Ash

Ash is a type of tree belonging to the genus flowering plants in the olive and lilac family, Oleaceae, known as Fraxinus. It contains 45-65 species of usually medium to large trees, mostly deciduous though a few subtropical species are evergreen. The leaves are opposite (rarely in whorls of three), and mostly pinnately compound, simple in a few species. The seeds, popularly known as keys or helicopter seeds, are a type of fruit known as a samara. Rowans (or Mountain Ashes) are unrelated to true ashes and belong to the genus Sorbus though the leaves and buds are superficially similar.

Wandlore
The ash wand cleaves to its one true master and ought not to be passed on or gifted from the original owner, because it will lose power and skill. This tendency is extreme if the core is of unicorn. Old superstitions regarding wands rarely bear close examination, but I find that the old rhyme regarding rowan, chestnut, ash and hazel wands (rowan gossips, chestnut drones, ash is stubborn, hazel moans) contains a small nugget of truth. Those witches and wizards best suited to ash wands are not, in my experience, lightly swayed from their beliefs or purposes.

However, the brash or over-confident witch or wizard, who often insists on trying wands of this prestigious wood, will be disappointed by its effects. The ideal owner may be stubborn, and will certainly be courageous, but never crass or arrogant.

Etymology
The tree's common English name, ash, goes back to the Old English æsc, while the generic name originated in Latin. Both words also meant "spear" in their respective languages.