Fraxinus americana aka White Ash

Fraxinus americana, or white ash, belongs to the olive family. This large tree loses its leaves each fall. Its native range spans eastern Canada and central and eastern America. It forms part of forests in the northeastern United States. It grows fast and needs space for its wide crown. Young trees have an oval shape that rounds with age.

Garden trees reach about 50–90 feet [15–27 metres] tall. Their crowns can span 50–75 feet [15–23 metres]. Some trees reach 120 feet [37 metres] in height. Stout, gray twigs bear brown buds and opposite leaves. Deep grooves divide the gray-brown bark into diamond-shaped ridges. The pinnate leaves have five to nine leaflets, most often seven. Their upper sides look dark green, with paler green beneath. Fall brings yellow leaves with shades of burgundy or purple.

Small flowers open before the leaves, mainly in April and May. Bloom dates vary from March to June among sources. The flowers lack petals and may look green or purple. Male and female flowers grow on separate trees. Female trees form dry fruits, each with one wing. These samaras turn brown as they ripen in fall. Some stay on the branches through winter. Birds, squirrels, and other small mammals eat the seeds. The leaves also feed tiger swallowtail and mourning cloak caterpillars.

Give white ash full sun for growth and fall color. It grows best in deep, rich soil that stays moist. Good drainage suits it, though it can endure wetter ground. It accepts several soil types and a wide pH range. Sources list USDA zones 3–9 and UK hardiness H6. White ash has served as a lawn and street tree. Its shade suits parks, campuses, and other large sites. Its tough wood supplies bats, tool handles, furniture, and floors.

Emerald ash borer makes new planting hard to justify. It can kill infested trees within three to five years. Other risks include borers, scale, leaf spots, and ash yellows. Ash dieback and root rot can also cause harm. Wind, snow, and ice can break brittle branches. Female trees can shed messy fruit and produce unwanted seedlings. NC State lists the fruit as edible. PFAF reports bitter syrup but questions its use as food. PFAF lists no known hazards, rather than proving safety. Sources describe folk remedies, not evidence that these treatments work.