[Bernard]

I wonder if anyone can identify this 'weed' which has just appeared in my garden? Usually I can at least guess the genus of a flower but this has baffled me. The leaf is very distinctive and it has a branching habit which is less obvious in the photo.

[Goosegirl]

Um - nothing sprung to mind so am having a look through my Hessayon flower book. Could it be a variety of Nicotiana (can't see its leaves in the book pic though) and can't be Epimedium as it's too late in the season. Just to help us out, how high is it and what soil and light conditions are it growing in? If you have no luck on here, try contacting the RHS.

[mumofstig]

The leaves look like honesty, but that's got 4 petals not 5 

[Annen]

Could it be buckwheat?

[mumofstig]

It very much looks like it  Well done!

[Bernard]

Thanks for the help. I think you are right about buckwheat, having googled for images - none of them is entirely clear but I think it's right.
It was growing under other plants, found it when I cleared them. Only a few inches high. maybe has come from bird feed.