Oak woodland in Borrowdale, Cumbria UK, photographed in March. The picture shows a characteristic view of a sloping section of damp, so-called Atlantic oak woodland at the Western edge of Europe. Large boulders of volcanic origin are coated with a variety of mosses, with the tree flora ( seen in the background) consisting of sessile oak (Quercus petraea ), ash ( Fraxinus excelsior ) and hazel ( Corylus avellana ). Atlantic oak woodland is classified as a habitiat of high importance in the European Union's Habitat Directive. This reflects the high species diversity in such woodlands, notably amongst lower plant groups, including mosses and ferns, as well as lichens