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Encyclopedia > Pollen
SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis).
Closeup image of a cactus flower and its stamens
Honey bee on sedum with pollen basket
Pollen from Phacelia (in purple)
Pollen sticking to a bee. Insects involuntarily transporting pollen from flower to flower play an important role in many plants' reproductive cycles.
Marmelade fly sitting on a grey-haired rockrose, its face and legs covered in pollen.

Pollen is a fine to coarse powder consisting of microgametophytes (pollen grains), which produce the male gametes (sperm cells) of seed plants. The pollen grain with its hard coat protects the sperm cells during the process of their movement between the stamens of the flower to the pistil of the next flower. Download high resolution version (1228x935, 215 KB)Source and public domain notice at [1] Pollen from a variety of common plants: sunflower (Helianthus annuus), morning glory Ipomea purpurea, hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa) and castor bean (Ricinus communis). ... Download high resolution version (1228x935, 215 KB)Source and public domain notice at [1] Pollen from a variety of common plants: sunflower (Helianthus annuus), morning glory Ipomea purpurea, hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa) and castor bean (Ricinus communis). ... SEM Cambridge S150 at Geological Institute, University Kiel, 1980 SEM opened sample chamber The scanning electron microscope (SEM) is a type of electron microscope capable of producing high-resolution images of a sample surface. ... Sunflowers is also a painting by Vincent van Gogh. ... [[|Diversity]] Binomial name Ipomoea purpurea Trinomial name Type Species [[Image: ]] Synonyms Ipomoea purpurea, or the Common morning glory, is a widespread member of the genus Ipomoea. ... Binomial name Lilium auratum Lindl. ... Binomial name Ricinus communis The castor bean (Ricinus communis) is not a true bean, but a member of the Euphorbiaceae or spurge family. ... Image File history File links Download high-resolution version (1600x1067, 395 KB) Extreme closeup image of a cactus flower (Echinopsis spachiana) and its pollen If you are a (commercial) publisher and you want me to write you an email or paper mail giving you an authorization to use my... Image File history File links Download high-resolution version (1600x1067, 395 KB) Extreme closeup image of a cactus flower (Echinopsis spachiana) and its pollen If you are a (commercial) publisher and you want me to write you an email or paper mail giving you an authorization to use my... Image File history File links Download high-resolution version (900x642, 86 KB) Beschreibung en: Description: carnica bee on sedum telephium with pollen basket de: Beschreibung: Carnica-Biene auf Großer Fetthenne mit Pollenhöschen Source: picture taken by Frank Mikley on 2006-09-09 Location: Weissach im Tal (Baden-Wuerttemberg... Image File history File links Download high-resolution version (900x642, 86 KB) Beschreibung en: Description: carnica bee on sedum telephium with pollen basket de: Beschreibung: Carnica-Biene auf Großer Fetthenne mit Pollenhöschen Source: picture taken by Frank Mikley on 2006-09-09 Location: Weissach im Tal (Baden-Wuerttemberg... honeybee pollen basket The pollen basket or corbicula is part of the hind tibia of the back (posterior) legs of the honeybee. ... Image File history File links Metadata Size of this preview: 800 × 534 pixelsFull resolution (1024 × 683 pixel, file size: 215 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Metadata Size of this preview: 800 × 534 pixelsFull resolution (1024 × 683 pixel, file size: 215 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Species Many, see List of Phacelia Species Phacelia is a genus in the family Boraginaceae of about 150 species of herbs, native of Western North America (the most), Eastern U.S.A. and South America. ... Download high resolution version (1024x768, 142 KB) http://pdphoto. ... Download high resolution version (1024x768, 142 KB) http://pdphoto. ... In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... A gamete (from Ancient Greek γαμετης; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ... The spermatophytes comprise those plants that produce seeds. ...

Contents

The structure of pollen

Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell containing two nuclei: a tube nucleus (that produces the pollen tube) and a generative nucleus (that divides to form the two sperm cells). The group of cells is surrounded by a cellulose cell wall and a thick, tough outer wall made of sporopollenin. Pollen may refer to the microspores of either angiosperms (flowering plants) or gymnosperms (conifers and cycads). ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Categories: Stub ...


