Green Ash

Trees of the Forest, Green Ash

June 25, 2007,

This tree has become one of the most popular trees for our streets and yards after onslaught of
Dutch elm disease. Green ash, also called red ash has one of the largest natural ranges in North America. It is found from Nova Scotia to Saskatchewan and as far south as the southern United States.

The leaves are pinately compound with five to seven toothed leaflets arranged oppositely along a central raceme. The leaflets are one to two inches long oval at the base and tapering to a point. The leaves are typically finely toothed above the middle of the leaf. The leaflets will fall off individually early in the fall and leave the slender hairy stalk on the tree through the winter. It has been said of green ash that it is last to leaf out and first to fall. Ash seeds are thin winged samaras that spiral down like propellers when they mature. Ash trees are dioecious, meaning there are both male and female plants. Female ash trees bear the seeds. Male ash plants will have flowers in the spring.

The Latin name of this tree, Fraxinus pennsylvanica refers to phraxix, Latin for to separate, and Pennsylvania the state where it was first identified in. I always assumed that its ability to split easily, as in firewood, was the source of the name, further research indicates it may refer to separating fields. Ashes were commonly planted in hedge rows to separate fields.

This tough hardy tree is still a favorite plant for shelterbelts. Ash trees have had a long history of human use. From baseball bats to furniture ash is a hard, strait grained wood.

When used as firewood green ash has high heat energy only slightly less energy than oak, fortunately it does not rot quickly if left uncovered.

This native tree is still highly recommended for planting and does grow quite quickly. Ash is susceptible to a defoliating fungus, anthracnose that attacks the leaf stems and leaves in the spring. If spring weather is cool and damp the trees may defoliate or have distorted foliage. Typically the tree will develop new leaves and it may not be a major problem. If the weather does not co-operate and the fungus persists over a number of years the tree may be weakened and develop unusual growth. Another problem pest with green ash is plant bug; this small insect punctures the tissue of the leaf and feeds leaving the leaf doted with small yellow dots. This may all change with the introduction of emerald ash borer.

Take the time to establish good branch structure if you are developing a tree for your yard. Keep in mind that in the wild, green ash is a river bottom tree and is tolerant of flooding. It prefers open sites but will grow in an existing canopy. It is moderately shade tolerant. Typically it will be found a bit higher in the riparian zone than Manitoba maple and below burr oak. Its neighbors may include willow, cottonwood, and where applicable American elm. For more information on native trees contact an ISA Certified Arborist.