weed

1. 1. A plant considered undesirable, unattractive, or troublesome, especially one growing where it is not wanted, as in a garden.
   2. Rank growth of such plants.
2. A water plant, especially seaweed.
3. The leaves or stems of a plant as distinguished from the seeds: dill weed.
4. Something useless, detrimental, or worthless, especially an animal unfit for breeding.
5. Slang.
   1. Tobacco.
   2. A cigarette.
   3. Marijuana.

1. To clear of weeds.
2. To remove (weeds). Often used with out: weed out dandelions.
3. To eliminate as unsuitable or unwanted. Often used with out: weed out unqualified applicants.

To remove weeds.

[Middle English, from Old English wēod, herb, grass, weed.]

1. A token of mourning, as a black band worn on a man's hat or sleeve.
2. weeds The black mourning clothes of a widow.
3. An article of clothing; a garment. Often used in the plural.

[Middle English wede, garment, from Old English wǣd.]

For more information on weed, visit Britannica.com.

Etymologically, "weed" derives from the Old English word for "grass" or "herb," but during the Middle Ages the meaning has changed to indicate an undesirable plant that grows where it is not wanted, especially among agricultural plots. This has historically been the primary meaning of the word, although in the nineteenth century, American writers grew increasingly aware that calling a plant a "weed" was an arbitrary human judgment, as there is no natural category of weeds. In the words of Ralph Waldo Emerson, a weed "is a plant whose virtues have not yet been discovered." Today, biologists tend to share that opinion, since many of the plants that are designated as weeds are, in fact, closely related to popular crops. Indeed, "weed" has fallen out of usage among biologists, although those who study agriculture still find the term useful in discussions of weed control and management.

American weed control only developed out of the manual methods of pulling and hoeing in the early twentieth century, when salts and other chemicals began to be used as herbicides. However, since the 1970s, as environmental and health concerns have been raised, less toxic methods of weed control have been explored, although it has been found that any interference can have unintended ecological effects. For example, the introduction of a natural predator of an unwanted species—termed "biological control"—can devastate other local species or even, by reducing competition, cause a different species to grow out of control.

Moreover, "weed" has recently developed a new meaning in North America as a term that is applied to socalled invasive species, or non-native plants. Throughout the history of the Americas, as people have immigrated they have tended to bring along the flora and fauna of their homeland, thus intentionally—and at times unintentionally—introducing new species to the continents. Some of these non-native species have multiplied to such an extent that they threaten, or have already destroyed, the biological balance of local environments. This problem has been especially pronounced in Hawaii, Florida, California, and New York State. However, the term "weed" is generally not applied to all introduced or non-native plants but rather to those that are doing the greatest harm to biodiversity and are least controllable through human interference.

Scientists have discovered certain common characteristics among many of the most successful invasive species. They tend to be able to flourish in a variety of climactic zones and to reproduce easily and quickly over long periods with small seeds that are less likely to be eaten. However, non-native plants may also have an advantage in that they can exploit unfilled niches in their new lands while perhaps avoiding traditional enemies. Modern mobility and faster forms of transportation are exacerbating the problem in America and around the world.

Some of the most notorious invasive weeds in America today include kudzu, tumbleweeds, and leafy spurge. Kudzu, from Japan and perhaps originally China, is a semi-woody vine that came to dominate much of the American Southeast in the later twentieth century. Its introduction was encouraged by the American government early in the century to help improve soil and stop erosion, and attempts have continued for decades to undo the ecological damage that its widespread planting and subsequent spread have caused.

Tumbleweeds are now considered to be emblematic of the American West, and some tumbleweed species are indeed native to North America, while others originated in Europe and Asia. They do well with little water and were once cultivated in the hopes of being a food source for livestock. Leafy spurge, which was introduced from Europe and Asia in the early nineteenth century, is believed to be harmful to cattle if eaten. As with kudzu, attempts are being made to control tumbleweeds, leafy spurge, and other invasive weeds through biological, chemical, and manual methods to prevent further environmental and economic damage.

The history of American weeds is not only the story of importations and largely unsuccessful attempts to control non-native species, for native American species have also traveled to new lands. Notoriously, native ragweed, whose pollen causes Americans with hay fever to suffer every fall, has made an appearance in Europe, where it is spreading despite attempts to control it.

Bibliography

Van Driesche, Jason, and Roy van Driesche. Nature Out of Place: Biological Invasions in the Global Age. Washington, D.C.: Island Press, 2000.

Zimdahl, Robert L. Fundamentals of Weed Science. San Diego, Calif.: Academic Press, 1993.

