As with many other thistles in America, carduus nutans
is an introduced species, native to Asia and Europe, now a troublesome weed across most of the US. The flower head is formed of numerous narrow disc florets, rich purple in color, and reaching a diameter of 2 inches. Below are several rings of particularly large and spiny bracts, initially green then becoming purple with maturity, when the flower has a symmetric spherical shape, and tends to droop downwards. Flowers are supported by a thick, rigid, lightly hairy stem that branches readily and has the familiar prickly leaves along the lower half, especially around the base. In favorable locations the plant may have as many as 50 flower heads.