Pigweed

Any of several coarse annual plants of cosmopolitan distribution that are often troublesome weeds. Several of them belong to the genus Amaranthus, of the family Amaranthaceae. Prostrate pigweed, or mat amaranth (A. graecizans), grows along the ground surface with stems rising at the tips; spiny pigweed, or spiny amaranth (A. spinosus), has spines at the base of the leafstalks;