Fraxinus quadrangulata Michx.

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Common names:
blue ash, blue ash
Description:
Growth form:
Small to medium-sized tree,
Size:
10 - 20 m tall, trunk diameter 30 cm - 0.5 m.
Form
narrow and rounded with many short, sturdy branches.
Bark
light gray tinged with red, moderately thin, and irregularly divided into large, scaly plates that give the trunk a slightly shaggy appearance.
Twigs
stout and square, with short, corky ridges extending between the nodes, orangish with rusty hairs, becoming brownish gray and hairless. Leaf scars crescent-shaped, with several bundle scars forming a U.
Buds
dark reddish brown, small, rounded, and slightly hairy. Terminal bud 6 - 8 mm long and blunt. Uppermost pair of lateral buds adjacent to the terminal bud at nearly the same level.
Leaves
opposite, pinnately compound, 20 - 38 cm long, with five to eleven leaflets (usually seven). Leaflets short-stalked, yellowish green above, paler with tufts of hairs along the veins beneath, 7 - 13 cm long, 2.5 - 5 cm wide, oblong egg-shaped to lance-shaped with a tapering base and long-pointed tip, coarsely toothed, thick, and firm. Leaves turn yellow in autumn.
Flowers
borne in a branched inflorescence, purplish, small, and lacking petals.
Fruit
dry, single-seeded, winged (samara), 2.5 - 5 cm long, oblong and notched at the tip. Wing broad, often twisted, extending to the base of the flat seed cavity and surrounding it.
Help:
Plant Glossary
Similar species:
The square stems of Fraxinus quadrangulata immediately distinguishes it from any other ash in the Chicago Region.
Flowering:
April to mid-May, as leaves begin to unfold
Habitat and ecology:
Typically found in calcareous woodlands and wet-mesic sites.
Regional occurrence:
native
Notes:
The inner bark of Fraxinus quadrangulata was once soaked in water to produce a blue dye, and its sap will turn blue when exposed to the air. The wood is used for flooring and interior finish, and the tree is sometimes planted as an ornamental. The emerald ash borer (Agrilus planipennis) is a serious insect threat to all native ashes (see link below).
Etymology:
Fraxinus is the Latin word for ash. Quadrangulata is Latin for "four-angled," which refers to the square twigs.
vPlants
name code: FRQU ; page author: The Morton Arboretum ; page date: 2006-12-03
Further information (external links):
Google: Text Search Image Search
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References:
Barnes, B. V., and W. H. Wagner, Jr. 2004. Michigan trees: A guide to the trees of the Great Lakes region. Ann Arbor, MI: University of Michigan Press.
Little, E. L. 1980. National Audubon Society field guide to North American trees: Eastern region. New York: Alfred A. Knopf: Distributed by Random House.
Mohlenbrock, R. H. 1996. Forest trees of Illinois. 8th ed. Illinois: Illinois Department of Natural Resources, Division of Forest Resources.

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Fraxinus quadrangulata

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