Weed - Revision history

Raffi at 19:45, 13 March 2010

2010-03-13T19:45:49Z

Raffi at 06:55, 28 March 2007

2007-03-28T06:55:19Z

New page

[[Image:Weedflower.JPG|thumb|200px|right|[[Dog violet]] (Viola conspersa), a common weed.]]

A '''weed''' in a general sense is a [[plant]], usually wild or feral, that is considered by the speaker to be a [[nuisance]] in a [[garden]], [[lawn]], or other [[agricultural]] development.

More specifically the term is often used to describe plants that grow and reproduce aggressively.<ref>ISBN 0-7167-1031-5 Janick, Jules. Horticultural science. San Francisco: W.H. Freeman, 1979. Page 308.</ref> Weeds may be unwanted because they are unsightly, or because they limit the growth of other plants by blocking light or using up [[nutrient]]s from the [[soil]]. They also can harbor and spread plant [[pathogen]]s that can infect and degrade the quality of [[crop]] or [[Horticulture|horticultural]] plants.

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, [[beneficial weed|many "weeds" are beneficial]], even in gardens or other cultivated-plant settings.

In its more specific use, weeds are naturally occurring plants, that due to their aggressive growth, are [[colonize]]rs and may damage plants and landscapes that are desirable to people. Weedy plants generally share similar [[adaptive]] speciation that gives them advantages and allows them to proliferate in disturbed environments such as agricultural fields or areas with disturbed soils like roadsides, construction sites and other areas that have had the soil and/or natural vegetative cover damaged.

These plants have naturally evolved to colonize disturbed environments. These naturally occurring environments include [[dune]]s and other windswept areas with shifting soils, [[alluvial]] flood plains, river banks and [[delta]]s, areas that are often burned plus others. The weedy nature of these species tends to give them an advantage over more desirable crop species because they tend to grow quickly and [[reproduce]] quickly, have heavy seed set with seeds that persist in the [[seed bank]] for many years or short lifespans with multiple generations in the same growing season. Perennial weeds often have underground stems that spread out under the soil surface. A theory has been developed to express the interrelationship of these plants with the environment, called [[R/K_selection_theory|r/K selection theory]]. [[Invasive species]] are also considered weeds.

Weeds and human civilization have a long history. Since human agricultural practices often [[mimic]] the natural environments that weedy species have evolved in, they are adapted to grow and proliferate in fields. Often their seeds are collected and transported with crops after the harvesting of [[grain]]s, so that many of these weed species have moved out of their natural geographic locations and have spread around the world with humans to become [[cosmopolitan]] species.

Many modern species of domesticated [[flower]] actually originated as weeds in cultivated fields. The most attractive weeds were the ones least likely to be disturbed by the farmers, and so this selection process produced, over thousands of years, increasingly attractive plants, until they finally attracted conscious domestication.

Not all weeds have the same ability to damage crops and horticultural plants; some have been classified as [[noxious weeds]] because if left unchecked, they often dominate the environment where crop plants are to be grown, often because they are foreign species mistakenly or accidentally imported into a region where they have no natural enemies. Most noxious weeds in North America are not native to North America but have come from other areas of the world. With the conversion of land to agriculture and distribution of food crops from other parts of the world, these weeds have ideal areas for growth and reproduction, with humans being the [[vector]] of transpor
t and the producer of disturbed environments for their growth.

Some weeds, such as the [[dandelion]], are edible, and their leaves and roots may be used for [[food]] or [[herbal medicine]]. So-called "[[beneficial weed]]s" may have other beneficial effects, such as drawing away the attacks of crop-destroying insects. Indeed, dandelions are one of several types which break up hardpan in overly cultivated fields, helping crops grow deeper root systems.

