2007 Schools Wikipedia Selection. Related subjects: Plants

A common weed flower
A common weed flower

The notion of "weed" is almost entirely in the eye of the beholder. A weed in one situation might be a wildflower in another. For example, dandelions are widely viewed as weeds, but some consider them attractive flowers. Some weeds are edible, and their leaves and roots may be utilized for food or herbal medicine. It is typically necessary for a plant to grow easily and spread persistently to be considered a weed, because plants which need to be carefully nurtured are easily removed.

Weed control

In order to reduce weed growth, many weed control strategies have been developed. The most basic is ploughing, which cuts the roots of annual weeds. Today, chemical weed killers known as herbicides are widely used. Modern herbicides such as glyphosate are designed to leave no harmful residue in the soil, although the surfactants can be detrimental to watercourses. But these often have a bad effect on wildlife as farmers overuse it and it can get in water supply. In domestic gardens, methods of weed control include covering an area of ground with several layers of wet newspaper or a black plastic sheet for several weeks. In the case of using wet newspaper, the multiple layers prevent light from reaching all plants beneath, which kills them. Saturating the newspaper with water daily speeds the decomposition of the dead plants. Any weed seeds that start to sprout because of the water will also be deprived of sunlight, be killed, and decompose. After several weeks, all germinating weed seeds present in the ground should be dead. Then the newspaper can be removed and the ground can be planted. The decomposed plants will help fertilize the plants or seeds planted later. In the case of using the black plastic sheet, the greenhouse effect is used to kill the plants beneath the sheet. A 5-10 cm layer of wood chip mulch on the ground will also prevent most weeds from sprouting. Also, gravel can be spread over the ground as an inorganic mulch.

In agriculture, irrigation is sometimes used as a weed control measure such as in the case of paddy fields.

Some Examples

Here is a partial list of plants that are commonly considered weeds.

  • Broadleaf plantain
  • Burdock
  • Cannabis
  • Creeping Charlie
  • Dandelion
  • Kudzu
  • Leafy Spurge
  • Milk Thistle
  • Ragweed
  • Red sorrel
  • Sumac
  • Wild Carrot
  • Winter Cress

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