Arizona walnut is a round-crowned deciduous tree with furrowed bark on the trunk, gray twigs, and reddish brown new growth covered with hairs visible under a 10x hand lens. Leaves up to foot long with 4 to 8 pairs of leaflets along a central axis and a single leaflet at the tip the margins finely toothed and the midrib of the lateral leaflet off-center, the wider part of the blade toward the leaf tip. Flowers inconspicuous, in elongate green clusters. Fruit spherical, 1 to 1 1/2 inches in diameter, intermediate in size between Black Walnut (Juglans nigra) and Little Walnut (Juglans microcarpa).