Identifying characteristics:
The European mountain ash is a small, fast-growing tree with a short trunk
and an open, rounded crown to 45 feet. The leaves
are 5 to 10 inches long, alternate and pinnately compound, with 11 to 19
coarsely-toothed, opposite leaflets. Each leaflet is a dark green color
above, whitish beneath and hairy on both sides. The flowers
are produced in May in showy, flat-topped clusters of small, white flowers.
The red fruits are conspicuous, attractive
pomes, hanging in large, dense clusters and may persist on the tree into
winter. The winter buds of this species are covered with scales with
whitish-gray hairs, whereas the buds of the American mountain ash (Sorbus
americana) are hairless and sticky. Buds are broadly cone-shaped and
0.3 to 0.5 inches long. The bark is
thin, gray and smooth, becoming scaly with age.
Similar species:
Ecology:
Distribution: Native to Europe and western Asia, the European mountain
ash was introduced to the US in colonial times. It is hardy to zone 3 and
has naturalized in Canada. The American mountain ash (Sorbus americana)
and the showy mountain ash (S. decora) are native to the US as far
south as southwestern Wisconsin, but their range does not extend into Iowa.
The American mountain ash (Sorbus americana) is a handsome, spreading,
round-topped small tree. It is slow-growing, is intolerant of shade and,
although it will grow well on rocky hillsides, prefers moist soils.
Habitat: Found along fencerows, swamps and streams, this species tolerates extreme acidity-disliking shallow, chalky soils-but is sensitive to pollution. This tree is sensitive to most of the pests and diseases that plague the rose family and is therefore not recommended for monoculture avenue plantings where a uniform effect is desired. Canker can be problematic, especially on weakened trees and rust is often also found on alternate hosts, the junipers (Juniperus sp.) and incense cedar (Libocedrus sp.). It is subject to sunscald and frost cracking.
Uses:
Wood: The wood is light brown, fine-grained and hard, occasionally
used for tool handles and other wooden wares.
Wildlife: The fruits are eagerly devoured by birds and therefore few berries may be left on the tree into winter.
Horticulture: The bright red fruits and reddish fall foliage make this species the most popular mountain ash used for landscaping purposes in the US. Cultivars include "Asplenifolia," with deeply-cut, fern-like leaves; "Dirkenii," with new leaves emerging yellow; and "Edulis," a native of the Czech Republic and Slovinia, a hardy, strong grower with large leaves and fruit.
