It spreads by seeds, often forming nearly impenetrable stands. It can grow under a wide range of environmental conditions. Leaves are up to 10 inches long, dark green with a light green midrib , spiny, and deeply lobed . Solitary, lightly spiny, and nodding flower heads develop at the stem tips in midsummer and grow to a diameter of 1 to 3 inches.
Blossoms are deep rose to violet or sometimes white in color.
Herbicides offer effective control.