A weed is a plant that is considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals. Weeds can be 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. The concept of weeds 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.
Although the term "weed" has no botanical significance, 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. Some plants that are widely regarded as weeds are intentionally grown in gardens and other cultivated settings, and are sometimes called beneficial weeds. Similarly, volunteer plants from a previous crop are regarded as weeds when growing in a subsequent crop.
Weeds can interfere with a variety of human activities, and many methods have been developed to suppress or eliminate them. These methods vary with the nature of the weed itself, the means at hand for disposal, and the relation of the method to the environment. Some common methods include herbicides, mulching, and manual removal.
