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
Aphis pomi "A. pomi", especially at high temperatures. Besides occurring on apple ("Malus domestica"), "Aphis pomi" infests other plants in the family Rosaceae including pear ("Pyrus communis "), hawthorn ("Crataegus monogyna"), medlar ("Mespilus germanica"), quince ("Cydonia oblonga"), mountain ash ("Sorbus aucuparia"), rose ("Rosa") and spiraea ("Spiraea"). It is an autoecious species, completing its life cycle on a single host species. Overwintering eggs hatch in spring and the aphids colonise the growing tips of the shoots causing the edges of the leaves to curl. These aphids are all viviparous females and give birth to other wingless aphids by parthenogenesis. In June some winged