1.
Liriodendron tulipifera
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It is native to eastern North America from Southern Ontario and Illinois eastward to southeastern Massachusetts and Rhode Island, and south to central Florida and Louisiana. It can grow to more than 50 m in virgin forests of the Appalachian Mountains, often with no limbs until it reaches 25–30 m in height. It is fast-growing, without the problems of weak wood strength. April marks the start of the period in the southern USA. The flowers are green or yellow, with an orange band on the tepals. The tulip tree is the tree of Indiana, Kentucky. The tulip tree is one of the largest of the trees of the eastern United States, known to reach the height of 60 m, with a trunk 3 m in diameter. It prefers deep, rich, and rather moist soil, it is common, though not abundant, growth is fairly rapid, and the typical form of its head is conical. The bark is brown, and furrowed, the branchlets are smooth, and lustrous, initially reddish, maturing to dark gray, and finally brown. The wood is yellow to brown, and the sapwood creamy white, light, soft, brittle, close. Specific gravity,0.4230, density,422 g/dm3, winter buds, Dark red, covered with a bloom, obtuse, scales becoming conspicuous stipules for the unfolding leaf, and persistent until the leaf is fully grown. Flower-bud enclosed in a two-valved, caducous bract, the alternate leaves are simple, pinnately veined, measuring five to six inches long and wide. In autumn they turn a clear, bright yellow, perfect, solitary, terminal, greenish yellow, borne on stout peduncles, an inch and a half to two inches long, cup-shaped, erect, conspicuous. The bud is enclosed in a sheath of two bracts which fall as the blossom opens. Calyx, Sepals three, imbricate in bud, reflexed or spreading, somewhat veined, early deciduous, corolla, Cup-shaped, petals six, two inches long, in two rows, imbricate, hypogynous, greenish yellow, marked toward the base with yellow. Stamens, Indefinite, imbricate in many ranks on the base of the receptacle, filaments thread-like, short, anthers extrorse, long, two-celled, adnate, pistils, Indefinite, imbricate on the long slender receptacle. Ovary one-celled, style acuminate, flattened, stigma short, one-sided, recurved, fruit, Narrow light brown cone, formed from many samaras which are dispersed by wind, leaving the axis persistent all winter. A description from Our native trees and how to identify them by Harriet Louise Keeler, The leaves are of unusual shape and develop in a most peculiar, the leaf-buds are composed of scales as is usual, and these scales grow with the growing shoot
2.
Populus tremula
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It also occurs at one site in northwest Africa in Algeria. In the south of its range, it occurs at altitudes in mountains. The English name Waverly, meaning quaking aspen, is both a surname and unisex given name and it is a substantial deciduous tree growing to 40 m tall by 10 m broad, with a trunk attaining over 1 m in diameter. The bark is pale greenish-grey and smooth on young trees with dark grey diamond-shaped lenticels, becoming dark grey and fissured on older trees. The adult leaves, produced on branches of trees, are nearly round, slightly wider than long, 2–8 cm diameter, with a coarsely toothed margin. The leaves on seedlings and fast-growing stems of suckers are of a different shape and they are also often much larger, up to 20 cm long, their petiole is also less flattened. The flowers are wind-pollinated catkins produced in spring before the new leaves appear, they are dioecious. The fluff assists wind dispersal of the seeds when the split open at maturity. It can be distinguished from the closely related North American Populus tremuloides by the leaves being more coarsely toothed, like other aspens, it spreads extensively by suckers, which may be produced up to 40 m from the parent tree, forming extensive clonal colonies. Eurasian aspen is a water and light demanding species that is able to colonize an open area after fire. After an individual has been damaged or destroyed, root suckers are produced abundantly on the lateral roots. Fast growth continues until the age of about 20 years when crown competition increases, after that, growth speed decreases and culminates at about 30 years of age. Aspen can reach an age of 200 years and it is a very hardy species and tolerates long, cold winters and short summers. Aspen is resistant to browsing pressure by fallow deer due to its unpleasant taste, the aspen is found in cultivation in parks and large gardens. The hybrid with Populus alba, known as poplar, Populus × canescens, is widely found in Europe. Hybrids with several other aspens have also bred at forestry research institutes in order to find trees with greater timber production. The wood of aspen is light soft and has very little shrinkage and it is used for lumber and matches but is also valued in the pulp and paper industry, being particular useful for writing paper. In addition, it is used for plywood and different types of flake, furthermore, the tree plays an important role in production of wood for renewable energy
3.
