Friday I tackled on of those spots, the back corner where my yard meets my brother's and the house on the other side (I'm on a corner), back behind an overgrown boxwood and around some nearly senescent azaleas that I worked on earlier this year, clearing out deadwood and cutting things back. (This is the corner with the birdhouse, thus my birding post earlier.) Catbriar seems to like azaleas--or it likes any shrub where it can grow undisturbed under the roots, sending up briar-filled strands through the branches where I see them taunting me. There's one in the azalea out my breakfast-counter window now--I haven't done anything about it, knowing that just clipping it off is futile.
Friday, though, I went back in that corner where about 5 shoots were sticking up, and started digging. You have to track the roots back to one or more tubers, then dig those out--otherwise the catbriar still has food to send up many more briars. And tracking the root of the catbriar means digging in and around all the other roots in the area--I was most of the way under one azalea at one point, with a hole more than a foot deep, working with a trowel to dig this stuff out. Oak tree roots provided further cover. When I quit, this was my collection of roots. I didn't get it all--there's always the end that snaps when you tug a little, and then can't be found to continue the dig. I'm sure this is an evolutionary strategy it's developed against the gardener-as-predator.