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
Forests of the Iberian Peninsula form small enclaves or copses at the foot of rocky cliff edges or in the clearings of beech forests, on poor or acidic soils, accompanied by aspen ("Populus tremula") and mountain ash ("Sorbus aucuparia"). Birch may also grow in pure stands near the beech forests, in the mountainous areas on siliceous bedrock; these areas are typically of only small extent and generally quite patchy with sessile oak ("Quercus petraea") and trees of the genus "Sorbus". The silver fir ("Abies alba") is found on the cool, deep-soiled slopes of the flanks of the Pyrenees, from Navarre to Montseny, forming pure fir