Arizona Black Walnut
Arizona Black Walnut is another medium-sized riparian tree usually widely scattered along mid-elevation stream channels mixed with other riparian tree species. I defined a tree previously as having a single trunk, but walnuts very often have several (2-6) stems. The bark is distinctively deeply furrowed, dark gray-brown, and somewhat shaggy. Leaves are similar to those of the Velvet Ash in that what appears to be a single leaf is actually part of a compound leaf made of many leaflets. Arizona Black Walnut leaves, however, are much bigger, comprised of 9-15 leaflets in 4-7 pairs plus the terminal leaflet. The male and female flower structures are quite different from each other. Female flowers are produced in pairs, while the male flowers are produced in catkins (like the cottonwoods and willows) with many flowers in one catkin.