The dictionary definition is any plant considered undesirable, unattractive, or troublesome, especially a plant growing where it is not wanted in cultivated ground. Some celebrated authors have had their own definition of a weed. Ralph Waldo Emerson wrote, "What is a weed? A plant whose virtues have not yet been discovered." James Russell Lowell wrote in 1848, "A weed is no more than a flower in disguise." Ella Wheeler Wilcox, a Wisconsin poet (more famous for her expression "Laugh, and the world laughs with you; Weep, and you weep alone") wrote in her poem "The Weed" that "a weed is but an unloved flower." Finally, Shakespeare wrote in Richard III, "great weeds do grow apace."

1. a plant growing out of place.
2. of horses, see sporadic lymphangitis.

• noxious w. (1) — a plant defined by law as being particularly undesirable, invasive and difficult to control.

1. According to Emerson, “a plant whose virtues have not yet been discovered.” A less generous but more useful definition from the American Heritage Dictionary calls a weed “a plant considered undesirable, unattractive, or troublesome, especially one growing where it is not wanted, as in a garden.”
2. The stems and leaves of a plant, as opposed to its seeds, as in “dill weed.”

Weeds could indicate that the dreamer may have to weed out some ideas or negative thoughts from their consciousness. Their appearance could also indicate that some good friendships and/or relationships have gone to seed.

This article is about plants specifically called weeds. For other uses, see Weed (disambiguation).

A dandelion is a common weed all over the world, especially in Europe, Asia and the Americas.

A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-made settings such as gardens, lawns or agricultural areas, but also in parks, woods and other natural areas. More specifically, the term is often used to describe native or nonnative plants that grow and reproduce aggressively.^[1] Generally, a weed is a plant in an undesired place.

Weeds may be unwanted for a number of reasons: they might be unsightly, or crowd out or restrict light to more desirable plants or use limited nutrients from the soil. They can harbor and spread plant pathogens that infect and degrade the quality of crop or horticultural plants. Some weeds are a nuisance because they have thorns or prickles, some have chemicals that cause skin irritation or are hazardous if eaten, or have parts that come off and attach to fur or clothes.

The term weed in its general sense is a subjective one, without any classification value, since a "weed" is not a weed when growing where it belongs or is wanted. Indeed, a number of "weeds" have been used in gardens or other cultivated-plant settings. An example is the corncockle, Agrostemma, which was a common field weed exported from Europe along with wheat, but now sometimes grown as a garden plant.^[2]

Professor Richard C. Lewontin of Harvard University defines weeds as plants that create environmental conditions in which it cannot reproduce. He takes the example of pine trees that crowd out sunlight such that its own offspring cannot grow. Weeds continue to exist, because the environment is continually being disturbed to create open conditions for new generations, such as forest fires and human activity.^[3]

Contents 1 Distribution 2 Relation to humans 3 Examples 4 See also 5 References 5.1 Notes 5.2 Bibliography 5.3 External links

Distribution

Yellow starthistle, a thistle native to southern Europe and the Middle East that is an invasive weed in parts of North America.

Weedy plants generally share similar adaptations that give them advantages and allow them to proliferate in disturbed environments whose soil or natural vegetative cover has been damaged. Naturally occurring disturbed environments include dunes and other windswept areas with shifting soils, alluvial flood plains, river banks and deltas, and areas that are often burned. Since human agricultural practices often mimic these natural environments where weedy species have evolved, weeds have adapted to grow and proliferate in human-disturbed areas such as agricultural fields, lawns, roadsides, and construction sites. The weedy nature of these species often gives them an advantage over more desirable crop species because they often grow quickly and reproduce quickly, have seeds that persist in the soil seed bank for many years, or have short lifespans with multiple generations in the same growing season. Perennial weeds often have underground stems that spread out under the soil surface or, like ground ivy (Glechoma hederacea), have creeping stems that root and spread out over the ground.^[4]

Some plants become dominant when introduced into new environments because they are freed from specialist consumers; in what is sometimes called the “natural enemies hypothesis,” plants freed from these specialist consumers may increase their competitive ability. In locations were predation and mutual competitive relationships no longer exist, some plants are able to increase allocation of resources into growth or reproduction. The weediness of some species that are introduced into new environments can be caused by the introduction of new chemicals; sometimes called the "novel weapons hypothesis," these introduced allelopathyic chemicals, which indigenous plants are not yet adapted to, may limit the growth of established plants or the germination and growth of seeds and seedlings.^[5][6]

Relation to humans

As long as humans have cultivated plants, weeds have been a problem. Weeds have even been mentioned in religious and literature texts like the following quotes from Genesis and a Shakespearean sonnet:

"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,"^[7]

"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."^[8]

700 cattle that were killed overnight by a poisonous weed.^[9]

Weed seeds are often collected and transported with crops after the harvesting of grains. Many weed species have moved out of their natural geographic locations and have spread around the world with humans. (See Invasive species.) Not all weeds have the same ability to damage crops and horticultural plants or cause harm to animals. Some have been classified as noxious weeds by governmental authorities because if left unchecked, they often dominate the environment where crop plants are to be grown or cause harm to livestock. They are often foreign species mistakenly or accidentally imported into a region where there are few natural controls to limit their population and spread. Many weeds have ideal locations for growth and reproduction because of the large areas of open soil created by the conversion of land to field agriculture. Farming practices that produce unvegetated soils part of the year and human distribution of food crops mixed with seeds of weeds from other parts of the world have facilitated the colonization of vast new areas for many weedy species; humans are the vector of transport and the producer of disturbed environments, thus many weedy species have an ideal association with humans.

