Donated plant, identification request

Grenage

My mother in law gave us this plant in winter, as she's moved house.  My other half liked it, but neither of them know what it is - it only recently came into life.

It could be Japanese knotweed for all I know, so I'd like to identify it before it hits the garden.

Any help would be appreciated.

punkdoc

It is a Persicaria, but not JKW.
I am not sure which one.

AnniD

 I'd say it was a Persicaria. Edited to add, Sorry @punkdoc, crossed with your post. 

Grenage

Ah thank you.  Looking at the pictures online, I think I recall similar flowers to Persicaria amplexicaulis in her garden.  Perhaps that was it!

josusa47

At first glance, I thought it WAS Japanese knotweed!

Busy-Lizzie

I have a persicaria with leaves like that, quite a thug in my garden, it too was a present, but it's not JKW.

Lyn

I have one as well, a present from Nutcutlet. It behaves very well. I love the flowers and have transplanted several pieces around the garden. 

Dovefromabove

I have a similar one, Persicaria 'Darjeeling Red' ... it's leaves turn red in the autumn ... a gorgeous thing.  A present from a GW friend 

Lyn

Did it come from the same garden as mine did Dove? 

Grenage

I have placed it in an area that should be easily contained! Thanks for your help in identification.

Dovefromabove

Lyn said:

Did it come from the same garden as mine did Dove? 

Not this one ... although there are many plants here that did