Allelopathic plants.: 6.: Amaranthus spp.

Members of the genus Amaranthus are widely distributed in tropical, subtropical and temperate regions of the world. Only few Amaranthus spp. are grown as grain crop or as leafy vegetable. It is one of the many under utilized food crops. Few are serious weeds in crops, pastures and roadsides competing with other weeds and grasses. It is the most widely distributed weed genus world over in the arable crops. A. retroflexus, A. spinosus and A. viridis are world's worst weeds. A. retroflexus and A. viridis have exhibited resistance to the widely used herbicides, the triazines. The weedy species are allelopathic and inhibits the crop growth. Several allelochemicals have been characterized from the plants of A. spinosus.