A number of weeds, such as the dandelion Taraxacum, are edible, and their leaves and roots may be used for food or herbal medicine. Burdock is common weed over much of the world, and is sometimes used to make soup and other medicine in East Asia. These so-called "beneficial weeds" may have other beneficial effects, such as drawing away the attacks of crop-destroying insects, but often are breeding grounds for insects and pathogens that attack other plants. Dandelions are one of several species which break up hardpan in overly cultivated fields, helping crops grow deeper root systems. Some modern species of domesticated flower actually originated as weeds in cultivated fields and have been bred by people into garden plants for their flowers or foliage.

Examples

• Ailanthus altissima
• Bermuda grass - perennial, spreading by runners, rhizomes and seeds.
• Bindweed
• Broadleaf plantain – perennial, spreads by seeds that persist in the soil for many years
• Burdock – biennial
• Clover - annual, biennial, or perennial^[10]
• Creeping Charlie – perennial, fast-spreading plants with long creeping stems
• Dandelion – perennial, wind-spread, fast-growing, and drought-tolerant
• Goldenrod – perennial
• Japanese Knotweed
• Kudzu – perennial
• Leafy spurge – perennial, with underground stems
• Cannabis^[11][12]
• Milk thistle – annual or biennial
• Poison ivy – perennial
• Ragweed – annual
• Sorrel – annual
• St John's wort - perennial
• Sumac – woody perennial
• Wild carrot – biennial
• Wood sorrel – perennial

The five plants designated "injurious weeds" under UK law are:^[13]

• common ragwort
• spear thistle
• creeping or field thistle
• curled dock
• broad leaved dock

See also

• Crop weeds
• Herbicide
• Introduced species
• Invasive species
• List of beneficial weeds
• Pesticide
• R-selection
• Vavilovian mimicry
• Weed control
• Weed of cultivation
• Weedy species

References

Notes

1. ^ Janick, Jules (1979). Horticultural Science (3rd ed.). San Francisco: W.H. Freeman. p. 308. ISBN 0-7167-1031-5. 
2. ^ "Detailed information on Corn Cockle (Agrostemma githago)". PlantFiles. http://davesgarden.com/pf/go/1341/. Retrieved February 15, 2009. 
3. ^ A speech given on the radio program Big Ideas, (5/11/2003): "A weed is literally a plant... which comes into a disturbed habitat, which then changes the nature of the soil, the shading, and everything, and the moisture, ectcetera, in such a way that it cannot reproduce itself in that habitat."
4. ^ Saupe, Stephen G.. "Plant Foraging: Two Case Studies". http://employees.csbsju.edu/ssaupe/biol327/Lecture/Plant_Foraging_case_study.pdf. Retrieved February 15, 2009. 
5. ^ Willis, Rick J. (2007), "The History of Allelopathy", Springer: 8, ISBN 140204092X, http://www.google.com/books?id=C-nPBYjDAjYC&pg=PA3&, retrieved 2009-08-17 
6. ^ http://plantecology.dbs.umt.edu/Full%20text%20papers%20and%20abstracts/2004%20papers/Callaway&Ridenour2004NOVEL.pdf
7. ^ Genesis 3:17-19 New International Version
8. ^ Shakespeare, William. Those parts of thee that the world's eye doth view. Infoplease. http://www.infoplease.com/t/lit/shakespeare-sonnets/69.html. Retrieved February 15, 2009. 
9. ^ Coupe, Sheena, ed (1989). Frontier country: Australia's outback heritage. Vol. 1. Willougby: Weldon Russell. p. 298. 
10. ^ On lawns and elsewhere, some people consider clover a weed, and some do not, as it has some beneficial effects.
11. ^ "PLANTS Profile for Cannabis sativa (marijuana)". Natural Resources Conservation Service. United States Department of Agriculture. http://plants.usda.gov/java/profile?symbol=CASA3. Retrieved February 15, 2009. 
12. ^ Mathre, Mary Lynn, ed. (1997), Cannabis in medical practice: a legal, historical and pharmacological overview of the therapeutic use of Marijuana, Jefferson, NC: McFarland, p. 208, ISBN 9780786403615, http://books.google.com/books?id=1AWGDhIOvk0C&pg=PA208&dq=Cannabis+is+a++weedy+species&lr=&ei=lvI9SdTZEJ-qyATrzfTcCw&client=firefox-a, retrieved February 15, 2009 
13. ^ "Weeds Act 1959". Department for Environment, Food and Rural Affairs (Defra), UK. Archived from the original on 2007-09-26. http://web.archive.org/web/20070926235042/http://www.defra.gov.uk/rds/weeds-act.htm. Retrieved February 15, 2009. 

