1.
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
2.
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
3.
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
4.
Ranunculaceae
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Ranunculaceae is a family of over 2,000 known species of flowering plants in 43 genera, distributed worldwide. The largest genera are Ranunculus, Delphinium, Thalictrum, Clematis, Ranunculaceae are mostly herbaceous annuals or perennials, but some woody climbers or shrubs. Most members of the family have flowers which can be showy or inconspicuous. The sepals and petals are free and typically number four or five. In many species, the sepals are colorful and appear petal-like, in these species, the petals can be inconspicuous or absent. Most species have both basal and cauline leaves, which are compound or lobed but can be simple. They are typically alternate, or occasionally opposite or even whorled, many species, especially the perennials form rhizomes that develop new roots each year. Flowers may be solitary, but are frequently found aggregated in cymes, panicles, the fruit is most commonly an achene or a follicle. Ranunculaceae contain protoanemonin, which is toxic to humans and animals, other poisonous or toxic compounds, alkaloids and glycosides, are also common. Takhtajan included the Ranunculaceae as the family in the Ranunculales which he placed in a subclass. Previously, Thorn placed the Ranunculaceae in the Berberidales, an order within the Superorder Magnolianae, earlier Cronquist in 1981 included the Ranunculaceae along with seven other families in the Rancunculales which was included in the Magnoliidae, which he regarded as a subclass. David, placed the Ranuculaceae, together with the Eupteleaceae, Lardizabalaceae, Menispermaceae, Berberidaceae, and Papaveraceae in the Ranunculales and this follows the work of the Angiosperm Phylogeny Group. The family Ranunculaceae sensu stricto is one of seven families included in the order Ranunculales within the eudicots according to the Angiosperm Phylogeny Group classification, the family is monophyletic with Glaucidium as sister to the remaining genera. This phylogeny is illustrated in the APG Poster, early subdivisions of the family, such as Adanson, simply divided it based on one-seeded or many-seeded fruit. Prantl envisaged three tribes, Paeonieae, Hellebroreae and Anemoneae with Paeonia, Glaucidium and Hydrastis forming Paeoniaae, by the twentieth century Langlet used chromosome types to create two subfamilies, Ranunculoideae and Thalictroideae. Paeonia was separated from Ranuculaceae and placed in its own family of Paeoniaceae, other genera originally included in Ranunculaceae include Circaeaster which was placed in its own family Circaeasteraceae. Tamuras complete system was structured as follows, Subfamilies and tribes Subfamily Ranunculoideae Hutch, when subjected to molecular phylogenetic analysis only Thalictroideae is monophyletic. The position of Glaucidium and some of its unique morphological characteristics prompted Stevens to suggest that it be given subfamilial rank as the monotypic Glaucidioideae, similarly Hydrastis has been assigned to subfamily Hydrastidoideae
5.
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
6.
Nectar
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Common nectar-consuming pollinators include mosquitoes, hoverflies, wasps, bees, butterflies and moths, hummingbirds, and bats. M. scutellata and the honey bee. Nectar is an important item, the sugar source for honey. It is also useful in agriculture and horticulture because the adult stages of some predatory insects feed on nectar, for example, the social wasp species Apoica flavissima relies on nectar as a primary food source. In turn, these wasps then hunt agricultural pest insects as food for their young, for example, thread-waisted wasps are known for hunting caterpillars that are destructive to crops. Caterpillars however, do eventually become butterflies and moths, which are important pollinators. Nectar secretion increases as the flower is visited by pollinators, after pollination, the nectar is frequently reabsorbed into the plant. Nectar is derived from Greek nektar, the drink of the gods. The current meaning, sweet liquid in flowers, is first recorded in AD1600, floral nectaries are generally located at the base of the perianth, so pollinators are made to brush the flowers reproductive structures, the stamen and pistil, while accessing the nectar. A septal nectary is nectar-producing tissue that is found in the wall of a plant ovary, septal nectaries function as a way of attracting pollinators. Plants that rely on insects, birds, or bats for pollination often have septal nectaries, aside from attracting pollinators, septal nectaries have also been known to attract plant protectors. Some plants, like Ruellia radicans, have nectaries that continue to secrete nectar even after the petals have been shed and this attracts ants which will in turn protect the developing fruits of the plant from seed predators and herbivores in exchange for nectar. Extrafloral nectaries are nectar-secreting plant glands that develop outside of flowers and are not involved in pollination and they are highly diverse in form, location, size, and mechanism. They have been described in virtually all above-ground plant parts—including leaves, petioles, stipules, cotyledons, fruits and they range from single-celled trichomes to complex cup-like structures that may or may not be vascularized. In contrast to floral nectaries, nectar produced outside the flower generally have a defensive function, the nectar attracts predatory insects which will eat both the nectar and any plant-eating insects around, thus functioning as bodyguards. Foraging predatory insects show a preference for plants with extrafloral nectaries, particularly species of ants and wasps. Among passion flowers, for example, extrafloral nectaries prevent herbivores by attracting ants, in many carnivorous plants, extrafloral nectaries are also used to attract insect prey. Extrafloral nectaries were originally believed to simply be excretory in nature and their defensive functions were first recognized by the Italian botanist Federico Delpino in his important monograph Funzione mirmecofila nel regno vegetale
7.
