850 Fraxinus americanaCommon Names: white ash Family: Oleaceae (olive Family)
White ash is the largest and grandest of the 16 North American ash species. This handsome deciduous forest tree once grew to heights of 100-120 ft (30.5-36.6 m), with tall straight trunks 4-6 ft (1.2-1.8 m) in diameter, but such giants were confined to the finest soils of the Tennessee and Ohio River Valleys, and have been replaced by farmland. Today white ashes commonly grow 40-60 ft (12.2-18.3 m) tall with 40 ft (12.2 m) crownspreads. White ash has a strong framework with stout main branches growing upright and smaller branches spreading outward. The bark of mature trees is dark brown and deeply fissured by interlacing ridges forming a characteristic diamond pattern. Ashes have opposite branching and their pinnately compound leaves are arranged along the branchlets in opposing pairs, with an odd leaflet at the end. The leaves of white ash are 8-14 in (20.3-35.6 cm) long and have 5, 7 or 9 (usually 7) leaflets, each 3-5 in (7.6-12.7 cm) long and pointed at the tip. They are thin and papery and dark green above and whitish beneath, turning shades of yellow, red or purple in autumn.
White ash is dioecious - male and female flowers are on separate trees. The little petal-less flowers appear just before the leaves unfold in early spring. They are arranged in hanging clusters and not very showy. The fruits, produced in late summer, are winged samaras about 2 in (5.1 cm) long, borne in crowded hanging clusters. They are thin and papery and look a little like dragonfly wings.
Several cultivars are available; some of these do not produce fruit and are thus better suited for tidy lawns. 'Autumn Blaze' has purple autumn foliage. 'Autumn Purple' is similar, but is a male clone and thus nonfruiting. 'Rosehill' has bronzy red autumn foliage and also is a nonfruiting selection. 'Pendula' has drooping branches. White ash can be distinguished from other ashes by the whitish appearance of the leaf undersides, and the upland habitat. Ashes can be distinguished from hickories by their opposite, rather than alternate, compound leaves.
White ash, Fraxinus americana, is the most widespread and generally most common ash in North America. It ranges throughout the East from Nova Scotia and Maine, west through southern Ontario and Minnesota to eastern Nebraska, and south to eastern Texas and northern Florida. White ash is not a tree of swamps and marshes as are many of the other American members of the genus. This one occurs in well-drained soils along rivers and on lower slopes in mixed forests. White ash never occurs in pure stands and is rarely a dominant tree in the forest; it grows in small groups or singly with other forest trees such as red maple (Acer rubrum), sweet gum (Liquidambar styraciflua), American beech (Fagus grandifolia), tulip tree (Liriodendron tulipifera), white pine (Pinus strobus), eastern hemlock (Tsuga canadensis), white spruce, and various oaks (like Quercus rubra) and hickories (like Carya ovata).
CultureWhite ash grows slowly at about 1-2 ft (0.3-0.6 m) per year, for the first 5-10 years, then picks up over then next several decades. It does well in neutral to alkaline soils. During youth, prune to maintain a single leader, as forked crotches are weak and may break in later years. Light: Full sun. Moisture: White ash needs a moist, but well-drained soil. It is not drought tolerant. Hardiness: USDA Zones 4 - 9. Propagation: Sow ash seed outdoors as soon as it is collected in the fall. Germination will occur in spring. Seeds that have been stored require 2-3 months of cold stratification. Cultivars are grafted onto seedling rootstock.
The white ash is a beautiful specimen and shade tree for parks and larger landscapes. It is tolerant of urban pollution and exposed conditions. With its stout, upward reaching branches and symmetrical crown, the white ash presents a handsome silhouette in winter. They are sometimes used as street trees. White ash is quite tolerant of salt (but not highly exposed beach front conditions), and is well suited to the coastal garden. Choose nonfruiting cultivars if the litter of fallen samaras and numerous volunteer seedlings are undesirable.
White ash is the most valuable of the ashes for timber; the wood is lightweight yet hard and strong, and used to make tool handles, furniture and baseball bats. Native Americans made baskets and snowshoes from the flexible but strong young branches. The fruits are eaten by birds and small mammals, and deer browse the young twigs.
White ash is a large tree, better suited to large landscapes such as parks, golf courses and campuses, than to most home landscapes. Narrowleaf ash (Fraxinus angustifolia) might be a better choice for residential lawns. There are some 65 species of Fraxinus, most from North America, Europe and Asia; most of these are smaller than the white ash, and many are wetland trees.
Steve Christman 11/10/00; updated 11/1/03, 6/20/04