Identifying characteristics:
The blue ash is a medium-sized tree (to 70 feet tall) with a narrow, open,
rounded crown and a slightly tapered trunk. The pinnately-compound leaves are opposite, with 5 to 11 (usually
7) short-stalked, coarsely-toothed, lance-shaped leaflets. The leaflets
are smooth, light green above and paler beneath with fine hairs along the
midrib near the base, which is asymmetrical. Fall color is pale yellow to
clear, bright yellow. Apetalous, usually bisexual flowers
are produced in loose panicles before the leaves appear. The winged fruits (samaras) are 1 to 2 inches
long, with broadly flattened seed cases, and are rounded or often notched
at the tip. This is the only ash with square twigs winged with corky
ridges between the nodes. Buds are small and covered with 3 pairs
of reddish-brown, slightly hairy, overlapping scales. Leaf scars
are large, raised and inversely heart-shaped. Unlike other ashes, the bark is divided into plate-like, often
shaggy scales. The inner bark, once used for making dye, is mucilaginous
and turns blue upon exposure to air.
Similar species:
- black ash (F. nigra)
- white ash (F. americana)
- green ash (F. pennsylvanica)
Ecology:
Distribution: This ash is native to the oak and hickory forests of
the midwest and parts of Kentucky and Tennessee, although nowhere is it
abundant. It grows in the southeastern part of Iowa in Lee and Des Moines
Counties on dry bluffs overlooking the Mississippi and Des Moines Rivers.
Habitat: This species is the most drought-resistant of the eastern ashes, and is usually found on dry, limestone uplands and hillsides, but also grows on floodplains. This tree is susceptible to most pest and diseases common to ashes, including ash borer, leaf spot, powdery mildew, caterpillars and aphids.
Uses:
Wood: The blue ash is moderately important as a timber tree. The
wood is often sold to mills as white ash. It is moderately hard and
heavy, durable, coarse-grained and somewhat brittle. The wood is used for
flooring and interior finishes. The heartwood is light yellow, streaked
with brown; the sapwood is paler and very thick. The sapwood is favored
for use as tool handles due to its strength, appearance and thickness.
Wildlife: The seeds are a moderately important food source for birds and mammals. Deer feed on the young twigs and leaves.
Horticulture: This fast-growing, long-lived ash is sometimes used as an ornamental shade tree in parks and gardens and would probably be used more if it was easier to propagate. 'True Blue' is an alkaline-tolerant cultivar that keeps its green color throughout the growing season and does not "yellow-out."