Pollen is produced in the microsporangium (contained in the anther of an angiosperm flower, male cone of a coniferous plant, or male cone of other seed plants). Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see Electron micrograph at top right). Most, but certainly not all, are spherical. Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the Forget-me-not (Myosotis spp.), is around 6 µm (0.006  mm) in diameter. The study of pollen is called palynology and is highly useful in paleoecology, paleontology, archeology, and forensics. Stamens of the Amaryllis with prominent anthers carrying pollen Insects, while collecting nectar, unintentionally transfer pollen from one flower to another, bringing about pollination The stamen (from Latin stamen meaning thread of the warp) is the male organ of a flower. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... For other uses, see Flower (disambiguation). ... Mature female European Black Pine cone Male cones of a pine A cone (in formal botanical usage: strobilus, plural strobili) is an organ on plants in the division Pinophyta (conifers) that contains the reproductive structures. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † “Conifer” redirects here. ... An electron micrograph is a micrograph made with an electron microscope. ... Subgenera Subgenus Strobus Subgenus Ducampopinus Subgenus Pinus See Pinus classification for complete taxonomy to species level. ... FIR may stand for: finite impulse response (a property of some digital filters) far infrared, i. ... Species About 35; see text. ... Species about 50 The Forget-me-nots are the genus Myosotis of flowering plants in the family Boraginaceae. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... Pollen under microscope Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedimentary rocks and sediments. ... Paleontology, palaeontology or palæontology (from Greek: paleo, ancient; ontos, being; and logos, knowledge) is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. ... Archaeology or sometimes in American English archeology (from the Greek words αρχαίος = ancient and λόγος = word/speech) is the study of human cultures through the recovery, documentation and analysis of material remains, including architecture, artefacts, biofacts, human remains, and landscapes. ... Forensics redirects here. ...


In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of sporogenous cells form with in the anther, the fertile sporogenous cells are surrounded by layers of sterile cells that grow into the wall of the pollen sac, some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells. Four haploid microspores are produced from each diploid sporogenous cell called microsporocytes, after meiotic division. After the formation of the four microspores, which are contained by callose walls, the development of the pollen grain walls begins. The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. The exine is made up of a resistant compound called sporopollenin; the intine is made up of cellulose and pectin. The exine is what is preserved in the fossil record.


Pollen grains may have furrows, the orientation of which (relative to the original tetrad of microspores) classify the pollen as colpate or sulcate. The number of furrows or pores helps classify the flowering plants, with eudicots having three colpi (tricolpate), and other groups having one sulcus.[1] [2] Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... In the APG-system, the names eudicots or tricolpates are applied to a monophyletic group that includes most of the (former) dicotyledons. ...


Except in the case of some submerged aquatic plants, the mature pollen-grain has a double wall, a thin delicate wall of unaltered cellulose (the endospore or intine) and a tough outer cuticularized exospore or exine. The exine often bears spines or warts, or is variously sculptured, and the character of the markings is often of value for identifying genus, species, or even cultivar or individual. In some flowering plants, germination of the pollen grain often begins before it leaves the microsporangium, with the generative cell forming the two sperm cells. Not to be confused with Gemination in phonetics. ...


Pollination

Main article: Pollination

The transfer of pollen grains to the female reproductive structure (pistil in angiosperms) is called pollination. This transfer can be mediated by the wind, in which case the plant is described as anemophilous (literally wind-loving). Anemophilous plants typically produce great quantities of very lightweight pollen grains, sometimes with air-sacs. Non-flowering seed plants (e.g. pine trees) are characteristically anemophilous. Anemophilous flowering plants generally have inconspicuous flowers. Entomophilous (literally insect-loving) plants produce pollen that is relatively heavy, sticky and protein-rich, for dispersal by insect pollinators attracted to their flowers. Many insects and some mites are specialized to feed on pollen, and are called palynivores. Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes, sperm) to the plant carpel of flowering plants, the structure that contains the ovule (which in turn houses the female gamete... Amaryllis style and stigmas A carpel is the outer, often visible part of the female reproductive organ of a flower; the basic unit of the gynoecium. ... Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes, sperm) to the plant carpel of flowering plants, the structure that contains the ovule (which in turn houses the female gamete... Anemophily is a form of pollination whereby pollen is distributed by wind. ... Subgenera Subgenus Strobus Subgenus Ducampopinus Subgenus Pinus See Pinus classification for complete taxonomy to species level. ... Closeup of a bee pollinating a flower Entomophily is a form of pollination whereby pollen is distributed by insects, particularly bees, Lepidoptera (e. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... A pollinator is the agent that moves pollen from the male anthers of a flower to the female stigma of a flower to accomplish fertilization or syngamy of the female gamete in the ovule of the flower by the male gamete from the pollen grain. ... For other uses, see Flower (disambiguation). ... Mites, along with ticks, belong to the subclass Acarina (also known as Acari) and the class Arachnida. ... Honeybee collecting pollen In zoology, a palynivore is an animal which selectively eats the nutrient-rich pollen produced by flowering plants, including gymnosperms. ...