Utah
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Utah is a state in the western United States. It became the 45th state admitted to the U. S. on January 4,1896, Utah is the 13th-largest by area, 31st-most-populous, and 10th-least-densely populated of the 50 United States. Utah has a population of more than 3 million, approximately 80% of whom live along the Wasatch Front, Utah is bordered by Colorado to the east, Wyoming to the northeast, Idaho to the north, Arizona to the south, and Nevada to the west. It also touches a corner of New Mexico in the southeast, approximately 62% of Utahns are reported to be members of The Church of Jesus Christ of Latter-day Saints or LDS, which greatly influences Utahn culture and daily life. The LDS Churchs world headquarters is located in Salt Lake City, Utah is the only state with a majority population belonging to a single church. The state is a center of transportation, education, information technology and research, government services, mining, in 2013, the U. S. Census Bureau estimated that Utah had the second fastest-growing population of any state. St. George was the metropolitan area in the United States from 2000 to 2005. Utah also has the 14th highest median income and the least income inequality of any U. S. state. A2012 Gallup national survey found Utah overall to be the best state to live in based on 13 forward-looking measurements including various economic, lifestyle, the name Utah is derived from the name of the Ute tribe. It means people of the mountains in the Ute language, according to other sources Utah is derived from the Apache name Yudah which means Tall. These Native American tribes are subgroups of the Ute-Aztec Native American ethnicity and were sedentary, the Ancestral Pueblo people built their homes through excavations in mountains, and the Fremont people built houses of straw before disappearing from the region around the 15th century. Another group of Native Americans, the Navajo, settled in the region around the 18th century, in the mid-18th century, other Uto-Aztecan tribes, including the Goshute, the Paiute, the Shoshone, and the Ute people, also settled in the region. These five groups were present when the first European explorers arrived, the southern Utah region was explored by the Spanish in 1540, led by Francisco Vásquez de Coronado, while looking for the legendary Cíbola. A group led by two Catholic priests—sometimes called the Dominguez-Escalante Expedition—left Santa Fe in 1776, hoping to find a route to the coast of California, the expedition traveled as far north as Utah Lake and encountered the native residents. The Spanish made further explorations in the region, but were not interested in colonizing the area because of its desert nature, in 1821, the year Mexico achieved its independence from Spain, the region became known as part of its territory of Alta California. European trappers and fur traders explored some areas of Utah in the early 19th century from Canada, the city of Provo, Utah was named for one, Étienne Provost, who visited the area in 1825. The city of Ogden, Utah was named after Peter Skene Ogden, in late 1824, Jim Bridger became the first known English-speaking person to sight the Great Salt Lake. Due to the salinity of its waters, Bridger thought he had found the Pacific Ocean
8.
