, spheroidal, tricolpate, tectated-columelliform monads, the surface with interwoven bars parallel to the edges of the colpus, chromosomal number, 2n =48 in Tetracentron and 2n =38,40 in Trochodendron. Pollination is probably myiophyllous, even though Tetracentron shows a clear anemophilous syndrome, the pulverulent seeds are dispersed by the wind. Trochodendron is present in both protandrous and protogynous forms that are self-compatible, the plants are found in wooded formations, Trochodendron between 300 m and 2.700 m above sea level and Tetracentron between 1.100 m and 3.600 m above sea level. Epicuticular waxes are basically composed of nonacosan-10-ol, the trocodendraceae are a group of flowering plants that include the clade Eudicotyledoneae. Based on molecular and morphological data, the APW considers that it constitutes the family in the Order Trochodendrales. The current classification of Trochodendraceae is the APG III system published in October 2009, unlike the APG and APG II systems, this system places the family as the only family in the order Trochodendrales. It also includes Tetracentron, synonymizing Tetracentraceae fully with Trochodenraceae, the APG II system, of 2003 retained the classification used in the 1998 APG system recognizing Trochodendraceae as a family. APG and APG II did not place the family in an order, both APG systems accepts this as a family of two modern species, but it does allow the option of separating out the family Tetracentraceae. This segregation would lead to two families with one each, Tetracentraceae with Tetracentron sinense and Trochodendraceae with Trochodendron aralioides
19.
Buxales
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The Buxales are a small order of eudicot flowering plants, recognized by the APG III system of 2009. The order includes the family Buxaceae, the families Didymelaceae and Haptanthaceae may also be recognized or may be included in the Buxaceae, many members of the order are evergreen shrubs or trees, although some are herbaceous perennials. They have separate male and female flowers, mostly on the same plant, some species are of economic importance either for the wood they produce or as ornamental plants. The Buxales have relatively few obvious shared features distinguishing them from related groups of plants, one is the presence of a particular type of alkaloid or pseudoalkaloid, pregnane steroids. They have unisexual flowers, most being monoecious, the flowers are small, less than 7 mm across. The tepals have a vascular bundle. Didymeles, the genus in the family Didymelaceae, consists of two species of evergreen tree occurring only in Madagascar. It is dioecious, i. e. with staminate and carpellate flowers on separate plants, Buxaceae is more diverse, with five or six genera totalling about 115 species, and is found in most temperate and tropical areas of the world. Most species are shrubs or small trees, but some are herbaceous perennials. In the APG III system of 2009, the order includes two families, Buxaceae and Haptanthaceae, unlike previous classifications, APG III does not recognize the family Didymelaceae, but includes the genus Didymeles in Buxaceae. It also keeps Didymelaceae separate from Buxaceae, in the 2016 APG IV system, Haptanthaceae is incorporated into Buxaceae, which leaves Buxaceae the only family under Buxales. The Buxales are placed within the eudicots but outside the core eudicots, the monophyly of the order and its general position relative to other eudicots has been confirmed by many studies. One possible phylogenetic tree is shown below, where the ordering of the basal eudicots is still uncertain. One difference between the basal eudicots and the eudicots is that the latter appear to have undergone a complete duplication of the nuclear genome which is absent in the former. Didymelaceae or Buxaceae Didymeles Thouars Buxaceae Buxus L. Pachysandra Michx, Buxaceae or Haptanthaceae Haptanthus Goldberg & C. Nelson In the Cronquist system of 1981, the Buxaceae were associated with the Euphorbiaceae s. l. and the Didymelaceae were given their own order. In the APG II system of 2003, the Buxaceae were a family unplaced as to order in the eudicots, optionally including the genus Didymeles, some species of the Buxaceae are of economic importance. Buxus sempervirens and Buxus macowanii produce hard wood valued for carving and engraving, species are also used as ornamental garden plants. Common box is used for hedging and border edging, species of Pachysandra are used as ground cover
20.
Gunnerales
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The Gunnerales are an order of flowering plants. In the APG III system it contains two genera, Gunnera and Myrothamnus, in the Cronquist system, the Gunneraceae were in the Haloragales and Myrothamnaceae in the Hamamelidales. DNA analysis was definitive, but the grouping of the two families was a surprise, given their very dissimilar morphologies, in Cronquists old system, and Takhtajans, the Gunneraceae were in the Rosidae, and the Myrothamnaceae were in the Hamamelids. In modern classification systems such as APGIII, this order was the first to derive from the core eudicots, phloem cells contain a large number of plastids and the leaves have dented borders. The plants are dioecious, have flowers without perianth. The Myrothamnaceae are a reviviscent shrub of arid habitats, and the hydathodes are poorly developed, both have flowers without perianth, but the details of pollen differ. In Wilkinson 200013 is a table of differences, Gunnerales in Stevens, P. F. Angiosperm Phylogeny Website
21.
Dilleniales
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The Dilleniales are an order of flowering plants, potentially containing one family, Dilleniaceae. The APG III system of 2009, like the earlier APG II system of 2003, left the Dilleniaceae unplaced as to order, stevens at the Angiosperm Phylogeny Website has subsequently placed Dilleniaceae in the order Dilleniales. The Cronquist system, of 1981, recognized such an order and it used the following circumscription, order Dilleniales family Dilleniaceae family Paeoniaceae The Takhtajan system of 1969 had the families Dilleniaceae and Crossosomataceae in the order. The APG III system assigned the second of these families, the Paeoniaceae, to the order Saxifragales
22.
