Broad Buckler Fern

 In areas of Filnore Woods where the soil is slightly more acidic, you can find the triangular fronds of Broad Buckler Fern. 

The fronds are darker green than most ferns and the pinnae (like leaflets) are more spreading and widely spaced.

Looking closely you can see that the fern is tripinnate, i.e. the frond is divided into pinnae, which in turn are divided into pinnules and these in turn are divded into pinnulets.  This distiguishes Broad Buckler Fern from other common ferns.

Another clue is that the edges of the little pinnulets are usually curled back slightly, giving a convex look to the foliage.