93-451: A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Plants with characteristics that make them hazardous, aesthetically unappealing, difficult to control in managed environments, or otherwise unwanted in farm land , orchards , gardens , lawns , parks , recreational spaces, residential and industrial areas, may all be considered weeds. The concept of weeds
186-539: A close association with human activities. Some plants become dominant when introduced into new environments because the animals and plants in their original environment that compete with them or feed on them are absent; in what is sometimes called the "natural enemies hypothesis", plants freed from these specialist consumers may become dominant. An example is Klamath weed , which threatened millions of hectares of prime grain and grazing land in North America after it
279-789: A common weed in European wheat fields, but is now sometimes grown as a garden plant. As pioneer species , weeds begin the process of ecological succession after a disturbance event. The rapid, aggressive growth of weeds rapidly prevents erosion in newly exposed bare soil, and has substantially slowed topsoil loss due to anthropogenic disturbances. It has been suggested that weeds, with their aggressive ability to adapt, could provide humans with vital tools and knowledge for climate change adaptation . Some researchers argue that researching weed species could offer valuable insights for crop breeding, or that weeds themselves hold potential as hardy, climate-change-resistant crops. Adaptable weeds could also be
372-440: A crop, because their presence disrupts the incidence of positive cues which pests use to locate their food. Weeds may also act as a "living mulch", providing ground cover that reduces moisture loss and prevents erosion. Weeds may also improve soil fertility; dandelions, for example, bring up nutrients like calcium and nitrogen from deep in the soil with their tap root, and clover hosts nitrogen-fixing bacteria in its roots, fertilizing
465-884: A dye shop with remains of both woad and madder have been excavated and dated to the 10th century. In medieval times, centres of woad cultivation lay in Lincolnshire and Somerset in England, Jülich and the Erfurt area in Thuringia in Germany, Piedmont and Tuscany in Italy, and Gascogne , Normandy , the Somme Basin (from Amiens to Saint-Quentin ), Brittany and, above all, Languedoc in France. This last region, in
558-684: A dye. There has also been some revival of the use of woad for craft purposes. The first archaeological finds of woad seeds date to the Neolithic period. The seeds have been found in the cave of l'Audoste, Bouches-du-Rhône , France. Impressions of seeds of Färberwaid (Isatis tinctoria L.) or German indigo, of the plant family Brassicaceae , have been found on pottery in the Iron Age settlement of Heuneburg , Germany. Seed and pod fragments have also been found in an Iron Age pit at Dragonby, North Lincolnshire, United Kingdom. The Hallstatt burials of
651-550: A negative connotation, many plants known as weeds can have beneficial properties. A number of weeds, such as the dandelion ( Taraxacum ) and lamb's quarter , are edible, and their leaves or roots may be used for food or herbal medicine . Burdock is common over much of the world, and is sometimes used to make soup and medicine in East Asia . Some weeds attract beneficial insects , which in turn can protect crops from harmful pests. Weeds can also prevent pest insects from finding
744-425: A plant that is a weed in one context, is not a weed when growing in a situation where it is wanted. Some plants that are widely regarded as weeds are intentionally grown in gardens and other cultivated settings. For this reason, some plants are sometimes called beneficial weeds . Similarly, volunteer plants from a previous crop are regarded as weeds when growing in a subsequent crop. Thus, alternative nomenclature for
837-551: A protective response. The first such plant receptors were identified in rice and in Arabidopsis thaliana . Plants have some of the largest genomes of all organisms. The largest plant genome (in terms of gene number) is that of wheat ( Triticum aestivum ), predicted to encode ≈94,000 genes and thus almost 5 times as many as the human genome . The first plant genome sequenced was that of Arabidopsis thaliana which encodes about 25,500 genes. In terms of sheer DNA sequence,
930-420: A range of physical and biotic stresses which cause DNA damage , but they can tolerate and repair much of this damage. Plants reproduce to generate offspring, whether sexually , involving gametes , or asexually , involving ordinary growth. Many plants use both mechanisms. When reproducing sexually, plants have complex lifecycles involving alternation of generations . One generation, the sporophyte , which
1023-410: A region where there are few natural controls to limit their population and spread. In a range of contexts, weeds can have negative impacts by: "What would the world be, once bereft, of wet and wildness? Let them be left. O let them be left; wildness and wet; Long live the weeds and the wilderness yet." — Gerard Manley Hopkins' poem Inversnaid While the term "weed" generally has
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#17327726224111116-529: A scenario sometimes called the "novel weapons hypothesis". These chemicals may limit the growth of established plants or the germination and growth of seeds and seedlings. Weed growth can also inhibit the growth of later-successional species in ecological succession . Introduced species have been observed to undergo rapid evolutionary change to adapt to their new environments, with changes in plant height, size, leaf shape, dispersal ability, reproductive output, vegetative reproduction ability, level of dependence on
