Notice the grayish/blackish bark which is deeply furrowed.
It's hard to see from this distance, but the leaves are arranged alternately on the twig and are compound with more than 11 leaflets and range from one to two feet long.
Be careful when planting around a black walnut tree. The tree secretes juglone into the soil which is a respiratory inhibitor in many plants. As always, practice good companion planting and you should be fine.