In non-flowering seed plants, pollen germinates in the pollen chamber, located beneath and inside the micropyle. A pollen tube is produced, which grows into the nucellus to provide nutrients for the developing sperm cells. Sperm cells of Pinophyta and Gnetophyta are without flagella, and are carried by the pollen tube, while those of Cycadophyta and Ginkgophyta have many flagella. Location of ovules inside a Helleborus foetidus flower Ovule literally means small egg. ... Pollen may refer to the microspores of either angiosperms (flowering plants) or gymnosperms (conifers and cycads). ... Location of ovules inside a Helleborus foetidus flower Ovule literally means small egg. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † “Conifer” redirects here. ... taxa: Gnetales Welwitschiales Ephedrales The plant division Gnetophyta or gnetophytes comprise three related families of woody plants grouped in the gymnosperms, a paraphyletic group of seed plant divisions. ... A flagellum (plural, flagella) is a whip-like organelle that many unicellular organisms, and some multicellular ones, use to move about. ... Families Cycadaceae cycas family Stangeriaceae stangeria family Zamiaceae zamia family Leaves and male cone of Cycas revoluta Cycads are an ancient group of seed plants characterized by a large crown of compound leaves and a stout trunk. ... Binomial name Ginkgo biloba L. The Ginkgo (Ginkgo biloba), sometimes also known as the Maidenhair tree, is a unique tree with no living relatives. ...


When placed on the stigma of a flowering plant, under favorable circumstances, a pollen grain puts forth a pollen tube which grows down the tissue of the style to the ovary, and makes its way along the placenta, guided by projections or hairs, to the micropyle of an ovule. The nucleus of the tube cell has meanwhile passed into the tube, as does also the generative nucleus which divides (if it hasn't already) to form two sperm cells. The sperm cells are carried to their destination in the tip of the pollen-tube. Amaryllis style and stigmas A carpel is the outer, often visible part of the female reproductive organ of a flower; the basic unit of the gynoecium. ... Pollen may refer to the microspores of either angiosperms (flowering plants) or gymnosperms (conifers and cycads). ... Longitudinal section of female flower of squash showing ovary, ovules, pistil, and petals In the flowering plants, an ovary is a part of the female reproductive organ of the flower or gynoecium. ... The placenta (Latin for cake, referencing its appearance in humans) is an ephemeral organ present in placental vertebrates, such as eutherial mammals and sharks during gestation (pregnancy). ... This article or section does not adequately cite its references or sources. ... For other uses, see Sperm (disambiguation). ...


Pollen as a carrier of ecological information in plants

A Russian theoretical biologist, Vigen Geodakyan (Geodakian), has suggested that the quantity of pollen reaching a pistillate flower can transmit ecological information and also regulate evolutionary plasticity in cross-pollinating plants. Plentiful pollen indicates optimum environmental conditions (for example a plant that is situated at the center of its natural range, in ideal growing conditions, with a large number of male plants nearby, and favorable weather conditions), whereas a small amount of pollen indicates extreme conditions (at the borders of its range, with a deficiency of male plants, and adverse weather conditions). Geodakian believes that the quantity of pollen reaching a pistillate flower defines the sex ratio, dispersion and sexual dimorphism of a plant population. High pollen quantity leads to a reduction of these characteristics and stabilization of a population. Small quantity leads to their increase and destabilization of a population.[3] Amaryllis style and stigmas A carpel is the outer, often visible part of the female reproductive organ of a flower; the basic unit of the gynoecium. ... For the journal, see Ecology (journal). ... We dont have an article called Phenotypic plasticity Start this article Search for Phenotypic plasticity in. ... Sex ratio by country for total population. ... Female (left) and male Common Pheasant, illustrating the dramatic difference in both color and size, between the sexes Sexual dimorphism is the systematic difference in form between individuals of different sex in the same species. ...


