Anne,
I agree with Tmaritta, Cathy and Max, it certainly has the look of Riihimäen.
There is (I think) the same olive green one
here, pictured with another Riihimäen vase of the same colour; this second vase is, I think, definitely Riihimäen - it normally has the 'Polar Bear' stamp. The colours look identical.
robbo