Leaf
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A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot, Leaves are collectively referred to as foliage, as in autumn foliage. Although leaves can be seen in different shapes, sizes and textures, typically a leaf is a thin, dorsiventrally flattened organ, borne above ground. Most leaves have distinctive upper surface and lower surface that differ in colour, hairiness, broad, flat leaves with complex venation are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In others, such as the clubmosses, with different evolutionary origins, some leaves, such as bulb scales are not above ground, and in many aquatic species the leaves are submerged in water. Succulent plants often have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls, furthermore, several kinds of leaf-like structures found in vascular plants are not totally homologous with them. Examples include flattened plant stems called phylloclades and cladodes, and flattened leaf stems called phyllodes which differ from both in their structure and origin. Many structures of plants, such as the phyllids of mosses and liverworts and even of some foliose lichens. Leaves are the most important organs of most vascular plants and these are then further processed by chemical synthesis into more complex organic molecules such as cellulose, the basic structural material in plant cell walls. The plant must therefore bring these three together in the leaf for photosynthesis to take place. Once sugar has been synthesized, it needs to be transported to areas of growth such as the plant shoots and roots. Vascular plants transport sucrose in a tissue called the phloem. The phloem and xylem are parallel to each other but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch to form veins which supply as much as the leaf as possible and they are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance plants adapted to windy conditions may have pendent leaves, such as in many willows, the flat, or laminar, shape also maximises thermal contact with the surrounding air, promoting cooling. Functionally, in addition to photosynthesis the leaf is the site of transpiration and guttation. Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and these are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. For xerophytes the major constraint is not light flux or intensity, some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. and Bulbine mesembryanthemoides
9.
Glossary of leaf morphology
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The following is a defined list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple or compound, the edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. For more terms describing other aspects of leaves besides their overall morphology see the leaf article, leaves of most plants include a flat structure called the blade or lamina, but not all leaves are flat, some are cylindrical. Leaves may be simple, with a leaf blade, or compound. In flowering plants, as well as the blade of the leaf, there may be a petiole and stipules, leaf structure is described by several terms that include, Being one of the more visible features, leaf shape is commonly used for plant identification. Edge and margin are both interchangeable in the sense that they refer to the perimeter of a leaf. Leaves may also be folded or rolled in various ways, the folding of leaves within a bud is vernation, ptyxis is the folding of an individual leaf in a bud
10.
Meadow
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A meadow is a field habitat vegetated by grass and other non-woody plants. Meadows are of importance because they are open, sunny areas that attract and support flora. Meadows may be naturally occurring or artificially created from cleared shrub or woodland and they often host a multitude of wildlife, providing areas for courtship displays, nesting, food gathering and sometimes sheltering if the vegetation is high enough. Many meadows support an array of wildflowers, which makes them of utmost importance to insects like bees and other pollinating insects. In agriculture, a meadow is grassland which is not regularly grazed by domestic livestock, especially in the United Kingdom and Ireland, the term meadow is commonly used in its original sense to mean a hay meadow, signifying grassland mown annually in the summer for making hay. Agricultural meadows are typically lowland or upland fields upon which hay or pasture grasses grow from self-sown or hand-sown seed, traditional hay meadows were once common in rural Britain, but are now in decline. Ecologist Professor John Rodwell states that over the past century, England, fewer than 15.000 hectares of lowland meadows remain in the UK and most sites are relatively small and fragmented. 25% of the UKs meadows are found in Worcestershire, with Fosters Green Meadow managed by the Worcestershire Wildlife Trust being a major site. A similar concept to the hay meadow is the pasture, which differs from the meadow in that it is grazed through the summer, rather than being allowed to grow out, the term, grassland, is used to describe both hay meadows and grass pastures. The specific agricultural practices in relation to the meadow can take on various expressions, as mentioned, this could be hay production or providing food for grazing cattle and livestock but also to give room for orchards or honey production. A transitional state can be artificially-maintained through a system, in which cultivated soil. For example, some of todays meadows originated thousands of years ago, types of perpetual meadows may include, Alpine meadows occur at high elevations above the tree line and maintained by harsh climatic conditions. Coastal meadows maintained by salt sprays, desert meadows restricted by low precipitation or lack of nutrients and humus. Prairies maintained by periods of drought or subject to wildfires. Wet meadows saturated with water much of the year. Apart from the meadows, meadows are often conceived of as artificial or cultural habitats, since they have emerged from and continually require human intervention to persist. It can be argued however, that meadows are really semi-cultural habitats, the reason is, that in many places the natural, pristine populations of free roaming large grazers are either extinct or very limited due to human activities. This reduces or removes their natural influence on the surrounding ecology, mankind has influenced the ecology and the landscape for millennia in many parts of the world, so it can sometimes be difficult to discern what is natural and what is cultural
11.