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
4.
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
5.
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
6.
Eudicots
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The eudicots, Eudicotidae or eudicotyledons are a monophyletic clade of flowering plants that had been called tricolpates or non-magnoliid dicots by previous authors. The close relationships among flowering plants with tricolpate pollen grains was initially seen in studies of shared derived characters. These plants have a trait in their pollen grains of exhibiting three colpi or grooves paralleling the polar axis. Later molecular evidence confirmed the basis for the evolutionary relationships among flowering plants with tricolpate pollen grains. The term means true dicotyledons, as it contains the majority of plants that have been considered dicots and have characteristics of the dicots, the term eudicots has subsequently been widely adopted in botany to refer to one of the two largest clades of angiosperms, monocots being the other. The remaining angiosperms are sometimes referred to as basal angiosperms or paleodicots, the other name for the eudicots is tricolpates, a name which refers to the grooved structure of the pollen. Members of the group have tricolpate pollen, or forms derived from it and these pollens have three or more pores set in furrows called colpi. In contrast, most of the seed plants produce monosulcate pollen. The name tricolpates is preferred by some botanists to avoid confusion with the dicots, numerous familiar plants are eudicots, including many common food plants, trees, and ornamentals. Most leafy trees of midlatitudes also belong to eudicots, with exceptions being magnolias and tulip trees which belong to magnoliids, and Ginkgo biloba. The name eudicots is used in the APG system, of 1998 and it is applied to a clade, a monophyletic group, which includes most of the dicots. The eudicots can be divided into two groups, the basal eudicots and the core eudicots, basal eudicot is an informal name for a paraphyletic group. The core eudicots are a monophyletic group, a 2010 study suggested the core eudicots can be divided into two clades, Gunnerales and a clade called Pentapetalae, comprising all the remaining core eudicots
7.
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
8.
Malpighiales
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The Malpighiales comprise one of the largest orders of flowering plants, containing about 16,000 species, about 7. 8% of the eudicots. The order is very diverse, containing plants as different as the willow, violet, Poinsettia, and coca plant and it is not part of any of the classification systems based only on plant morphology. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago, the Malpighiales are divided into 32 to 42 families, depending upon which clades in the order are given the taxonomic rank of family. In the APG III system,35 families are recognized, medusagynaceae, Quiinaceae, Peraceae, Malesherbiaceae, Turneraceae, Samydaceae, and Scyphostegiaceae are consolidated into other families. The largest family, by far, is the Euphorbiaceae, with about 6300 species in about 245 genera, in a 2009 study of DNA sequences of 13 genes,42 families were placed into 16 groups, ranging in size from one to 10 families. Almost nothing is known about the relationships among these 16 groups, Malpighiales and Lamiales are the two large orders whose phylogeny remains mostly unresolved. Malpighiales is a member of a group called the COM clade, which consists of the orders Celastrales, Oxalidales. Some describe it as containing an order, Huales, separating the family Huaceae into its own order. Some recent studies have placed Malpighiales as sister to Oxalidales sensu lato, the COM clade is part of an unranked group known as Fabidae or eurosids I. The fabids, in turn, are part of a group that has long recognized, namely. The family Malpighiaceae was the family for one of the orders created by Jussieu in his 1789 work Genera Plantarum. Friedrich von Berchtold and Jan Presl described such an order in 1820, unlike modern taxonomists, these authors did not use the suffix ales in naming their orders. The name Malpighiales is attributed by some to Carl von Martius, in the 20th century, it was usually associated with John Hutchinson, who used it in all three editions of his book, The Families of Flowering Plants. The name was not used by those who later, in the 1970s, 80s. The taxon was largely presaged by Hans Hallier in 1912 in an article in the Archiv, the first semblance of Malpighiales as now known came from a phylogeny of seed plants published in 1993 and based upon DNA sequences of the gene rbcL. This study recovered a group of rosids unlike any found in any previous system of plant classification. Malpighiales is monophyletic and in phylogenetic studies, it receives strong statistical support. Since the APG II system was published in 2003, minor changes to the circumscription of the order have been made, the family Peridiscaceae has been expanded from two genera to three, and then to four, and transferred to Saxifragales
9.
