Mountain Ash Tree

A Few Facts About The Mountain Ash Tree

There are two main species of the mountain ash tree, the European mountain ash, Sorbus aucuparia, and the North American mountain ash, Sorbus americana. The European species is the more "tree like" of the two, while the American mountain ash often has a more shrubby appearance. Both species are found in the wild, where they are not particularly long-lived, and both species are very popular as landscaping trees or shrubs.


The mountain ash is a deciduous tree, and has compound, toothed leaves. The tree blossoms in late spring or early summer, but the flowers are very small, occurring in bunches. The mountain ash tree is probably best known for its clusters of berries, ranging in color from orange-red to a deep scarlet, depending upon the species. The berries form in the summer as the blossoms fade, and last not only through the fall months but normally well into the winter months as well. As such, the mountain ash tree provides a valuable source of food for birds and small mammals during the winter months.

Not A True Ash - A mountain ash tree grows rather rapidly at first, but the rate of growth slows down markedly as the tree matures. Some trees grow only to a height of around 10' and resemble large shrubs more so than trees. Others can reach a height of 30' and have definite tree like characteristics. The mountain ash very likely got its name from the shape of its leaves and the color and texture of its bark, which closely resembles a true ash. The mountain ash is not an ash tree however, but is a member of the rose family (Rosaceae). Though a distinct species, the mountain ash will hybridize easily with a number of other trees, particularly the Chokeberry and the Hawthorns. In some localities the mountain ash is known as the Dogberry tree, and is called the Roundwood tree or Missey-mossey in other locales, but in most places the name mountain ash is favored.

Hardy in USDA Zone 3 and above, the mountain ash tree is essentially a cool to temperate climate tree. It is found in the wild in southern Canada and the northern tier of states in the US, from Newfoundland on the Atlantic coast, to the American Midwest. The mountain ash is also prevalent in the Pacific Northwest, but primarily as a landscape tree rather than growing in the wild. In the wild, the mountain ash prefers open areas as it is not particularly tolerant of shade. Its main enemies are the Gypsy Moth, whose larvae can defoliate a tree, and fire, which is not well equipped to withstand because of its low height and thin bark. A tree killed by fire however will often send up new sprouts from the burned stump.

Not Poisonous But Not Real Good Eating Either - Many of us were taught at an early age not to eat the berries. It was a known fact that the berries were greatly appreciated by many species of birds. In the Rocky Mountain states, and certainly in many other locations as well, a flock of Cedar waxwings can often be seen descending upon a mountain ash in the fall and feasting on the berries. The waxwings will hang around for several days, and then resume their flight to warmer climates. As far as human are concerned however, the berries were often thought by many to be poisonous, and many people still believe that. The truth is, the berries are edible, but they are extremely acidic, and it would be difficult indeed to eat more than a few raw berries at one time. They can however be cooked and made into a jelly, or used to make wine. For the most part though, birds and mammals, such as squirrels and chipmunks, will take care of most of the berries during the winter months.

If You Want Fiery Red Foliage - If you decide to grow a mountain ash tree on your own properly, it will require fertile soil to get off to a good start. It's not drought tolerant at all, and the soil must be kept most until the tree matures, or it will either not survive or not grow to a decent height. The mountain ash also does not do well in warmer climates. Those found growing wild in the southern states are almost always located in the higher elevations, where the days tend to be cooler. A mountain ash with its fiery red foliage in the fall can make quite a stunning addition to the garden, whether standing alone or among other deciduous trees whose leaves turn various shades of yellow and orange in the fall.