Helenium flexuosum is a North American plant species in the daisy family known by the common name purple sneezeweed or southern sneezeweed. It is widespread across much of eastern and central United States and Canada, from Nova Scotia west to Ontario, Minnesota, and Kansas, south to Florida, Louisiana, and eastern Texas.

Helenium flexuosum is a perennial herb up to 100 cm (40 inches) tall. One plant can produce 80 or more flower heads in a branching array. Each head has up to 700 yellow or purple disc florets, sometimes with no ray florets, sometimes with 8-13 yellow, red, purple, or brown ray florets. The species grows in fields, ditches, and streambanks.