118-661: The American Society of Plant Biologists (ASPB) is a non-profit professional society for research and education in plant science with over 4,000 members world-wide. It was founded in 1924, as the American Society of Plant Physiologists (ASPP). The name was changed to the American Society of Plant Biologists (ASPB) as of 2001. Membership in the society is open to any person from any country who deals with physiology, molecular biology, environmental biology, cell biology and plant biophysics or related issues. The society publishes
236-502: A reticle graduated to allow measuring distances in the focal plane. The other (and older) type has simple crosshairs and a micrometer mechanism for moving the subject relative to the microscope. Very small, portable microscopes have found some usage in places where a laboratory microscope would be a burden. At very high magnifications with transmitted light, point objects are seen as fuzzy discs surrounded by diffraction rings. These are called Airy disks . The resolving power of
354-483: A botanically and pharmacologically important herbal Historia Plantarum in 1544 and a pharmacopoeia of lasting importance, the Dispensatorium in 1546. Naturalist Conrad von Gesner (1516–1565) and herbalist John Gerard (1545– c. 1611 ) published herbals covering the supposed medicinal uses of plants. Naturalist Ulisse Aldrovandi (1522–1605) was considered the father of natural history , which included
472-501: A child at the time, leading to speculation that, for Johannes' claim to be true, the compound microscope would have to have been invented by Johannes' grandfather, Hans Martens. Another claim is that Janssen's competitor, Hans Lippershey (who applied for the first telescope patent in 1608) also invented the compound microscope. Other historians point to the Dutch innovator Cornelis Drebbel with his 1621 compound microscope. Galileo Galilei
590-414: A considerable problem in agriculture, and the biology and control of plant pathogens in agriculture and natural ecosystems . Ethnobotany is the study of the relationships between plants and people. When applied to the investigation of historical plant–people relationships ethnobotany may be referred to as archaeobotany or palaeoethnobotany . Some of the earliest plant-people relationships arose between
708-452: A continuum between the major morphological categories of root, stem (caulome), leaf (phyllome) and trichome . Furthermore, it emphasises structural dynamics. Modern systematics aims to reflect and discover phylogenetic relationships between plants. Modern Molecular phylogenetics largely ignores morphological characters, relying on DNA sequences as data. Molecular analysis of DNA sequences from most families of flowering plants enabled
826-400: A hierarchical classification of plant species that remains the reference point for modern botanical nomenclature . This established a standardised binomial or two-part naming scheme where the first name represented the genus and the second identified the species within the genus. For the purposes of identification, Linnaeus's Systema Sexuale classified plants into 24 groups according to
944-486: A high-powered macro lens and generally do not use transillumination . The camera is attached directly to a computer's USB port to show the images directly on the monitor. They offer modest magnifications (up to about 200×) without the need to use eyepieces and at a very low cost. High-power illumination is usually provided by an LED source or sources adjacent to the camera lens. Digital microscopy with very low light levels to avoid damage to vulnerable biological samples
1062-508: A lens close to the object being viewed to collect light (called the objective lens), which focuses a real image of the object inside the microscope (image 1). That image is then magnified by a second lens or group of lenses (called the eyepiece ) that gives the viewer an enlarged inverted virtual image of the object (image 2). The use of a compound objective/eyepiece combination allows for much higher magnification. Common compound microscopes often feature exchangeable objective lenses, allowing
1180-425: A magnification of 40 to 100×. Adjustment knobs move the stage up and down with separate adjustment for coarse and fine focusing. The same controls enable the microscope to adjust to specimens of different thickness. In older designs of microscopes, the focus adjustment wheels move the microscope tube up or down relative to the stand and had a fixed stage. The whole of the optical assembly is traditionally attached to
1298-537: A matched cover slip between the objective lens and the sample. The refractive index of the index-matching material is higher than air allowing the objective lens to have a larger numerical aperture (greater than 1) so that the light is transmitted from the specimen to the outer face of the objective lens with minimal refraction. Numerical apertures as high as 1.6 can be achieved. The larger numerical aperture allows collection of more light making detailed observation of smaller details possible. An oil immersion lens usually has
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#17328725715611416-438: A microscope is taken as the ability to distinguish between two closely spaced Airy disks (or, in other words the ability of the microscope to reveal adjacent structural detail as distinct and separate). It is these impacts of diffraction that limit the ability to resolve fine details. The extent and magnitude of the diffraction patterns are affected by both the wavelength of light (λ), the refractive materials used to manufacture
1534-565: A photon-counting camera. The earliest microscopes were single lens magnifying glasses with limited magnification, which date at least as far back as the widespread use of lenses in eyeglasses in the 13th century. Compound microscopes first appeared in Europe around 1620 including one demonstrated by Cornelis Drebbel in London (around 1621) and one exhibited in Rome in 1624. The actual inventor of
1652-404: A plant sucks water through them under water stress. Lignin is also used in other cell types like sclerenchyma fibres that provide structural support for a plant and is a major constituent of wood. Sporopollenin is a chemically resistant polymer found in the outer cell walls of spores and pollen of land plants responsible for the survival of early land plant spores and the pollen of seed plants in
1770-552: A polymer of fructose is used for the same purpose in the sunflower family Asteraceae . Some of the glucose is converted to sucrose (common table sugar) for export to the rest of the plant. Unlike in animals (which lack chloroplasts), plants and their eukaryote relatives have delegated many biochemical roles to their chloroplasts , including synthesising all their fatty acids , and most amino acids . The fatty acids that chloroplasts make are used for many things, such as providing material to build cell membranes out of and making
