Campanula or not ?

Hi,

Bought this Campanula Glomerata Superba earlier this year and it has put up these nice flowering stems.
However looking down at the base of the plant, new leaf growth has now also appeared but it does seem to have somewhat different leaves to those on the flowering stems.

Wondered if it was one and the same plant or if its a cuckoo plant ?

 

Cuckoo plant!

 

Looks a bit like dock to me.

 

Going to be a bit of a devil to remove as its shoots are right next to the Campanula stems.

Could try painting some weedkiller onto its leaves, but not sure when it gets down into its roots it would also affect the Campanula with them being so close together ?

Perhaps removing most of its leaves manually to slow down its growth until we can empty the pot and untangle their roots in the Autumn ?

 

As a veteran of weedy pots, just keep removing any leaves which pop up. Once the Campanula finishes flowering you could tip it out and separate the intruder. Having said that, it may come up easier than you think so always worth giving it a tug and a wiggle. The light compost nurseries use often means weeds aren’t that securely rooted especially when young before they’ve got entangled

 

Definitely an interloper, which is quite common in bought plants at this time of year.
If that was mine, I'd empty the pot and separate the plants, and then repot the Campanula, but I appreciate you may not want to do that.
The alternative is to do as others have said about removing the foliage each time it appears.