Color, dark purple. Leaves, very deeply cut and the divisions very prickly. Flower-heads, large, on leafless peduncles, with a few bracts near the base, terminal. Stem, tall, 3 to 8 feet high, angled, woolly when young, smoother with age. Involucre, not prickly. July to October.
Common in swamps and wet woods, New England to Florida and westward.