Canna indica ,also known as Indian shot , African arrowroot , edible canna , purple arrowroot , Sierra Leone arrowroot , is a plant species in the family Cannaceae . It is native to much of South America, Central America , the West Indies , Mexico , and the southeastern United States . The seeds aresmall, globular, black pellets, hard and dense enough to sink in water. They resemble shotgun pellets giving rise to the plant’s common name of Indian shot. According to the BBC “The story goes that during the Indian Mutiny of the 19th century, soldiers used the seeds of a Canna indica when they ran out of bullets.The seeds are hard enough to shoot through wood and still survive and later germinate. Canna indica is a perennial growing to between 0.5 m and 2.5 m, depending on the variety. It is hardy to zone 10 and is frost tender. The flowers are hermaphrodite . Canna indica sps. can be used for the treatment of industrial waste waters through constructed wetlands. It is effective for the removal of high organic load, color and chlorinated organic compounds from paper mill wastewater.