1209-436: A seed impression on an Anglo-Saxon pot. The authors theorize that vitrum could have actually referred to copper(II) sulfate 's naturally occurring variant chalcanthite or to the mineral azurite . A later study concluded the amount was "not of sufficient magnitude to provide convincing evidence that the copper was deliberately applied as paint". Woad was an important dyeing agent in much of Europe and parts of England during
1302-556: A source of transgenic genes which could confer useful traits upon crops. Weed species have been used in the restoration of land in Australia using a method called natural sequence farming. This method allows non-native weeds to stabilize and restore degraded areas where native species are not yet capable of regenerating themselves. "We've got to be one of the most bomb-proof species on the planet." — Paleontologist David Jablonsky An alternate definition often used by biologists
1395-531: A tattoo pigment have claimed that it does not work well, and is actually caustic and causes scarring when put into the skin. It has also been claimed that Caesar was referring to some form of copper - or iron -based pigment. Analysis done on the Lindow Man did return evidence of copper. The same study also noted that the earliest definite reference to the woad plant in the British Isles dates to
1488-475: A weed species. Like other weedy species, humans are widely dispersed in a wide variety of environments, and are highly unlikely to go extinct no matter how much damage the environment faces. White clover is considered by some to be a weed in lawns, but in many other situations is a desirable source of fodder, honey and soil nitrogen. A short list of some plants that often are considered to be weeds follows: Many invasive weeds were introduced deliberately in
1581-400: A weed. Many weed species have moved out of their natural geographic ranges and spread around the world in tandem with human migrations and commerce. Weed seeds are often collected and transported with crops after the harvesting of grains , so humans are a vector of transport as well as a producer of the disturbed environments to which weed species are well adapted, resulting in many weeds having
1674-618: A woad mill model, photos and other items used in woad production. A major market for woad was at Görlitz in Lausitz. The citizens of the five Thuringian Färberwaid (dye woad) towns of Erfurt , Gotha , Tennstedt , Arnstadt and Langensalza had their own charters. In Erfurt, the woad-traders gave the funds to found the University of Erfurt . Traditional fabric is still printed with woad in Thuringia, Saxony and Lusatia today: it
1767-404: Is diploid (with 2 sets of chromosomes ), gives rise to the next generation, the gametophyte , which is haploid (with one set of chromosomes). Some plants also reproduce asexually via spores . In some non-flowering plants such as mosses, the sexual gametophyte forms most of the visible plant. In seed plants (gymnosperms and flowering plants), the sporophyte forms most of the visible plant, and
1860-408: Is a flowering plant in the family Brassicaceae (the mustard family) with a documented history of use as a blue dye and medicinal plant. Its genus name, Isatis , derives from the ancient Greek word for the plant, ἰσάτις . It is occasionally known as Asp of Jerusalem . Woad is also the name of a blue dye produced from the leaves of the plant. Woad is native to the steppe and desert zones of
1953-547: Is a similar process. Structures such as runners enable plants to grow to cover an area, forming a clone . Many plants grow food storage structures such as tubers or bulbs which may each develop into a new plant. Some non-flowering plants, such as many liverworts, mosses and some clubmosses, along with a few flowering plants, grow small clumps of cells called gemmae which can detach and grow. Plants use pattern-recognition receptors to recognize pathogens such as bacteria that cause plant diseases. This recognition triggers
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#17327726224112046-666: Is also observed to be strongly selected for among some invasive populations, such as Solidago canadensis in China . Many weed species are now found almost worldwide, with novel adaptations that suit regional populations to their environments. Some negative impacts of weeds are functional: they interfere with food and fiber production in agriculture , wherein they must be controlled to prevent lost or diminished crop yields. In other settings, they interfere with other cosmetic, decorative, or recreational goals, such as in lawns , landscape architecture , playing fields , and golf courses . In
2139-428: Is any species, not just plants, that can quickly adapt to any environment. Some traits of weedy species are the ability to reproduce quickly, disperse widely, live in a variety of habitats, establish a population in strange places, succeed in disturbed ecosystems and resist eradication once established. Such species often do well in human-dominated environments as other species are not able to adapt. Common examples include
2232-577: Is described in The History of Woad and the Medieval Woad Vat (1998) ISBN 0-9534133-0-6 . Woad is biodegradable and safe in the environment. In Germany, there have been attempts to use it to protect wood against decay without applying dangerous chemicals. Production of woad is increasing in the UK for use in inks , particularly for inkjet printers , and dyes. In certain locations,