Flower
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A flower, sometimes known as a bloom or blossom, is the reproductive structure found in plants that are floral. The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs, Flowers may facilitate outcrossing or allow selfing. Some flowers produce diaspores without fertilization, Flowers contain sporangia and are the site where gametophytes develop. Many flowers have evolved to be attractive to animals, so as to them to be vectors for the transfer of pollen. After fertilization, the ovary of the flower develops into fruit containing seeds, the essential parts of a flower can be considered in two parts, the vegetative part, consisting of petals and associated structures in the perianth, and the reproductive or sexual parts. A stereotypical flower consists of four kinds of structures attached to the tip of a short stalk, each of these kinds of parts is arranged in a whorl on the receptacle. The four main whorls are as follows, Collectively the calyx, corolla, the next whorl toward the apex, composed of units called petals, which are typically thin, soft and colored to attract animals that help the process of pollination. Androecium, the whorl, consisting of units called stamens. Stamens consist of two parts, a called a filament, topped by an anther where pollen is produced by meiosis. Gynoecium, the innermost whorl of a flower, consisting of one or more units called carpels, the carpel or multiple fused carpels form a hollow structure called an ovary, which produces ovules internally. Ovules are megasporangia and they in turn produce megaspores by meiosis which develop into female gametophytes and these give rise to egg cells. The gynoecium of a flower is described using an alternative terminology wherein the structure one sees in the innermost whorl is called a pistil. A pistil may consist of a carpel or a number of carpels fused together. The sticky tip of the pistil, the stigma, is the receptor of pollen, the supportive stalk, the style, becomes the pathway for pollen tubes to grow from pollen grains adhering to the stigma. The relationship to the gynoecium on the receptacle is described as hypogynous, perigynous, although the arrangement described above is considered typical, plant species show a wide variation in floral structure. These modifications have significance in the evolution of flowering plants and are used extensively by botanists to establish relationships among plant species, the four main parts of a flower are generally defined by their positions on the receptacle and not by their function. Many flowers lack some parts or parts may be modified into other functions and/or look like what is typically another part, in some families, like Ranunculaceae, the petals are greatly reduced and in many species the sepals are colorful and petal-like. Other flowers have modified stamens that are petal-like, the flowers of Peonies and Roses are mostly petaloid stamens
12.
Petal
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Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators, together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals, the calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished sepals and petals, when the undifferentiated tepals resemble petals, they are referred to as petaloid, as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, a name is lilioid monocots. Although petals are usually the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, the role of the corolla in plant evolution has been studied extensively since Charles Darwin postulated a theory of the origin of elongated corollae and corolla tubes. If the petals are free from one another in the corolla, the corolla in some plants forms a tube. Petals can differ dramatically in different species, the number of petals in a flower may hold clues to a plants classification. For example, flowers on eudicots most frequently have four or five petals while flowers on monocots have three or six petals, although there are exceptions to this rule. The petal whorl or corolla may be radially or bilaterally symmetrical. If all of the petals are essentially identical in size and shape, many flowers are symmetrical in only one plane and are termed irregular or zygomorphic. In irregular flowers, other parts may be modified from the regular form. Examples of zygomorphic flowers may be seen in orchids and members of the pea family, in many plants of the aster family such as the sunflower, Helianthus annuus, the circumference of the flower head is composed of ray florets. Each ray floret is anatomically an individual flower with a large petal. Florets in the centre of the disc typically have no or very reduced petals, in some plants such as Narcissus the lower part of the petals or tepals are fused to form a floral cup above the ovary, and from which the petals proper extend. Petal often consists of two parts, the upper, broad part, similar to leaf blade, called the limb, claws are developed in petals of some flowers of the family Brassicaceae, such as Erysimum cheiri. The inception and further development of shows a great variety of patterns