Salicaceae
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The Salicaceae are a family, the willow family, of flowering plants. The traditional family included the willows, poplar, aspen, recent genetic studies summarized by the Angiosperm Phylogeny Group have greatly expanded the circumscription of the family to contain 56 genera and about 1220 species. In the Cronquist system, the Salicaceae were assigned to their own order, Salicales, the family is placed by the APG in the order Malpighiales. Media related to Salicaceae at Wikimedia Commons Data related to Salicaceae at Wikispecies
10.
Carl Linnaeus
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Carl Linnaeus, also known after his ennoblement as Carl von Linné, was a Swedish botanist, physician, and zoologist, who formalised the modern system of naming organisms called binomial nomenclature. He is known by the father of modern taxonomy. Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus, Linnaeus was born in the countryside of Småland, in southern Sweden. He received most of his education at Uppsala University. He lived abroad between 1735 and 1738, where he studied and also published a first edition of his Systema Naturae in the Netherlands and he then returned to Sweden, where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on journeys through Sweden to find and classify plants. In the 1750s and 1760s, he continued to collect and classify animals, plants, and minerals, at the time of his death, he was one of the most acclaimed scientists in Europe. The philosopher Jean-Jacques Rousseau sent him the message, Tell him I know no man on earth. The German writer Johann Wolfgang von Goethe wrote, With the exception of Shakespeare and Spinoza, Swedish author August Strindberg wrote, Linnaeus was in reality a poet who happened to become a naturalist. Among other compliments, Linnaeus has been called Princeps botanicorum, The Pliny of the North and he is also considered as one of the founders of modern ecology. In botany, the abbreviation used to indicate Linnaeus as the authority for species names is L. In older publications, sometimes the abbreviation Linn. is found, Linnæus was born in the village of Råshult in Småland, Sweden, on 23 May 1707. He was the first child of Nicolaus Ingemarsson and Christina Brodersonia and his siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, and Emerentia Linnæa. One of a line of peasants and priests, Nils was an amateur botanist, a Lutheran minister. Christina was the daughter of the rector of Stenbrohult, Samuel Brodersonius, a year after Linnæus birth, his grandfather Samuel Brodersonius died, and his father Nils became the rector of Stenbrohult. The family moved into the rectory from the curates house, even in his early years, Linnæus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and often showed flowers to Linnaeus, soon Linnæus was given his own patch of earth where he could grow plants
11.
Type species
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A similar concept is used for suprageneric groups called a type genus. In botanical nomenclature, these terms have no standing under the code of nomenclature. In botany, the type of a name is a specimen which is also the type of a species name. The species name that has that type can also be referred to as the type of the genus name, names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types. In bacteriology, a species is assigned for each genus. Every named genus or subgenus in zoology, whether or not currently recognized as valid, is associated with a type species. In practice, however, there is a backlog of untypified names defined in older publications when it was not required to specify a type, a type species is both a concept and a practical system that is used in the classification and nomenclature of animals. The type species represents the species and thus definition for a particular genus name. In the Glossary, type species is defined as The nominal species that is the type of a nominal genus or subgenus. The type species permanently attaches a formal name to a genus by providing just one species within that genus to which the name is permanently linked. The species name in turn is fixed, in theory, to a type specimen, for example, the type species for the land snail genus Monacha is Monacha cartusiana. That genus is placed within the family Hygromiidae. The type genus for that family is the genus Hygromia, the concept of the type species in zoology was introduced by Pierre André Latreille. The International Code of Zoological Nomenclature states that the name of the type species should always be cited. It gives an example in Article 67.1, Astacus marinus Fabricius,1775 was later designated as the type species of the genus Homarus, thus giving it the name Homarus marinus. However, the species of Homarus should always be cited using its original name. 3, the type of the genus name Elodes is quoted as the type of the species name Hypericum aegypticum, Glossary of scientific naming Genetypes – genetic sequence data from type specimens. Holotype Paratype Principle of Typification Type Type genus
12.
