In the center of the lawn by the south wing of McTyeire Hall stands the largest walnut tree in the arboretum. With a diameter of 72 cm (28 in.), it isn't particularly large compared to the biggest trees on campus. However, very large walnut trees are relatively rare because they are often cut for their valuable wood.

Walnut trees are relatively easy to recognize. The bark of large trees is deeply furrowed and the alternate leaves have many leaflets, with the terminal leaflet often missing. When the fruts are present, they are unmistakable. They are large and round, with smooth, green hulls that do not split. Removing the hull reveals a very hard, ridged nut. The meat of the wild nut is prized, although it has a stronger flavor than commercial walnuts.