Saxifragales
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The Saxifragales are an order of flowering plants. Their closest relatives are a large group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the more widely, including Saxifragales as their most basal group. Saxifragales is one of the eight groups that compose the core eudicots, the others are Gunnerales, Dilleniaceae, Rosids, Santalales, Berberidopsidales, Caryophyllales, and asterids. Saxifragales have a fossil record. The extant members are apparently remnants of a diverse and widespread order. The Saxifragales order, as it is now understood, is based upon the results of phylogenetic studies of DNA sequences. It is not part of any of the classification based on plant morphology. The order is divided into groups as shown on the phylogenetic tree below. These groups are informal and are not understood to have any taxonomic rank. These are distributed into 15 families, or into 12 families if Haloragaceae sensu lato is recognized as a family consisting of Haloragaceae sensu stricto, Penthorum, Tetracarpaea, about 95% of the species are in five families, Crassulaceae, Saxifragaceae, Grossulariaceae, Haloragaceae, and Hamamelidaceae. Most of the families are monogeneric, the number of genera in each family is, Some authors do not recognize Choristylis as a separate genus from Itea. Similarly, some authors sink Liquidambar and Semiliquidambar into Altingia, thus Altingiaceae and Iteaceae are monogeneric in some classifications. Within the Saxifragales is a group known as the Saxifragaceae alliance. It comprises four families, Pterostemonaceae, Iteaceae, Grossulariaceae, and these have long been known to be related to each other, but the circumscription of Saxifragaceae has changed dramatically. It is now a smaller family than it had been. Crassulaceae and Tetracarpaeaceae have long associated with Saxifragaceae. Penthorum has usually been associated with Crassulaceae, but sometimes with Saxifragaceae, two members of the core Saxifragales had sometimes been placed near Saxifragaceae, but usually elsewhere
23.
Rosids
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The rosids are members of a large clade of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms. The clade is divided into 16 to 20 orders, depending upon circumscription and classification and these orders, in turn, together comprise about 140 families. Fossil rosids are known from the Cretaceous period, molecular clock estimates indicate that the rosids originated in the Aptian or Albian stages of the Cretaceous, between 125 and 99.6 million years ago. The name is based upon the name Rosidae, which had usually been understood to be a subclass, in 1967, Armen Takhtajan showed that the correct basis for the name Rosidae is a description of a group of plants published in 1830 by Friedrich Gottlieb Bartling. The clade was later renamed Rosidae and has been variously delimited by different authors, the name rosids is informal and not assumed to have any particular taxonomic rank like the names authorized by the ICBN. The rosids are monophyletic based upon evidence found by molecular phylogenetic analysis, three different definitions of the rosids were used. Some authors included the orders Saxifragales and Vitales in the rosids, others excluded both of these orders. The circumscription used in this article is that of the APG IV classification, which includes Vitales, the rosids and Saxifragales form the superrosids clade. This is one of three groups compose the Pentapetalae, the others being Dilleniales and the superasterids. The rosids consist of two groups, the order Vitales and the eurosids, the eurosids, in turn, are divided into two groups, fabids and malvids. The rosids consist of 17 orders, in addition to Vitales, there are 8 orders in fabids and 8 orders in malvids. Some of the orders have only recently been recognized and these are Vitales, Zygophyllales, Crossosomatales, Picramniales, and Huerteales. The phylogeny of Rosids shown below is adapted from the Angiosperm Phylogeny Group website, the nitrogen-fixing clade contains a high number of actinorhizal plants. Not all plants in this clade are actinorhizal, however, media related to Rosids at Wikimedia Commons
24.
Berberidopsidales
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Berberidopsidales is an order of Southern Hemisphere woody flowering plants. The name is accepted in the APG III system of plant taxonomy. APG II system, of 2003, mentions the possibility of recognizing the order, however, APG II left the families unplaced as to order, assigning them to the clade core eudicots. The APG III system of 2009 formally recognized the order, the family Aextoxicaceae is a monotypic family native to Chile, Berberidopsidaceae is a family of 2 genera and 3 species native to Chile and eastern Australia
25.
Santalales
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The Santalales are an order of flowering plants with a cosmopolitan distribution, but heavily concentrated in tropical and subtropical regions. It derives its name from its type genus Santalum, mistletoe is the common name for a number of parasitic plants within the order. Most have seeds without testae, which is unusual for flowering plants, furthermore, it indicates disagreements about Santalaceae which need to include Viscaceae to be monophyletic. Studies based on DNA sequences also indicate the family Schoepfiaceae should be resurrected to accommodate Schoepfia, Arjona, in the classification system of Dahlgren the Santalales were in the superorder Santaliflorae. The genera Dipentodon and Medusandra are regarded as unplaced by APG II, the family Medusandraceae consisted of two genera, Soyauxia and Medusandra. Molecular evidence places them within the family Peridiscaceae of the order Saxifragales, dwarf mistletoes, biology, pathology, and systematics. Soltis, Douglas E. Soltis, Pamela S. Endress, Peter K. Chase, Santalales on the Parasitic Plant Connection web page NCBI Taxonomy Browser
26.
Caryophyllales
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Caryophyllales is an order of flowering plants that includes the cacti, carnations, amaranths, ice plants, beets, and many carnivorous plants. Many members are succulent, having fleshy stems or leaves, the members of Caryophyllales include about 6% of eudicot species. This order is part of the core eudicots, currently, the Caryophyllales contains 33 families,692 genera and 11,155 species. As with all taxa, the circumscription of Caryophyllales has changed within various classification systems, all systems recognize a core of families with centrospermous ovules and seeds. More recent treatments have expanded the Caryophyllales to include many carnivorous plants, although the monophyly of the order has been strongly supported, their placement is still uncertain. Systematists are undecided on whether Caryophyllales should be placed within the complex or sister to the asterid clade. This primitive flower might well be found in stock as Wernham, Bessy. Caryophyllales is separated into two suborders, Caryophyllineae and Polygonineae and these two suborders were formerly recognized as two orders, Polygonales and Caryophyllales. As circumscribed by the APG III system, this includes the same families as the APG II system plus the new families, Limeaceae, Lophiocarpaceae, Montiaceae, Talinaceae. Kewaceae, Limeaceae, Macarthuriaceae, Microteaceae, and Petiveriaceae were added in APG IV, recent molecular and biochemical evidence has resolved additional well-supported clades within the Caryophyllales. The APG favours much larger orders and families, and the order Caryophyllales sensu APG should rather be compared to subclass Caryophyllidae sensu Cronquist, a part of the difference lies with what families are recognized. The plants in the Stegnospermataceae and Barbeuiaceae were included in Cronquists Phytolaccaceae, the Chenopodiaceae are included in Amaranthaceae by APG. New to the order are the Asteropeiaceae and Physenaceae, each containing a single genus, earlier systems, such as the Wettstein system, last edition in 1935, and the Engler system, updated in 1964, had a similar order under the name Centrospermae. Tree of Life Characteristics and Phylogenetic Relationships
27.
