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Phyllody
Phyllody is the abnormal development of floral parts into leafy structures. It is generally caused by phytoplasma or virus infections, though it may also be because of environmental factors that result in an imbalance in plant hormones. Phyllody causes the affected plant to become partially or entirely sterile, as it is unable to normally produce flowers. The condition is also known as phyllomorphy or frondescence; though the latter may sometimes refer more generically to foliage, leafiness, or the process of leaf growth. Phyllody is usually differentiated from floral virescence, wherein the flowers merely turn green in color but otherwise retain their normal structure. However, floral virescence and phyllody (along with witch's broom and other growth abnormalities), commonly occur together as symptoms of the same diseases. The term chloranthy is also often used for phyllody (particularly flowers exhibiting complete phyllody, such that it resembles leaf buds more than flowers) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllody On Coneflower With Aster Yellows
Phyllody is the abnormal development of floral parts into leafy structures. It is generally caused by phytoplasma or virus infections, though it may also be because of environmental factors that result in an imbalance in plant hormones. Phyllody causes the affected plant to become partially or entirely sterile, as it is unable to normally produce flowers. The condition is also known as phyllomorphy or frondescence; though the latter may sometimes refer more generically to foliage, leafiness, or the process of leaf growth. Phyllody is usually differentiated from floral virescence, wherein the flowers merely turn green in color but otherwise retain their normal structure. However, floral virescence and phyllody (along with witch's broom and other growth abnormalities), commonly occur together as symptoms of the same diseases. The term chloranthy is also often used for phyllody (particularly flowers exhibiting complete phyllody, such that it resembles leaf buds more than flowers) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytoplasma
Phytoplasmas are obligate intracellular parasites of plant phloem tissue and of the insect vectors that are involved in their plant-to-plant transmission. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-like organisms. Since their discovery, phytoplasmas have resisted all attempts at ''in vitro'' culture in any cell-free medium; routine cultivation in an artificial medium thus remains a major challenge. Phytoplasmas are characterized by the lack of a cell wall, a pleiomorphic or filamentous shape, a diameter normally less than 1 μm, and a very small genome. Phytoplasmas are pathogens of agriculturally important plants, including coconut, sugarcane, and sandalwood, in which they cause a wide variety of symptoms ranging from mild yellowing to death. Phytoplasmas are most prevalent in tropical and subtropical regions. They are transmitted from plant to plant by vectors (normally sap-sucking insects such as leafhoppers) in which they both sur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Hormone
Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense, stress tolerance and through to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones. Went and Thimann coined the term "phytohormone" and used it in the title of their 1937 book. Phytohormones occur across the plant kingdom, and even in algae, where they have similar functions to those seen in higher plants. Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites. Characteristics The word hormone is derived from Greek, meaning ''set in motion''. Plant hormones affect gene ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teratology
Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. These may include growth retardation, delayed mental development or other congenital disorders without any structural malformations. Teratogens are substances that may cause birth defects via a toxic effect on an embryo or fetus. Known teratogens include: retinol, thalidomide, mercury, alcohol, lead, polychlorinated biphenyls (PCBs), and 2,3,7,8-tetrachlorodibenzodioxin. Etymology The term was borrowed in 1842 from the French , where it was formed in 1830 from the Greek (word stem ), meaning "sign sent by the gods, portent, marvel, monster", and ('' -ology''), used to designate a discourse, treaty, science, theory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metamorphosis Of Plants
''Versuch die Metamorphose der Pflanzen zu erklären'', known in English as ''Metamorphosis of Plants'', was published by German poet and philosopher Johann Wolfgang von Goethe in 1790. In this work, Goethe essentially discovered the (serially) homologous nature of leaf organs in plants, from cotyledons, to photosynthetic leaves, to the petals of a flower. Although Sir Richard Owen, the British vertebrate anatomist, is generally credited with first articulating a definition of the word "homology" (in 1843), it is clear that Goethe had already arrived at a sophisticated view of homology and transformation (within an idealist morphological perspective) more than fifty years earlier. See also *Goethean science *Phyllody *Teratology Teratology is the study of abnormalities of physiological development in organisms during their life span. It is a sub-discipline in medical genetics which focuses on the classification of congenital abnormalities in dysmorphology. The related t ... E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Witch's Broom
