Achyranthes aspera (common names: chaff-flower,^[1] prickly chaff flower,^[2] devil’s horsewhip,^[3] Sanskrit: अपामार्ग apāmārga) is a species of plant in the family Amaranthaceae. It is distributed throughout the tropical world.^[4] It can be found in many places growing as an introduced species and a common weed.^[5] It is an invasive species in some areas, including many Pacific Islands environments.^[6]