Most nature fairies are the descendents of pre-Christian Gods and Goddesses, or of the spirits of streams, lakes and trees. Black Annis, a blue faced said to haunt the Dane Hills of Leicestershire, and Gentle Annie, who governs storms in the Scottish Lowlands may be descended from the Irish Goddess Danu (Anu), mother of Irelands Cave Fairies. Their Highland sister Cailleach Bheur or Blue Hag, seems to be the spirit of Winter. She freezes the ground by stricking it with her staff, and loses her power when spring comes.
Water spirits such as mermaids and mermen, river spirits and the spirits of rivers and lakes are the most common nature fairies. Tradition has turned some of them into ghosts. Peg O’Nell, a spirit of the river Ribble in Lancashire, is said to be the ghost of a drowned sevent girl; but like other river spirits, such as Peg Powler of the River Tees, she is supposed to demand a regular sacrifice of human life so it seems that the ghost story was grafted onto a much older legend. Even the spirit of the river Severn is traced back to a princess who was drowned in it.
In Wales, many stories survive of beautiful lake maidens who come ashore to marry young farmers, bringing herds of water cattle as a dowry. Usually, tabboo’s surround the marriage: the fairy wife must never be touched with iron, and she must never be struck. Most of these marriages end when the tabboo is accidently broken, and the lake maiden returns to the water taking her cattle with her.
Oak men are the most widespead tree spirits, and stories are told about them from the North of England to Somerset. Sometimes the trees themselves are the fairies ; sometimes the oak men are kind forest dwarfs who look after animals as brownies look after humans. They can be dangerous, espescially if the trees they live in are cut down. In Somerset, angry oak men are supposed to haunt any coppice from felled oaks, and it is thought wise by local country folk to avoid such a coppice after sunset.