Purple flower

Red star - thistle Also known as caltrops, purple knapweed.

This an annual or Biennial plant growing erect to a maximum height of one to 1.3 metres. The stems are hairless and grooved. It sometimes takes the shape of a mound, and it is finely to densely hairy to spiny. The leaves are dotted with resin glands. The lowermost may reach a length of 20 centimeters and are deeply cut into lobes.