2325-506: Is important in agriculture and horticulture . Methods include hand cultivation with hoes , powered cultivation with cultivators , smothering with mulch or soil solarization , lethal wilting with high heat, burning, or chemical attack with herbicides and cultural methods such as crop rotation and fallowing land to reduce the weed population. It has long been assumed that weeds, in the sense of rapidly-evolving plants taking advantage of human-disturbed environments, evolved in response to
2418-616: Is known as Blaudruck (literally, "blue print(ing)"). In the Marche region, the cultivation of the plant was an important resource for the Duchy of Urbino in Italy. To fully understand the importance of the ford industry in the State of Urbino , it is enough to read the comprehensive Chapters of the art of wool in 1555, which dictated prescriptions regarding the cultivation and trade of woad, whether in loaves or macerated (powdered). Testifying to
2511-496: Is known as botany , a branch of biology . All living things were traditionally placed into one of two groups, plants and animals . This classification dates from Aristotle (384–322 BC), who distinguished different levels of beings in his biology , based on whether living things had a "sensitive soul" or like plants only a "vegetative soul". Theophrastus , Aristotle's student, continued his work in plant taxonomy and classification. Much later, Linnaeus (1707–1778) created
2604-441: Is often made out to be. Some people find in it a kind of soothing monotony. It leaves their minds free to develop the plot for their next novel or to perfect the brilliant repartee with which they should have encountered a relative's latest example of unreasonableness. As anthropogenic climate change increases temperatures and atmospheric carbon dioxide, many weeds are expected to become harder to control and to expand their ranges, at
2697-410: Is particularly difficult to counteract, since it may confer resistance to multiple herbicides at once, including herbicides the plants' ancestors were never exposed to. Various methods of adjusting herbicide application to avoid resistance, such as rotating herbicides used and tank mixing herbicides, have all been questioned in terms of their efficacy for preventing resistance from arising. Understanding
2790-407: Is particularly significant in agriculture , where the presence of weeds in fields used to grow crops may cause major losses in yields. Invasive species , plants introduced to an environment where their presence negatively impacts the overall functioning and biodiversity of the ecosystem, may also sometimes be considered weeds. Taxonomically , the term "weed" has no botanical significance, because
2883-414: Is that for much of human history, women and children were an abundant source of cheap labor to control weeds, and not directly acknowledged. Weeds are assumed to have existed since the beginning of agriculture, and accepted as an "inevitable nuisance." Though the plants are not named using a specific term denoting a "weed" in the contemporary sense, plants that may be interpreted as "weeds" are referenced in
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2976-511: Is used as an herbal medicinal tea in China for colds and tonsillar ailments. Used as a tea, it has a brownish appearance and (unlike most Chinese medicines) is mildly sweet in taste. The dye chemical extracted from woad is indigo , the same dye extracted from "true indigo", Indigofera tinctoria , but in a lower concentration. Following the Portuguese discovery of the sea route to India by
3069-689: The Antarctic flora , consisting of algae, mosses, liverworts, lichens, and just two flowering plants, have adapted to the prevailing conditions on that southern continent. Plants are often the dominant physical and structural component of the habitats where they occur. Many of the Earth's biomes are named for the type of vegetation because plants are the dominant organisms in those biomes, such as grassland , savanna , and tropical rainforest . Woad Isatis tinctoria , also called woad ( / ˈ w oʊ d / ), dyer's woad, dyer's-weed , or glastum ,
3162-456: The Bible : Cursed is the ground because of you; through painful toil you will eat of it all the days of your life. It will produce thorns and thistles for you, and you will eat the plants of the field. By the sweat of your brow you will eat your food until you return to the ground. Some early Roman writers referenced weeding activities in agricultural fields, but weed control in the pre-modern era
3255-617: The Caucasus , Central Asia to Eastern Siberia and Western Asia but is now also found in South-Eastern and Central Europe and western North America . Since ancient times, woad was an important source of blue dye and was cultivated throughout Europe, especially in Western and Southern Europe. In medieval times, there were important woad-growing regions in England, Germany and France. Towns such as Toulouse became prosperous from
3348-706: The Cretaceous so rapid that Darwin called it an " abominable mystery ". Conifers diversified from the Late Triassic onwards, and became a dominant part of floras in the Jurassic . In 2019, a phylogeny based on genomes and transcriptomes from 1,153 plant species was proposed. The placing of algal groups is supported by phylogenies based on genomes from the Mesostigmatophyceae and Chlorokybophyceae that have since been sequenced. Both
3441-559: The Hochdorf Chieftain's Grave and Hohmichele contained textiles dyed with woad. Melo and Rondão write that woad was known "as far back as the time of the ancient Egyptians, who used it to dye the cloth wrappings applied for the mummies." Skelton states that one of the early dyes discovered by the ancient Egyptians was "blue woad (Isatis tinctoria)." Lucas writes, "What has been assumed to have been Indian Indigo on ancient Egyptian fabrics may have been woad." Hall states that
