Especially useful in the treatment of skin diseases, black walnut is of the highest value in curing scrofulous diseases, herpes, eczema etc. Bark. Height 35' to 75' with a diameter of 9" to 30"; clear trunk for 20' or more on large trees; crown wide and irregularly shaped. The most popular color? The bark and leaves of the black walnut are viewed as alterative, anodyne, astringent, blood tonic, detergent, emetic, laxative, pectoral and vermifuge. Even Dr John Christopher, the well known American herbalist, on his website, claims it is the bark and leaves. There are 332 black walnut bark for sale on Etsy, and they cost $11.27 on average. High Cholesterol. According to my research, I believe it is the bark of the black walnut tree as well as the leaves, but not the hulls. The bark and leaves are alterative, anodyne, astringent, blood tonic, detergent, emetic, laxative, pectoral and vermifuge. Black walnut benefits and uses include natural digestive cleansing. Black walnut (Juglans nigra) is a type of nut thought to offer a number of health benefits.The tree nut contains tannins, a class of substances with antioxidant and anti-inflammatory properties. Long used in certain systems of herbal medicine, a black walnut extract is available in dietary supplement form and is believed to help in the treatment of certain illnesses including infections. The most common black walnut bark material is wood. On young trees, smooth and dark brown; thick and black on older trees with deep furrowed and rough broken ridges; inner bark bright yellow and bitter because of tannic acid. The nuts of the black walnut are believed to aid in decreasing cholesterol levels and to improve overall heart health and function. Form.