1888-460: A process that generates molecular oxygen (O 2 ) as a by-product. The light energy captured by chlorophyll a is initially in the form of electrons (and later a proton gradient ) that's used to make molecules of ATP and NADPH which temporarily store and transport energy. Their energy is used in the light-independent reactions of the Calvin cycle by the enzyme rubisco to produce molecules of
2006-505: A pure form of carbon made by pyrolysis of wood, has a long history as a metal- smelting fuel, as a filter material and adsorbent and as an artist's material and is one of the three ingredients of gunpowder . Cellulose , the world's most abundant organic polymer, can be converted into energy, fuels, materials and chemical feedstock. Products made from cellulose include rayon and cellophane , wallpaper paste , biobutanol and gun cotton . Sugarcane , rapeseed and soy are some of
2124-478: A rigid arm, which in turn is attached to a robust U-shaped foot to provide the necessary rigidity. The arm angle may be adjustable to allow the viewing angle to be adjusted. The frame provides a mounting point for various microscope controls. Normally this will include controls for focusing, typically a large knurled wheel to adjust coarse focus, together with a smaller knurled wheel to control fine focus. Other features may be lamp controls and/or controls for adjusting
2242-603: A sample; there are many techniques which can be used to extract other kinds of data. Most of these require additional equipment in addition to a basic compound microscope. Optical microscopy is used extensively in microelectronics, nanophysics, biotechnology, pharmaceutic research, mineralogy and microbiology. Optical microscopy is used for medical diagnosis , the field being termed histopathology when dealing with tissues, or in smear tests on free cells or tissue fragments. In industrial use, binocular microscopes are common. Aside from applications needing true depth perception ,
2360-457: A simple 2-lens ocular system in the late 17th century that was achromatically corrected, and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor disadvantages. Antonie van Leeuwenhoek (1632–1724) is credited with bringing the microscope to the attention of biologists, even though simple magnifying lenses were already being produced in
2478-526: A student of Aristotle who invented and described many of its principles and is widely regarded in the scientific community as the "Father of Botany". His major works, Enquiry into Plants and On the Causes of Plants , constitute the most important contributions to botanical science until the Middle Ages , almost seventeen centuries later. Another work from Ancient Greece that made an early impact on botany
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#17328725715612596-454: A useful proxy for temperature in historical climatology , and the biological impact of climate change and global warming . Palynology , the analysis of fossil pollen deposits in sediments from thousands or millions of years ago allows the reconstruction of past climates. Estimates of atmospheric CO 2 concentrations since the Palaeozoic have been obtained from stomatal densities and
2714-1010: A variety of spatial scales in groups, populations and communities that collectively constitute vegetation. Regions with characteristic vegetation types and dominant plants as well as similar abiotic and biotic factors, climate , and geography make up biomes like tundra or tropical rainforest . Herbivores eat plants, but plants can defend themselves and some species are parasitic or even carnivorous . Other organisms form mutually beneficial relationships with plants. For example, mycorrhizal fungi and rhizobia provide plants with nutrients in exchange for food, ants are recruited by ant plants to provide protection, honey bees , bats and other animals pollinate flowers and humans and other animals act as dispersal vectors to spread spores and seeds . Plant responses to climate and other environmental changes can inform our understanding of how these changes affect ecosystem function and productivity. For example, plant phenology can be
2832-495: A variety of other types of microscopes, which differ in their optical configurations, cost, and intended purposes. A simple microscope uses a lens or set of lenses to enlarge an object through angular magnification alone, giving the viewer an erect enlarged virtual image . The use of a single convex lens or groups of lenses are found in simple magnification devices such as the magnifying glass , loupes , and eyepieces for telescopes and microscopes. A compound microscope uses
2950-628: A way of drug discovery . Plants can synthesise coloured dyes and pigments such as the anthocyanins responsible for the red colour of red wine , yellow weld and blue woad used together to produce Lincoln green , indoxyl , source of the blue dye indigo traditionally used to dye denim and the artist's pigments gamboge and rose madder . Sugar, starch , cotton, linen , hemp , some types of rope , wood and particle boards , papyrus and paper, vegetable oils , wax , and natural rubber are examples of commercially important materials made from plant tissues or their secondary products. Charcoal ,
3068-452: A wider range of shared characters and were widely followed. The Candollean system reflected his ideas of the progression of morphological complexity and the later Bentham & Hooker system , which was influential until the mid-19th century, was influenced by Candolle's approach. Darwin 's publication of the Origin of Species in 1859 and his concept of common descent required modifications to
3186-406: Is De materia medica , a five-volume encyclopedia about preliminary herbal medicine written in the middle of the first century by Greek physician and pharmacologist Pedanius Dioscorides . De materia medica was widely read for more than 1,500 years. Important contributions from the medieval Muslim world include Ibn Wahshiyya 's Nabatean Agriculture , Abū Ḥanīfa Dīnawarī 's (828–896)
3304-405: Is peppermint , Mentha × piperita , a sterile hybrid between Mentha aquatica and spearmint, Mentha spicata . The many cultivated varieties of wheat are the result of multiple inter- and intra- specific crosses between wild species and their hybrids. Angiosperms with monoecious flowers often have self-incompatibility mechanisms that operate between the pollen and stigma so that
3422-476: Is a broad, multidisciplinary subject with contributions and insights from most other areas of science and technology. Research topics include the study of plant structure , growth and differentiation, reproduction , biochemistry and primary metabolism , chemical products, development , diseases , evolutionary relationships , systematics , and plant taxonomy . Dominant themes in 21st-century plant science are molecular genetics and epigenetics , which study