3534-594: The Hôtel d'Assézat . One merchant, Jean de Bernuy, a Spanish Jew who had fled the Spanish Inquisition , was credit-worthy enough to be the main guarantor of the ransomed King Francis I after his capture at the Battle of Pavia by Charles V of Spain . Much of the woad produced here was used for the cloth industry in southern France, but it was also exported via Bayonne , Narbonne and Bordeaux to Flanders,
3627-531: The Neolithic agricultural revolution approximately 12,000 years ago. However, researchers have found evidence of "proto-weeds" behaving in similar ways at Ohalo II , a 23,000-year-old archeological site in Israel . The idea of "weeds" as a category of undesirable plant has not been universal throughout history. Before 1200 A.D., little evidence exists of concern with weed control or of agricultural practices solely intended to control weeds. A possible reason for this
3720-457: The carpels or ovaries , which develop into fruits that contain seeds . Fruits may be dispersed whole, or they may split open and the seeds dispersed individually. Plants reproduce asexually by growing any of a wide variety of structures capable of growing into new plants. At the simplest, plants such as mosses or liverworts may be broken into pieces, each of which may regrow into whole plants. The propagation of flowering plants by cuttings
3813-463: The common pigeon , brown rat and the raccoon . Other weedy species have been able to expand their range without actually living in human environments, as human activity has damaged the ecosystems of other species. These include the coyote , the white-tailed deer and the brown headed cowbird . In response to the idea that humans may face extinction due to environmental degradation , paleontologist David Jablonsky counters by arguing that humans are
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3906-623: The eukaryotes that form the kingdom Plantae ; they are predominantly photosynthetic . This means that they obtain their energy from sunlight , using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll . Exceptions are parasitic plants that have lost the genes for chlorophyll and photosynthesis, and obtain their energy from other plants or fungi. Most plants are multicellular , except for some green algae. Historically, as in Aristotle's biology ,
3999-435: The mycorrhizal network , and level of phenotype plasticity appearing on timescales of decades to centuries. Invasive species can be more adaptable in their new environments than in their native environments, occupying broader ranges in areas where they are invasive than in areas where they are native. Hybridization between similar species can produce novel invasive plants that are better adapted to their surroundings. Polyploidy
4092-746: The soil seed bank for many years. Perennial weeds often have underground stems that spread under the soil surface or, like ground ivy ( Glechoma hederacea ), have creeping stems that root and spread out over the ground. These traits make many disturbance-adapted plants highly successful as weeds. On top of the ability of individual plants to adapt to their conditions, weed populations also evolve much more quickly than older models of evolution account for. Once established in an agricultural setting, weeds have been observed to undergo evolutionary changes to adapt to selective pressures imposed by human management. Some examples include changes in seed dormancy, changes in seasonal life cycles, changes in plant morphology, and
4185-1003: The "chlorophyte algae" and the "streptophyte algae" are treated as paraphyletic (vertical bars beside phylogenetic tree diagram) in this analysis, as the land plants arose from within those groups. The classification of Bryophyta is supported both by Puttick et al. 2018, and by phylogenies involving the hornwort genomes that have also since been sequenced. Rhodophyta [REDACTED] Glaucophyta [REDACTED] Chlorophyta [REDACTED] Prasinococcales Mesostigmatophyceae Chlorokybophyceae Spirotaenia [REDACTED] Klebsormidiales [REDACTED] Chara [REDACTED] Coleochaetales [REDACTED] Hornworts [REDACTED] Liverworts [REDACTED] Mosses [REDACTED] Lycophytes [REDACTED] [REDACTED] Gymnosperms [REDACTED] Angiosperms [REDACTED] Plant cells have distinctive features that other eukaryotic cells (such as those of animals) lack. These include
4278-559: The Britanni used to colour their bodies blue with vitrum , a word that means primarily ' glass ' , but also the domestic name for the woad ( Isatis tinctoria ), besides the Gaulish loanword glastum (from Proto-Celtic * glastos ' green ' ). The connection seems to be that both glass and the woad are "water-like" ( Latin : vitrum is from Proto-Indo-European *wed-ro- , ' water-like ' ). In terms of usage,
4371-526: The Latin vitrum is more often used to refer to glass rather than woad. The use of the word for the woad might also be understood as "coloured like glass", applied to the plant and the dye made from it. Gillian Carr conducted experiments using indigo pigment derived from woad mixed with different binders to make body paint. The resulting paints yielded colours from "grey-blue, through intense midnight blue, to black". People with modern experiences with woad as
4464-642: The Low Countries, Italy, and above all Britain and Spain. After cropping the woad eddish could be let out for grazing sheep. The woad produced in Lincolnshire and Cambridgeshire in the 19th century was shipped out from the Port of Wisbech , Spalding and Boston , both the last to northern mills and the USA. The last portable woad mill was at Parson Drove , Cambridgeshire, Wisbech & Fenland Museum has
