How to Tell the Difference Between Ash & Chestnut

Estimate the size of chestnuts compared to those of the ash species. American chestnut once grew to as tall as 80 feet, but few specimens today get taller than 25 feet before the chestnut blight takes its toll. Ash trees are much larger and mature individuals reach sizes between 40 and 80 feet, depending upon the species. For example, black ash (Fraxinus nigra) tops out at 50 feet, while white ash (Fraxinus Americana) grows to 80 feet high.

Observe the base of the trunks of chestnut trees; most are about 4 inches in diameter. Chestnuts in the wild will sprout out of the stumps of dead chestnut trees. Ash trees have a normal trunk, with diameters between 12 and 24 inches common.

Examine the foliage of chestnuts versus that of the ashes. Chestnuts possess simple leaves, growing between 5 and 9 inches in length, with serrations along the edges. Chestnut leaves are oblong and the leaves are dark green, turning shades of yellow, brown or gold in the fall. Ash trees have compound leaves. They have a central stem with a number of leaflets attached to it that compose each leaf. Black ash has between seven and 11 leaflets, each one between 3 and 5 inches long. White ash will have between five and nine leaflets on each long stem. Ash leaves turn colors like gold, red and burgundy in autumn.

Inspect the fruits of the ash and chestnut. Both types of trees have separate male and female plants, with the female ash tree producing a seed called a samara. The samaras of the ash trees resemble small paddles, containing a seed and reaching lengths between 1 and 2 inches. Chestnuts generate a spiny burr from its female flowers, containing two or three shiny brown, egg-shaped, edible nuts

Look at the bark of chestnut trees, comparing it to that of the ashes. Chestnut trees do not mature enough to feature the fissured, dark-gray bark of adult trees, instead having a smoother, olive-brown bark that has a shiny appearance, crisscrossed with small horizontal lines. The ash trees have gray bark full of rough furrows.