The Green Ash Tree
Fraxinus pennsylvania, or the green ash, is a medium-sized deciduous tree native to eastern and midwestern North America. This hardy tree is remarkably tolerant of air pollution, poor soils, and salt spray, in addition to flooding, which led to its widespread use as an urban street tree. Green ash can grow to 70 feet tall, with a canopy spread of up to 50 feet, which also makes it an ideal shade tree. Green ash trees are dioecious, meaning that each tree has either male or female flowers. The flowers are small and not ornamentally attractive, but the female flowers, once pollinated, develop into a winged fruit.
At Madison Square Park, these trees are one of the plants utilized to track seasonal changes. Ash trees have a distinct yellow fall color and are often the first trees to show fall colors at Madison Square Park. Unfortunately, ash trees are struggling with the introduction of forgein pests such as Emerald Ash Borer (EAB)—an invasive wood-boring bug native to Asia. EAB is highly lethal to the 16 species of ash native to North America, including the green ash. This bug has a mortality rate of 99.9% for green ash. Trees affected by EAB die over several years, becoming unsightly and hazardous when located in populated areas. As a result, we here at the Park work with arborists to take preventative measures to ensure that our green ash trees remain unaffected and safe.
Fun Facts About Green Ash Trees
- Like all ash trees, they can be identified by the distinctive x-shaped ridges in their bark that give them a diamond pattern
- In New York, green ash trees are among the largest, frequently reaching heights upwards of 100 feet
- Green ash trees turn bright yellow in the fall; one member of our team has remarked that it’s not autumn at Madison Square Park until the ashes change colors
- Green ash is in the same family as olives, jasmine, and lilacs
- Green ash wood, often called swamp ash by guitarists, is prized by electric guitar makers for its timbre
- Green ash and other native ashes are an important food source for the tadpoles of North American frogs, who feed on leaves that have fallen into their ponds