Species
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In biology, a species is the basic unit of biological classification and a taxonomic rank. A species is defined as the largest group of organisms in which two individuals can produce fertile offspring, typically by sexual reproduction. While this definition is often adequate, looked at more closely it is problematic, for example, with hybridisation, in a species complex of hundreds of similar microspecies, or in a ring species, the boundaries between closely related species become unclear. Other ways of defining species include similarity of DNA, morphology, all species are given a two-part name, a binomial. The first part of a binomial is the genus to which the species belongs, the second part is called the specific name or the specific epithet. For example, Boa constrictor is one of four species of the Boa genus, Species were seen from the time of Aristotle until the 18th century as fixed kinds that could be arranged in a hierarchy, the great chain of being. In the 19th century, biologists grasped that species could evolve given sufficient time, Charles Darwins 1859 book The Origin of Species explained how species could arise by natural selection. Genes can sometimes be exchanged between species by horizontal transfer, and species may become extinct for a variety of reasons. In his biology, Aristotle used the term γένος to mean a kind, such as a bird or fish, a kind was distinguished by its attributes, for instance, a bird has feathers, a beak, wings, a hard-shelled egg, and warm blood. A form was distinguished by being shared by all its members, Aristotle believed all kinds and forms to be distinct and unchanging. His approach remained influential until the Renaissance, when observers in the Early Modern period began to develop systems of organization for living things, they placed each kind of animal or plant into a context. Many of these early delineation schemes would now be considered whimsical, animals likewise that differ specifically preserve their distinct species permanently, one species never springs from the seed of another nor vice versa. In the 18th century, the Swedish scientist Carl Linnaeus classified organisms according to shared physical characteristics and he established the idea of a taxonomic hierarchy of classification based upon observable characteristics and intended to reflect natural relationships. At the time, however, it was widely believed that there was no organic connection between species, no matter how similar they appeared. However, whether or not it was supposed to be fixed, by the 19th century, naturalists understood that species could change form over time, and that the history of the planet provided enough time for major changes. Jean-Baptiste Lamarck, in his 1809 Zoological Philosophy, described the transmutation of species, proposing that a species could change over time, in 1859, Charles Darwin and Alfred Russel Wallace provided a compelling account of evolution and the formation of new species. Darwin argued that it was populations that evolved, not individuals and this required a new definition of species. Darwin concluded that species are what appear to be, ideas
13.