4557-579: The Reformation, Christian theology that emphasized the degradation of nature after the Fall of Man , and humankind's role and duty to dominate and subdue nature, became more developed and widespread. Various European writers designated certain plants as "vermin" and "filth," though many plants identified as such were valued by gardeners or by herbalists and apothecaries, and some questioned the idea that any plant could be without purpose or value. Laws mandating
4650-599: The Unicorn (1495–1505), though typically it is the dark blue of the woad that has lasted best. Medieval uses of the dye were not limited to textiles. For example, the illustrator of the Lindisfarne Gospels ( c. 720 ) used a woad-based pigment for blue paint. As does the late 13th century North Italian manual on book illumination Liber colorum secundum magistrum Bernardum describe its usage. In Viking Age levels at archaeological digs at York ,
4743-864: The Viridiplantae, along with the red algae and the glaucophytes , in the clade Archaeplastida . There are about 380,000 known species of plants, of which the majority, some 260,000, produce seeds . They range in size from single cells to the tallest trees . Green plants provide a substantial proportion of the world's molecular oxygen; the sugars they create supply the energy for most of Earth's ecosystems and other organisms , including animals, either eat plants directly or rely on organisms which do so. Grain , fruit , and vegetables are basic human foods and have been domesticated for millennia. People use plants for many purposes , such as building materials , ornaments, writing materials , and, in great variety, for medicines . The scientific study of plants
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#17327726224114836-801: The amount of cytoplasm stays the same. Most plants are multicellular . Plant cells differentiate into multiple cell types, forming tissues such as the vascular tissue with specialized xylem and phloem of leaf veins and stems , and organs with different physiological functions such as roots to absorb water and minerals, stems for support and to transport water and synthesized molecules, leaves for photosynthesis, and flowers for reproduction. Plants photosynthesize , manufacturing food molecules ( sugars ) using energy obtained from light . Plant cells contain chlorophylls inside their chloroplasts, which are green pigments that are used to capture light energy. The end-to-end chemical equation for photosynthesis is: This causes plants to release oxygen into
4929-757: The ancient Egyptians created their blue dye "by using indigotin, otherwise known as woad." A dye known as סטיס , satis in Aramaic , is mentioned in the Babylonian Talmud . Celtic blue is a shade of blue, also known as glas celtig in Welsh , or gorm ceilteach in both the Irish language and in Scottish Gaelic . Julius Caesar reported (in Commentarii de Bello Gallico ) that
5022-431: The atmosphere. Green plants provide a substantial proportion of the world's molecular oxygen, alongside the contributions from photosynthetic algae and cyanobacteria. Plants that have secondarily adopted a parasitic lifestyle may lose the genes involved in photosynthesis and the production of chlorophyll. Growth is determined by the interaction of a plant's genome with its physical and biotic environment. Factors of
5115-467: The basis of the modern system of scientific classification , but retained the animal and plant kingdoms , naming the plant kingdom the Vegetabilia. When the name Plantae or plant is applied to a specific group of organisms or taxa , it usually refers to one of four concepts. From least to most inclusive, these four groupings are: There are about 382,000 accepted species of plants, of which
5208-458: The case of invasive species , they can be of concern for environmental reasons, when introduced species outcompete native plants and cause broader damage to ecosystem health and functioning. Some weed species have been classified as noxious weeds by government authorities because, if left unchecked, they often compete with native or crop plants or cause harm to livestock . They are often foreign species accidentally or imprudently imported into
5301-647: The control of weeds emerged as early as the seventeenth century; in 1691 a law in New York required the removal of "poysonous and Stincking Weeds" in front of houses. In the nineteenth century, manual labor was used to control weeds in European towns and cities, and chemical methods of weed control emerged. For example, a French journal in 1831 documented a mixture of sulfur, lime and water boiled in an iron cauldron as an effective herbicide to prevent grass from growing among cobblestones. The cultural association between weeds and moral or spiritual degradation persisted into
5394-539: The development of a chemical process to synthesize the pigment, both the woad and natural indigo industries collapsed in the first years of the 20th century. The last commercial harvest of woad until recent times occurred in 1932, in Lincolnshire , Britain. Small amounts of woad are now grown in the UK and France to supply craft dyers. The classic book about woad is The Woad Plant and its Dye by J. B. Hurry, Oxford University Press of 1930, which contains an extensive bibliography. A method for producing blue dye from woad
5487-488: The development of forests in swampy environments dominated by clubmosses and horsetails, including some as large as trees, and the appearance of early gymnosperms , the first seed plants . The Permo-Triassic extinction event radically changed the structures of communities. This may have set the scene for the evolution of flowering plants in the Triassic (~ 200 million years ago ), with an adaptive radiation in