Asterids
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In the APG IV system for the classification of flowering plants, the name asterids denotes a clade. Most of the taxa belonging to this clade had been referred to the Asteridae in the Cronquist system, the name asterids resembles the earlier botanical name but is intended to be the name of a clade rather than a formal ranked name, in the sense of the ICBN. The phylogenetic tree presented hereafter has been proposed by the APG IV project, genetic analysis carried out after APG II maintains that the sister to all other asterids are the Cornales. A second order that split from the base of the asterids are the Ericales, the remaining orders cluster into two clades, the lamiids and the campanulids. The structure of both of these clades has changed in APG III, in APG III system, the following clades were renamed, euasterids I → lamiids euasterids II → campanulids Asterids in Stevens, P. F. Angiosperm Phylogeny Website
28.
Arabis
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Arabis /ˈɛərəbᵻs/, or rockcress, is a genus of flowering plants, within the family Brassicaceae, subfamily Brassicoideae. The species are herbaceous, annual or perennial plants, growing to 10–80 cm tall, usually hairy, with simple entire to lobed leaves 1–6 cm long. The fruit is a long, slender capsule containing 10-20 or more seeds and these two groups are not each others closest relatives, so have been split into two separate genera. Most of the Old World members remain in the genus Arabis, whereas most of the New World members have moved into the genus Boechera. Selected species Arabis aculeolata Arabis alpina Arabis armena Arabis blepharophylla Arabis caucasica Willd, many others are regarded as weeds
29.
Clade
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A clade is a group of organisms that consists of a common ancestor and all its lineal descendants, and represents a single branch on the tree of life. The common ancestor may be an individual, a population, a species, 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, over 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, the term clade was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis, a concept Huxley borrowed from Bernhard Rensch. Many commonly named groups are clades, for example, rodents or insects, because in each case, their name refers to 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 and these clades include smaller clades, such as chipmunk or ant, each of which consists of even smaller clades. The clade rodent is in included in the mammal, vertebrate. The phenomenon of convergent evolution is, however, responsible for cases where there are misleading similarities in the morphology of groups that evolved from different lineages. The publication of Darwins theory of evolution in 1859 gave this view increasing weight, thomas Henry Huxley, an early advocate of evolutionary theory, proposed a revised taxonomy based on clades. For example, he grouped birds with reptiles, based on fossil evidence, german biologist Emil Hans Willi Hennig is considered to be the founder of cladistics. Taxonomists have increasingly worked to make the taxonomic system reflect evolution, when it comes to naming, however, this principle is not always compatible with the traditional rank-based nomenclature. For these and other reasons, phylogenetic nomenclature has been developed, a clade is by definition monophyletic, meaning that it contains one ancestor 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, the latter term coined by Ernst Mayr, derived from clade. The results of analyses are tree-shaped diagrams called cladograms, they. Three methods of defining clades are featured in phylogenetic nomenclature, node-, stem-, the relationship between clades can be described in several ways, A clade located within a clade is said to be nested within that clade. In the diagram, the clade, i. e. the apes. Two clades are sisters if they have a common ancestor
30.
Magnoliids
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Magnoliids are a group of flowering plants. Until recently, the group included about 9,000 species, including magnolias, nutmeg, bay laurel, cinnamon, avocado, black pepper, tulip tree and that group is characterized by trimerous flowers, pollen with one pore, and usually branching-veined leaves. Magnoliidae is the name of a subclass, and magnoliids is an informal name that does not conform to the International Code of Nomenclature for algae, fungi. The circumscription of a subclass will vary with the system being used. The only requirement is that it must include the family Magnoliaceae, the informal name magnoliids is used by some researchers to avoid the confusion that recently surrounds the name Magnoliidae. More recently, the group has been redefined under the PhyloCode as a clade comprising the Canellales, Laurales, Magnoliales. Chase & Reveal have proposed, Magnoliidae as the used for the entire group of flowering plants. The APG III and its predecessor systems did not originally use formal botanical names above the rank of order, under those systems, larger clades were usually referred to by informal names, such as magnoliids or magnoliid complex. The formal name in Linnean nomenclature was specified in a separate APG publication as the existing name Magnolianae Takht, the APG III recognizes a clade within the angiosperms for the magnoliids. The circumscription is, The clade includes most of the groups of the angiosperms. This clade was formally named Magnoliidae in 2007 under provisions of the PhyloCode, the Cronquist system used the name Magnoliidae for one of six subclasses. In their systems, the name Magnoliidae is used for a larger group including all dicotyledons. This is also the case in some of the derived from the Cronquist system. Dahlgren divided his Magnolianae into ten orders, more than other systems of the time and this revised system diverges from the Cronquist system, but agrees more closely with the circumscription later published under APG II. Comparison of classification systems is often difficult, two authors may also describe the same group with nearly identical composition, but each may then apply a different name to that group or place the group at a different taxonomic rank. For example, the composition of Cronquists subclass Magnoliidae is nearly the same as Thornes superorder Magnolianae, because of these difficulties and others, the synoptic table below imprecisely compares the definition of magnoliid groups in the systems of four authors. For each system, only orders are named in the table, all orders included by a particular author are listed and linked in that column. When a taxon is not included by that author, but was included by an author in another column, the sequence of each system has been altered from its publication in order to pair corresponding taxa between columns
31.