Dependence of the secondary sex ratio on the amount of fertilizing pollen was confirmed on four dioecious plant species from three families — Rumex acetosa (Polygonaceae),[4][5] Melandrium album (Cariophyllaceae),[6][7] Cannabis sativa[8] and Humulus japonicus (Cannabinaceae).[9] (see summary of all these data in review article[10]). Sex ratio by country for total population. ...


Dependence of offspring phenotype variety on amount of pollen was observed by Ter-Avanesyan in 1949. All three studied species of plants (cotton plant, black-eyed pea, and wheat) showed dependence in the direction forecasted by the theory — fertilization with a small amount of pollen resulted in an increase in the diversity of the offspring. Ter-Avanesian writes that as a result of a limited pollination “instead of homogenous sorts we get populations”.[11][12]


Pollen in the fossil record

Pollen's sporopolenin outer sheath affords it some resistance to the rigours of the fossilisation process that destroy weaker objects; it is also produced in huge quantities. As such, there is an extensive fossil record of pollen grains, often disassociated from their parent plant. The discipline of palynology is devoted to the study of pollen, which can be used both for biostratigraphy and to gain information about the abundance and variety of plants alive - which can itself yield important information about paleoclimates. Pollen is first found in the fossil record in the late Devonian period[verification needed] and increases in abundance until the present day. Pollen under microscope Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter (POM) and kerogen found in sedimentary rocks and sediments. ... For the Celtic language, see Southwestern Brythonic language; for the residents of the English county, see Devon. ...


Hay fever

Main article: Hay fever

Allergy to pollen is called hay fever. Generally pollens that cause allergies are those of anemophilous plants (pollen is dispersed by air currents.) Such plants produce large quantities of lightweight pollen (because wind dispersal is random and the likelihood of one pollen grain landing on another flower is small) which can be carried for great distances and are easily inhaled, bringing it into contact with the sensitive nasal passages. Image File history File links Question_book-3. ... For the play, see Hay Fever. ... Allergy is an abnormal reaction to a substance foreign to the body that is acquired, predictable and rapid. ... For the play, see Hay Fever. ...


In the US, people often mistakenly blame the conspicuous goldenrod flower for allergies. Since this plant is entomophilous (its pollen is dispersed by animals), its heavy, sticky pollen does not become independently airborne. Most late summer and fall pollen allergies are probably caused by ragweed, a widespread anemophilous plant. Species See text. ... Species See text. ...


Arizona was once regarded as a haven for people with pollen allergies, although several ragweed species grow in the desert. However, as suburbs grew and people began establishing irrigated lawns and gardens, more irritating species of ragweed gained a foothold and Arizona lost its claim of freedom from hay fever. Official language(s) English Spoken language(s) English 74. ... This article is about arid terrain. ... “Suburbia” redirects here. ... Irrigation is the artificial application of water to the soil usually for assisting in growing crops. ...


Anemophilous spring blooming plants such as oak, birch, hickory, pecan, and early summer grasses may also induce pollen allergies. Most cultivated plants with showy flowers are entomophilous and do not cause pollen allergies. Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus (from Latin oak tree), which are listed in the List of Quercus species, and some related genera, notably... Species Many species; see text and classification Birch is the name of any tree of the genus Betula, in the family Betulaceae, closely related to the beech/oak family, Fagaceae. ... Species See text Comparison of Carya nuts Ripe hickory nuts ready to fall, Andrews, SC Hickory is a tree of the genus Carya, including 17-19 species of deciduous trees with pinnately compound leaves and large nuts. ... Binomial name Carya illinoinensis (Wangenh. ... For other uses, see Grass (disambiguation). ...


Pollen in human diets

A variety of producers have started selling pollen for human consumption, often marketed as a healthy food.


The FDA has not found any harmful effects of pollen consumption, except from the usual allergies. However, FDA does not allow pollen marketers in the United States to make health claims about their produce, as no scientific basis for these has ever been proved. Furthermore, there are possible dangers not only from allergic reactions but also from contaminants such as pesticides and from fungi and bacteria growth related to poor storage procedures. A manufacturers's claim that pollen collecting helps the bee colonies is also controversial.[13] The United States Food and Drug Administration is the government agency responsible for regulating food, dietary supplements, drugs, cosmetics, medical devices, biologics and blood products in the United States. ...