5580-438: The evolution of resistance to herbicides . Rapid life cycles, large populations, and ability to spread large numbers of seeds long distances also allow weed species with these general characteristics to evolve quickly. The concept of weeds also overlaps with the concept of invasive species , both in the sense that human activities tend to introduce weeds outside their native range, and that an introduced species may be considered
5673-465: The existing plant and soil community has been disrupted or damaged in some way. Adaptation to disturbance can give weeds advantages over desirable crops, pastures, or ornamental plants. The nature of the habitat and its disturbances will affect or even determine which types of weed communities become dominant. In weed ecology some authorities speak of the relationship between "the three Ps": plant, place, perception. These have been very variously defined, but
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#17327726224115766-800: The expense of less "weedy" species. For example, kudzu , the infamous invasive vine found throughout the Southeastern United States, is expected to spread northward due to climate change. Increased competitive strength of agricultural weeds in future climate conditions threaten future ability to grow crops. Existing weed management practices will likely fail under future changes in climate conditions, meaning new agricultural techniques will be needed for global food security. Suggested techniques are holistic, transitioning away from reliance on herbicide, and include aggressive adaptation of agroforestry and use of allelopathic crop residues to suppress weeds. Plant See text Plants are
5859-407: The first place, and may have not been considered nuisances at the time, but rather beneficial. Weed control encompasses a range of methods used by humans to stop, reduce or prevent the growth and reproduction of weeds within agricultural or other managed environments. Some weed control is preventative, implementing protocols to stop weeds from invading new areas. Cultural weed control involves shaping
5952-409: The gametophyte is very small. Flowering plants reproduce sexually using flowers, which contain male and female parts: these may be within the same ( hermaphrodite ) flower, on different flowers on the same plant , or on different plants . The stamens create pollen , which produces male gametes that enter the ovule to fertilize the egg cell of the female gametophyte. Fertilization takes place within
6045-583: The great majority, some 283,000, produce seeds . The table below shows some species count estimates of different green plant (Viridiplantae) divisions . About 85–90% of all plants are flowering plants. Several projects are currently attempting to collect records on all plant species in online databases, e.g. the World Flora Online . Plants range in scale from single-celled organisms such as desmids (from 10 micrometres (μm) across) and picozoa (less than 3 μm across), to
6138-453: The habit of weeds is important for non-chemical methods of weed control, such as plowing, surface scuffling, promotion of more beneficial cover crops, and prevention of seed accumulation in fields. For example, amaranth is an edible plant that is considered a weed by mainstream modern agriculture. It produces copious seeds (up to 1 million per plant) that last many years, and is an early-emergent fast grower. Those seeking to control amaranth quote
6231-543: The importance that this crop had in the economy in addition to the archival documents was the identification of a hundred millstones surveyed by Delio Bischi in the province of Pesaro and Urbino, the original use of which had become completely unknown as their memory had been lost. The woad plant's roots are used in Traditional Chinese medicine to make a medicine known as banlangen ( bǎnlán'gēn 板蓝根 ) that purports to have antiviral properties. Banlangen
6324-529: The land 1,200 million years ago , but it was not until the Ordovician , around 450 million years ago , that the first land plants appeared, with a level of organisation like that of bryophytes. However, fossils of organisms with a flattened thallus in Precambrian rocks suggest that multicellular freshwater eukaryotes existed over 1000 mya. Primitive land plants began to diversify in
6417-412: The large water-filled central vacuole , chloroplasts , and the strong flexible cell wall , which is outside the cell membrane . Chloroplasts are derived from what was once a symbiosis of a non-photosynthetic cell and photosynthetic cyanobacteria . The cell wall, made mostly of cellulose , allows plant cells to swell up with water without bursting. The vacuole allows the cell to change in size while
6510-515: The largest trees ( megaflora ) such as the conifer Sequoia sempervirens (up to 120 metres (380 ft) tall) and the angiosperm Eucalyptus regnans (up to 100 m (325 ft) tall). The naming of plants is governed by the International Code of Nomenclature for algae, fungi, and plants and the International Code of Nomenclature for Cultivated Plants . The ancestors of land plants evolved in water. An algal scum formed on
6603-547: The last nineteenth century in American cities. Urban expansion and development created ideal habitats for weeds in nineteenth-century America. Reformers consequently saw weeds as a part of the larger problem of filth, disease, and moral corruption that plagued the urban environments, and weeds were seen as refuge for "tramps" and other criminal or undesirable people. The St. Louis Post-Dispatch credited weeds as causing diphtheria , scarlet fever , and typhoid . In St. Louis between