Witch's broom or witches' broom is a deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest. It is sometimes caused by pathogens. Diseases with symptoms of witches' broom, caused by phytoplasmas or basidiomycetes, are economically important in a number of crop plants, including the cocoa tree ''Theobroma cacao'', jujube (''Ziziphus jujuba'') and the timber tree ''Melia azedarach''. Causes A tree's characteristic shape, or habit, is in part the product of auxins, hormones which control the growth of secondary apices. The growth of an offshoot is limited by the auxin, while that of the parent branch is not. In cases of witch's broom, the normal hierarchy of buds is interrupted, and apices grow indiscriminately. This can be caused by cytokinin, a phytohormone which interferes with growth regulation. The phenomenon can a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calyx (botany)
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined by Noël Martin Joseph de Necker in 1790, and derived . Collectively the sepals are called the calyx (plural calyces), the outermost whorl of parts that form a flower. The word ''calyx'' was adopted from the Latin ,Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Derivation and Accent; Published by Gerald Duckworth & Co. London, 4th ed 1928 not to be confused with 'cup, goblet'. ''Calyx'' is derived from Greek 'bud, calyx, husk, wrapping' ( Sanskrit 'bud'), while is derived from Greek 'cup, goblet', and the words have been used interchangeably in botanical Latin. After flowering, most plants have no more use for the calyx which withers or becomes vestigial. Some plants retain a thorny calyx, either dried or live, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sepal
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined by Noël Martin Joseph de Necker in 1790, and derived . Collectively the sepals are called the calyx (plural calyces), the outermost whorl of parts that form a flower. The word ''calyx'' was adopted from the Latin ,Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Derivation and Accent; Published by Gerald Duckworth & Co. London, 4th ed 1928 not to be confused with 'cup, goblet'. ''Calyx'' is derived from Greek 'bud, calyx, husk, wrapping' ( Sanskrit 'bud'), while is derived from Greek 'cup, goblet', and the words have been used interchangeably in botanical Latin. After flowering, most plants have no more use for the calyx which withers or becomes vestigial. Some plants retain a thorny calyx, either dried or live, as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture. Typically, they also look different from the parts of the flower, such as the petals or sepals. A plant having bracts is referred to as bracteate or bracteolate, while one that lacks them is referred to as ebracteate and ebracteolate, without bracts. Variants Some bracts are brightly-coloured and serve the function of attracting pollinators, either together with the perianth or instead of it. Examples of this type of bract include those of ''Euphorbia pulcherrima'' (poinsettia) and ''Bougainvillea'': both of these have large colourful bracts surrounding much smaller, less colourful flowers. In grasses, each floret (flower) is enclosed in a pair of papery bracts, called the lemma (lower bract) and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American People
Americans are the Citizenship of the United States, citizens and United States nationality law, nationals of the United States, United States of America.; ; Although direct citizens and nationals make up the majority of Americans, many Multiple citizenship, dual citizens, expatriates, and green card, permanent residents could also legally claim American nationality. The United States is home to race and ethnicity in the United States, people of many racial and ethnic origins; consequently, culture of the United States, American culture and Law of the United States, law do not equate nationality with Race (human categorization), race or Ethnic group, ethnicity, but with citizenship and an Oath of Allegiance (United States), oath of permanent allegiance. Overview The majority of Americans or their ancestors Immigration to the United States, immigrated to the United States or are descended from people who were Trans Atlantic Slave Trade, brought as Slavery in the United States ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek Language
Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark Ages, Dark Ages (), the Archaic Greece, Archaic period (), and the Classical Greece, Classical period (). Ancient Greek was the language of Homer and of fifth-century Athens, fifth-century Athenian historians, playwrights, and Ancient Greek philosophy, philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Homeric Greek, Epic and Classical periods of the language. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regarded as a separate historical stage, although its earliest form closely resembles Attic Greek and its latest form a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Latin
Contemporary Latin is the form of the Literary Latin used since the end of the 19th century. Various kinds of contemporary Latin can be distinguished, including the use of New Latin words in taxonomy and in science generally, and the fuller ecclesiastical use in the Catholic Church – but Living or Spoken Latin (the use of Latin as a language in its own right as a full-fledged means of expression) is the primary subject of this article. Token Latin Latin is still present in words or phrases used in many languages around the world, as a relic of the great importance of New Latin, which was the formerly dominant international ''lingua franca'' down to the 19th century in a great number of fields. Some minor communities also use Latin in their speech. Mottos The official use of Latin in previous eras has survived at a symbolic level in many mottos that are still being used and even coined in Latin to this day. Old mottos like , found in 1776 on the Seal of the United States, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
