Plant propagation is the process of growing new plants from a variety of sources: seeds and other plant parts. Plant propagation can refer to the artificial or natural dispersal of plants. Seeds and spores can be used for reproduction. Seeds are produced from sexual reproduction within a species, because genetic recombination has occurred. A plant grown from seeds may have different characteristics from its parents; some species produce seeds, such as cold treatment. The seeds of many Australian plants and plants from southern Africa and the American west require smoke or fire to germinate; some plant species, including many trees, do not produce seeds until they reach maturity, which may take many years. Seeds can be difficult to acquire and some plants do not produce seed at all; some plants may produce not fertile seed. In certain cases, this is done to prevent the accidental spreading of these plants, for example by birds and other animals. Plants have a number of mechanisms for vegetative reproduction.
Some of these have been taken advantage of by horticulturists and gardeners to multiply or clone plants rapidly. Humans may utilize these processes as propagation methods, such as tissue grafting. Plants are produced using material from a single parent and as such there is no exchange of genetic material, therefore vegetative propagation methods always produce plants that are identical to the parent. Vegetative reproduction uses plants parts such as roots and leaves. In some plants seeds can be produced without fertilization and the seeds contain only the genetic material of the parent plant. Therefore, propagation via asexual seeds or apomixis is asexual reproduction but not vegetative propagation. Techniques for vegetative propagation include: Air or ground layering Division Grafting and bud grafting used in fruit tree propagation Micropropagation Stolons or runners Storage organs such as bulbs, corms and rhizomes Striking or cuttings Twin-scaling Offsets A heated propagator is a horticultural device to maintain a warm and damp environment for seeds and cuttings to grow in.
This can be in the form of a clear enclosed bin sitting over a hotpad, or a portable heater pointed at the bin. The key is to keep the moisture in the clear bin, while keeping lighting over the top of it, usually. An electric seed-propagation mat is a heated rubber mat covered by a metal cage, used in gardening; the mats are made so that planters containing seedlings can be placed on top of the metal cage without the risk of starting a fire. In extreme cold, gardeners place a loose plastic cover over the planters/mats which creates a sort of miniature greenhouse; the constant and predictable heat allows people to garden in the winter months when the weather is too cold for seedlings to survive naturally. When combined with a lighting system, many plants can be grown indoors using these mats. Adventitious Clonal colony Fruit tree propagation Orthodox seed Recalcitrant seed Selection methods in plant breeding based on mode of reproduction Propagation of grapevines Weeping willow is an ornamental tree (Salix babylonica and related hybrids.
<http://aggie-horticulture.tamu.edu/ornamental/a-reference-guide-to-plant-care-handling-and-merchandising/propagating-foliage-flowering-plants/>. Charles W. Heuser; the Complete Book of Plant Propagation, Taunton Press, 1997. ISBN 1561582344
Plant genetics is the study of genes, genetic variation, heredity in Plants. It is considered a field of biology and botany, but intersects with many other life sciences and is linked with the study of information systems. Plant genetics differs in a few key areas; the discoverer of genetics was a late 19th-century scientist and Augustinian friar. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring, he observed that organisms inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of. Much of Mendel's work with plants still forms the basis for modern plant genetics. Plants, like all known organisms, use DNA to pass on their traits. Animal genetics focuses on parentage and lineage, but this can sometimes be difficult in plant genetics due to the fact that plants can, unlike most animals, be self-fertile. Speciation can be easier in many plants due to unique genetic abilities, such as being well adapted to polyploidy.
Plants are unique in that they are able to produce energy-dense carbohydrates via photosynthesis, a process, achieved by use of Chloroplast|chloroplasts]]. Chloroplasts, like the superficially similar mitochondria, possess their own DNA. Chloroplasts thus provide an additional reservoir for genes and genetic diversity, an extra layer of genetic complexity not found in animals; the study of plant genetics has major economic impacts: many staple crops are genetically modified to increase yields, confer pest and disease resistance, provide resistance to herbicides, or to increase their nutritional value. The earliest evidence of plant domestication found has been dated to 11,000 years before present in ancestral wheat. While selection may have happened unintentionally, it is likely that by 5,000 years ago farmers had a basic understanding of heredity and inheritance, the foundation of genetics; this selection over time gave rise to new crop species and varieties that are the basis of the crops we grow and research today.