3540-493: Is a microscope equipped with a digital camera allowing observation of a sample via a computer . Microscopes can also be partly or wholly computer-controlled with various levels of automation. Digital microscopy allows greater analysis of a microscope image, for example, measurements of distances and areas and quantitation of a fluorescent or histological stain. Low-powered digital microscopes, USB microscopes , are also commercially available. These are essentially webcams with
3658-408: Is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast . The object
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3776-430: Is available using sensitive photon-counting digital cameras. It has been demonstrated that a light source providing pairs of entangled photons may minimize the risk of damage to the most light-sensitive samples. In this application of ghost imaging to photon-sparse microscopy, the sample is illuminated with infrared photons, each spatially correlated with an entangled partner in the visible band for efficient imaging by
3894-415: Is best to begin with prepared slides that are centered and focus easily regardless of the focus level used. Many sources of light can be used. At its simplest, daylight is directed via a mirror . Most microscopes, however, have their own adjustable and controllable light source – often a halogen lamp , although illumination using LEDs and lasers are becoming a more common provision. Köhler illumination
4012-762: Is gathered by ethnobotanists. This information can relay a great deal of information on how the land once was thousands of years ago and how it has changed over that time. The goals of plant ecology are to understand the causes of their distribution patterns, productivity, environmental impact, evolution, and responses to environmental change. Plants depend on certain edaphic (soil) and climatic factors in their environment but can modify these factors too. For example, they can change their environment's albedo , increase runoff interception, stabilise mineral soils and develop their organic content, and affect local temperature. Plants compete with other organisms in their ecosystem for resources. They interact with their neighbours at
4130-492: Is not practical. A mechanical stage, typical of medium and higher priced microscopes, allows tiny movements of the slide via control knobs that reposition the sample/slide as desired. If a microscope did not originally have a mechanical stage it may be possible to add one. All stages move up and down for focus. With a mechanical stage slides move on two horizontal axes for positioning the specimen to examine specimen details. Focusing starts at lower magnification in order to center
4248-463: Is often provided on more expensive instruments. The condenser is a lens designed to focus light from the illumination source onto the sample. The condenser may also include other features, such as a diaphragm and/or filters, to manage the quality and intensity of the illumination. For illumination techniques like dark field , phase contrast and differential interference contrast microscopy additional optical components must be precisely aligned in
4366-513: Is placed on a stage and may be directly viewed through one or two eyepieces on the microscope. In high-power microscopes, both eyepieces typically show the same image, but with a stereo microscope , slightly different images are used to create a 3-D effect. A camera is typically used to capture the image ( micrograph ). The sample can be lit in a variety of ways. Transparent objects can be lit from below and solid objects can be lit with light coming through ( bright field ) or around ( dark field )
4484-512: Is sometimes cited as a compound microscope inventor. After 1610, he found that he could close focus his telescope to view small objects, such as flies, close up and/or could look through the wrong end in reverse to magnify small objects. The only drawback was that his 2 foot long telescope had to be extended out to 6 feet to view objects that close. After seeing the compound microscope built by Drebbel exhibited in Rome in 1624, Galileo built his own improved version. In 1625, Giovanni Faber coined
4602-451: Is still a major foundation of modern botany. Her books Plant Anatomy and Anatomy of Seed Plants have been key plant structural biology texts for more than half a century. The discipline of plant ecology was pioneered in the late 19th century by botanists such as Eugenius Warming , who produced the hypothesis that plants form communities , and his mentor and successor Christen C. Raunkiær whose system for describing plant life forms
4720-400: Is still given to these groups by botanists, and fungi (including lichens) and photosynthetic protists are usually covered in introductory botany courses. Palaeobotanists study ancient plants in the fossil record to provide information about the evolutionary history of plants . Cyanobacteria , the first oxygen-releasing photosynthetic organisms on Earth, are thought to have given rise to
4838-444: Is still in use today. The concept that the composition of plant communities such as temperate broadleaf forest changes by a process of ecological succession was developed by Henry Chandler Cowles , Arthur Tansley and Frederic Clements . Clements is credited with the idea of climax vegetation as the most complex vegetation that an environment can support and Tansley introduced the concept of ecosystems to biology. Building on
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4956-495: Is the science of plant life and a branch of biology . A botanist , plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek word botanē ( βοτάνη ) meaning " pasture ", " herbs " " grass ", or " fodder "; Botanē is in turn derived from boskein ( Greek : βόσκειν ), "to feed" or "to graze ". Traditionally, botany has also included
5074-498: Is the study of ferns and allied plants. A number of other taxa of ranks varying from family to subgenus have terms for their study, including agrostology (or graminology) for the study of grasses, synantherology for the study of composites, and batology for the study of brambles. Study can also be divided by guild rather than clade or grade . Dendrology is the study of woody plants. Many divisions of biology have botanical subfields. These are commonly denoted by prefixing
5192-543: Is typically limited to around 1000x because of the limited resolving power of visible light. While larger magnifications are possible no additional details of the object are resolved. Alternatives to optical microscopy which do not use visible light include scanning electron microscopy and transmission electron microscopy and scanning probe microscopy and as a result, can achieve much greater magnifications. There are two basic types of optical microscopes: simple microscopes and compound microscopes. A simple microscope uses
