Palmer Amaranth (Amaranthus palmeri) is an annual plant native to the arid southwestern U.S. and northwestern Mexico. Palmer Amaranth was accidentally introduced to the southeastern U.S. Its life cycle is adapted to desert conditions, germinating and growing quickly to produce many seeds when moisture is available. One female plant can produce more than 250,00 seeds. It often invades areas of disturbance and native prairies, outcompeting native species.
Palmer Amaranth commonly reaches heights of 6-8 feet, with alternative leaves that grow symmetrically around the stem. Some leaves have a milky v-shaped mark. Female plants have tall seed head spikes that grow up to three feet long.
Palmer Amaranth is hard to control once it is established, as it has developed resistance to many herbicides. Prevention is the best management approach, when small populations can be identified early and hand-pulled. Spread can also be prevented by always cleaning clothing, vehicles, and equipment after leaving infested areas. Large populations can be controlled by a combination of mowing and herbicide treatment, or prescribed burn.