Bright greeen plant in swampy area of pond. Leaves: long oval, sawtooth edge.
No interactions present.
Looks like Chamerian angustifolium
Wild Flower Society member
Oddly enough, that is the one Willowherb I would have thought that it does not look like! Certainly the wrong habitat for that, too, isn't it?
My Flickr photos...
Had a bit of a hunt for possibilities mentioned, but nothing quite right. The habitat confuses.
It's obvious I'll have to return to the site in June or thereabouts to see eventual height and what the flowers are like. Will post result.
Codlins-and-Cream, grows by fresh water and in ditches
Lat/Lng: 51.2953, 1.0671
OS grid ref: TR139595