Green Ash is the most widespread native ash. It grows to a height of 60 to 70 feet, with a slim trunk and a dense rounded or irregular crown. The trunk is frequently poorly formed as the tree searches for bright light.

The largest known specimen in Minnesota is in Nicollet County - 180 inches in circumference, 91 feet high, 67 foot crown spread, scoring 288 points. The national champion is in Hocking OH - 230 inches in circumference, 92 feet high, 106 foot crown spread, scoring 349 points.

Bark is light gray to brown, furrowed into into interlacing corky ridges that form a diamond pattern. The inner bark is reddish.

New Twigs are brightly green, becoming gray and may have fine hair initially, hairless later. New lateral buds appear on the top of the old leaf scars which are semi-circular with the top part more flat.

Leaves are opposite and pinnately compound, 6 to 10 inches long, with 5 to 9 (usually 7) shiny green leaflets in pairs plus the terminal leaflet; these are ovate to lance-shaped in form, whose margins are either smooth or coarsely saw-toothed. Each leaflet has a short stalk and the leaf has a much longer stalk. The underside of the leaflet is only slighter paler in color such that some might say they were the same, and may be slightly hairy. Fall color is yellow.

Flowers: The tree is dioecious, that is the male and female flowers are on different plants. Both appear before the leaves in small clusters on the prior years wood. They are light green to greenish-purplish, only 1/8 inch long, with a small tubular calyx and without corollas. Male flowers have two stamens with long anthers and the male flowers turn brown after release of pollen. The female flowers have a pistil with a single style. The male clusters are tightly composed whereas the female clusters start that way but then greatly expand to form a loose panicle containing 200 to 300 flowers. Flowers are cross pollinated by wind. Some studies indicate that male trees flower every year but female trees flower every 2 to 5 years.

Seed: Female flowers mature to a single narrow winged samara, 1-1/4 to 2-1/4 inches long, that is flattened in appearance due to the thin seed cavity for the small seed, and the wing extends nearly to the base of the samara. These turn straw-yellow, mature in autumn and disperse by wind in fall and winter. They do not germinate until the following spring as a cold stratification period is needed. Trees usually need to reach 20 to 30 feet in height before they bear seed.

 

Habitat: In its native habitat Green Ash is found in moist riparian soils, hence, one of the alternate common names - Water Ash. It adapts to a wide variety of soils and moisture conditions. Seedlings do best in moist shady soil but for mature growth they must then have full sun. The root system is extensive but shallow. The tree will re-sprout easily and quickly from stumps and cuts. The Emerald Ash Borer is a serious pest of this tree. The twigs and small branches are somewhat brittle and the tree is quite good at self-pruning in a windstorm - ask anyone who has the tree in a lawn area.

Names: The genus, Fraxinus, is the old Latin name for this genus meaning 'spear'. Ash wood, being tough and elastic, was originally used for spears and bows in the old world. The species, pennsylvanica means 'of Pennsylvania' where the tree was first classified. The author name for the plant classification - ‘Marshall’ refers to Humphry Marshall (1722-1801), American Botanist, who published in 1785 - Arboretum Americanum: The American Grove, an Alphabetical Catalogue of Forest Trees and Shrubs, Natives of the American United States.

In earlier times in North America certain similar trees were called 'Red Ash' and in the time of Francois Michaux (Ref. #26D) the scientific name of Fraxinus viridis was applied to the Green Ash and F. tomentosa was applied to the Red Ash. The term "Red Ash" is used interchangeably today with "Green Ash", with Green Ash preferred by most listings although persons in certain geographic areas of the trees occurrence prefer Red Ash. More notes on the name under "uses" below the photos.

Comparisons: Green Ash is easily confused with Black Ash (F. nigra) and White Ash (F. americana). Comparison of the samaras is the best method of identification. Black Ash leaflets do not have stalks.