Italian Thistle (Carduus pycnocephalus, Carduus tenuiflorus) 

• Blooms May to June
• Flowers are purplish to pinkish in cylindrical heads, either solitary or in clusters
• Grows 1 to 4 feet tall
• Stems have spiny wings
• Leaves deeply cut into 2 to 5 pairs of lobes, have white spots and undersurface slightly woolly

Top photo by Mitch Bixby
Bottom photo from "Weeds of the West" - Western Society of Weed Science, 1991