Dicotyledon
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The dicotyledons, also known as dicots, were one of the two groups into which all the flowering plants or angiosperms were formerly divided. The name refers to one of the characteristics of the group. There are around 200,000 species within this group, the other group of flowering plants were called monocotyledons or monocots, typically having one cotyledon. Historically, these two formed the two divisions of the flowering plants. Rather, a number of lineages, such as the magnoliids and groups now known as the basal angiosperms. The traditional dicots are thus a paraphyletic group, the largest clade of the dicotyledons are known as the eudicots. They are distinguished from all other flowering plants by the structure of their pollen, aside from cotyledon number, other broad differences have been noted between monocots and dicots, although these have proven to be differences primarily between monocots and eudicots. Many early-diverging dicot groups have monocot characteristics such as scattered vascular bundles, trimerous flowers, in addition, some monocots have dicot characteristics such as reticulated leaf veins. Traditionally the dicots have been called the Dicotyledones, at any rank, if treated as a class, as in the Cronquist system, they could be called the Magnoliopsida after the type genus Magnolia. In some schemes, the eudicots were treated as a separate class, the remaining dicots may be kept in a single paraphyletic class, called Magnoliopsida, or further divided. Some botanists prefer to retain the dicotyledons as a class, arguing its practicality. The following lists show the orders in the APG III system traditionally called dicots, together with the older Cronquist system
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Synapomorphy
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In phylogenetics, apomorphy and synapomorphy refer to derived characteristic of a clade. Apomorphy implies a characteristic that is different from the form of an ancestor, i. e. an innovation, synapomorphy is a shared derived character or trait state that distinguishes a clade from other organisms. In other words, it is an apomorphy shared by members of a monophyletic group, and thus assumed to be present in their most recent common ancestor. The word synapomorphy, coined by German entomologist Willi Hennig, is derived from the Greek words σύν, syn = shared, ἀπό, apo = away from, a derived character is a character that is derived from an ancestral character over evolutionary history. Derived characters are used in determining phylogenetic relationships, the concept of synapomorphy is relative to a given clade in the tree of life. What counts as a synapomorphy for one clade may well be a character or plesiomorphy at a less inclusive or nested clade. For example, the presence of mammary glands is a synapomorphy for mammals in relation to tetrapods but is a symplesiomorphy for mammals in relation to one another, rodents and primates, for example
33.
Molecular
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A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge, however, in quantum physics, organic chemistry, and biochemistry, the term molecule is often used less strictly, also being applied to polyatomic ions. In the kinetic theory of gases, the molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are in fact monoatomic molecules. A molecule may be homonuclear, that is, it consists of atoms of one element, as with oxygen, or it may be heteronuclear. Atoms and complexes connected by non-covalent interactions, such as hydrogen bonds or ionic bonds, are not considered single molecules. Molecules as components of matter are common in organic substances and they also make up most of the oceans and atmosphere. Also, no typical molecule can be defined for ionic crystals and covalent crystals, the theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding, which means that solid metals are also not made of molecules. In glasses, atoms may also be together by chemical bonds with no presence of any definable molecule. The science of molecules is called molecular chemistry or molecular physics, in practice, however, this distinction is vague. In molecular sciences, a molecule consists of a system composed of two or more atoms. Polyatomic ions may sometimes be thought of as electrically charged molecules. The term unstable molecule is used for very reactive species, i. e, according to Merriam-Webster and the Online Etymology Dictionary, the word molecule derives from the Latin moles or small unit of mass. Molecule – extremely minute particle, from French molécule, from New Latin molecula, diminutive of Latin moles mass, a vague meaning at first, the vogue for the word can be traced to the philosophy of Descartes. The definition of the molecule has evolved as knowledge of the structure of molecules has increased, earlier definitions were less precise, defining molecules as the smallest particles of pure chemical substances that still retain their composition and chemical properties. Molecules are held together by covalent bonding or ionic bonding. Several types of non-metal elements exist only as molecules in the environment, for example, hydrogen only exists as hydrogen molecule. A molecule of a compound is made out of two or more elements, a covalent bond is a chemical bond that involves the sharing of electron pairs between atoms
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Phenotypic trait
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For example, eye color is a character of an organism, while blue, brown and hazel are traits. A phenotypic trait is an obvious, observable, and measurable trait, it is the expression of genes in an observable way. An example of a trait is hair color, underlying genes, which make up the genotype, control the hair color, but the actual hair color. The inheritable unit that may influence a trait is called a gene, a gene is a portion of a chromosome, which is a very long and compacted string of DNA and proteins. An important reference point along a chromosome is the centromere, the distance from a gene to the centromere is referred to as the locus or map location. The nucleus of a cell contains two of each chromosome, with homologous pairs of chromosomes having the same genes at the same loci. Different phenotypic traits are caused by different forms of genes, or alleles, a gene is only a DNA code sequence, the slightly different variations of that sequence are called alleles. Alleles can be different and produce different product RNAs. Combinations of different alleles thus go on to different traits through the information flow charted above. For example, if the alleles on homologous chromosomes exhibit a simple dominance relationship and his most famous analyses were based on clear-cut traits with simple dominance. He determined that the units, what we now call genes. His tool was statistics The biochemistry of the intermediate proteins determines how they interact in the cell, therefore, biochemistry predicts how different combinations of alleles will produce varying traits. Extended expression patterns seen in diploid organisms include facets of incomplete dominance, codominance, incomplete dominance is the condition in which neither allele dominates the other in one heterozygote. Instead the phenotype is intermediate in heterozygotes, thus you can tell that each allele is present in the heterozygote. Codominance refers to the relationship that occurs when two alleles are both expressed in the heterozygote, and both phenotypes are seen simultaneously. Multiple alleles refers to the situation there are more than 2 common alleles of a particular gene. Blood groups in humans is a classic example, the ABO blood group proteins are important in determining blood type in humans, and this is determined by different alleles of the one locus. Schizotypy is an example of a phenotypic trait found in schizophrenia-spectrum disorders
