Purple star thistle flowers
Steve Dewey, Utah State University, Bugwood.org
Purple Star Thistle
Purple starthistle is native to the Mediterranean region of southern Europe and northern Africa. It was first detected in the U.S. in the early 1900s.
Keywords: Asteraceae, biennial, cobwebby hairs, spiny flower bracts, prickles; Common names: red star thistle, St. Barnaby's thistle, golden starthistle
|Distribution Map||Distribution Source Image|
Purple star thistle distribution
Purple star thistle is a biennial that reproduces rapidly by seed. Its stems and leaves are covered with cobwebby hairs that are lost on the leaves of mature plants. The lower leaves are deeply divided, and upper leaves are narrow and undivided. Flower heads are ¾ to 1 in. long and lavender to deep purple. Flower bracts have rigid, straw-colored spines about 1 in. long, with 1 to 3 pairs of lateral prickles near their base. The plumeless seeds have no bristles and are straw-colored and mottled with dark brown. Purple star thistle infests rangeland, pastures, and roadsides and invades and displaces native vegetation. This plant is unpalatable, but may replace valuable forage species. It is very competitive and capable of adapting to diverse climatic and soil conditions.