==Examples==
Some plants that are commonly considered weeds include:
*[[Broadleaf plantain]]
*[[Burdock]]
*[[Creeping Charlie]]
*[[Dandelion]]
*[[Kudzu]]
*[[Leafy spurge]]
*[[Milk thistle]]
*[[Ragweed]]
*[[Red sorrel]]
*[[Sumac]]
*[[Wild carrot]]

==See also==
*[[Herbicide]]
*[[List of beneficial weeds]]
*[[Pesticide]]
*[[Susun Weed]]
*[[Tad Weed]]
*[[Weed control]]
*[[Weedy species]]

==References==
<references/>

==External links==
*[http://www.ppws.vt.edu/weedindex.htm Weed Identification Guide] from [[Virginia Tech]] (Southeastern United States)

*[http://www.cwss-scm.ca/Weeds/index.html Common weeds of the northern United States and Canada] from Canadian Weed Science Society

[[Category:Botany]]
[[Category:Agriculture]]
[[Category:Lawn weeds|*]]
[[Category:Lawn care]]

@@ Line 11: / Line 11: @@
 These plants have naturally evolved to colonize disturbed environments. These naturally occurring environments include [[dune]]s and other windswept areas with shifting soils, [[alluvial]] flood plains, river banks and [[delta]]s, areas that are often burned plus others. The weedy nature of these species tends to give them an advantage over more desirable crop species because they tend to grow quickly and [[reproduce]] quickly, have heavy seed set with seeds that persist in the [[seed bank]] for many years or short lifespans with multiple generations in the same growing season. Perennial weeds often have underground stems that spread out under the soil surface. A theory has been developed to express the interrelationship of these plants with the environment, called [[R/K_selection_theory|r/K selection theory]].  [[Invasive species]] are also considered weeds.
-Weeds and human civilization have a long history. Since human agricultural practices often [[mimic]] the natural environments that weedy species have evolved in, they are adapted to grow and proliferate in fields.  Often their seeds are collected and transported with crops after the harvesting of [[grain]]s, so that many of these weed species have moved out of their natural geographic locations and have spread around the world with humans to become [[cosmopolitan]] species.
+Weeds classified as [[noxious weeds]], when left unchecked, often dominate the environment where crop plants are to be grown, often because they are foreign species mistakenly or accidentally imported into a region where they have no natural enemies.
-Many modern species of domesticated [[flower]] actually originated as weeds in cultivated fields. The most attractive weeds were the ones least likely to be disturbed by the farmers, and so this selection process produced, over thousands of years, increasingly attractive plants, until they finally attracted conscious domestication.
+Some weeds, such as the [[dandelion]], are edible, and their leaves and roots may be used for [[food]] or [[herbal medicine]]. So-called "[[beneficial weed]]s" may have other beneficial effects, such as drawing away the attacks of crop-destroying insects. Indeed, dandelions are one of several types which break up hardpan in overly cultivated fields, helping crops grow deeper root systems.
-Not all weeds have the same ability to damage crops and horticultural plants; some have been classified as [[noxious weeds]] because if left unchecked, they often dominate the environment where crop plants are to be grown, often because they are foreign species mistakenly or accidentally imported into a region where they have no natural enemies.  Most noxious weeds in North America are not native to North America but have come from other areas of the world. With the conversion of land to agriculture and distribution of food crops from other parts of the world, these weeds have ideal areas for growth and reproduction, with humans being the [[vector]] of transpor
+It is best to get them when the soil is moist, and temperatures are low.  There are many strategies, and tools to help.
-Some weeds, such as the [[dandelion]], are edible, and their leaves and roots may be used for [[food]] or [[herbal medicine]]. So-called "[[beneficial weed]]s" may have other beneficial effects, such as drawing away the attacks of crop-destroying insects. Indeed, dandelions are one of several types which break up hardpan in overly cultivated fields, helping crops grow deeper root systems.
+===Lawns===
 ==Examples==
@@ Line 50: / Line 68: @@
 ==External links==
 *[http://www.ppws.vt.edu/weedindex.htm Weed Identification Guide] from [[Virginia Tech]] (Southeastern United States)
 *[http://www.cwss-scm.ca/Weeds/index.html Common weeds of the northern United States and Canada] from Canadian Weed Science Society