Deciduous
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In a more general sense, deciduous means the dropping of a part that is no longer needed or falling away after its purpose is finished. In plants it is the result of natural processes, in botany and horticulture, deciduous plants, including trees, shrubs and herbaceous perennials, are those that lose all of their leaves for part of the year. In some cases leaf loss coincides with winter—namely in temperate or polar climates, in other parts of the world, including tropical, subtropical, and arid regions, plants lose their leaves during the dry season or other seasons, depending on variations in rainfall. The converse of deciduous is coniferous, where foliage is shed on a different schedule from deciduous trees, plants that are intermediate may be called semi-deciduous, they lose old foliage as new growth begins. Other plants are semi-evergreen and lose their leaves before the growing season. Many deciduous plants flower during the period when they are leafless, the absence of leaves improves wind transmission of pollen for wind-pollinated plants and increases the visibility of the flowers to insects in insect-pollinated plants. This strategy is not without risks, as the flowers can be damaged by frost or, in dry season regions, leaf drop or abscission involves complex physiological signals and changes within plants. The process of photosynthesis steadily degrades the supply of chlorophylls in foliage, the brightest leaf colors are produced when days grow short and nights are cool, but remain above freezing. These other pigments include carotenoids that are yellow, brown, anthocyanin pigments produce red and purple colors, though they are not always present in the leaves. Rather, they are produced in the foliage in late summer, parts of the world that have showy displays of bright autumn colors are limited to locations where days become short and nights are cool. In other parts of the world, the leaves of deciduous trees simply fall off without turning the bright colors produced from the accumulation of anthocyanin pigments, the beginnings of leaf drop starts when an abscission layer is formed between the leaf petiole and the stem. This layer is formed in the spring during active new growth of the leaf, the cells are sensitive to a plant hormone called auxin that is produced by the leaf and other parts of the plant. The elongation of cells break the connection between the different cell layers, allowing the leaf to break away from the plant. It also forms a layer that seals the break, so the plant does not lose sap, in the spring, these proteins are used as a nitrogen source during the growth of new leaves or flowers. Plants with deciduous foliage have advantages and disadvantages compared to plants with evergreen foliage, evergreens suffer greater water loss during the winter and they also can experience greater predation pressure, especially when small. Losing leaves in winter may reduce damage from insects, repairing leaves, removing leaves also reduces cavitation which can damage xylem vessels in plants. This then allows deciduous plants to have xylem vessels with larger diameters, the deciduous characteristic has developed repeatedly among woody plants. Trees include maple, many oaks and nothofagus, elm, aspen, Deciduous shrubs include honeysuckle, viburnum, and many others
14.
Northern Hemisphere
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The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined as being in the celestial hemisphere relative to the invariable plane of the solar system as Earths North pole. Due to the Earths axial tilt, winter in the Northern Hemisphere lasts from the December solstice to the March Equinox, the dates vary each year due to the difference between the calendar year and the astronomical year. Its surface is 60. 7% water, compared with 80. 9% water in the case of the Southern Hemisphere, the Arctic is the region north of the Arctic Circle. Its climate is characterized by cold winters and cool summers, precipitation mostly comes in the form of snow. The Arctic experiences some days in summer when the Sun never sets, the duration of these phases varies from one day for locations right on the Arctic Circle to several months near the North Pole, which is the middle of the Northern Hemisphere. Between the Arctic Circle and the Tropic of Cancer lies the Northern Temperate Zone, the changes in these regions between summer and winter are generally mild, rather than extreme hot or cold. However, a temperate climate can have very unpredictable weather, tropical regions are generally hot all year round and tend to experience a rainy season during the summer months, and a dry season during the winter months. In the Northern Hemisphere, objects moving across or above the surface of the Earth tend to turn to the right because of the coriolis effect, as a result, large-scale horizontal flows of air or water tend to form clockwise-turning gyres. These are best seen in circulation patterns in the North Atlantic. For the same reason, flows of air down toward the surface of the Earth tend to spread across the surface in a clockwise pattern. Thus, clockwise air circulation is characteristic of high pressure weather cells in the Northern Hemisphere, conversely, air rising from the northern surface of the Earth tends to draw air toward it in a counterclockwise pattern. Hurricanes and tropical storms spin counter-clockwise in the Northern Hemisphere, the shadow of a sundial moves clockwise in the Northern Hemisphere. When viewed from the Northern Hemisphere, the Moon appears inverted compared to a view from the Southern Hemisphere, the North Pole faces away from the galactic center of the Milky Way. The Northern Hemisphere is home to approximately 6.57 billion people which is around 90% of the total human population of 7.3 billion people
15.
