The 45-65 species of usually medium to large trees, mostly deciduous though a few subtropical species, are evergreen. The tree's common English name, ash, goes back to the Old English, while the generic name originated in Latin. Both words also meant "spear" in their respective languages. The leaves are opposite (rarely in whorls of three), and are simple in a few species. The seeds, popularly known as keys or helicopter seeds, are a type of fruit known as a samara.
Ash also referred to as Yggdrasil in Northern Europe and known as the world tree was very sacred to the druids. Its main symbolism being that of stability as it links the inner and other worlds. It is used in spells that require focus and strength and is often used to banish mental strife. It is said that if you put its leaves under your pillow it will induce psychic dreams.