References

  1. ^ Kenneth R. Sporne (1972). "Some Observations on the Evolution of Pollen Types in Dicotyledons". New Phytologist 71 (1): 181–185. doi:10.1111/j.1469-8137.1972.tb04826.x. 
  2. ^ Walter S. Judd and Richard G. Olmstead (2004). "A survey of tricolpate (eudicot) phylogenetic relationships". American Journal of Botany 91: 1627-1644.  (full text)
  3. ^ Geodakyan V. A. (1977). The Amount of Pollen as a Regulator of Evolutionary Plasticity of Cross-Pollinating Plants. “Doklady Biological Sciences” 234 N 1-6, 193–196.
  4. ^ Соrrеns С. (1922) Geschlechtsbestimmung und Zahlenverhaltnis der Geschlechter beim Sauerampfer (Rumex acetosa). “Biol. Zbl.” 42, 465-480.
  5. ^ Rychlewski J., Kazlmierez Z. (1975) Sex ratio in seeds of Rumex acetosa L. as a result of sparse or abundant pollination. “Acta Biol. Cracov” Scr. Bot., 18, 101-114.
  6. ^ Correns C. (1928) Bestimmung, Vererbung und Verteilung des Geschlechter bei den hoheren Pflanzen. Handb. Vererbungswiss., 2, 1-138.
  7. ^ Mulcahy D. L. (1967) Optimal sex ratio in Silene alba. “Heredity” 22 № 3, 41.
  8. ^ Riede W. (1925) Beitrage zum Geschlechts- und Anpassungs-problem. “Flora” 18/19
  9. ^ Kihara H., Hirayoshi J. (1932) Die Geschlechtschromosomen von Humulus japonicus. Sieb. et. Zuce. In: 8th Congr. Jap. Ass. Adv. Sci., p. 363—367 (cit.: Plant Breeding Abstr., 1934, 5, № 3, p. 248, ref. № 768).
  10. ^ Geodakyan, V.A. & Geodakyan, S.V., (1985) Is there a negative feedback in sex determination? “Zurnal obschej biol.” 46 201-216 (in Russian). ).
  11. ^ Ter-Avanesyan D. V. (1949). Tr. Prikl. Bot, Genet, Selekt., 28 119.
  12. ^ Ter-Avanesian D. V. (1978) Significance of pollen amount for fertilization. “Bull. Torrey Bot. Club.” 105 N 1, 2–8.
  13. ^ Malcolm T. Sanford. Producing Pollen. University of Florida, Institute of Food and Agricultural Sciences. Retrieved on 2007-08-30.. Document ENY118. Original publication date November 1, 1994. Revised February 1, 1995. Reviewed May 1, 2003.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 242nd day of the year (243rd in leap years) in the Gregorian calendar. ...

See also

Pollen count is the measurement of the number of grains of pollen in a cubic meter of air. ... Northern pollen sources for honeybees The pollen source in a given area depends on the type of vegetation present and the length of their bloom period. ... Molecular structure of apigenin, a polyphenol antioxidant A polyphenol antioxidant is a type of antioxidant containing a polyphenolic substructure. ... The evolution of sex is a major puzzle in modern evolutionary biology. ... Sex ratio by country for total population. ... Honeybee collecting pollen In zoology, a palynivore is an animal which selectively eats the nutrient-rich pollen produced by flowering plants, including gymnosperms. ...

External links

Clumps of yellow pollen on a flower head.

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. Download high resolution version (750x658, 82 KB)Pollen on flower. ... Download high resolution version (750x658, 82 KB)Pollen on flower. ... Encyclopædia Britannica, the eleventh edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... The public domain comprises the body of all creative works and other knowledge—writing, artwork, music, science, inventions, and others—in which no person or organization has any proprietary interest. ...


