[Adam Cheeseman]

I'd go along with Paul on this one. I have Marsh Woundwort growing in my garden and along the Thames near me. It is every bit as dark as the plant in the picture. Also Marsh leaves are obviously pointed as in this picture whereas Hedge leaves tend to be more rounded. Assuming this pic was taken in a wild place, I personally haven't seen Hedge Woundwort growing alongside Yellow Loosestrife.

Cheers,

Adam