5310-553: The Angiosperm Phylogeny Group to publish in 1998 a phylogeny of flowering plants, answering many of the questions about relationships among angiosperm families and species. The theoretical possibility of a practical method for identification of plant species and commercial varieties by DNA barcoding is the subject of active current research. Botany is divided along several axes. Some subfields of botany relate to particular groups of organisms. Divisions related to
5428-495: The Book of Plants , and Ibn Bassal 's The Classification of Soils . In the early 13th century, Abu al-Abbas al-Nabati , and Ibn al-Baitar (d. 1248) wrote on botany in a systematic and scientific manner. In the mid-16th century, botanical gardens were founded in a number of Italian universities. The Padua botanical garden in 1545 is usually considered to be the first which is still in its original location. These gardens continued
5546-417: The C 4 carbon fixation pathway for photosynthesis which avoid the losses resulting from photorespiration in the more common C 3 carbon fixation pathway. These biochemical strategies are unique to land plants. Phytochemistry is a branch of plant biochemistry primarily concerned with the chemical substances produced by plants during secondary metabolism . Some of these compounds are toxins such as
5664-595: The Charles Reid Barnes Life Membership Award since 1925. It established the Stephen Hales Prize in 1927. As of 2007, the society began to designate Fellows of the ASPB for "long-term contributions to plant biology". ASPB Fellows are distinct from ASPB's "Plantae Fellows", who are selected from a variety of countries and backgrounds for their work as science communicators. The first President of
5782-504: The alkaloid coniine from hemlock . Others, such as the essential oils peppermint oil and lemon oil are useful for their aroma, as flavourings and spices (e.g., capsaicin ), and in medicine as pharmaceuticals as in opium from opium poppies . Many medicinal and recreational drugs , such as tetrahydrocannabinol (active ingredient in cannabis ), caffeine , morphine and nicotine come directly from plants. Others are simple derivatives of botanical natural products. For example,
5900-565: The auxin plant hormones by Kenneth V. Thimann in 1948 enabled regulation of plant growth by externally applied chemicals. Frederick Campion Steward pioneered techniques of micropropagation and plant tissue culture controlled by plant hormones . The synthetic auxin 2,4-dichlorophenoxyacetic acid or 2,4-D was one of the first commercial synthetic herbicides . 20th century developments in plant biochemistry have been driven by modern techniques of organic chemical analysis , such as spectroscopy , chromatography and electrophoresis . With
6018-626: The cell theory with Theodor Schwann and Rudolf Virchow and was among the first to grasp the significance of the cell nucleus that had been described by Robert Brown in 1831. In 1855, Adolf Fick formulated Fick's laws that enabled the calculation of the rates of molecular diffusion in biological systems. Building upon the gene-chromosome theory of heredity that originated with Gregor Mendel (1822–1884), August Weismann (1834–1914) proved that inheritance only takes place through gametes . No other cells can pass on inherited characters. The work of Katherine Esau (1898–1997) on plant anatomy
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#17328725715616136-444: The cellulose and lignin used to build their bodies, and secondary products like resins and aroma compounds . Plants and various other groups of photosynthetic eukaryotes collectively known as " algae " have unique organelles known as chloroplasts . Chloroplasts are thought to be descended from cyanobacteria that formed endosymbiotic relationships with ancient plant and algal ancestors. Chloroplasts and cyanobacteria contain
6254-427: The indigenous people of Canada in identifying edible plants from inedible plants. This relationship the indigenous people had with plants was recorded by ethnobotanists. Plant biochemistry is the study of the chemical processes used by plants. Some of these processes are used in their primary metabolism like the photosynthetic Calvin cycle and crassulacean acid metabolism . Others make specialised materials like
6372-437: The optical power of a single lens or group of lenses for magnification. A compound microscope uses a system of lenses (one set enlarging the image produced by another) to achieve a much higher magnification of an object. The vast majority of modern research microscopes are compound microscopes, while some cheaper commercial digital microscopes are simple single-lens microscopes. Compound microscopes can be further divided into
6490-426: The pines , and flowering plants ) and the free-sporing cryptogams including ferns , clubmosses , liverworts , hornworts and mosses . Embryophytes are multicellular eukaryotes descended from an ancestor that obtained its energy from sunlight by photosynthesis . They have life cycles with alternating haploid and diploid phases. The sexual haploid phase of embryophytes, known as the gametophyte , nurtures
6608-420: The 16th century. Van Leeuwenhoek's home-made microscopes were simple microscopes, with a single very small, yet strong lens. They were awkward in use, but enabled van Leeuwenhoek to see detailed images. It took about 150 years of optical development before the compound microscope was able to provide the same quality image as van Leeuwenhoek's simple microscopes, due to difficulties in configuring multiple lenses. In
6726-418: The 1850s, John Leonard Riddell , Professor of Chemistry at Tulane University , invented the first practical binocular microscope while carrying out one of the earliest and most extensive American microscopic investigations of cholera . While basic microscope technology and optics have been available for over 400 years it is much more recently that techniques in sample illumination were developed to generate
6844-408: The 3-carbon sugar glyceraldehyde 3-phosphate (G3P). Glyceraldehyde 3-phosphate is the first product of photosynthesis and the raw material from which glucose and almost all other organic molecules of biological origin are synthesised. Some of the glucose is converted to starch which is stored in the chloroplast. Starch is the characteristic energy store of most land plants and algae, while inulin ,
6962-506: The Candollean system to reflect evolutionary relationships as distinct from mere morphological similarity. Botany was greatly stimulated by the appearance of the first "modern" textbook, Matthias Schleiden 's Grundzüge der Wissenschaftlichen Botanik , published in English in 1849 as Principles of Scientific Botany . Schleiden was a microscopist and an early plant anatomist who co-founded
