I've been trying to get rid of this for years and I suspect it is either a Campanula or Adenophora. I'd like to get a firmer identification to see if I can find more info to eradicate it.
This is what it looks like this spring. This is after trying to smother it with thick cardboard and a thick layer of bark mulch last spring and it's still back.
I don't have a photo of it in bloom because it's been years since I allowed it to bloom, for all the good it's done me.
I did a google images search and this is similar to what it looks like in bloom. The flowers on my plant are lighter purple and not as large. And not sure the leaves are as pointed as this, but looking at my own photo of the plant, I guess they are pretty pointed.
This post was edited by prairiemoon2 on Thu, Apr 24, 14 at 16:30
This looks like bellflower (campanula.)
Here is a link that might be useful: Bellflower
It's hard to distinguish Adenophora from Campanula--I'm including a link to Rob's Plants which explains how. Both Ladybells (Adenophora lilifolia) and Campanula rapunculoides are extremely aggressive; the latter more so. Both are rhizomatus which explains your difficulty in ridding your garden of this bully. Based on your description I suspect you have C. rapunculoides.
Here is a link that might be useful: difference between Adenophora and Campanula
Thank you both for the help. So far I think I have the Campanula rapunculoides. It behaves the way it's been described and looks like it too. I guess if I want to be sure, I will have to allow one of them to bloom this year and try the test. Thanks, I knew there was some way to distinguish them but I couldn't remember. And thanks for the link, Seedmoney!
Well, I waited for the plant to bloom and it is in bloom now. I have not allowed it to bloom for awhile, trying to get rid of it, but I wanted to take apart a flower to get a definite identification of it.
From the information I found at the link above and similar sites on this subject, I did disect a blossom and has to be the Campanula rapunculoides. I also have seen it described as having blossoms on only one side of the stem and sure enough that's what I have.
Just for anyone's information that is having trouble with the same plant.
Sure looks like the creeping bellflower I have in my yard. I didn't even plant it! I've been trying to dig it out for years, it's even more tenacious than goutweed if you can believe. Horrible plant.
Did you remove the cardboard smother?
No, I didn't remove it, they grew up right through it once the cardboard started to breakdown. Sad but true.
Ugh, and wow. Smothering with cardboard will kill most, but some plants can do that. TY for the info, I had no idea that plant was so tough to smother. Sounds like a much longer time is needed. Putting a new layer down when the old started to wear thin might have helped it work, IDK. I do usually use thick, corrugated cardboard from like moving boxes, not the thin kind from a cereal type box, overlapping at the seams by at least 9-12".
A tarp might work, if you can put enough mulch or chipped wood (or OM of any type) to make sure no light is getting through, physically push on plants trying to grow up, and to help prevent the wind from moving it. I'd leave it alone for a year.
The next step is sheet metal. Nothing has been able to break through that, that I've tried it on, but overlapping the seams is much more tricky. Good luck getting rid of it, by whatever method you might want to try.