Weed

Weed, any plant that is useless or destructive, or that grows where it is not desired. A plant that grows abundantly in an area where it is not wanted crowds out and takes nutrition, water, and space away from plants that are being cultivated. Injurious plants may be considered weeds. For example, poison ivy and oak can produce a skin rash; goldenrod and ragweed can cause hay fever; and thistles have prickly leaves that can hurt skin. Herbicides and soil cultivation are among methods developed to control the proliferation of weeds.