7080-449: The Society was Charles Albert Shull (1924–1925), with founder R. B. Harvey as Secretary-Treasurer. Other presidents of the Society include Harry Beevers (1961–1962) and Aubrey Naylor (1960–1961). The first woman to be president of the society was Elisabeth Gantt (1988–1989). Plant science Botany , also called plant science (or plant sciences ), plant biology or phytology ,
7198-474: The Vegetable Kingdom at the start of chapter XII noted "The first and most important of the conclusions which may be drawn from the observations given in this volume, is that generally cross-fertilisation is beneficial and self-fertilisation often injurious, at least with the plants on which I experimented." An important adaptive benefit of outcrossing is that it allows the masking of deleterious mutations in
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#17328725715617316-412: The above pair of categories gives rise to fields such as bryogeography (the study of the distribution of mosses). Different parts of plants also give rise to their own subfields, including xylology , carpology (or fructology) and palynology , these been the study of wood, fruit and pollen/spores respectively. Botany also overlaps on the one hand with agriculture, horticulture and silviculture, and on
7434-439: The ancestor of plants by entering into an endosymbiotic relationship with an early eukaryote, ultimately becoming the chloroplasts in plant cells. The new photosynthetic plants (along with their algal relatives) accelerated the rise in atmospheric oxygen started by the cyanobacteria , changing the ancient oxygen-free, reducing , atmosphere to one in which free oxygen has been abundant for more than 2 billion years. Among
7552-447: The base of most food chains because they use the energy from the sun and nutrients from the soil and atmosphere, converting them into a form that can be used by animals. This is what ecologists call the first trophic level . The modern forms of the major staple foods , such as hemp , teff , maize, rice, wheat and other cereal grasses, pulses , bananas and plantains, as well as hemp , flax and cotton grown for their fibres, are
7670-500: The blue-green pigment chlorophyll a . Chlorophyll a (as well as its plant and green algal-specific cousin chlorophyll b ) absorbs light in the blue-violet and orange/red parts of the spectrum while reflecting and transmitting the green light that we see as the characteristic colour of these organisms. The energy in the red and blue light that these pigments absorb is used by chloroplasts to make energy-rich carbon compounds from carbon dioxide and water by oxygenic photosynthesis ,
7788-446: The broader historical sense of botany include bacteriology , mycology (or fungology) and phycology - the study of bacteria, fungi and algae respectively - with lichenology as a subfield of mycology. The narrower sense of botany in the sense of the study of embryophytes (land plants) is disambiguated as phytology. Bryology is the study of mosses (and in the broader sense also liverworts and hornworts). Pteridology (or filicology)
7906-455: The characters may be artificial in keys designed purely for identification ( diagnostic keys ) or more closely related to the natural or phyletic order of the taxa in synoptic keys. By the 18th century, new plants for study were arriving in Europe in increasing numbers from newly discovered countries and the European colonies worldwide. In 1753, Carl Linnaeus published his Species Plantarum ,
8024-419: The compound microscope is unknown although many claims have been made over the years. These include a claim 35 years after they appeared by Dutch spectacle-maker Johannes Zachariassen that his father, Zacharias Janssen , invented the compound microscope and/or the telescope as early as 1590. Johannes' testimony, which some claim is dubious, pushes the invention date so far back that Zacharias would have been
8142-406: The condenser. The stage is a platform below the objective lens which supports the specimen being viewed. In the center of the stage is a hole through which light passes to illuminate the specimen. The stage usually has arms to hold slides (rectangular glass plates with typical dimensions of 25×75 mm, on which the specimen is mounted). At magnifications higher than 100× moving a slide by hand
8260-461: The developing diploid embryo sporophyte within its tissues for at least part of its life, even in the seed plants, where the gametophyte itself is nurtured by its parent sporophyte. Other groups of organisms that were previously studied by botanists include bacteria (now studied in bacteriology ), fungi ( mycology ) – including lichen -forming fungi ( lichenology ), non- chlorophyte algae ( phycology ), and viruses ( virology ). However, attention
8378-403: The development of fluorescent probes for specific structures within a cell. In contrast to normal transilluminated light microscopy, in fluorescence microscopy the sample is illuminated through the objective lens with a narrow set of wavelengths of light. This light interacts with fluorophores in the sample which then emit light of a longer wavelength . It is this emitted light which makes up
8496-459: The earliest was the Padua botanical garden . These gardens facilitated the academic study of plants. Efforts to catalogue and describe their collections were the beginnings of plant taxonomy and led in 1753 to the binomial system of nomenclature of Carl Linnaeus that remains in use to this day for the naming of all biological species. In the 19th and 20th centuries, new techniques were developed for
8614-419: The efforts of early humans to identify – and later cultivate – plants that were edible, poisonous, and possibly medicinal, making it one of the first endeavours of human investigation. Medieval physic gardens , often attached to monasteries , contained plants possibly having medicinal benefit. They were forerunners of the first botanical gardens attached to universities , founded from the 1540s onwards. One of
8732-453: The extensive earlier work of Alphonse de Candolle , Nikolai Vavilov (1887–1943) produced accounts of the biogeography , centres of origin , and evolutionary history of economic plants. Particularly since the mid-1960s there have been advances in understanding of the physics of plant physiological processes such as transpiration (the transport of water within plant tissues), the temperature dependence of rates of water evaporation from
8850-563: The fossil record. It is widely regarded as a marker for the start of land plant evolution during the Ordovician period. The concentration of carbon dioxide in the atmosphere today is much lower than it was when plants emerged onto land during the Ordovician and Silurian periods. Many monocots like maize and the pineapple and some dicots like the Asteraceae have since independently evolved pathways like Crassulacean acid metabolism and
