Rowan Several of the Asian species are widely cultivated as ornamental trees. North American native species in the subgenus "Sorbus (Sorbus)" include the American mountain-ash "Sorbus americana" and Showy mountain-ash "Sorbus decora" in the east and Sitka mountain-ash "Sorbus sitchensis" in the west. Numerous hybrids, mostly behaving as true species reproducing by apomixis, occur between rowans and whitebeams; these are variably intermediate between their parents but generally more resemble whitebeams and are usually grouped with them (q.v.). Rowans are excellent small ornamental trees for parks, gardens and wildlife areas. Several of the Chinese species, such as White-fruited rowan ("Sorbus glabrescens") are
Sorbus × hybrida midrib as separate leaflets. All three polyploid species are apomictic species which breed true without pollination. "Sorbus" × "hybrida" is grown as an ornamental tree in northern Europe, and is locally naturalised in the British Isles. The cultivar 'Gibbsii' has gained the Royal Horticultural Society's Award of Garden Merit. Sorbus × hybrida Sorbus "×" hybrida, the oakleaf mountain ash, Swedish service-tree or Finnish whitebeam, is a hybrid species of whitebeam native to Scandinavia in Norway, eastern Sweden, and southwestern Finland, and locally in the Baltic States in Latvia. It is a medium-sized deciduous tree growing to 10–15 m tall with