The Japanese mountain-ash is a medium sized (height 20-30 feet, width 20-30 feet) deciduous tree, with a rounded crown and moderate growth rate. It grows best on moist, well-drained soil, in full sun. Its compound leaves have between 11-15 opposite, serrate leaflets change to a deep purple or red in autumn. White flowers appear in early summer on 4-6" corymb; orange to red fruit appears in autumn. This ornamental tree is hardy in USDA zones 5-7. (1) 

Fruit provides palatable browse for many animals and birds, but is not suitable for human consumption, except, perhaps for various folk remedies; the plant is not toxic. (1)  (5) Recent scientific studies indicate methanol extract of Sorbus commixta cortex prevents vascular inflammation in rats with a high fructose-induced metabolic syndrome. (6)

The Japanese mountain ash and related species (most often the European Mountain ash, Sorbus aucuparia) are sometimes referred to in folklore as "Rowan" trees, but this use has almost disappeared from the modern lexicon. The rowans were thought by the Celts and other primitive peoples of The British Isles to have magical properties.

Trees are essential elements of livable communities and a healthful environment. They are not only beautiful, they carry out many beneficial environmental functions. Trees absorb carbon dioxide, the major greenhouse gas (up to 50 pounds per tree each year), and release oxygen. They shelter and provide nesting habitats for wildlife, retain moisture in soils, hold topsoil in place, and provide shade and cooling.

Trees also provide fruits, nuts, oils, and syrups; pulp for paper, cloth, and rope; and wood for innumerable products and heat. Trees provide both direct and indirect economic benefits. Air-conditioning costs are less in a tree-shaded home, and heating costs are reduced when a home has properly selected and placed windbreaks. Beyond energy savings, landscaping with mature trees increases the value of property.

Indirect economic benefits extend beyond the individual to the community or region. Customers pay lower electricity bills when power companies use less water in their cooling towers and fewer measures to control air pollution. Communities also save money if fewer facilities must be built to control storm water.

Trees make the world more beautiful. They add color, structure, height, and grace to our neighborhoods, parkways, and streetscapes. Trees also neutralize the harshness and stress of urban life. They enrich our lives. Our forests, woodlands, parks, and preserves help us feel more relaxed and serene. A day or even an hour in the woods can help us feel rejuvenated. Trees are magnets for wildlife, which also add beauty, value, and interest to our world.

City and suburban trees often serve several architectural functions. They provide privacy, frame views, and screen out objectionable sights. They reduce glare and reflection, direct pedestrian traffic, and provide background for and soften, complement, or enhance architecture or topography.
--From The Morton Arboretum "Go Green"