Unidentified growing object!

This plant reaches about 1m high, then in summer produces large spherical heads of flowers purple out side and lilac within, which have the scent of hyacinths. In its earlier phase it looks like a weed, and is extremely invasive. It spreads by runners and one plant could colonise the average suburban garden in a season! One problem which arises when gardening in a new country is that many of the weeds are different - for a long time I was not sure whether this was a weed or not! I have asked many local people if they recognise it without any luck, including my professional colleaues at the local market where I sell my plants, so I assume this is not a local weed or someone else would have it! The previous owner produced  water plants and was fond of the rare. It survives frosts of -20°

 Can any body help?

At the risk of scoring a hat-trick of mis-identifications, I suggest that you look at Polygonum bistorta and varieties thereof.

Also try Eupatorium, which is what the flowers look like, but the leaves are a bit big for that.

Many thanks to both for your suggestions, but neither fit unfortunately. The flowers are in sphericals heads rather than the spears of a polygonum - though it certainly shares that species habit of running everywhere. The leaves are much bigger than an eupatorium, the biggest being about 6"x9". Before flowering it really does look like a common weed of which I forget the name (it flowers like a dandelion) but later becomes more exotic. I suspect it may be an unusual bog plant, which would fit with the activities of the previous owner and also with the only local suggestion I have had.

@Dovefromabove - you made me laugh!

I struck lucky twice but I don't know this one.

I'm not following you around, I just like the ID threads. I like to learn the names of new plants.

You always remember the ones you get wrong!

Check out members of the Ginger family such as Cautleya, Hedychium and Roscoea.

Hi there , It could well be American Poke Weed but the flowers look a little bit different.

it is American Poke weed , It has big black berries in the autumn which give the whole plant an aura of poisionous menace, which would be correct !

http://www.plantdatabase.co.uk/Phytolacca_americana

( sorry couldn't find it on the GW database)

I think birds like the berries so that is how it could have appeared in your garden !

Hello le jardin anglais,

I agree with Allymc that it's phytolacca. It can be a bad weed, although it's pretty spectacular.

Emma

gardenersworld.com team