Rowan is attested from the 1520s in the sense "fruit of the service tree", adopted via French "sorbe" from Latin "sorbum" "service-berry". "Sorbus domestica" is also known as "whitty pear", the adjective whitty meaning "pinnate". The name "mountain-ash" for "Sorbus domestica" is due to a superficial similarity of the rowan leaves to those of the ash, not to be confused in "Fraxinus ornus", a true ash that is also known as "mountain ash". "Sorbus torminalis" is also known as "chequer tree"; its fruits, formerly used to flavour beer, are called "chequers", perhaps from the spotted pattern of the fruit. The name
Fraxinus excelsior narrow crown. The bark is smooth and pale grey on young trees, becoming thick and vertically fissured on old trees. The shoots are stout, greenish-grey, with jet black buds (which distinguish it from most other ash species, which have grey or brown buds). The leaves are opposite, long, pinnately compound, with 7–13 leaflets with coarsely serrated margins, elliptic to narrowly elliptic, long and broad and sessile on the leaf rachis. There are no stipules. These features distinguish ash from mountain ash ("Sorbus aucuparia") in which the leaves are alternate with paired stipules. The leaves are often among the last to