Size: Showy mountain ash trees grow from 25 to 35 feet at maturity. They are relatively narrow trees, spreading from 2/3rds to 3/4ths of their height. They increase 12 to 18 inches in height per year. At five years they are typically 8 feet tall and 5 feet wide. Relatively short-lived, their life expectancy is from 25 to 50 years depending on how successfully they are able to thwart their main enemy, borers. Their branches form fairly low to the ground growing out and then up. Their bark is yellowish orange or bronze colored.
Foliage: The leaves of the showy mountain ash are arranged opposite each other on narrow stems, up to 8 inches long, one leaf at the end. Usually there are 11 to 15 per stem on mountain ashes, but showy ones have 9 to 11 slightly broader leaves per stem. They emerge in mid-May. Each leaflet on the stem is long and narrow with finely toothed edges. They are a dull gray underneath and evolve from a light green in spring to a summer blue-green to golden, yellow-orange, or even reddish purple in the fall. They drop in October.
Flowers and Fruit: These showy mountain ashes produce flat clusters of white, fluffy flowers that stand tall at the ends of their branches. These clusters may be up to 4 inches across, hence the "showy" name for this tree. They bloom in late May or early June after the tree leafs out fully, their arrival signaled by their sweet fragrance. These flowers gradually develop into drooping bunches of bright red berries, each about 1/2 inch in diameter. These appear in late August through October and are coveted by many kinds of wild fowl, songbirds, mammals and even humans who have made flour, preserves, and beverages from them.