Black Walnut (Juglans nigra)



Common to Southwestern Ontario, there are isolated stands in the Ottawa Valley and black walnut trees are also being planted in other parts of the settled landscape in Eastern Ontario, where they are naturalizing. This tree is valued for its nuts and timber. Black walnut grows to about 30 metres in height with a straight trunk and open rounded crown. The roots are deep and wide-spreading, often with a taproot. Black walnut thrives on deep, moist, well-drained soils and does not do well in the shade but requires sun. The husks of the nuts are rich in toxins and tannins. The roots and decaying leaves of the black walnut release a toxin into the soil that prevents other broad-leaf plants from taking root close by. Black walnut makes an excellent yard tree if there is sufficient space.