Black walnut trees have yellow-green, compound leaves.
Black walnut---Juglans nigra L.---is native to and grows best on the deep well-drained soils of Missouri and the northern plains, or on alluvial (high in clay, silt and sand from rivers) soils in the South. Its leaves contain astringent properties, used medicinally by Native Americans, in folk medicine and by modern herbalists and alternative medicine practitioners.
Buds
The buds are pale, silky to the touch, ovate-shaped and grayish, according to the North Dakota State University Agricultural Department. Arranged in an alternating formation, buds are about one-third inch long, and slightly longer than wide.
Leaf and Leaflet
The leaves also have alternating formation and are pinnately compound (leaflets arranged in opposing pairs). Walnut tree leaflets may be up to 3 1/2 inches long and 1 1/2 inches wide. The entire leaf can be more than a foot long.
According to Purdue University, black walnut leaflets are generally smaller and narrower in shape compared with other walnut trees, and each leaf can have as many as 23 leaflets. They are round, asymmetric and finely serrated on the edges. The black walnut leaflets are yellow-green on the top, while pale and hairy on the bottom. Frequently absent on leaves from mature trees, the leaflet at the end of the long leaf is the terminal leaflet. In autumn, leaves change quickly from yellow-green to yellow-brown, with little showy color and may begin to drop by mid- to late summer in response to drought.
Odor
When rubbed or bruised, most parts of black walnut trees are aromatic, especially their leaves. When crushed, the leaves have a distinct pungent "walnut" smell.
Native American Use
Native Americans used the black walnut leaf to combat acne, eczema and ringworm. Its strong astringent properties promote antibacterial responses. Black walnut leaf is a source of vitamin C and thus protects from scurvy.
Folk Medicine
According to traditional folk medicine, black walnut relieves headaches, hepatitis, scabies and skin conditions.
Alternative Medicine
Alternative medical practitioners still use black walnut to treat a range of illnesses---everything from eczema to liver and gallbladder problems. High in tannic acid, black walnut leaf shares properties with other tannins, such as tea. Treatments to reduce perspiration, or for eczema, herpes and ulcers often use black walnut leaf as an external astringent. For hemorrhoid, liver and gallbladder problems, the black walnut leaf comes in capsule form.
Associated Properties
Medicinal properties associated with black walnut leaf include: anthelminthic (used against parasitic worm infestation), antibacterial, anti-candidiasis, antifungal, anti-inflammatory, antiviral, astringent and immune support.
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