Mythology
Although perhaps the most venerated of trees, rowan has a '...tradition [that] does not allow the use of the tree's timber, bark, leaves or flowers, nor the cutting of these, except for sacred purposes under special conditions' (Fife 1994). However, placing rowan twigs above doorways for protection against misfortune, was highly recommended. The rowan symbolised the after-life, being a medium between this world and the next, and so its wood was burnt on funeral pyres and for divination.
As protection against spells or anything evil, rowan is legendary. Its power is enhanced by the fact that it appears to be able to grow where soil exists, such as in the forks of other trees or on bare rock. In fact, growing on another tree reinforced its qualities as belonging to both earth and heaven, like mistletoe. In Ireland, rowan is associated with Brigid, the muse of the arts, spinning and weaving (although Brigid's month falls in February, that of Nuin/ash).
Like hawthorn, rowan is a traditional material for spindles and spinning wheels. Used for divination and to invoke spiritual beings (and part of the cleansing ceremonies of the spring festival, Beltane) rowan trees were commonly planted at sacred sites and stone circles. An inspirational tree, rowan has the old Icelandic name of runa (secret or whisper), in common with the runes, for which it was used.
An old custom that lived on until modern times in various parts of Europe, was the annual use of the Life Rod in the spring, in which every human, animal (and even orchard tree) were beaten with it. This 'beating' was a form of blessing or 'flame' to bring the gifts of life, health fertility and good luck. Although occasionally willow or hazel were used, traditionally this needed to be rowan, a fact indicated in its old Anglo-saxon name of cvicbeam (cvic, or quick, meaning life). Quicken-tree therefore means a sharing out the blessings of life.
When Diarmid and Grainne flee from the revenge of Fionn, leader of the Fianna,
and come to the wood of Dubhros, they find a magic rowan. This tree was
grown from a berry of the 'Land of the Ever-Living Ones' (elves), and guarded
day and night by Searbhan Lochlannach, The Surly One of Lochlann, to prevent
anyone eating its berries. A gigantic, ugly hulk, with one eye and a mighty iron
club, Searbhan allowed Diarmid and Grainne to hide in the tree and eat its
berries, which were intoxicating and rejuvenating, while Fionn and four hundred
warriors of the Fianna, waited at the foot of the tree to kill the lovers.
Fortunately for the latter, Aonghas Og ('young angus', a powerful spirit and
Diarmid's tutor), helps Grainne to disappear immediately into the Otherworld.
This gate between worlds feat neatly indicates the tree as quicken/rowan, as do
the themes of health, young lovers, music and above all, protection.
Rowan twigs were believed to provide protection from lightning, and the tree is actually one of the species most rarely struck by lightning. In Icelandic legend, Thor nearly drowns in a river but is able to grab the branch of a rowan tree to pull himself out. Since Thor governs thunder and lightning, associations of rowan and lightning can be found throughout Europe. Rowan bark was talisman against witches, conjurers, sorcerers and the devil, and indeed any spell or evil. And, more well known, it was considered lucky to have a rowan growing near the home, and '...a bunch of the berries worn in the girdle or bodice kept women from being bewitched' (Trevelyan 1909).
Added notes: For control of spirits and protective against bad luck, rowan is burned to summon power, and (was used to bring) the spirits of the dead to battle. At the feast of Beltane (in May), lambs were encouraged to jump through rowan hoops and, on quarter days (equinoxes and solstices), a 'wand' of rowan was placed above all doorways, especially of byres, and under vessels in the dairy to guard both cows and milk from witchcraft, the evil eye and all infectious diseases (murrain was one such). Protective necklaces from berries, collar from wand increases hound's speed, tied to cow's tail to protects milk and beast. Associations include fire-flame, red, Hercules golden cup, berries the colour of blood.