The Willow

Willow, a prolific tree of wet places, is the most versatile wood of all. It was used for baskets, fences, hurdles, and all manner of other products. A derivative of aspirin can be obtained from the bark, so it was prized by healers.
Its alternative name is 'withy'. Willow and withy both derive from the same root word as 'witch' and 'wicked'. The tree was highly valued by witches, a point which perhaps links to its healing properties: women who understood herb-lore were often accused of witchcraft.
Willow is the material the Druids supposedly made their wicker [another derivitive of willow] baskets for human sacrifices, although this may be Roman anti-Druid propaganda. You set the wood on fire, it burns away, the victims walk away. Doesn't really work.
Willow was also associated with the Greek Muses: their abode, Helicon, derives from the Greek 'helice' meaning willow.

Next time, another sacred tree.