Rowan

The rowan tree is also called a mountain ash. They can grow at very high altitudes and are found sometimes growing in odd positions, influenced by gravity and even weather. The bark of rowan trees are almost white. They produce blossoms that develope clusters of red edible sweet berries, high in vitamin C. These trees provide a food source for many animals including birds and butterflies. The ancient Celts nicknamed these trees fid na ndruad, which translates as "witch trees" and "wizards trees". Also the Celts believed that the rowan tree is otherworldly and was imported from a place called The Land of Promise.
Rowans and rowan berries were considered protection against evil spirits and the undead, so rowans were planted in graveyards. It was believed that a rowan stick was used to stir milk to stop it curdling. Rowan twigs are considered a good divining rod to locate water and treasure. People used rowan charms to prevent ailments such as rheumatism.
Unfortunately rowans get sick by diseases such as fire blight and silver leaf.
The ancient Norse and Germanic tribes used rowan wood to carve runic staves. The tiny stems of rowan berries are in star shapes that look like mini pentegrams. There are many pendants carved from rowans that can be found at online jewel and amulet shops.
In Finnish mythology, Rauni is a healer and goddess of the rowan tree. Rowans have been said to often grow next to megaliths, stone circles, fairy rings and dragon lines.