The rowans or mountain-ashes are shrubs or trees in genus Sorbus of family Rosaceae. They are native throughout the cool temperate regions of the Northern Hemisphere, with the highest species diversity in the mountains of western China and the Himalaya, where numerous apomictic microspecies occur. The name rowan was originally applied to the species Sorbus aucuparia, and is also used for other species in Sorbus subgenus Sorbus. Rowans are unrelated to the true ash trees, which belong to the genus Fraxinus, family Oleaceae, though their leaves bear superficial similarity.