Pinguicula grandiflora commonly known as a Butterwort Example of a cross section of a stem [1] Botany is the scientific study of plant life. ... Ethnobotany is the study of the relationship between plants and people: Fromethno - study of people and botany - study of plants. ... Paleobotany (from the Greek words paleon = old and botanikos = of herbs) is the branch of paleontology dealing with the recovery and identification of plant remains from geological contexts, and their use in the reconstruction of past environments and the history of life. ... Plant anatomy or phytotomy is the general term for the study of the structure of plants. ... For the journal, see Ecology (journal). ... Evolutionary developmental biology (evo-devo) refers to the study of developmental programs and patterns from an evolutionary perspective. ... Plant anatomy or phytotomy is the general term for the study of the structure of plants. ... A germination rate experiment Plant physiology is a subdiscipline of botany concerned with the function, or physiology, of plants. ... Download high resolution version (454x765, 178 KB)Coconut Palm on Martinique. ... For other uses, see Plant (disambiguation). ... Plant evolution is an aspect of the study of biological evolution, involving predominantly the evolution of plants suited to live on land, the greening of the various land masses by the filling of their niches with land plants, and the diversification of the groups of land plants. ... For the programming language, see algae (programming language). ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... Classes Marattiopsida Osmundopsida Gleicheniopsida Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. ... Divisions Pinophyta (or Coniferophyta) - Conifers Ginkgophyta - Ginkgo Cycadophyta - Cycads Gnetophyta - Gnetum, Ephedra, Welwitschia Gymnosperm (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, which are usually arranged in cone-like structures. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... For other uses, see Flower (disambiguation). ... For other uses, see Fruit (disambiguation). ... Look up foliage in Wiktionary, the free dictionary. ... Tunica-Corpus model of the apical meristem. ... For other uses, see Root (disambiguation). ... Stem showing internode and nodes plus leaf petiole and new stem rising from node. ... Stoma of a leaf under a microscope. ... Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem. ... For other uses, see Wood (disambiguation). ... Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ... Plant cells separated by transparent cell walls. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Photosynthesis splits water to liberate O2 and fixes CO2 into sugar The leaf is the primary site of photosynthesis in plants. ... Plant hormones (also known as plant growth regulators (PGRs) and phytohormones) are chemicals that regulate a plants growth. ... Plant cells with visible chloroplasts. ... Transpiration is the evaporation of excess water from aerial parts and of plants, especially leaves but also stems, flowers and fruits. ... Sporic or diplohaplontic life cycle. ... In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... Close-up of an Echinopsis spachiana flower, showing both carpels and stamen, making it a complete flower. ... Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (containing the male gametes, sperm) to the plant carpel of flowering plants, the structure that contains the ovule (which in turn houses the female gamete... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... Young sporophytes of the common moss Tortula muralis. ... Plant taxonomy is the science that finds, describes, classifies and names plants. ... A botanical name is a formal name conforming to the ICBN. As with its zoological and bacterial equivalents it may also be called a scientific name. Botanical names may be in one part (genus and above), two parts (species) or three parts (below the rank of species). ... Botanical nomenclature Plants are given formal names, governed by the ICBN. Within the limits set by the ICBN there is a separate set of rules, the ICNCP, for those plants in cultivation that require separate recognition, so-called cultivars. ... Studying a plant sample in the Herbarium In botany, a herbarium is a collection of preserved plant specimens. ... The International Association for Plant Taxonomy (IAPT) is devoted to plant systematics, taxonomy and nomenclature. ... The International Code of Botanical Nomenclature (ICBN) is the set of rules that governs plant nomenclature, i. ... Writing the Species Plantarum was one of Carolus Linnaeus two great contributions to the Scientific community. ...

  Results from FactBites:
 
Pollen.com - Your Local Pollen Reports and Allergy Forecasts including the only 4 Day Allergy Alert Forecast. If you ... (187 words)
During a field investigation he discovered pine pollen several hundred miles from the nearest pine forest.
With some surprise he concluded that this pollen must have floated through the air to its destination.
The Allergy Alert™ Emails provide you with a daily two-day forecast of allergy conditions in your area, as long as your area is critical — to help you manage today's allergies and plan ahead for the conditions tomorrow.
BBC - Weather Centre - Pollen (519 words)
This pollen index is supplied by the National Pollen and Aerobiology Research Unit.
The pollen forecasts are made using information from the National Pollen Network, local vegetation, weather patterns in the winter and spring that influence grass growth, and the weather forecasts.
The pollen from silver birch trees is the most important tree pollen type for hay fever sufferers and usually occurs in April.
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