Oh no!!! Not you too!!! You poor soul. Wait! I see that it is growing in a pot- was that by intention? If so, how could you do this to yourself? :)-----By the way, welcome to GOY. All kidding aside, this is a very invasive weed that goes by the name of Smartweed where I come from. In the UK it goes by the name of Knotweed. In the last month I have pulled out of my garden and filled seven garbage bags of this plant. Now if you know of anyone who you really dislike, give it to them as a potted patio plant gift.

Yep! Its a weed, get rid of it before it drops it's seeds.
Welcome to Goy, so many helpful people on here :o)))

Is that the same one you get in your garden Loosestrife? We get loads of those, but I've never seen one as big as this before, I whip 'em out when they're small, but I thought yours was a different variety... not that it matters really, they're all invasive pests.

The same one Bambo and they get that big. Each individual plant can produce on average 19,000 seeds. There is no stopping it dead in its tracks and never to return once it gets into the garden.

Why do you guys call it Smartweed?

It was considered a herbal remedy for many ailments and one of the methods of ingesting this plant would be to chew on it thereby extracting it's juices. When chewed, the plant gives a burning sensation to the inside of the mouth, it hurts or using a synonym of hurt would be to say that it SMARTS, hence the name of Smartweed. The origination of the name had no connection to intelligence though it turns anyone trying to eradicate this weed into a blithering idiot.

Ah, that kind of smart (sting), not clever smart then.

Was it purchased as Persicaria? - lots of varieties with different habits - not all of which will run riot in West Yorkshire (check out Beth Chatto Garden or Rowden Gardens for some of the commercial varieties - I'm looking at persicaria amplexicaulis alba for my little yard)

I have some big drifts of Persicaria at work and i love them...as do the bees.. I grow P. amplexicaulis 'Firetail'