There is a plant called Ludwigia peruviana. It is a perennial wetland shrub which is prohibited in Qld. S.A. & N.S.W. I'm not sure this is it but perhaps you could Google up some pics and decide for yourself.
Cheers,
Dee.

I should say that Dee is right with the identification...what a pity, its a rather pretty weed. What a magnificent photo beautifully presented!

Don't know either, I'm afraid but it's a great piccie!
but then, I'd expect no less from Barbarah! :)))

Yes it is a pretty weed, but dosn't that always happen.
And another great pic from Barbara as usual 10/10
Cheers..MM.

Wouldn't usually look at a request for an ID as I don't think I could be much help but since it was from Barbara I had to see. Gorgeous photograph as always.

Thanks Dee & everyone else.
Such a pity a delicate looking flower such as this, is such a pain in the environment.