Asked June 26, 2016, 12:25 AM EDT

The Denver Metro area in infested with thistles that have overtaken a lot of the empty lots and open spaces. They are tenacious, spreading like wildfire from the roots. The bloom which has pretty much just ended is purple. I suspect Canada thistles but would like an expert opinion. They grow really close together and are very stickey.

Jefferson County Colorado

1 Response

What you describe is probably Canada thistle, but without a photo or sample I can't be certain.