Aspen
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Aspen is a common name for certain tree species, some, but not all, are classified by botanists in the section Populus, of the Populus genus. They are all medium-sized deciduous trees reaching 15–30 m tall, each individual tree can live for 40–150 years above ground, but the root system of the colony is long-lived. In some cases, this is for thousands of years, sending up new trunks as the older trunks die off above ground, for this reason, it is considered to be an indicator of ancient woodlands. One such colony in Utah, given the nickname of Pando, is estimated to be 80,000 years old, some aspen colonies become very large with time, spreading about 1 m per year, eventually covering many hectares. They are able to survive forest fires, because the roots are below the heat of the fire, aspens do not thrive in the shade, and it is difficult for seedlings to grow in an already mature aspen stand. Fire indirectly benefits aspen trees, since it allows the saplings to flourish in open sunlight in the burned landscape, young aspen bark is an important seasonal forage for the European hare and other animals in early spring. Aspen is also a tree of choice of the European beaver, aspen wood is white and soft, but fairly strong, and has low flammability. It has a number of uses, notably for making matches, shredded aspen wood is used for packing and stuffing, sometimes called excelsior. It is also a popular animal bedding, since it lacks the phenols associated with pine and juniper, heat-treated aspen is a popular material for the interiors of a sauna. Trees portal Fox, Mark, Linda E. Tackaberry, Pascal Drouin, Yves Bergeron, Robert L. Bradley, microbial community structure of soils under four productivity classes of aspen forests in Northern British Columbia
16.
Populus sect. Aigeiros
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Populus section Aigeiros is a section of three species in the genus Populus, the poplars. Like some other species in the genus Populus, they are known as cottonwoods. The species are native to North America, Europe, and western Asia, in the past, as many as six species were recognized, but recent trends have been to accept just three species, treating the others as subspecies of P. deltoides. An important feature of the leaves is the petiole, which is flattened sideways so that the leaves have a type of movement in the wind. Male and female flowers are in catkins, appearing before the leaves in spring. The seeds are borne on cottony structures that allow them to be blown long distances in the air before settling to ground, the cottonwoods are exceptionally tolerant of flooding, erosion, and flood deposits filling around the trunk. Although each of the three species has a different leaf pattern, they all have the same general diamond leaf shape. Eastern cottonwood is one of the largest North American hardwood trees and it is a riparian zone tree. It occurs throughout the eastern United States and in extreme southern Canada, the leaves are alternate and simple, with coarsely toothed edges, and subcordate at the base. The leaf shape is triangular, hence the species name. In the typical subspecies P. d. deltoides, the leaves are broad and triangular, further west, the subspecies P. d. monilifera has somewhat narrower leaves, 5–10 cm wide at the base. This is also the tree of Nebraska, Wyoming. In West Texas, New Mexico, and Colorado, the subspecies P. d. wislizeni occurs, fremonts cottonwood is native to the southwestern United States and western Mexico. In the United States, the species can be found in California, Nevada, arizona, New Mexico, Texas and Colorado. In Mexico, it can be found in the states of Baja California, Baja California Sur, Sonora, Chihuahua, Coahuila, Nuevo León, Mexico State, and Puebla. It differs from the eastern cottonwood mainly in the leaves having fewer, larger serrations on the edge, some taxonomists formerly considered P. fremontii to be a subspecies of P. deltoides. Black poplar is native to Europe and Western Asia, is distinct in its smaller leaves, 5–11 centimetres across. Cottonwoods are widely grown for timber production along wet river banks, the wood is coarse and of fairly low value, used for pallet boxes, shipping crates, and similar purposes where a cheap but strong enough wood is suitable
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Science (journal)
