Sorbus americana the red cascade mountain-ash, or "Sorbus americana" 'Dwarfcrown'. It is planted in gardens, and as a street tree. Sorbus americana The tree species Sorbus americana is commonly known as the American mountain-ash. It is a deciduous perennial tree, native to eastern North America. The American mountain-ash and related species (most often the European mountain-ash, "Sorbus aucuparia") are also referred to as rowan trees. "Sorbus americana" is a relatively small tree, reaching in height. The American mountain-ash attains its largest specimens on the northern shores of Lake Huron and Lake Superior. It resembles the European mountain-ash, "Sorbus aucuparia". Native to eastern
Sorbus mougeotii which differs only in slightly broader leaves. It is also closely related to "Sorbus intermedia" (Swedish whitebeam), which differs in having the leaves grey-white below and more deeply lobed, with the lobes spreading rather than forward-pointing, the fruit oval and less bright red, and in forming a stouter tree with a single trunk and more horizontal branching. All are tetraploid apomictic species which breed true without pollination, and ultimately of hybrid origin between "Sorbus aria" and "Sorbus aucuparia". It is widely grown as an ornamental tree in northern Europe, though usually unrecognised, misidentified as "Sorbus intermedia". Although described in 1858,