Amaranthus retroflexus is a species of flowering plant in the family Amaranthaceae with several common names, including red-root amaranth, redroot pigweed, red-rooted pigweed, common amaranth, pigweed amaranth, and common tumbleweed. Amaranthus retroflexus, true to one of its common names, forms a tumbleweed.[3] It is native to the tropical Americas, 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 (9.8 ft). The leaves are nearly 15 cm (5.9 in) long on large individuals, the ones higher on the stem having a lance shape and those lower on the plant diamond or oval in shape. The plant is monoecious, with individuals bearing both male and female flowers. The inflorescence is a large, dense cluster of flowers interspersed with spiny green bracts. The fruit is a capsule less than 2 mm (0.079 in) long[4] with a "lid" which opens to reveal a tiny black seed. Another of A. retroflexus's common names is "pigweed" because it grows where hogs are pasture-fed. (Wikipedia)