Fraxinus pennsylvanica is a medium-sized deciduous tree reaching 12–25 metres (39–82 feet) (rarely to 45 m or 148 ft) tall with a trunk up to 60 centimetres (24 inches) in diameter.

; green ash) on the basis of the hairless leaves with narrower leaflets of the latter, but the two intergrade completely, and the distinction is no longer upheld by most botanists.

[4] Like other species in the section Melioides, Fraxinus pennsylvanica is dioecious, with male and female flowers produced on separate individuals.

Seedlings of the tree have a high tolerance to water logging[12] which may explain why the natural habitat of green ash is almost exclusively stream sides and bottomlands.

That epidemic was the result of a similar overuse of elms in urban environments, leading to a monoculture that lacked any disease or pest resistance.

Scientifically for green ash this is because modern cultivars utilized regionally were parented from sometimes only four individual trees selected for unique traits and male seedless flowering.

Instead, Norway, silver, red and sugar maples, honey locust, linden/basswood, redbud, crabapples, and hackberry, among others, were also utilized during this recovery period and in new urban and suburban areas.

[21] Both American elm and green ash were extremely popular due to rapid growth and tolerance of urban pollution and road salt, so many housing developments in Michigan were lined from end to end with ashes, a result of which the beetles had an enormous food supply to boost their population well above Infestation thresholds.

[citation needed] Green ash is one of the most widely planted ornamental trees throughout the United States and much of Canada but mostly Alberta, including in western areas where it is not native.

[23] For the last two centuries American elm and ash, which both belong to the ancient Elm-Ash-Cottonwood Bottomland ecosystem,[24] achieved distinction as North America's two most popularly planted urban species, used primarily for their superior survival traits and slowly maturing 180–300 year majestic natural beauty.

[citation needed] Other continents learned of American ash species' urban survivability and unique beauty through the worldwide popularity of Midwestern Prairie style ecology and architectural movement.

Modernizing cities in Russia and China then began using imported green ash a century ago to line streets and landscape new public parks.

[25][26] Advantages of green ash include its tolerance of harsh urban environmental conditions, ease of propagation, and (in eastern North America) its value for wildlife as a native keystone species.