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Botany
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Botany, also called plant science, plant biology or phytology, is the science of plant life and a branch of biology. A botanist or plant scientist is a scientist who specialises in this field, the term botany comes from the Ancient Greek word βοτάνη meaning pasture, grass, or fodder, βοτάνη is in turn derived from βόσκειν, to feed or to graze. Nowadays, botanists study approximately 410,000 species of plants of which some 391,000 species are vascular plants. Medieval physic gardens, often attached to monasteries, contained plants of medical importance and they were forerunners of the first botanical gardens attached to universities, founded from the 1540s onwards. One of the earliest was the Padua botanical garden and these gardens facilitated the academic study of plants. Efforts to catalogue and describe their collections were the beginnings of plant taxonomy, in the last two decades of the 20th century, botanists exploited the techniques of molecular genetic analysis, including genomics and proteomics and DNA sequences to classify plants more accurately. Modern botany is a broad, multidisciplinary subject with inputs from most other areas of science, dominant themes in 21st century plant science are molecular genetics and epigenetics, which are the mechanisms and control of gene expression during differentiation of plant cells and tissues. Botany originated as herbalism, the study and use of plants for their medicinal properties, many records of the Holocene period date early botanical knowledge as far back as 10,000 years ago. This early unrecorded knowledge of plants was discovered in ancient sites of human occupation within Tennessee, the early recorded history of botany includes many ancient writings and plant classifications. Examples of early works have been found in ancient texts from India dating back to before 1100 BC, in archaic Avestan writings. His major works, Enquiry into Plants and On the Causes of Plants, constitute the most important contributions to science until the Middle Ages. De Materia Medica was widely read for more than 1,500 years, important contributions from the medieval Muslim world include Ibn Wahshiyyas Nabatean Agriculture, Abū Ḥanīfa Dīnawarīs the Book of Plants, and Ibn Bassals The Classification of Soils. In the early 13th century, Abu al-Abbas al-Nabati, and Ibn al-Baitar wrote on botany in a systematic and scientific manner and these gardens continued the practical value of earlier physic gardens, often associated with monasteries, in which plants were cultivated for medical use. They supported the growth of botany as an academic subject, lectures were given about the plants grown in the gardens and their medical uses demonstrated. Botanical gardens came much later to northern Europe, the first in England was the University of Oxford Botanic Garden in 1621, throughout this period, botany remained firmly subordinate to medicine. German physician Leonhart Fuchs was one of the three German fathers of botany, along with theologian Otto Brunfels and physician Hieronymus Bock, Fuchs and Brunfels broke away from the tradition of copying earlier works to make original observations of their own. Bock created his own system of plant classification, physician Valerius Cordus authored a botanically and pharmacologically important herbal Historia Plantarum in 1544 and a pharmacopoeia of lasting importance, the Dispensatorium in 1546. Naturalist Conrad von Gesner and herbalist John Gerard published herbals covering the medicinal uses of plants, naturalist Ulisse Aldrovandi was considered the father of natural history, which included the study of plants
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Basal angiosperms
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The basal angiosperms are the flowering plants which diverged from the lineage leading to most flowering plants. In particular, the most basal angiosperms were called the ANITA grade which is made up of Amborella, ANITA stands for Amborella, Nymphaeales and Illiciales, Trimeniaceae-Austrobaileya. The basal angiosperms are only a few hundred species, compared with hundreds of thousands of species of eudicots, monocots or magnoliids and they diverged from the ancestral angiosperm lineage before the five groups comprising the mesangiosperms diverged from each other. The exact relationships between Amborella, Nymphaeales and Austrobaileyales are not yet clear, a 2014 paper says that it presents the most convincing evidence to date that Amborella plus Nymphaeales together represent the earliest diverging lineage of extant angiosperms. Paleodicots is a name used by botanists to refer to angiosperms which are not monocots or eudicots. The paleodicots correspond to Magnoliidae sensu Cronquist 1981 and to Magnoliidae sensu Takhtajan 1980, some of the paleodicots share apparently plesiomorphic characters with monocots, e. g. scattered vascular bundles, trimerous flowers, and non-tricolpate pollen. The paleodicots are not a group and the term has not been widely adopted. Subsequent research has added Hydatellaceae to the paleodicots, the term paleoherb is another older term for flowering plants which are neither eudicots nor monocots
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Monophyletic
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In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it consists of an ancestral species and all its descendants. The term is synonymous with the uncommon term holophyly, monophyletic groups are typically characterized by shared derived characteristics. Monophyly is contrasted with paraphyly and polyphyly, as shown in the second diagram, a paraphyletic group consists of all of the descendants of a common ancestor minus one or more monophyletic groups. These definitions have taken time to be accepted. When the cladistic school of thought became mainstream in the 1960s, indeed, taxonomists sometimes used terms without defining them, leading to confusion in the early literature, a confusion which persists. On the broadest scale, definitions fall into two groups, willi Hennig defined monophyly as groups based on synapomorphy. Some authors have sought to define monophyly to include paraphyly as any two or more groups sharing a common ancestor, however, this broader definition encompasses both monophyletic and paraphyletic groups as defined above. Therefore, most scientists today restrict the term monophyletic to refer to groups consisting of all the descendants of one common ancestor, however, when considering taxonomic groups such as genera and species, the most appropriate nature of their common ancestor is unclear. Assuming that it would be one individual or mating pair is unrealistic for sexually reproducing species, some argue that using a broader definition, such as a species and all its descendants, does not really work to define a genus. According to D. M. Glossary of scientific naming Clade Paraphyly Polyphyly Crown group Abbey, graphical explanation of basic phylogenetic terms. Carr, Steven M. Concepts of monophyly, polyphyly & paraphyly
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Pollen
