Spouse is desperate to know what this plant is.

http://i5.tinypic.com/167nktv.jpg

It grew in our garden last year as a volunteer, we left it because it had
such an interesting form. this grows right at the edge of a trodden earth
path, next to a concrete block

The flower is tiny, just a few stamens. The leaf stems have a bluish bloom
which doesn't show on the picture. This specimen is about three feet high
(1m).
It seeded last year and there have been several seedlings which we've had to
pull out to plant vegetables.

It would be nice to know.

Mary