Sorbus × hybrida by thrushes and waxwings, which disperse the seeds. It is a tetraploid species of hybrid origin between "S. aucuparia" (European rowan) and "S. intermedia" (Swedish whitebeam), the latter being a tetraploid triple hybrid between "S. aucuparia", "S. torminalis", and either "S. aria" or one of its close relatives. "S. intermedia" differs from "S. hybrida" in having the leaves less deeply lobed with no separate leaflets. Closely related "Sorbus meinichii" is a triploid or tetraploid species of hybrid origin between "S. hybrida" and "S. aucuparia" and differs in having the basal four to six pairs of lobes cut right to the
Sorbus aucuparia be applied to other species in "Sorbus" subgenus "Sorbus", and mountain ash may be used for several other distantly related trees. The species is unrelated to the true ash trees (genus "Fraxinus"), which also carry pinnate leaves or the species "Eucalyptus regnans", also called mountain ash, native to Tasmania and Victoria in southeastern Australia. "S. aucuparia" was previously categorized as "Pyrus aucuparia". The author citation "Sorbus aucuparia" L. belongs to Carl Linnaeus. "Sorbus aucuparia" occurs as a tree or shrub that grows up to between 5 and 15 m in height. The crown is loose and roundish or irregularly shaped