The field of plant genetics began with the work of Gregor Johann Mendel, called the "father of genetics". He was an Augustinian scientist born on 20 July 1822 in Austria-Hungary, he worked at the Abbey of St. Thomas in Bruno, where his organism of choice for studying inheritance and traits was the pea plant. Mendel's work tracked many phenotypic traits of pea plants, such as their height, flower color, seed characteristics. Mendel showed that the inheritance of these traits follows two particular laws, which were named after him, his seminal work on genetics, “Versuche über Pflanzen-Hybriden”, was published in 1866, but went entirely unnoticed until 1900 when prominent botanists in the UK, like Sir Gavin de Beer, recognized its importance and re-published an English translation. Mendel died in 1884; the significance of Mendel's work was not recognized until the turn of the 20th century. Its rediscovery prompted the foundation of modern genetics, his discoveries, deduction of segregation ratios, subsequent laws have not only been used in research to gain a better understanding of plant genetics, but play a large role in plant breeding.
Mendel's works along with the works of Charles Darwin and Alfred Wallace on selection provided the basis for much of genetics as a discipline. In the early 1900s, botanists and statisticians began to examine the segregation ratios put forth by Mendel. W. E. Castle discovered that while individual traits may segregate and change over time with selection, that when selection is stopped and environmental effects are taken into account, the genetic ratio stops changing and reach a sort of stasis, the foundation of Population Genetics; this was independently discovered by G. H. Hardy and W. Weinberg, which gave rise to the concept of Hardy-Weinberg equilibrium published in 1908. For a more thorough exploration of the history of population genetics, see History of Population Genetics by Bob Allard. Around this same time and plant breeding experiments in maize began. Maize, self-pollinated experiences a phenomena called inbreeding depression. Researchers, like Nils Heribert-Nilsson, recognized that by crossing plants and forming hybrids, they were not only able to combine traits from two desirable parents, but the crop experienced heterosis or hybrid vigor.
This was the beginning of identifying gene epistasis. By the early 1920's, Donald Forsha Jones had invented a method that led to the first hybrid maize seed that were available commercially; the large demand for hybrid seed in the U. S. Corn Belt by the mid 1930's led to a rapid growth in the seed production industry and seed research; the strict requirements for producing hybrid seed led to the development of careful population and inbred line maintenance, keeping plants isolated and unable to out-cross, which produced plants that better allowed researchers to tease out different genetic concepts. The structure of these populations allowed scientist such a T. Dobzhansky, S. Wright, R. A. Fisher to develop evolutionary biology concepts as well as explore speciation over time and the statistics underlying plant genetics, their work layed the foundations for future genetic discoveries such as linkage disequilibrium in 1960. While breeding experiments were taking place, other scientists such as Nikolai Vavilov and Charles M. Rick were interested in wild progenitor species of modern crop plants.
Botanists between the 1920's and 1960's would travel to regions of high plant diversity and seek out wild species that had given r
Biomechanics is the study of the structure and motion of the mechanical aspects of biological systems, at any level from whole organisms to organs and cell organelles, using the methods of mechanics. The word "biomechanics" and the related "biomechanical" come from the Ancient Greek βίος bios "life" and μηχανική, mēchanikē "mechanics", to refer to the study of the mechanical principles of living organisms their movement and structure. Biological fluid mechanics, or biofluid mechanics, is the study of both gas and liquid fluid flows in or around biological organisms. An studied liquid biofluids problem is that of blood flow in the human cardiovascular system. Under certain mathematical circumstances, blood flow can be modelled by the Navier–Stokes equations. In vivo whole blood is assumed to be an incompressible Newtonian fluid. However, this assumption fails. At the microscopic scale, the effects of individual red blood cells become significant, whole blood can no longer be modelled as a continuum.
When the diameter of the blood vessel is just larger than the diameter of the red blood cell the Fahraeus–Lindquist effect occurs and there is a decrease in wall shear stress. However, as the diameter of the blood vessel decreases further, the red blood cells have to squeeze through the vessel and can only pass in single file. In this case, the inverse Fahraeus -- the wall shear stress increases. An example of a gaseous biofluids problem is that of human respiration. Respiratory systems in insects have been studied for bioinspiration for designing improved microfluidic devices; the main aspects of Contact mechanics and tribology are related to friction and lubrication. When the two surfaces come in contact during motion i.e. rub against each other, friction and lubrication effects are important to analyze in order to determine the performance of the material. Biotribology is a study of friction and lubrication of biological systems human joints such as hips and knees. For example and tibial components of knee implant rub against each other during daily activity such as walking or stair climbing.