8968-451: The functional relationships between plants and their habitats – the environments where they complete their life cycles . Plant ecologists study the composition of local and regional floras , their biodiversity , genetic diversity and fitness , the adaptation of plants to their environment, and their competitive or mutualistic interactions with other species. Some ecologists even rely on empirical data from indigenous people that
9086-411: The genome of progeny. This beneficial effect is also known as hybrid vigor or heterosis. Once outcrossing is established, subsequent switching to inbreeding becomes disadvantageous since it allows expression of the previously masked deleterious recessive mutations, commonly referred to as inbreeding depression. Optical microscope The optical microscope , also referred to as a light microscope ,
9204-444: The global carbon and water cycles and plant roots bind and stabilise soils, preventing soil erosion . Plants are crucial to the future of human society as they provide food, oxygen, biochemicals , and products for people, as well as creating and preserving soil. Historically, all living things were classified as either animals or plants and botany covered the study of all organisms not considered animals. Botanists examine both
9322-439: The high quality images seen today. In August 1893, August Köhler developed Köhler illumination . This method of sample illumination gives rise to extremely even lighting and overcomes many limitations of older techniques of sample illumination. Before development of Köhler illumination the image of the light source, for example a lightbulb filament, was always visible in the image of the sample. The Nobel Prize in physics
9440-496: The image. Since the mid-20th century chemical fluorescent stains, such as DAPI which binds to DNA , have been used to label specific structures within the cell. More recent developments include immunofluorescence , which uses fluorescently labelled antibodies to recognise specific proteins within a sample, and fluorescent proteins like GFP which a live cell can express making it fluorescent. All modern optical microscopes designed for viewing samples by transmitted light share
9558-621: The important botanical questions of the 21st century are the role of plants as primary producers in the global cycling of life's basic ingredients: energy, carbon, oxygen, nitrogen and water, and ways that our plant stewardship can help address the global environmental issues of resource management , conservation , human food security , biologically invasive organisms , carbon sequestration , climate change , and sustainability . Virtually all staple foods come either directly from primary production by plants, or indirectly from animals that eat them. Plants and other photosynthetic organisms are at
9676-478: The internal functions and processes within plant organelles , cells, tissues, whole plants, plant populations and plant communities. At each of these levels, a botanist may be concerned with the classification ( taxonomy ), phylogeny and evolution , structure ( anatomy and morphology ), or function ( physiology ) of plant life. The strictest definition of "plant" includes only the "land plants" or embryophytes , which include seed plants (gymnosperms, including
9794-576: The latter ranges from 0.14 to 0.7, corresponding to focal lengths of about 40 to 2 mm, respectively. Objective lenses with higher magnifications normally have a higher numerical aperture and a shorter depth of field in the resulting image. Some high performance objective lenses may require matched eyepieces to deliver the best optical performance. Some microscopes make use of oil-immersion objectives or water-immersion objectives for greater resolution at high magnification. These are used with index-matching material such as immersion oil or water and
9912-403: The leaf shapes and sizes of ancient land plants . Ozone depletion can expose plants to higher levels of ultraviolet radiation-B (UV-B), resulting in lower growth rates. Moreover, information from studies of community ecology , plant systematics , and taxonomy is essential to understanding vegetation change , habitat destruction and species extinction . Inheritance in plants follows
10030-576: The leaf surface and the molecular diffusion of water vapour and carbon dioxide through stomatal apertures. These developments, coupled with new methods for measuring the size of stomatal apertures, and the rate of photosynthesis have enabled precise description of the rates of gas exchange between plants and the atmosphere. Innovations in statistical analysis by Ronald Fisher , Frank Yates and others at Rothamsted Experimental Station facilitated rational experimental design and data analysis in botanical research. The discovery and identification of
10148-486: The light path to generate an improved contrast image from a sample. Major techniques for generating increased contrast from the sample include cross-polarized light , dark field , phase contrast and differential interference contrast illumination. A recent technique ( Sarfus ) combines cross-polarized light and specific contrast-enhanced slides for the visualization of nanometric samples. Modern microscopes allow more than just observation of transmitted light image of
10266-486: The light path. The actual power or magnification of a compound optical microscope is the product of the powers of the eyepiece and the objective lens. For example a 10x eyepiece magnification and a 100x objective lens magnification gives a total magnification of 1,000×. Modified environments such as the use of oil or ultraviolet light can increase the resolution and allow for resolved details at magnifications larger than 1,000x. Many techniques are available which modify
10384-576: The maintenance of biodiversity . Botany originated as herbalism , the study and use of plants for their possible medicinal properties . The early recorded history of botany includes many ancient writings and plant classifications. Examples of early botanical works have been found in ancient texts from India dating back to before 1100 BCE, Ancient Egypt , in archaic Avestan writings, and in works from China purportedly from before 221 BCE. Modern botany traces its roots back to Ancient Greece specifically to Theophrastus ( c. 371 –287 BCE),
10502-493: The major groups of organisms that carry out photosynthesis , a process that uses the energy of sunlight to convert water and carbon dioxide into sugars that can be used both as a source of chemical energy and of organic molecules that are used in the structural components of cells. As a by-product of photosynthesis, plants release oxygen into the atmosphere, a gas that is required by nearly all living things to carry out cellular respiration. In addition, they are influential in
