Any plant growing where it is not wanted. Many weeds are adapted to exploit disturbed areas of land and, unless measures are taken to prevent it, weeds are the first plants to establish themselves on cleared patches of ground. Many weeds are annual plants that produce large quantities of seed and often pass through several generations in a single year. An example of such a weed is shepherd's purse (Capsella bursa-pastoris). Weeds, especially those closely related to crop plants, may also harbour various pests and diseases. For example, the roots of the black nightshade (Solarium nigrum) are often infected by the potato cyst eelworm. See also rogue. |
