Ash, Blue
Fraxinus quadrangulata
Oleaceae - Olive

Description

Leaves: Dark green to yellow-green in summer, yellow in late summer to fall; shiny, and hairless above; paler below with soft, short hair along midrib near base; opposite, pinnately compound (like a feather); 7" to 14" in length; leaflets small and narrow (2" to 5" long and 1" to 2" wide), 5 to 11 per leaf, thick, egg-shaped to lance-shaped, edges coarsely toothed, leaflets taper to a slender point and are somewhat triangular and unequal at the base; leaflet stalk is short; deciduous.

Twigs/buds: Twigs orange-brown, stout, and pubescent; have four corky ridges, making them almost square in cross-section and explaining the Latin name "quadrangulata"; twigs can produce a bluish dye. Buds are dark gray or reddish brown and somewhat hairy.

Flowers/fruit: Flowers perfect; the inflorescence is a panicle of small flowers, appearing in April or May. Fruit is a samara (winged), 1" to 2" long, oblong to egg-shaped, broad, twisted, notched near apex; maturing in October, falling soon after.

Bark: Gray, thin; shows fissured, plate-like scales on older trunks; shaggy; exposed inner bark becomes blue.

Wood: Unimportant because the tree is not common, though it is moderately important in the Midwest; straight-grained; wood shows hardness, weight, and strength; part of the white ash group which has the following properties: heartwood brown, sapwood light-colored; wood from second-growth trees desirable because of its qualities, including strength, shock-resistance, stiffness, weight, and hardness. The white ash group is used for making cabinets, veneer, furniture, millwork, flooring, and crates.

General: Native to the eastern half of the U.S., from Michigan to Tennessee. It is a scattered tree, often found in dry or upland soils, limestone outcrops, or valleys with rich soil and deciduous trees. A medium tree from 40' to 80' in height, its canopy is often rounded, narrow, open and irregular with spreading branches. It should be able to tolerate somewhat high soil pH. Somewhat susceptible to borers. Prefers full sun.

Landscape Use: I have not seen this species in Utah, but I hear it is here. Cultivated occasionally, it can be planted and will do well in Utah. It differs from green ash in having twigs with four corky ridges and sharply toothed leaflets. The trunk is usually straight, slender, and slightly tapered. Zones 4-7.

In the last few years an exotic pest, emerald ash borer (EAB), has been making its way across the U.S. So far it has decimated populations of ornamental and native ashes and recently was found to attack fringetree (Chionanthus spp.) as well. So far EAP has not made it to Utah, but it seems likely it will. So, plant ashes and fringetrees with caution since they may not be around for long. Some have hope that trunk injection of insecticides may work to control the pest.

Cultivar: 'True Blue'

Characteristics

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