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Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes. If pollen lands on a compatible pistil or female cone, it germinates, individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is useful in paleoecology, paleontology, archaeology. Pollen in plants is used for transferring haploid male genetic material from the anther of a flower to the stigma of another in cross-pollination. In a case of self-pollination, this takes place from the anther of a flower to the stigma of the same flower. Pollen itself is not the male gamete, each pollen grain contains vegetative cells and a generative cell. In flowering plants the vegetative tube cell produces the pollen tube, pollen is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower. Pollen grains come in a variety of shapes, sizes. Pollen grains of pines, firs, and spruces are winged, the smallest pollen grain, that of the forget-me-not, is around 6 µm in diameter. Wind-borne pollen grains can be as large as about 90–100 µm, in angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of cells form within the anther. The fertile sporogenous cells are surrounded by layers of cells that grow into the wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells, in a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell, after meiotic division. After the formation of the four microspores, which are contained by callose walls, the exine is what is preserved in the fossil record. Two basic types of microsporogenesis are recognised, simultaneous and successive, in simultaneous microsporogenesis meiotic steps I and II are completed prior to cytokinesis, whereas in successive microsporogenesis cytokinesis follows. While there may be a continuum with intermediate forms, the type of microsporogenesis has systematic significance, the predominant form amongst the monocots is successive, but there are important exceptions. During microgametogenesis, the unicellular microspores undergo mitosis and develop into mature microgametophytes containing the gametes, in some flowering plants, germination of the pollen grain may begin even before it leaves the microsporangium, with the generative cell forming the two sperm cells. Except in the case of submerged aquatic plants, the mature pollen grain has a double wall
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Spermatophyte
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The spermatophytes, also known as phanerogams or phenogamae, comprise those plants that produce seeds, hence the alternative name seed plants. They are a subset of the embryophytes or land plants and these terms distinguished those plants with hidden sexual organs from those with visible sexual organs. In addition to the taxa listed above, the record contains evidence of many extinct taxa of seed plants. The so-called seed ferns were one of the earliest successful groups of land plants, glossopteris was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the Permian period. A whole genome duplication event in the ancestor of seed plants occurred about 319 million years ago and this gave rise to a series of evolutionary changes that resulted in the origin of seed plants. A middle Devonian precursor to seed plants from Belgium has been identified predating the earliest seed plants by about 20 million years, runcaria, small and radially symmetrical, is an integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the mutlilobed integument and it is suspected that the extension was involved in anemophilous pollination. Runcaria sheds new light on the sequence of character acquisition leading to the seed, runcaria has all of the qualities of seed plants except for a solid seed coat and a system to guide the pollen to the seed. Seed-bearing plants were divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetophytes, cycads, ginkgo. Older morphological studies believed in a relationship between the gnetophytes and the angiosperms, in particular based on vessel elements. However, molecular studies have shown a clade of gymnosperms. For example, one common proposed set of relationships is known as the hypothesis and looks like, However
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Gymnosperm
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The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. The term gymnosperm comes from the Greek composite word γυμνόσπερμος, meaning naked seeds and their naked condition stands in contrast to the seeds and ovules of flowering plants, which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, often modified to form cones, the gymnosperms and angiosperms together compose the spermatophytes or seed plants. By far the largest group of living gymnosperms are the conifers, followed by cycads, gnetophytes, in early classification schemes, the gymnosperms were regarded as a natural group. There is conflicting evidence on the question of whether the living gymnosperms form a clade, for the most recent classification on extant gymnosperms see Christenhusz et al. There are 12 families,83 known genera with a total of ca 1080 known species, subclass Cycadidae Order Cycadales Family Cycadaceae, Cycas Family Zamiaceae, Dioon, Bowenia, Macrozamia, Lepidozamia, Encephalartos, Stangeria, Ceratozamia, Microcycas, Zamia. It is widely accepted that the gymnosperms originated in the late Carboniferous period and this appears to have been the result of a whole genome duplication event around 319 million years ago. Early characteristics of seed plants were evident in fossil progymnosperms of the late Devonian period around 383 million years ago, the scorpionflies likely engaged in pollination mutualisms with gymnosperms, long before the similar and independent coevolution of nectar-feeding insects on angiosperms. Evidence has also found that mid-Mesozoic gymnosperms were pollinated by Kalligrammatid lacewings. Conifers are by far the most abundant extant group of gymnosperms with six to eight families, with a total of 65-70 genera, conifers are woody plants and most are evergreens. The leaves of many conifers are long, thin and needle-like, other species, including most Cupressaceae and some Podocarpaceae, have flat, agathis in Araucariaceae and Nageia in Podocarpaceae have broad, flat strap-shaped leaves. Cycads are the next most abundant group of gymnosperms, with two or three families,11 genera, and approximately 338 species, the other extant groups are the 95-100 species of Gnetales and one species of Ginkgo. Pine, fir, spruce, and cedar are all examples of conifers that are used for lumber, some other common uses for gymnosperms are soap, varnish, nail polish, food, gum, and perfumes. Gymnosperms, like all plants, have a sporophyte-dominant life cycle. Two spore types, microspores and megaspores, are produced in pollen cones or ovulate cones. Gametophytes, as with all plants, develop within the spore wall. Pollen grains mature from microspores, and ultimately produce sperm cells, megagametophytes develop from megaspores and are retained within the ovule. During pollination, pollen grains are transferred between plants, from pollen cone to the ovule, being transferred by wind or insects
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Asteraceae
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Asteraceae or Compositae is a very large and widespread family of flowering plants. The family currently has 32,913 accepted species names, in 1,911 genera and 13 subfamilies, in terms of numbers of species, the Asteraceae are rivaled only by the Orchidaceae. Many members have composite flowers in the form of flower heads surrounded by involucral bracts, when viewed from a distance, each capitulum may have the appearance of being a single flower. The name Asteraceae comes from the type genus Aster, from the Greek ἀστήρ, meaning star, Compositae is an older but still valid name which refers to the fact that the family is one of the few angiosperm ones to have composite flowers. Most members of Asteraceae are herbaceous, but a significant number are also shrubs, vines, the family has a worldwide distribution, from the polar regions to the tropics, colonizing a wide variety of habitats. It is most common in the arid and semiarid regions of subtropical, the Asteraceae may represent as much as 10% of autochthonous flora in many regions of the world. Asteraceae is an important family, providing products such as cooking oils, lettuce, sunflower seeds, artichokes, sweetening agents, coffee substitutes. Several genera are of importance, including pot marigold, Calendula officinalis, Echinacea, various daisies, fleabane, chrysanthemums, dahlias, zinnias. Asteraceae are important in medicine, including Grindelia, yarrow. A number of species are considered invasive, including, most notably in North America, dandelion, the name