If the performance of tibial component needs to be analyzed, the principles of biotribology are used to determine the wear performance of the implant and lubrication effects of synovial fluid. In addition, the theory of contact mechanics becomes important for wear analysis. Additional aspects of biotribology can include analysis of subsurface damage resulting from two surfaces coming in contact during motion, i.e. rubbing against each other, such as in the evaluation of tissue engineered cartilage. Comparative biomechanics is the application of biomechanics to non-human organisms, whether used to gain greater insights into humans or into the functions and adaptations of the organisms themselves. Common areas of investigation are Animal locomotion and feeding, as these have strong connections to the organism's fitness and impose high mechanical demands. Animal locomotion, has many manifestations, including running and flying. Locomotion requires energy to overcome friction, drag and gravity, though which factor predominates varies with environment.
Comparative biomechanics overlaps with many other fields, including ecology, developmental biology and paleontology, to the extent of publishing papers in the journals of these other fields. Comparative biomechanics is applied in medicine as well as in biomimetics, which looks to nature for solutions to engineering problems. Computational biomechanics is the application of engineering computational tools, such as the Finite element method to study the mechanics of biological systems. Computational models and simulations are used to predict the relationship between parameters that are otherwise challenging to test experimentally, or used to design more relevant experiments reducing the time and costs of experiments. Mechanical modeling using finite element analysis has been used to interpret the experimental observation of plant cell growth to understand how they differentiate, for instance. In medicine, over the past decade, the Finite element method has become an established alternative to in vivo surgical assessment.
One of the main advantages of computational biomechanics lies in its ability to determine the endo-anatomical response of an anatomy, without being subject to ethical restrictions. This has led FE modeling to the point of becoming ubiquitous in several fields of Biomechanics while several projects have adopted an open source philosophy; the mechanical analysis of biomaterials and biofluids is carried forth with the concepts of continuum mechanics. This assumption breaks down when the length scales of interest approach the order of the micro structural details of the material. One of the most remarkable characteristic of biomaterials is their hierarchical structure. In other words, the mechanical characteristics of these materials rely on physical phenomena occurring in multiple levels, from the molecular all the way up to the tissue and organ levels. Biomaterials are classified in two groups and soft tissues. Mechanical deformation of hard tissues may be analysed with the theory of linear elasticity.
On the other hand, soft tissues undergo large deformations and thus their analysis rely on the finite strain theory and computer simulations. The interest in continuum biomechanics is spurred by the need for realism in the development of medical simulation
Plants are multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. Plants were treated as one of two kingdoms including all living things that were not animals, all algae and fungi were treated as plants. However, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes. By one definition, plants form the clade Viridiplantae, a group that includes the flowering plants and other gymnosperms and their allies, liverworts and the green algae, but excludes the red and brown algae. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria, their chloroplasts contain b, which gives them their green color. Some plants are parasitic or mycotrophic and have lost the ability to produce normal amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although asexual reproduction is common.
There are about 320 thousand species of plants, of which the great majority, some 260–290 thousand, are seed plants. Green plants provide a substantial proportion of the world's molecular oxygen and are the basis of most of Earth's ecosystems on land. Plants that produce grain and vegetables form humankind's basic foods, have been domesticated for millennia. Plants have many cultural and other uses, as ornaments, building materials, writing material and, in great variety, they have been the source of medicines and psychoactive drugs; the scientific study of plants is known as a branch of biology. All living things were traditionally placed into one of two groups and animals; this classification may date from Aristotle, who made the distincton between plants, which do not move, animals, which are mobile to catch their food. Much when Linnaeus created the basis of the modern system of scientific classification, these two groups became the kingdoms Vegetabilia and Animalia. Since it has become clear that the plant kingdom as defined included several unrelated groups, the fungi and several groups of algae were removed to new kingdoms.
However, these organisms are still considered plants in popular contexts. The term "plant" implies the possession of the following traits multicellularity, possession of cell walls containing cellulose and the ability to carry out photosynthesis with primary chloroplasts; when the name Plantae or plant is applied to a specific group of organisms or taxon, it refers to one of four concepts. From least to most inclusive, these four groupings are: Another way of looking at the relationships between the different groups that have been called "plants" is through a cladogram, which shows their evolutionary relationships; these are not yet settled, but one accepted relationship between the three groups described above is shown below. Those which have been called "plants" are in bold; the way in which the groups of green algae are combined and named varies between authors. Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom.
The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the green algae, red algae and brown algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, they are no longer classified as plants as defined here; the Viridiplantae, the green plants – green algae and land plants – form a clade, a group consisting of all the descendants of a common ancestor. With a few exceptions, the green plants have the following features in common, they undergo closed mitosis without centrioles, have mitochondria with flat cristae. The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. Two additional groups, the Rhodophyta and Glaucophyta have primary chloroplasts that appear to be derived directly from endosymbiotic cyanobacteria, although they differ from Viridiplantae in the pigments which are used in photosynthesis and so are different in colour.
