This is a common plant in the south west of England and especially so in many places in Dorset. The hart's-tongue fern (Phyllitis scolopendrium) can be abundant where the environment is suitable.
It can be food in woods, especially woodland on hill sides, hedgerows, among rocks, on walls, on the sides of ditches, even inside water wells. In short, it likes warm, darkish, damp places.
The classic ferns have rather complex leaves but hart's-tongue has a smooth, shiny, undivided leaf in this familiar 'deer's tongue' shape which is so unique and enables it to be easily identified.
Hart's-tongue is, in fact, a 'spleenwort' which are a sub-family of the fern group. The spores are released from little brown 'pockets' that form on the back of the leaf. The Hart's-tongue is in leaf all year round but produces new ones each spring.