Should I be afraid?.

Esspee

It grows on a single stem up to six feet tall with no basal rosette and sends out runners replicating itself.  I am pretty relaxed about what I allow to grow, usually leavIng visitors until I can assess whether or not I like the effect, and this one is attractive enough but I am rather wary that it might take over.  I would be happy if it clumped up towards the back of the border (I like the yellow flowers) but the runners all head toward the front dwarfing smaller plants.  It is while pulling up these wanderers that I have become concerned about the running underground stems.

 

Should I remove them before they set seed?

Thanks for your help.

 

Esspee

 Close up (photo seems a bit distorted - sorry)

Fairygirl

Looks like yellow Loosestrife. I don't care for it personally as it can take over a bit and the yellow's too brash for me,  but I know others like it. It's good for awkward spots and pondsides. 

punkdoc

Agree Fg, a right thug, and so is the plant!

Fairygirl

We had it beside the pond at my last house - I allowed it to stay as it was one of  the few things the b****y rabbits didn't eat  

It will gradually spread and outdo other plants Esspee, so if you like the other plants you have - might be best to remove it!

pansyface

It's the roots that you have to watch, not the seeds.

Fairygirl

They're sneaky pansyface!  I just kept chopping them to the ankles every time I walked past if they were becoming a nuisance, but they can be very  difficult if they pop up right in the middle of something delicate.

pansyface

At least they are bright pink, so you know what to look for.