Asteraceae comes to international scientific vocabulary from New Latin, from Aster, the type genus, + -aceae, a standardized suffix for plant family names in modern taxonomy. The genus name comes from the Classical Latin word aster, star, Compositae, an older but still valid name, means composite and refers to the characteristic inflorescence, a special type of pseudanthium found in only a few other angiosperm families. The study of family is known as synantherology. The vernacular name daisy, widely applied to members of family, is derived from its Old English name, dægesege, from dæges eage. This is because the open at dawn and close at dusk. Composite flowers have a distribution, and are found everywhere except Antarctica. They are especially numerous in tropical and subtropical regions, Compositae were first described in 1792 by the German botanist Paul Dietrich Giseke. Traditionally, two subfamilies were recognised, Asteroideae and Cichorioideae, the latter has been shown to be extensively paraphyletic, and has now been divided into 12 subfamilies, but the former still stands. The phylogenetic tree presented below is based on Panero & Funk updated in 2014, the diamond denotes a very poorly supported node, the dot a poorly supported node
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Taraxacum
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Taraxacum is a large genus of flowering plants in the family Asteraceae which consists of species commonly known as dandelion. They are native to Eurasia and North America, but the two species worldwide, T. officinale and T. erythrospermum, were imports from Europe that now propagate as wildflowers. Both species are edible in their entirety, the common name dandelion is given to members of the genus. Like other members of the Asteraceae family, they have small flowers collected together into a composite flower head. Each single flower in a head is called a floret, many Taraxacum species produce seeds asexually by apomixis, where the seeds are produced without pollination, resulting in offspring that are genetically identical to the parent plant. The species of Taraxacum are tap-rooted, perennial, herbaceous plants, the genus contains many species which usually reproduce by apomixis, resulting in many local populations and endemism. In the British Isles alone,234 microspecies are recognised in 9 loosely defined sections, in general, the leaves are 5–25 cm long or longer, simple, lobed, and form a basal rosette above the central taproot. The flower heads are yellow to orange coloured, and are open in the daytime, the heads are borne singly on a hollow stem that is usually leafless and rises 1–10 cm or more above the leaves. Stems and leaves exude a white, milky latex when broken, a rosette may produce several flowering stems at a time. The flower heads are 2–5 cm in diameter and consist entirely of ray florets, the flower heads mature into spherical seed heads called blowballs or clocks containing many single-seeded fruits called achenes. Each achene is attached to a pappus of hairs, which enable wind-aided dispersal over long distances. The flower head is surrounded by bracts in two series, the inner bracts are erect until the seeds mature, then flex downward to allow the seeds to disperse. The outer bracts are often reflexed downward, but remain appressed in plants of the sections Palustria and Spectabilia, some species drop the parachute from the achenes, the hair-like parachutes are called pappus, and they are modified sepals. Between the pappus and the achene is a called a beak. The beak breaks off from the achene quite easily, separating the seed from the parachute, a number of species of Taraxacum are seed-dispersed ruderals that rapidly colonize disturbed soil, especially the common dandelion, which has been introduced over much of the temperate world. After flowering is finished, the flower head dries out for a day or two. The dried petals and stamens drop off, the reflex. Many similar plants in the Asteraceae family with yellow flowers are known as false dandelions
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Myosotis
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Myosotis is a genus of flowering plants in the family Boraginaceae. In the northern hemisphere they are commonly called forget-me-nots or scorpion grasses, the common name forget-me-not was calqued from the German Vergissmeinnicht, and first used in English in 1398 AD via King Henry IV. Similar names and variations are found in many languages, Myosotis alpestris is the state flower of Alaska. Plants of this genus are confused with Chatham Islands forget-me-nots which belong to a related genus. Over five hundred species names have been recorded, but there are only 74 accepted species, the rest are either synonyms of currently accepted names or submissions awaiting resolution. The genus is restricted to two discrete geographic centres, western Eurasia with about 60 confirmed species and New Zealand with around 40 confirmed species. Very small numbers of species occur elsewhere including North America, South America, despite this, Mysosotis species are now common throughout temperate latitudes via the planting of cultivars and introductions of alien species. Many are popular in gardens, preferring moist habitats, in areas where they are not native, they have frequently escaped to wetlands and riverbanks. Only those native to the Northern hemisphere are commonly called Forget-me-not and it is equally possible that the genus originated in either the Northern Hemisphere or in New Zealand. One or two European species, especially the wood forget-me-not, Myosotis sylvatica have been introduced into most of the regions of Europe, Asia. Myosotis have 5-merous actinomorphic flowers with 5 sepals and petals, flowers are typically 1 cm diameter, flat, and blue, pink, white or yellow with yellow centres, growing on scorpioid cymes. They may be annual or perennial with alternate leaves and they typically flower in spring or soon after snow-melt in alpine eco-systems. Their root systems are generally diffuse and their seeds are found in small, tulip-shaped pods along the stem to the flower. The pods attach to clothing when brushed against and eventually fall off, seeds can be collected by putting a piece of paper under the stems and shaking the seed pods and some seeds will fall out. Myosotis scorpioides is also known as scorpion grass due to the curve of its inflorescence. Mysosotis are used as food plants by the larvae of some Lepidoptera species including the setaceous Hebrew character, currently 74 species are classified as accepted species at The Plant List, of which 40 are endemic to New Zealand. The full list of species includes the following, In a German legend, God named all the plants when an unnamed one cried out, Forget-me-not. God replied, That shall be your name, in another Greek legend, when the Creator thought he had finished giving the flowers their colours, he heard one whisper Forget me not
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Cabbage
