Plant ID's Please.... again :)

This is a rather interesting problem...scary if this hybrid Fallopia x bohemica can grow from seed as well as rhizomes. (quote link below...."Like its parents, Fallopia ×bohemica is gynodioecious. J. P. Bailey et al. (1996) reported it to be partially to fully fertile.")

I freely admit that I am well out of my depth on this.

I can only refer you to reliable accurate botanical sources such as the one below.
The main vein on fresh leaves seems to give clues...( provided you know what the heck you are looking at!)

http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250060601

Your details don't show where you live.
But in every county there are experts that regularly go out and id and record the flora in a given patch. Thus they monitor any changes...some plants will disappearing over time and new invasive sp will move in.

http://bsbi.org/local-botany

I suggest that you contact your local expert.
They should be able to look at the minute details of your plant to establish exacty what it is.
This plant might not have been recorded in your area.
It could be very important to id it accurately.... incase higher authorities wish to eradicate it before it spreads further.

 

Thanks very much @Silver surfer, most informative as always.

The local residents have reported it to the council but sweet FA has been done over it.

Looks like I'm gonna have to drop a line to the EA as this could turn into a disaster if birds eat the seeds and spread them locally or further.

It is in an area of tough marsh grass but literally 10ft from a heavily used public walkway consisting of sand and soil, so the rhizome transfer is entirely possible if it creeps in that direction.

Japweed is bad enough but this variant is a different beast and needs nuking. The council don't care but hopefully the Environment Agency will, with enough evidence provided.

 

If you're on Twitter, you could try tweeting @BSBIbotany with a photo.

 

I really feel an expert needs to see this for themselves.
Especially when you need to examine the leaf vein.

Quote...."abaxial face minutely dotted, glaucous, with hairs along veins unicellular or appearing so, obscure, shorter than 0.1 mm, tips acute, adaxial face glabrous. "

I don't think the pics are good enough to see the above.

 

Giant hogweed is in a completely different family to knotweeds so no chance of hybridisation. I think you mean giant knotweed, another East Asian introduction

 

Mowerman, may I suggest you also consider treating Himalayan Balsam?