The English Walnut (J. regia, also known as the Persian Walnut) is distinct in its leaves and nuts. When compared to other walnut leaves the English Walnut leaf is generally larger with fewer leaflets. The English Walnut is a common deciduous tree native to Europe, often called the Common Walnut there. It has been imported to the rich soils of the United States.
Identify the leaf sample
Count the leaves on the stem. All walnut trees have compound leaves, which means they have many leaflets on the same leaf stem. The English Walnut leaf has five to nine leaflets, always in odd intervals. The leaflets are symmetrical on the stem. Other walnut trees, such as the Black Walnut has 15 to 23 leaflets, where the related Butternut has 11 to 19. The English Walnut is therefore unique in its small number of leaflets.
Measure the leaflets. The English Walnut leaves measure between 2 to 5 inches. The leaves start out at the tip with a medium size and the largest leaflets are the first set of two from the tip. The leaflets get progressively smaller until they get to the nape of the stem. The Black Walnut leaflets are considered very small at 1 to 3 inches, and they are much thinner in width.
Examine the leaflets in detail. The leaflets of the English Walnut are oval and come to a point. The margins of the English Walnut leaflet are entire, meaning there is no serration along the edges. The veins in the English Walnut are even, wide and symmetrical. They are at intervals of about 2 to 5 cm along the leaflet stem.
Recheck the differences. When you look at the English Walnut compared to the related walnut family trees there are distinct differences. The English Walnut leaf when compared to the Black Walnut leaf is larger with fewer leaflets. The Black Walnut leaflet is much smaller and narrower in size and shape and the Black Walnut has small serration on the leaflets where the English Walnut is smooth.
The English Walnut leaf is approximately the same size and shape as a Butternut leaf, but the Butternut has more leaflets and serrated edges.