Acmella is a genus of plants in the aster family, Asteraceae, described as a genus in 1807. It is native to the Americas and has been introduced to Asia, Africa, the Pacific islands, and Australia. One familiar species is Acmella oleracea, which has been widely cultivated for centuries. It is used for food and medicine, and as an insecticide and an ornamental plant. Its common use as an herbal remedy for toothache and oral infections earned it the nickname toothache plant.