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Family: Juglandaceae - Walnut family
Latin name: Juglans nigra
Common name: Black walnut
Black walnut produces a toxin, known as “juglone”, which may inhibit the growth or kill other plants in that around them. The largest sources of juglone on the tree are located in the roots, but buds, leaves and nut hulls can also cause problems.
Mature black walnut trees are usually 70-90 feet tall and 2-3 feet in diameter at breast height. However, black walnut trees can reach 150 feet tall and 8 feet in diameter if they are growing in the forest or are planted close together.
The branches are widely spread and form a massive crown. The bark is thick and brown to grayish-black in color. The bark has deep furrows and narrow forking ridges. The furrows and ridges form a diamond pattern. The twigs are stout with notched leaf scars. They are light brown to orangish in color. The terminal buds are short, blunt, and covered with a few hairy scales. The leaves are up to 6 dm long with 9-23 leaflets attached directly to a stout rachis without a supporting stalk. The rachises are covered with fine short hairs. Flowers appear in late May to early June. The flowers bear 17-50 stamens, but lack pistils. The fruits are 4-6 cm in diameter and spherical shaped. They can be found in groups of 2-3 or solitary. The fruits have a thick, semi-fleshy, husk covered with short hairs and are yellowish-green in color. The nut is corrugated with rounded ridges.
Karren Wcisel © copyright 2004 - 2009
Please ask for permission before using my photographs. Larger sizes and additional photographs of the tree are usually available.