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Science, also widely referred to as Science Magazine, is the peer-reviewed academic journal of the American Association for the Advancement of Science and one of the worlds top academic journals. It was first published in 1880, is circulated weekly and has a print subscriber base of around 130,000. Because institutional subscriptions and online access serve an audience, its estimated readership is 570,400 people. Unlike most scientific journals, which focus on a field, Science. According to the Journal Citation Reports, Sciences 2015 impact factor was 34.661, although it is the journal of the AAAS, membership in the AAAS is not required to publish in Science. Papers are accepted from authors around the world, competition to publish in Science is very intense, as an article published in such a highly cited journal can lead to attention and career advancement for the authors. Fewer than 7% of articles submitted are accepted for publication, Science is based in Washington, D. C. United States, with an office in Cambridge, England. Science was founded by New York journalist John Michels in 1880 with financial support from Thomas Edison, however, the journal never gained enough subscribers to succeed and ended publication in March 1882. Entomologist Samuel H. Scudder resurrected the journal one year later and had some success while covering the meetings of prominent American scientific societies, however, by 1894, Science was again in financial difficulty and was sold to psychologist James McKeen Cattell for $500. In an agreement worked out by Cattell and AAAS secretary Leland O. Howard, after Cattell died in 1944, the ownership of the journal was transferred to the AAAS. After Cattells death in 1944, the journal lacked a consistent editorial presence until Graham DuShane became editor in 1956. In 1958, under DuShanes leadership, Science absorbed The Scientific Monthly, physicist Philip Abelson, a co-discoverer of neptunium, served as editor from 1962 to 1984. Under Abelson the efficiency of the process was improved and the publication practices were brought up to date. During this time, papers on the Apollo program missions and some of the earliest reports on AIDS were published, biochemist Daniel E. Koshland, Jr. served as editor from 1985 until 1995. From 1995 until 2000, neuroscientist Floyd E. Bloom held that position, biologist Donald Kennedy became the editor of Science in 2000. Biochemist Bruce Alberts took his place in March 2008, geophysicist Marcia McNutt became editor-in-chief in June 2013. During her tenure the family of journals expanded to include Science Robotics and Science Immunology, jeremy M. Berg became editor-in-chief on July 1,2016
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Populus trichocarpa
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Populus trichocarpa, the black cottonwood, western balsam-poplar or California poplar, is a deciduous broadleaf tree species native to western North America. It is used for timber, and is notable as an organism in plant biology. Its full genome sequence was published in 2006 and it is the first tree species to be sequenced. It is a tree, growing to a height of 30 metres to 50 metres and a trunk diameter of over 2 metres. It is normally fairly short-lived, but some trees may live for up to 400 years, a cottonwood in Willamette Mission State Park near Salem, Oregon holds the national and world records. Last measured in April,2008 this black cottonwood was found to be standing at 155 ft tall,29 ft around, the bark is grey and covered with lenticels, becoming thick and deeply fissured on old trees. The bark can become hard enough to cause sparks when cut with a chainsaw, the stem is grey in the older parts and light brown in younger parts. The crown is usually conical and quite dense. In large trees the lower branches droop downwards, the wood has a light coloring and a straight grain. The leaves are alternate, elliptic with a crenate margin and an acute tip, the buds are conical, long, narrow and sticky, with a strong balsam scent in spring when they open. Populus trichocarpa has an extensive and aggressive root system, which can invade, sometimes the roots can even damage the foundations of buildings by drying out the soil. Flowering and fruiting Populus trichocarpa is normally dioecious, male and female catkins are borne on separate trees, the species reaches flowering age at about 10 years. Flowers may appear in early March to late May in Washington and Oregon, and sometimes as late as mid-June in northern and interior British Columbia, Idaho, staminate catkins contain 30 to 60 stamens, elongate to 2 to 3 cm, and are deciduous. Pistillate catkins at maturity are 8 to 20 cm long with rotund-ovate, each capsule contains many minute seeds with long, white cottony hairs. Seed production and dissemination The seed ripens and is disseminated by late May to late June in Oregon and Washington, abundant seed crops are usually produced every year. Attached to its cotton, the seed is light and buoyant and can be transported long distances by wind, although highly viable, longevity of P. trichocarpa seed under natural conditions may be as short as two weeks to a month. This can be increased with cold storage, seedling development Moist seedbeds are essential for high germination, and seedling survival depends on continuously favorable conditions during the first month. Wet bottom lands of rivers and major streams frequently provide such conditions, P. trichocarpa seedlings do not usually become established in abundance after logging unless special measures are taken to prepare the bare, moist seedbeds required for initial establishment
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DNA sequencing
