Hill's Thistle

 ...To the untrained eye, the plant in these photographs may look a bit like Bull Thistle (Cirsium vulgare), but you can see at the bottom of the above photograph that the stem below the flowering head is not winged and spiny, as it would be in Bull Thistle.  In addition, this thistle would be dwarfed by Bull Thistle, as it grows to just over half a meter tall at the most. 

No, I didn't make the hour-plus drive to see a weed; I was visiting a known site for one of the rarest thistles in North America, a Great Lakes endemic, Hill's Thistle (Cirsium hillii).  I had planned my trip for early July because Hill's Thistle should have been in peak bloom, but as a result of the weird weather year that was 2012, all but one of the plants in the small population had finished blooming, and the one that still was flowering was well past its peak.  Hill's thistle was first collected back in 1890 by Rev. E.J. Hill, not more than a few miles from the location where I saw it in 122 years later.

 http://handlensandbinoculars.blogspot.com/2013/01/kill-thistles-right.html