ID and othe queries please

Firstly the plant I'm showing spreads rapidly and grows from any root left in the ground. It's very nice though when it flowers but it's very difficult to control.
Here's one that has come up and ready to flower.



Here is it's flower taken last year.



Any ideas what it is?
.

 

Acer problem. I've put it in a large pot in ericasious (sic) compost but the leaves are withering. Do Acers suffer from pollution or is it somthing else? I have another Acer that has gree/red leaves that has gone the same way.

 

For Petes sake i'm raising some of these in the greenhouse! I've been trying to get rid of these from my garden for 20 year!!!

 

I thought that they were half-hardy and hard to keep, obviously not lol

Thanks Marley.

 

The one's in the greenhouse are Ligtu Hybrids, just wondering whether they will go the same way? ie, grow out of control

 

I can't grow Acers either Robajobs. They don't like my soil (sandy) and don't like the sea air. I tried again earlier this year by planting one in a pot, within three weeks it was leafless and looked very sick. I won't be bothering again.

 

It's in the right compost in a large enough pot and only watered with rainwater. I've found out by searching the net it my not like sun. not that we've had a lot! My other acer is three years old and shows the same condition. I'm gonna put them where the sun don't shine lol

 

And definitely protect them from wind.

 

Will do but isn't it windy in Japan?