A fern with the wrong name

Spent a day in the New Forest looking for a few ferns that I've not seen before. The first target was Beech Fern, so that was going to be in an area of mature Beech wood right? Err, wrong, the grid reference took me to an area of Alder carr; about as unlike a Beech wood as a wood can be. Fortunately the book put my mind at rest - 'not especially, or in some districts at all, associated with beeches'. It's amazing how many species have inappropriate names.

I must have walked past these lots of times as they are within my Wood Warbler study area. You can be blind when you're focussing on other things.

Next stop was for Southern Polypody. I had details for a couple of specific trees on which this species was supposed to be growing but at the first site I wasn't entirely convinced by the identity of the ferns that I found. Those at the second site seemed more convincing.

I diverted to Hatchet Pond where I failed to find a couple of plants, probably too late in the year for them. I did find a live freshwater mussel which would be new if I could identify it! Unfortunately, with the limited information I have, I cannot be sure what it is.

Back to ferns for the last species of the day; Marsh Fern. In pre-GPS days I wouldn't have stood a chance of finding it and I do wonder how the first person ever did but the habitat (birch woodland on fairly wet ground) is not rare in the New Forest so it is equally a mystery as to why the species isn't more common than it is.