10620-474: The mechanisms and control of gene expression during differentiation of plant cells and tissues . Botanical research has diverse applications in providing staple foods , materials such as timber , oil , rubber, fibre and drugs, in modern horticulture , agriculture and forestry , plant propagation , breeding and genetic modification , in the synthesis of chemicals and raw materials for construction and energy production, in environmental management , and
10738-583: The name microscope for the compound microscope Galileo submitted to the Accademia dei Lincei in 1624 (Galileo had called it the " occhiolino " or " little eye "). Faber coined the name from the Greek words μικρόν (micron) meaning "small", and σκοπεῖν (skopein) meaning "to look at", a name meant to be analogous with "telescope", another word coined by the Linceans. Christiaan Huygens , another Dutchman, developed
10856-596: The number of their male sexual organs. The 24th group, Cryptogamia , included all plants with concealed reproductive parts, mosses , liverworts , ferns , algae and fungi . Botany was originally a hobby for upper-class women. These women would collect and paint flowers and plants from around the world with scientific accuracy. The paintings were used to record many species that could not be transported or maintained in other environments. Marianne North illustrated over 900 species in extreme detail with watercolor and oil paintings. Her work and many other women's botany work
10974-440: The objective lens and the numerical aperture (NA) of the objective lens. There is therefore a finite limit beyond which it is impossible to resolve separate points in the objective field, known as the diffraction limit . Assuming that optical aberrations in the whole optical set-up are negligible, the resolution d , can be stated as: Usually a wavelength of 550 nm is assumed, which corresponds to green light. With air as
11092-463: The objective lens. Polarised light may be used to determine crystal orientation of metallic objects. Phase-contrast imaging can be used to increase image contrast by highlighting small details of differing refractive index. A range of objective lenses with different magnification are usually provided mounted on a turret, allowing them to be rotated into place and providing an ability to zoom-in. The maximum magnification power of optical microscopes
11210-464: The optical configuration of the objective lens and eyepiece are matched to give the best possible optical performance. This occurs most commonly with apochromatic objectives. Objective turret, revolver, or revolving nose piece is the part that holds the set of objective lenses. It allows the user to switch between objective lenses. At the lower end of a typical compound optical microscope, there are one or more objective lenses that collect light from
11328-447: The other hand with medicine and pharmacology, giving rise to fields such as agronomy , horticultural botany, phytopathology and phytopharmacology . The study of plants is vital because they underpin almost all animal life on Earth by generating a large proportion of the oxygen and food that provide humans and other organisms with aerobic respiration with the chemical energy they need to exist. Plants, algae and cyanobacteria are
11446-404: The outcome of prehistoric selection over thousands of years from among wild ancestral plants with the most desirable characteristics. Botanists study how plants produce food and how to increase yields, for example through plant breeding , making their work important to humanity's ability to feed the world and provide food security for future generations. Botanists also study weeds, which are
11564-791: The pain killer aspirin is the acetyl ester of salicylic acid , originally isolated from the bark of willow trees, and a wide range of opiate painkillers like heroin are obtained by chemical modification of morphine obtained from the opium poppy . Popular stimulants come from plants, such as caffeine from coffee, tea and chocolate, and nicotine from tobacco. Most alcoholic beverages come from fermentation of carbohydrate -rich plant products such as barley (beer), rice ( sake ) and grapes (wine). Native Americans have used various plants as ways of treating illness or disease for thousands of years. This knowledge Native Americans have on plants has been recorded by enthnobotanists and then in turn has been used by pharmaceutical companies as
11682-464: The peer-reviewed journals Plant Physiology (1926-) and The Plant Cell (1989-) as well as ASPB News . The American Society of Plant Biologists also has partnered with the Society for Experimental Biology , and Wiley to publish an online-only science journal Plant Direct . In 2000, it published the first edition of the textbook Biochemistry & Molecular Biology of Plants . The society has given
11800-479: The plants with a highly fermentable sugar or oil content that are used as sources of biofuels , important alternatives to fossil fuels , such as biodiesel . Sweetgrass was used by Native Americans to ward off bugs like mosquitoes . These bug repelling properties of sweetgrass were later found by the American Chemical Society in the molecules phytol and coumarin . Plant ecology is the science of
11918-486: The pollen either fails to reach the stigma or fails to germinate and produce male gametes . This is one of several methods used by plants to promote outcrossing . In many land plants the male and female gametes are produced by separate individuals. These species are said to be dioecious when referring to vascular plant sporophytes and dioicous when referring to bryophyte gametophytes . Charles Darwin in his 1878 book The Effects of Cross and Self-Fertilization in
12036-442: The polymer cutin which is found in the plant cuticle that protects land plants from drying out. Plants synthesise a number of unique polymers like the polysaccharide molecules cellulose , pectin and xyloglucan from which the land plant cell wall is constructed. Vascular land plants make lignin , a polymer used to strengthen the secondary cell walls of xylem tracheids and vessels to keep them from collapsing when
12154-545: The practical value of earlier "physic gardens", often associated with monasteries, in which plants were cultivated for suspected medicinal uses. They supported the growth of botany as an academic subject. Lectures were given about the plants grown in the gardens. Botanical gardens came much later to northern Europe; the first in England was the University of Oxford Botanic Garden in 1621. German physician Leonhart Fuchs (1501–1566)
12272-461: The rise of the related molecular-scale biological approaches of molecular biology , genomics , proteomics and metabolomics , the relationship between the plant genome and most aspects of the biochemistry, physiology, morphology and behaviour of plants can be subjected to detailed experimental analysis. The concept originally stated by Gottlieb Haberlandt in 1902 that all plant cells are totipotent and can be grown in vitro ultimately enabled
