Rowan tree \Row"an tree`\ [Cf. Sw. r["o]nn, Dan. r["o]nne, Icel. reynir, and L. ornus.] (Bot.) A european tree ({Pyrus aucuparia}) related to the apple, but with pinnate leaves and flat corymbs of small white flowers followed by little bright red berries. Called also {roan tree}, and {mountain ash}. The name is also applied to two American trees of similar habit ({Pyrus Americana}, and {Pyrus sambucifolia}). [1913 Webster]