Invasive Plant/weed

A large pink flowering plant has grown up in my garden which has spread all over the garden.  I believe it is some sort of invasive weed ( I have checked the Himalayan Balsam but it does not seem the same).  I cut back the stems and flower the leaves are a diamond shape green leaf and the flower is a pink cluster, the base of the stem is bamboo like hard, brittle with a hollow centre.  The root has several tentacles and it spreads far and deep.  When dug up I found clustered around lots of white pod like shapes I have never seen before, almost like small bones in various sizes, when broken apart they had a hollow centre, they broke cleanly, when stamped on they had a sticky substance.  I have dug them all up but am terrified it will come back.  Can anyone tell me what it is and how I can get rid of it permanently.  The soil is quite dry with clay deep down and it seems to prefer the semi shade although it looks like it will grow anywhere.

Some images would help

  This is the flowering plant, it has large tentacle roots

Eileen2 wrote (see)

  This is the flowering plant, it has large tentacle roots

 

No picture??

Persicaria?

please see root and flower, have uploaded using format above not sure why you can't see it hopefully this will work.  I don't think this is Persicaria ezageeza

thank you

 The 1st pictures are the pods I found when digging them up, I have no idea what they are, and the 2nd picture is the base of the plant after I cut all the flowers and leaves off.

Looks a bit like Valerian to me.  I do have it in my garden but I have to keep it under control.  The roots do get big.  Some in my front garden had grown so thick that when I pulled it up it lifted up some of the tarmac pavement !!

Don't know if anyone else has any ideas but that is what I think it is.

Valerian; just dig it up each time it re-appears. Once I realised how invasive it is (and I don't like pink; there is a white version I have seen in one or two gardens in Cambridgeshire) I decided to eliminate it and it only took about three seasons. I still get the odd one popping up; it seems to like growing in gravel or very poor soil, but I just pull it out as one would with any unwanted plant. I believe the Romans used it to aid sleep.

Yep, Valerian, Centranthus ruber, I think.   Spreads mostly by seed, so try to get all the flowers off before it sets seed.   Not too difficult to control  i don't think - just keep at it!

thank you all so much, yes it seems it is garden Valerian, which has been allowed to get out of control.  It seems some varieties were used as some form of sedative. A great relief to know it is not something more noxious