These groups differ from green plants in that the storage polysaccharide is floridean starch and is stored in the cytoplasm rather than in the plastids. They appear to have had a common origin with Viridiplantae and the three groups form the clade Archaeplastida, whose name implies that their chloroplasts were derived from a single ancient endosymbiotic event; this is the broadest modern definition of the term'plant'. In contrast, most other algae not only have different pigments but have chloroplasts with three or four surrounding membranes, they are not close relatives of the Archaeplastida having acquired chloroplasts separately from ingested or symbiotic green and red algae. They are thus not included in the broadest modern definition of the plant kingdom, although they were in the past; the green plants or Viridiplantae were traditionally divided into the green algae (including
History of plant systematics
The history of plant systematics—the biological classification of plants—stretches from the work of ancient Greek to modern evolutionary biologists. As a field of science, plant systematics came into being only early plant lore being treated as part of the study of medicine. Classification and description was driven by natural history and natural theology; until the advent of the theory of evolution, nearly all classification was based on the scala naturae. The professionalization of botany in the 18th and 19th century marked a shift toward more holistic classification methods based on evolutionary relationships; the Sushrut first classify plant in 4 categories on basis of flowering pattern structure and life span. Vanspataya Vruksha Virudh Aushodh तासां स्थावराश्चतुर्विधाः- वनस्पतयो, वृक्षा, वीरुध, ओषधय इति | तासु, अपुष्पाः फलवन्तो वनस्पतयः, पुष्पफलवन्तो वृक्षाः, प्रतानवत्यः स्तम्बिन्यश्च वीरुधः, फलपाकनिष्ठा ओषधय इति ||Sushrut Sutra 1/21|| <<https://en.wikipedia.org/wiki/Sushruta>> The peripatetic philosopher Theophrastus, as a student of Aristotle in Ancient Greece, wrote Historia Plantarum, the earliest surviving treatise on plants, where he listed the names of over 500 plant species.
He did not articulate a formal classification scheme, but relied on the common groupings of folk taxonomy combined with growth form: tree shrub. The De Materia Medica of Dioscorides was an important early compendium of plant descriptions, classifying plants chiefly by their medicinal effects. In the 16th century, works by Otto Brunfels, Hieronymus Bock, Leonhart Fuchs helped to revive interest in natural history based on first-hand observation. With the influx of exotic species in the Age of Exploration, the number of known species expanded but most authors were far more interested in the medicinal properties of individual plants than an overarching classification system. Influential Renaissance books include those of Caspar Bauhin and Andrea Cesalpino. Bauhin described over 6000 plants, which he arranged into 12 books and 72 sections based on a wide range of common characteristics. Cesalpino based his system on the structure of the organs of fructification, using the Aristotelian technique of logical division.
In the late 17th century, the most influential classification schemes were those of English botanist and natural theologian John Ray and French botanist Joseph Pitton de Tournefort. Ray, who listed over 18,000 plant species in his works, is credited with establishing the monocot/dicot division and some of his groups — mustards, mints and grasses — stand today. Tournefort used an artificial system based on logical division, adopted in France and elsewhere in Europe up until Linnaeus; the book that had an enormous accelerating effect on the science of plant systematics was Species Plantarum by Linnaeus. It presented a complete list of the plant species known to Europe, ordered for the purpose of easy identification using the number and arrangement of the male and female sexual organs of the plants. Of the groups in this book, the highest rank that continues to be used today is the genus; the consistent use of binomial nomenclature along with a complete listing of all plants provided a huge stimulus for the field.
Although meticulous, the classification of Linnaeus served as an identification manual. It assumed that plant species were given by God and that what remained for humans was to recognise them and use them. Linnaeus was quite aware that the arrangement of species in the Species Plantarum was not a natural system, i.e. did not express relationships. However he did present some ideas of plant relationships elsewhere. Significant contributions to plant classification came from de Jussieu in 1789 and the early nineteenth century saw the start of work by de Candolle, culminating in the Prodromus. A major influence on plant systematics was the theory of evolution, resulting in the aim to group plants by their phylogenetic relationships. To this was added the interest in plant anatomy, aided by the use of the light microscope and the rise of chemistry, allowing the analysis of secondary metabolites; the strict use of epithets in botany, although regulated by international codes, is considered unpractical and outdated.
