Perennial sunflower species are not as common in garden use due to their tendency to spread rapidly and become invasive. The whorled sunflower, Helianthus verticillatus, was listed as an endangered species in 2014 when the U.S. Fish and Wildlife Service issued a final rule protecting it under the Endangered Species Act. The primary threats are industrial forestry and pine plantations in Alabama, Georgia, and Tennessee. They grow to 1.8 m and are primarily found in woodlands, adjacent to creeks and moist, prairie-like areas. Sunflowers originate in the Americas. They were first domesticated in what is now Mexico and the Southern United States. Domestic sunflower seeds have been found in Mexico, dating to 2100 BC. Native American people grew sunflowers as a crop from Mexico to Southern Canada. In the 16th century the first crop breeds were brought from America to Europe by explorers.