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Cabbage or headed cabbage is a leafy green or purple biennial plant, grown as an annual vegetable crop for its dense-leaved heads. It is descended from the cabbage, B. oleracea var. oleracea. Cabbage heads generally range from 0.5 to 4 kilograms, smooth-leafed firm-headed green cabbages are the most common, with smooth-leafed red and crinkle-leafed savoy cabbages of both colors seen more rarely. Under conditions of long sunlit days such as are found at high latitudes in summer. Some records are discussed at the end of the history section and it is difficult to trace the exact history of cabbage, but it was most likely domesticated somewhere in Europe before 1000 BC, although savoys were not developed until the 16th century. By the Middle Ages, it had become a prominent part of European cuisine, cabbage is prone to several nutrient deficiencies, as well as to multiple pests, and bacterial and fungal diseases. The Food and Agriculture Organization of the United Nations reports that production of cabbage. Almost half of these crops were grown in China, where Chinese cabbage is the most popular Brassica vegetable, cabbages are prepared in many different ways for eating. They can be pickled, fermented for dishes such as sauerkraut, steamed, stewed, sautéed, braised, cabbage is a good source of vitamin K, vitamin C and dietary fiber. Contaminated cabbage has been linked to cases of illness in humans. Cabbage is a member of the genus Brassica and the mustard family, several other cruciferous vegetables are considered cultivars of B. oleracea, including broccoli, collard greens, brussels sprouts, kohlrabi and sprouting broccoli. All of these developed from the wild cabbage B. oleracea var. oleracea, the varietal epithet capitata is derived from the Latin word for having a head. B. oleracea and its derivatives have hundreds of names throughout the world. Cabbage was originally used to refer to forms of B. oleracea. A related species, Brassica rapa, is commonly named Chinese, napa or celery cabbage and it is also a part of common names for several unrelated species. These include cabbage bark or cabbage tree and cabbage palms, which include several genera of palms such as Mauritia, Roystonea oleracea, Acrocomia, the original family name of brassicas was Cruciferae, which derived from the flower petal pattern thought by medieval Europeans to resemble a crucifix. The word brassica derives from bresic, a Celtic word for cabbage, many European and Asiatic names for cabbage are derived from the Celto-Slavic root cap or kap, meaning head. The late Middle English word cabbage derives from the word caboche and this in turn is a variant of the Old French caboce
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Brassicaceae
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Brassicaceae or Cruciferae is a medium-sized and economically important family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. The name Brassicaceae is derived from the included genus Brassica, the alternative older name, Cruciferae, meaning cross-bearing, describes the four petals of mustard flowers, which resemble a cross. Cruciferae is one of eight plant family names without the suffix -aceae that are authorized alternative names, the family contains 372 genera and 4060 accepted species. The largest genera are Draba, Erysimum, Lepidium, Cardamine, pieris rapae and other butterflies of the family Pieridae are some of the best-known pests of Brassicaceae species planted as commercial crops. The family is included in the Brassicales according to the APG system, older systems placed them into the Capparales, a now-defunct order that had a similar definition. This family comprises about 375 genera and 2500 species all over the world,94 species of 38 genera are found in Nepal, a close relationship has long been acknowledged between the Brassicaceae and the caper family, Capparaceae, in part because members of both groups produce glucosinolate compounds. The APG II system, therefore, has merged the two families under the name Brassicaceae, the APG III system has recently adopted this last solution, but this may change as a consensus arises on this point. This article deals with Brassicaceae sensu stricto, i. e. treating the Cleomaceae and Capparaceae as segregated families, the family consists mostly of herbaceous plants with annual, biennial, or perennial lifespans. The leaves are alternate, sometimes organized in basal rosettes, in rare shrubby crucifers of Mediterranean their leaves are mostly in terminal rosettes and they are very often pinnately incised and do not have stipules. The structure of the flowers is extremely uniform throughout the family and they have four free saccate sepals and four clawed free petals, staggered. They can be disymmetric or slightly zygomorphic, with a typical cross-like arrangement and they have six stamens, four of which are longer and are arranged in a cross like the petals and the other two are shorter. The pistil is made up of two fused carpels and the style is short, with two lobes. The flowers form ebracteate racemose inflorescences, often apically corymb-like, pollination occurs by entomogamy, nectar is produced at the base of the stamens and stored on the sepals. The fruit is a kind of capsule named siliqua. It opens by two valves, which are the modified carpels, leaving the attached to a framework made up of the placenta. Often, an indehiscent beak occurs at the top of the style, where a siliqua is less than three times as long as it is broad, it is usually termed a silicula. The siliqua may break apart at constrictions occurring between the segments of the seeds, thus forming a sort of loment, it may eject the seeds explosively or may be evolved in a sort of samara. The fruit is often the most important diagnostic character for plants in this family, most members share a suite of glucosinolate compounds that have a typical pungent odour usually associated with cole crops
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Apple
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The apple tree is a deciduous tree in the rose family best known for its sweet, pomaceous fruit, the apple. It is cultivated worldwide as a tree, and is the most widely grown species in the genus Malus. The tree originated in Central Asia, where its wild ancestor, Apples have been grown for thousands of years in Asia and Europe, and were brought to North America by European colonists. Apples have religious and mythological significance in many cultures, including Norse, Greek, Apple trees are large if grown from seed. Generally apple cultivars are propagated by grafting onto rootstocks, which control the size of the resulting tree, There are more than 7,500 known cultivars of apples, resulting in a range of desired characteristics. Different cultivars are bred for various tastes and uses, including cooking, eating raw, trees and fruit are prone to a number of fungal, bacterial and pest problems, which can be controlled by a number of organic and non-organic means. In 2010, the genome was sequenced as part of research on disease control. Worldwide production of apples in 2014 was 84.6 million tonnes, the apple is a deciduous tree, generally standing 1.8 to 4.6 m tall in cultivation and up to 12 m in the wild. When cultivated, the size, shape and branch density are determined by rootstock selection, the leaves are alternately arranged dark green-colored simple ovals with serrated margins and slightly downy undersides. Blossoms are produced in spring simultaneously with the budding of the leaves, the 3 to 4 cm flowers are white with a pink tinge that gradually fades, five petaled, with an inflorescence consisting of a cyme with 4–6 flowers. The central flower of the inflorescence is called the king bloom, it opens first, the fruit matures in late summer or autumn, and cultivars exist with a wide range of sizes. Commercial growers aim to produce an apple that is 7.0 to 8.3 cm in diameter, due to market preference. Some consumers, especially those in Japan, prefer a larger apple, while apples below 5.7 cm are generally used for making juice and have little market value. The skin of ripe apples is generally red, yellow, green, pink, the skin may also be wholly or partly russeted i. e. rough and brown. The skin is covered in a layer of epicuticular wax. The exocarp is generally pale yellowish-white, though pink or yellow also occur. The original wild ancestor of Malus pumila was Malus sieversii, found growing wild in the mountains of Central Asia in southern Kazakhstan, Kyrgyzstan, Tajikistan, in strains without recent admixture the contribution of the latter predominates. It had about 57,000 genes, the highest number of any plant genome studied to date and this new understanding of the apple genome will help scientists in identifying genes and gene variants that contribute to resistance to disease and drought, and other desirable characteristics
. PMID 20176954.