The notion of species, the fundamental classification unit, is up to subjective intuition and thus can not be well defined. As a result, estimate of the total number of existing "species" becomes a matter of preference. While scientists have agreed for some time that a functional and objective classification system must reflect actual evolutionary processes and genetic relationships, the technological means for creating such a system did not exist until recently. In the 1990s DNA technology saw immense progress, resulting in unprecedented accumulation of DNA sequence data from various genes present in compartments of plant cells. In 1998 a ground-breaking classification of the angiosperms consolidated molecular phylogenetics as the best available method. For the first time relatedness could be measured in real terms, namely similarity of the m
Biological anthropology known as physical anthropology, is a scientific discipline concerned with the biological and behavioral aspects of human beings, their extinct hominin ancestors, related non-human primates from an evolutionary perspective. It is a subfield of anthropology that provides a biological perspective to the systematic study of human beings; as a subfield of anthropology, biological anthropology itself is further divided into several branches. All branches are united in their common orientation and/or application of evolutionary theory to understanding human biology and behavior. Paleoanthropology is the study of fossil evidence for human evolution using remains from extinct hominin and other primate species to determine the morphological and behavioral changes in the human lineage, as well as the environment in which human evolution occurred. Human biology is an interdisciplinary field of biology, biological anthropology and medicine, which concerns international, population-level perspectives on health, anatomy, molecular biology and genetics.
Primatology is the study of non-human primate behavior and genetics. Primatologists use phylogenetic methods to infer which traits humans share with other primates and which are human-specific adaptations. Human behavioral ecology is the study of behavioral adaptations from the evolutionary and ecologic perspectives, it focuses on human adaptive responses to environmental stresses. Bioarchaeology is the study of past human cultures through examination of human remains recovered in an archaeological context; the examined human remains are limited to bones but may include preserved soft tissue. Researchers in bioarchaeology combine the skill sets of human osteology and archaeology, consider the cultural and mortuary context of the remains. Paleopathology is the study of disease in antiquity; this study focuses not only on pathogenic conditions observable in bones or mummified soft tissue, but on nutritional disorders, variation in stature or morphology of bones over time, evidence of physical trauma, or evidence of occupationally derived biomechanic stress.
Evolutionary psychology is the study of psychological structures from a modern evolutionary perspective. It seeks to identify which human psychological traits are evolved adaptations – that is, the functional products of natural selection or sexual selection in human evolution. Evolutionary biology is the study of the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor; these processes include natural selection, common descent, speciation. Biological Anthropology looks different today than it did twenty years ago; the name is relatively new, having been'physical anthropology' for over a century, with some practitioners still applying that term. Biological anthropologists look back to the work of Charles Darwin as a major foundation for what they do today. However, if one traces the intellectual genealogy and the culture back to physical anthropology's beginnings--going further back than the existence of much of what we know now as the hominin fossil record--then history focuses in on the field's interest in human biological variation.
Some editors, see below, have rooted the field deeper than formal science. Attempts to study and classify human beings as living organisms date back to ancient Greece; the Greek philosopher Plato placed humans on the scala naturae, which included all things, from inanimate objects at the bottom to deities at the top. This became the main system through which scholars thought about nature for the next 2,000 years. Plato's student Aristotle observed in his History of Animals that human beings are the only animals to walk upright and argued, in line with his teleological view of nature, that humans have buttocks and no tails in order to give them a cushy place to sit when they are tired of standing, he explained regional variations in human features as the result of different climates. He wrote about physiognomy, an idea derived from writings in the Hippocratic Corpus. Scientific physical anthropology began in the 17th to 18th centuries with the study of racial classification; the first prominent physical anthropologist, the German physician Johann Friedrich Blumenbach of Göttingen, amassed a large collection of human skulls, from which he argued for the division of humankind into five major races.
In the 19th century, French physical anthropologists, led by Paul Broca, focused on craniometry while the German tradition, led by Rudolf Virchow, emphasized the influence of environment and disease upon the human body. In the 1830s and 1840s, physical anthropology was prominent in the debate about slavery, with the scientific, monogenist works of the British abolitionist James Cowles Prichard opposing those of the American polygenist Samuel George Morton. In the late 19th century, German-American anthropologist Franz Boas impacted biological anthropology by emphasizing the influence of culture and experience on the human form, his research showed that head shape was malleable to environmental and nutritional factors rather than a stable "racial" trait. However, scientific racism still persisted in biological anthropology, with prominent figures such as Earnest Hooton and Aleš Hrdlička promoting theories of racial superiority and a European o