12390-626: The same basic components of the light path. In addition, the vast majority of microscopes have the same 'structural' components (numbered below according to the image on the right): The eyepiece , or ocular lens, is a cylinder containing two or more lenses; its function is to bring the image into focus for the eye. The eyepiece is inserted into the top end of the body tube. Eyepieces are interchangeable and many different eyepieces can be inserted with different degrees of magnification. Typical magnification values for eyepieces include 5×, 10× (the most common), 15× and 20×. In some high performance microscopes,
12508-676: The same fundamental principles of genetics as in other multicellular organisms. Gregor Mendel discovered the genetic laws of inheritance by studying inherited traits such as shape in Pisum sativum ( peas ). What Mendel learned from studying plants has had far-reaching benefits outside of botany. Similarly, " jumping genes " were discovered by Barbara McClintock while she was studying maize. Nevertheless, there are some distinctive genetic differences between plants and other organisms. Species boundaries in plants may be weaker than in animals, and cross species hybrids are often possible. A familiar example
12626-579: The sample. The objective is usually in a cylinder housing containing a glass single or multi-element compound lens. Typically there will be around three objective lenses screwed into a circular nose piece which may be rotated to select the required objective lens. These arrangements are designed to be parfocal , which means that when one changes from one lens to another on a microscope, the sample stays in focus . Microscope objectives are characterized by two parameters, namely, magnification and numerical aperture . The former typically ranges from 5× to 100× while
12744-409: The specimen by the user on the stage. Moving to a higher magnification requires the stage to be moved higher vertically for re-focus at the higher magnification and may also require slight horizontal specimen position adjustment. Horizontal specimen position adjustments are the reason for having a mechanical stage. Due to the difficulty in preparing specimens and mounting them on slides, for children it
12862-590: The study of fungi and algae by mycologists and phycologists respectively, with the study of these three groups of organisms remaining within the sphere of interest of the International Botanical Congress . Nowadays, botanists (in the strict sense) study approximately 410,000 species of land plants , including some 391,000 species of vascular plants (of which approximately 369,000 are flowering plants ) and approximately 20,000 bryophytes . Botany originated in prehistory as herbalism with
12980-450: The study of plants, including methods of optical microscopy and live cell imaging , electron microscopy , analysis of chromosome number , plant chemistry and the structure and function of enzymes and other proteins . In the last two decades of the 20th century, botanists exploited the techniques of molecular genetic analysis , including genomics and proteomics and DNA sequences to classify plants more accurately. Modern botany
13098-471: The study of plants. In 1665, using an early microscope, Polymath Robert Hooke discovered cells (a term he coined) in cork , and a short time later in living plant tissue. During the 18th century, systems of plant identification were developed comparable to dichotomous keys , where unidentified plants are placed into taxonomic groups (e.g. family, genus and species) by making a series of choices between pairs of characters . The choice and sequence of
13216-526: The use of genetic engineering experimentally to knock out a gene or genes responsible for a specific trait, or to add genes such as GFP that report when a gene of interest is being expressed. These technologies enable the biotechnological use of whole plants or plant cell cultures grown in bioreactors to synthesise pesticides , antibiotics or other pharmaceuticals , as well as the practical application of genetically modified crops designed for traits such as improved yield. Modern morphology recognises
13334-462: The use of dual eyepieces reduces eye strain associated with long workdays at a microscopy station. In certain applications, long-working-distance or long-focus microscopes are beneficial. An item may need to be examined behind a window , or industrial subjects may be a hazard to the objective. Such optics resemble telescopes with close-focus capabilities. Measuring microscopes are used for precision measurement. There are two basic types. One has
13452-431: The user to quickly adjust the magnification. A compound microscope also enables more advanced illumination setups, such as phase contrast . There are many variants of the compound optical microscope design for specialized purposes. Some of these are physical design differences allowing specialization for certain purposes: Other microscope variants are designed for different illumination techniques: A digital microscope
13570-485: The word plant (e.g. plant taxonomy, plant ecology, plant anatomy, plant morphology, plant systematics, plant ecology), or prefixing or substituting the prefix phyto- (e.g. phytochemistry , phytogeography ). The study of fossil plants is palaeobotany . Other fields are denoted by adding or substituting the word botany (e.g. systematic botany ). Phytosociology is a subfield of plant ecology that classifies and studies communities of plants. The intersection of fields from
13688-554: Was awarded to Dutch physicist Frits Zernike in 1953 for his development of phase contrast illumination which allows imaging of transparent samples. By using interference rather than absorption of light, extremely transparent samples, such as live mammalian cells, can be imaged without having to use staining techniques. Just two years later, in 1955, Georges Nomarski published the theory for differential interference contrast microscopy, another interference -based imaging technique. Modern biological microscopy depends heavily on
13806-399: Was one of "the three German fathers of botany", along with theologian Otto Brunfels (1489–1534) and physician Hieronymus Bock (1498–1554) (also called Hieronymus Tragus). Fuchs and Brunfels broke away from the tradition of copying earlier works to make original observations of their own. Bock created his own system of plant classification. Physician Valerius Cordus (1515–1544) authored
13924-412: Was the beginning of popularizing botany to a wider audience. Increasing knowledge of plant anatomy , morphology and life cycles led to the realisation that there were more natural affinities between plants than the artificial sexual system of Linnaeus. Adanson (1763), de Jussieu (1789), and Candolle (1819) all proposed various alternative natural systems of classification that grouped plants using
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