6696-665: The late Silurian , around 420 million years ago . Bryophytes, club mosses, and ferns then appear in the fossil record. Early plant anatomy is preserved in cellular detail in an early Devonian fossil assemblage from the Rhynie chert . These early plants were preserved by being petrified in chert formed in silica-rich volcanic hot springs. By the end of the Devonian, most of the basic features of plants today were present, including roots, leaves and secondary wood in trees such as Archaeopteris . The Carboniferous period saw
6789-792: The managed environment to make it less favorable for weeds. Once weeds are present in an area, a wide variety of means to destroy the weeds and their seeds can be employed. Since weeds are highly adaptable, relying on a single method to control weeds soon results in the invasion or adaptation of weeds that are not susceptible. Integrated pest management as it applies to weeds refers to a plan of controlling weeds that integrates multiple methods of weed control and prevention. Methods of preventative weed control include cleaning equipment, stopping existing weeds in nearby areas from producing seed, and avoiding seed or manure that could be contaminated with weeds. A wide variety of cultural weed control methods are used, including cover cropping , crop rotation , selecting
6882-484: The mantra "This year’s seeds become next year’s weeds!". However, another view of amaranth values the plant as a resilient food source. Some people have appreciated weeds for their tenacity, their wildness and even the work and connection to nature they provide. As Christopher Lloyd wrote in The Well-Tempered Garden : Many gardeners will agree that hand-weeding is not the terrible drudgery that it
6975-527: The medieval period. However, dye traders began to import indigo during the sixteenth and seventeenth centuries, which threatened to replace locally grown woad as the primary blue dye. The translation of vitrum as woad may date to this period. Woad was one of the three staples of the European dyeing industry, along with weld (yellow) and madder (red). Chaucer mentions their use by the dyer ("litestere") in his poem The Former Age : The three colours can be seen together in tapestries such as The Hunt of
7068-573: The most competitive cultivars of crops, mulching, planting with optimal density, and intercropping . Mechanical methods of weed control involve physically cutting, uprooting, or otherwise destroying weeds. On small farms, hand weeding is the dominant means of weed control, but as larger farms dominate agriculture, this method becomes less feasible. On many operations, however, some hand-weeding may be an unavoidable component of weed control. Tillage , mowing , and burning are common examples of mechanical weed control on larger scales. New technology increases
7161-440: The navigator Vasco da Gama in 1498, great amounts of indigo were imported from Asia. Laws were passed in some parts of Europe to protect the woad industry from the competition of the indigo trade. It was proclaimed that indigo caused yarns to rot. This prohibition was repeated in 1594 and again in 1603. In France, Henry IV , in an edict of 1609, forbade under pain of death the use of "the false and pernicious Indian drug". With
7254-501: The physical or abiotic environment include temperature , water , light, carbon dioxide , and nutrients in the soil. Biotic factors that affect plant growth include crowding, grazing, beneficial symbiotic bacteria and fungi, and attacks by insects or plant diseases . Frost and dehydration can damage or kill plants. Some plants have antifreeze proteins , heat-shock proteins and sugars in their cytoplasm that enable them to tolerate these stresses . Plants are continuously exposed to
7347-538: The plant kingdom encompassed all living things that were not animals , and included algae and fungi . Definitions have narrowed since then; current definitions exclude the fungi and some of the algae. By the definition used in this article, plants form the clade Viridiplantae (green plants), which consists of the green algae and the embryophytes or land plants ( hornworts , liverworts , mosses , lycophytes , ferns , conifers and other gymnosperms , and flowering plants ). A definition based on genomes includes
7440-428: The potential to adapt their morphology, growth, and appearance in response to their conditions. The potential within a single individual to adapt to a wide variety of conditions is sometimes referred to as an "all-purpose genotype." Disturbance-adapted plants typically grow rapidly and reproduce quickly, with some annual weeds having multiple generations in a single growing season. They commonly have seeds that persist in
7533-430: The range of mechanical weed control options. One newly emerging form of mechanical weed control uses electricity to kill weeds. Mechanical weed control has been increasingly replaced by the use of herbicides . The reliance on herbicides has resulted in the rapid evolution of herbicide resistance in weeds, making previously effective herbicide treatments useless for the control of weeds. In particular, glyphosate , which
7626-424: The same plants might be hardy pioneers, cosmopolitan species, volunteers, "spontaneous urban vegetation," etc. Although whether a plant is a weed depends on context, plants commonly defined as weeds broadly share biological characteristics that allow them to thrive in disturbed environments and to be particularly difficult to destroy or eradicate. In particular, weeds are adapted to thrive under human management in
