I will modify my complaints about the (lack of) effect of RoundUp on creeping bellflower. It depends on how well established the plant is. One thoroughly drenched plant in a crack in the sidewalk is now looking dead as a doornail, and a good thing, too, since I am not going to take a sledgehammer to the path to the garage in order to dig out that plant. I expect it was a relatively recent sprout from seed. Various other patches are still flourishing like the deadly sins, looking green, bushy, and smug. Those, I bet, have huge deep roots that are going to be a bugger to dig up.
I have now dug out the patch of bellflower by the clematis. I delayed tackling that because I was reluctant to risk killing the clematis (one purple, one red-violet, both glorious). That was where I started carefully painting the poison onto the leaves of the demon plants. I think I spritzed them twice after that, and they still looked . . . not healthy, but certainly not dead. When I dug, I found that while there were some new, plump, happy roots that had clearly sprouted recently, I was also able to dig out a great quantity of large old roots, many of which seemed rather sickly compared to the roots I dug out of a different bed last year. So the herbicide has some effect, and maybe if I just kept spraying it would eventually do the job. But I don’t trust bellflower not to come back, or develop a resistance, or something. So the digging continues. However, I feel somewhat more optimistic about the possibility that I really will be able to get rid of Campanula rapunculoides. Eventually.
I do hope I haven’t killed the clematis. I tried not to hurt it, but a lot of its roots were exposed for awhile, and I broke some. When I finished, I reburied its roots and gave it a drink. If it survives my excavations, I’m sure it will be happier not to be competing for resources with the invading Siberian.