Bibliography

External links

• Weed Identification Guide from Virginia Tech (Southeastern United States)
• Common weeds of the northern United States and Canada
• Michigan State University Weed Science

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
1.
n. - ukrudt, urt, splejs, mager krikke, spinkel fyr
v. tr. - luge ud, fjerne ukrudt, luge ukrudt, udrense
v. intr. - fjerne ukrudt, luge

2.
n. - sørgedragt, sørgebind

Nederlands (Dutch)
wieden, schoffelen, ongewenste elementen verwijderen, onkruid, weed, wiet, sigaret, slapjanus

Français (French)
1.
n. - (Bot) mauvaise herbe, (Bot) herbes aquatiques, (GB) mauviette (péj), tabac (hum), herbe (fam), marijuana
v. tr. - désherber
v. intr. - désherber

2.
n. - habits de deuil

Deutsch (German)
1.
n. - Unkraut, (Slang), Marihuana, Tabak, (Slang) schwächliches Tier, Schlappschwanz
v. - jäten, aussondern, säubern

2.
n. - Gewand

Ελληνική (Greek)
n. - αγριόχορτο, αγριοβότανο, ζιζάνιο
v. - βοτανίζω, ξεβοτανίζω, ξεχορταριάζω, σκαλίζω, καθαρίζω, ξεδιαλέγω, ξεσκαρτάρω

Italiano (Italian)
indumenti, vestiti da lutto, sarchiare, erbaccia, marijuana, smidollato

Português (Portuguese)
n. - erva daninha (f) (Bot.), charuto (m), roupa (f)
v. - capinar, extirpar

Русский (Russian)
сорняк, водоросль, табак, хилый человек, траурная повязка, что-л. нежелательное, полоть, очищать, избавляться

Español (Spanish)
1.
n. - mala hierba, maleza, marihuana
v. tr. - desherbar, escardar, desyerbar, desmalezar, sachar
v. intr. - escardar las malas hierbas

2.
n. - traje de luto, brazalete negro, crespón

Svenska (Swedish)
n. - ogräs, mager stackare, hästkrake, cigarr
v. - rensa (ogräs), rensa bort

中文（简体）(Chinese (Simplified))
野草, 杂草, 除...的草, 剔除, 除草

中文（繁體）(Chinese (Traditional))
1.
n. - 服喪用的黑紗

2.
n. - 雜草;野草
v. tr. - 給...除雜草
v. intr. - 除草

한국어 (Korean)
1.
n. - 잡초
v. tr. - ~에서 잡초를 뽑다, (무용물 등을) 치우다
v. intr. - 잡초를 뽑다, 방해꾼을 제거하다

2.
n. - 미망인의 상복, (모자 등에 다는) 상장

日本語 (Japanese)
n. - 雑草, たばこ, マリファナ, 弱々しい人, 喪服
v. - 雑草を抜く, 抜く

العربيه (Arabic)
‏(الاسم) عشبه ضارة تنبت بين الزرع النافع, نبته مائيه, شخص ضار, حيوان غير صالح للاستيلاد, ثوب (فعل) يزيل الاعشاب الضارة, يغربل, يتخلص من‏

עברית (Hebrew)
n. - ‮עשב רע, עשב שוטה, טבק, סיגריות, חשיש, אדם כחוש וחלש, סוס נחות‬
v. tr. - ‮ניכש עשבים, ייבל, סילק חלקים לא-רצויים, פטר חברה מחברים לא-רצויים‬
v. intr. - ‮שירש עשבים שוטים, ייבל‬
n. - ‮בגדי אבל של האלמנה‬

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Strictly speaking, a weed is simply a plant growing where it is not wanted. Weeds usually grow easily and spread, and they often interfere with the growth of more desirable plants. Weeds don't usually have nice features, like pretty flowers or tasty leaves, to make them more appealing to people or other animals. They are frequently hard to get rid of, growing back from the smallest bit left in the ground. People's opinions vary greatly about which plants are weeds. In the United States, for instance, most people consider dandelions weeds and spend a lot of time and effort trying to get rid of them. In France, however, they are grown as a crop, with their leaves used in salads and their roots processed to make a coffee-like drink.