By Adelafw
United Kingdom 
How can I get rid of Rudbeckia laciniata which is apparently the name of the tall yellow daisy-like flowers that are rampant in my garden from late summer. It took a while to find the name but apparently it is difficult to eradicate if it likes you soil. I am constantly diffing out the little plantlets, but they seem to like twining themselves around other things I do want to keep.
13 Jun, 2013
Answers
Agree with the above
13 Jun, 2013
Thank you Anchorman and Buddlejagar. It could be Helianthus Monarch, but will take photos of the ones I kept in a pot, before they seed, and will send, - probably next month... for further comment!
14 Jun, 2013
There are other very vigorous helianthus.
I bought "lemon Queen" last summer. This spring I saw what I thought was about 100 seedlings around the original plant. To my amazement i later found they were all runners attached to the original plant. I've hoed lots off but they keep on coming
It's lovely but not for the lazy gardener!
Here it is
http://www.flickr.com/photos/31559373@N00/7858839122/
14 Jun, 2013
that is it..... and I now hate it like poison.
15 Jun, 2013
Rudbeckias are usually quite well behaved and the really big plants are not quite hardy enough to become a nuisance, many growing as annuals. R. lacinata isn't that vigorous and can be identified by the leaves that are heavily incised.
It is more likely to be a perennial and vigorous Helianthus such as The Monarch. Just like with mint you will have to hunt out all the creeping rhizomes just under the soil surface.
13 Jun, 2013