Amaranthus retroflexus is a species of flowering plant in the Amaranthaceae family with several common names like Redroot Pigweed, Red-rooted Pigweed, Common Amaranth and Common Tumbleweed.
It is native to the tropical America, but is widespread as an introduced species on most continents in a great number of habitats. This is an erect, annual herb reaching a maximum height near 3 m.