Black Walnut

About Black Walnut in Alberta

Black Walnut is a foreign Alberta tree whose presence in the province is primarily planted rather than wild. Native to eastern and central North America, it appears in Alberta mainly in sheltered urban, estate, institutional, or other deliberate landscape settings where soil quality and microclimate are favorable. It is best recognized by its long compound leaves with many narrow leaflets, dark deeply furrowed bark, and large round green husks that blacken as they age. For ARA purposes, its importance in Alberta is mainly historical, horticultural, and rarity-based rather than ecological in the native-forest sense.

Identification: Leaves are long, alternate, and pinnately compound, usually with 15-19 leaflets and sometimes more. The leaflets are narrow, sharply serrated, and often taper to a long point. The terminal leaflet is often reduced or absent, which is a useful field character.

Alberta range and habitat: Black Walnut should not be treated as a wild Alberta tree. No strong evidence supports it as part of Alberta's native forest or riparian flora.