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DNA sequencing is the process of determining the precise order of nucleotides within a DNA molecule. It includes any method or technology that is used to determine the order of the four bases—adenine, guanine, cytosine, the advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. The first DNA sequences were obtained in the early 1970s by academic researchers using laborious methods based on two-dimensional chromatography, following the development of fluorescence-based sequencing methods with a DNA sequencer, DNA sequencing has become easier and orders of magnitude faster. DNA sequencing may be used to determine the sequence of genes, larger genetic regions, full chromosomes or entire genomes. DNA sequencing is also the most efficient way to sequence RNA or proteins, in fact, DNA sequencing has become a key technology in many areas of biology and other sciences such as medicine, forensics, or anthropology. Sequencing is used in biology to study genomes and the proteins they encode. Information obtained using sequencing allows researchers to identify changes in genes, associations with diseases and phenotypes, the field of metagenomics involves identification of organisms present in a body of water, sewage, dirt, debris filtered from the air, or swab samples from organisms. Knowing which organisms are present in an environment is critical to research in ecology, epidemiology, microbiology. Sequencing enables researchers to determine which types of microbes may be present in a microbiome, medical technicians may sequence genes from patients to determine if there is risk of genetic diseases. This is a form of testing, though some genetic tests may not involve DNA sequencing. DNA sequencing may be used along with DNA profiling methods for forensic identification, the canonical structure of DNA has four bases, thymine, adenine, cytosine, and guanine. DNA sequencing is the determination of the order of these bases in a molecule of DNA. However, there are other bases that may be present in a molecule. In some viruses, cytosine may be replaced by hydroxy methyl or hydroxy methyl glucose cytosine, in mammalian DNA, variant bases with methyl groups or phosphosulfate may be found. Depending on the technique, a particular modification, e. g. the 5mC common in humans. This situation changed after 1944 as a result of experiments by Oswald Avery, Colin MacLeod. This was the first time that DNA was shown capable of transforming the properties of cells, in 1953, James Watson and Francis Crick put forward their double-helix model of DNA, based on crystallized X-ray structures being studied by Rosalind Franklin. According to the model, DNA is composed of two strands of nucleotides coiled around each other, linked together by bonds and running in opposite directions
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Bark (botany)
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Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs, Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the bark and the outer bark. The inner bark, which in older stems is living tissue, the outer bark in older stems includes the dead tissue on the surface of the stems, along with parts of the innermost periderm and all the tissues on the outer side of the periderm. The outer bark on trees which lies external to the last formed periderm is also called the rhytidome, Bark has been used to make cloth, canoes, and ropes and used as a surface for paintings and map making. A number of plants are grown for their attractive or interesting bark colorations. What is commonly called bark includes a number of different tissues, Cork is an external, secondary tissue that is impermeable to water and gases, and is also called the phellem. The cork is produced by the cork cambium which is a layer of active cells which serve as a lateral meristem for the periderm. The cork cambium, which is called the phellogen, is normally only one cell layer thick. The phelloderm, which is not always present in all barks, is a layer of cells formed by, together, the phellem, phellogen and phelloderm constitute the periderm. Cork cell walls contain suberin, a substance which protects the stem against water loss, the invasion of insects into the stem. The cambium tissues, i. e. Phloem is a nutrient-conducting tissue composed of sieve tubes or sieve cells mixed with parenchyma, the cortex is the primary tissue of stems and roots. In stems the cortex is between the layer and the phloem, in roots the inner layer is not phloem. From the outside to the inside of a woody stem. The bark includes through, and is composed of periderm and phloem, as the stem ages and grows, changes occur that transform the surface of the stem into the bark. The epidermis is a layer of cells that cover the plant body, including the stems, leaves, flowers and fruits, in old stems the epidermal layer, cortex, and primary phloem become separated from the inner tissues by thicker formations of cork. Due to the cork layer these cells die because they do not receive water. This dead layer is the rough corky bark that forms around tree trunks, often a secondary covering called the periderm forms on small woody stems and many non woody plants, which is composed of cork, the cork cambium, and the phelloderm
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