Fraxinus americana

Native

Common an abundant

Dry to moist. Upland forests.

April to May

Purplish

40′ to 70′

This is a moderately fast-growing deciduous tree. In Minnesota mature trees are usually 40′ to 70′ tall and 10″ to 24″ in diameter at breast height. Large individuals can reach over 80′ in height and 40″ in diameter. It is a moderately long-lived tree, reaching up to 200 years old.

The trunk is straight and often unbranched nearly to the top. The crown is dense, narrow, and pyramid-shaped. The root system is deep where soil conditions permit. The crown is dense and usually rounded, sometimes irregular.

The bark on young trees is smooth and greenish-gray. It does not become flaky. As it ages it develops firm, narrow, raised, corky ridges. The ridges are interlaced and form a diamond-shaped pattern, and is identical to the bark of green ash.

The twigs are stout, round or oval in cross section, shiny, hairless, green or purplish, with scattered white dots (lenticels). The buds are dark brown. The terminal bud is 3 ⁄16″ to 9 ⁄16″ long, wider than long, blunt, and reddish-brown. The uppermost pair of lateral buds occurs at the base of the terminal bud. The leaf scars are half-round and on well-developed branches are deeply notched at the top. The buds originate well within the notch.

The leaves are deciduous, opposite, and pinnately compound. They are 8″ to 12″ long and are divided into 5 to 9, usually 7, leaflets. The leaflets are all clearly stalked. They are arranged in opposite pairs with 1 terminal leaflet. They are oval to lance-shaped, 2¾″ to 5″ long, and 1″ to 2″ wide. They are tapered at the base and taper to a point at the tip, often to an abrupt point with concave sides along the tip. The upper surface is dark green and hairless. The lower surface is distinctly paler or white and hairless except along the veins. The margins have infrequent, rounded teeth above the middle or are sometimes untoothed. In autumn the leaves turn yellow or bronze-purple and are shed as individual leaflets, not entire leaves. The tips of the leaflets do not droop.

Male and female flowers are borne on separate trees. They are borne in branched clusters in all parts of the crown. They are purplish, small, and inconspicuous, and have no petals. They appear in April to May just before or at the same time as the leaves.

The fruit is a 1″ to 2″ long, ⅛″ to 5 ⁄16″ wide samara consisting of a flattened seed case with a dry, flattened, papery, wing. The wing is rounded or notched at the tip, and encloses ⅓ of the seed case. The seed case is nearly as thick as wide, less than 6½ times as long as wide, and much thicker than the wing. It contains a single seed. The samara ripens in late summer and is dispersed from September to December.

Blue ash (Fraxinus quadrangulata) twigs are 4-angled, or winged.

The champion white ash in Minnesota is on state property in Canton, in Fillmore County. In 2009 it was measured at 87′ tall and 156″ in circumference (49½″ in diameter).