Resembles C. undulatum, but I'm not familiar with other thistles in this area.
San Diego County, California, US
Abundant in a disturbed area. Originally thought it was C. discolor, but the upper stem (cauline) leaves on the dead plant are not as dissected as C. discolor leaves usually are. Most likely C. altissimum.
Cirsium is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more accurately known as Plume thistles. These differ from other thistle genera (Carduus, Silybum and Onopordum) in having feathered hairs to their achenes. The other genera have a pappus of simple unbranched hair.