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 decora Sorbus decora Sorbus decora, commonly known as the northern mountain ash, showy mountain-ash, or dogberry, is a deciduous shrub or very small tree native to northeastern North America. It occurs throughout the Laurentian Mixed Forest Province, the New England-Acadian forest region, and the eastern Canadian boreal forests. Showy mountain-ash grows tall. Its leaves are odd-pinnately compound, with 11–17 leaflets. Each leaflet is long and wide. All parts are hairless to slightly hairy. Flowers are borne in 125- to more than 400-flowered panicles across. Each flower is across and has five white petals long, 14–20 stamens, and carpels with 3–4 styles.