7719-531: The same way as intentionally grown plants. Since the origins of agriculture on Earth, agricultural weeds have co-evolved with human crops and agricultural systems, and some have been domesticated into crops themselves after their fitness in agricultural settings became apparent. More broadly, the term "weed" is occasionally applied pejoratively to species outside the plant kingdom, species that can survive in diverse environments and reproduce quickly; in this sense it has even been applied to humans . Weed control
7812-616: The sixteenth century, the concept of a "weed" was better defined as a "noxious" or undesirable type of plant, as referenced metaphorically in William Shakespeare 's works. An example of a Shakespearean reference to weeds is found in Sonnet 69 : To thy fair flower add the rank smell of weeds: / But why thy odour matcheth not thy show, / The soil is this, that thou dost common grow. In London during this period, poor women were paid low wages to weed gardens and courtyards. After
7905-469: The smallest published genome is that of the carnivorous bladderwort ( Utricularia gibba) at 82 Mb (although it still encodes 28,500 genes) while the largest, from the Norway spruce ( Picea abies ), extends over 19.6 Gb (encoding about 28,300 genes). Plants are distributed almost worldwide. While they inhabit several biomes which can be divided into a multitude of ecoregions , only the hardy plants of
7998-401: The soil directly. The dandelion is also one of several species which break up hardpan in overly-cultivated fields, helping crops grow deeper root systems. Some garden flowers originated as weeds in cultivated fields and have been selectively bred for their garden-worthy flowers or foliage. An example of a crop weed that is grown in gardens is the corncockle , ( Agrostemma githago ), which was
8091-531: The triangle created by Toulouse , Albi and Carcassonne , known as the Lauragais , was for a long time the biggest producer of woad, or pastel , as it was locally known. One writer commented that "woad […] hath made that country the happiest and richest in Europe." The prosperous woad merchants of Toulouse displayed their affluence in splendid mansions, many of which still stand, as the Hôtel de Bernuy and
8184-1143: The weed traits listed by H.G. Baker are widely cited. Examples of such ruderal or pioneer species include plants that are adapted to naturally-occurring disturbed environments such as dunes and other windswept areas with shifting soils, alluvial flood plains, river banks and deltas , and areas that are burned repeatedly. Since human agricultural and horticultural practices often mimic these natural disturbances that weedy species have adapted for, some weeds are effectively preadapted to grow and proliferate in human-disturbed areas such as agricultural fields, lawns, gardens, roadsides, and construction sites. As agricultural practices continue and develop, weeds evolve further, with humans exerting evolutionary pressure upon weeds through manipulating their habitat and attempting to control weed populations. Due to their ability to survive and thrive in conditions challenging or hostile to other plants, weeds have been considered extremophiles . Due to their evolutionary heritage as disturbance-adapted pioneers, most weeds exhibit incredibly high phenotype plasticity, meaning that individual plants hold
8277-399: The woad trade. Woad was eventually replaced by the more colourfast Indigofera tinctoria and, in the early 20th century, both woad and Indigofera tinctoria were replaced by synthetic blue dyes. Woad has been used medicinally for centuries. The double use of woad is seen in its name: the term Isatis is linked to its ancient use to treat wounds; the term tinctoria references its use as
8370-442: The years of 1905-1910, weeds became viewed as a major public health hazard, believed to cause typhoid and malaria, and legal precedents were set in order to control weeds that would help facilitate the adoption of weed control laws throughout the country. "Weed" as a category of plant overlaps with the closely related concepts of ruderal and pioneer species . Pioneer species are specifically adapted to disturbed environments, where
8463-542: Was accidentally introduced. The Klamathweed Beetle , a species that specializes in consuming the plant, was imported during World War II. Within several years Klamath weed was reduced to a rare roadside weed. In locations where predation and mutually competitive relationships are absent, weeds have increased resources available for growth and reproduction. The weediness of some species that are introduced into new environments may be caused by their production of allelopathic chemicals which indigenous plants are not yet adapted to,
8556-413: Was once considered a revolutionary breakthrough in weed control, was relied upon heavily when it was first introduced to agriculture, resulting in rapid emergence of resistance. As of 2023, 58 weed species have developed resistance to glyphosate. Herbicide resistance in weeds has rapidly developed into new, increasingly challenging forms as the plants continually evolve. Non-target site resistance, or NTSR,
8649-465: Was probably an incidental effect of plowing. Ancient Egyptians, Assyrians, and Sumerians had no specific word for "weeds," seeing all plants as having some use. The English word "weed" can be traced back to the Old English weod , which refers to woad , rather than a category of plant as in the modern usage; in early medieval European herbals, each plant is regarded as having its own "virtues". By
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