The black walnut is a native of eastern North America
, where it grows alongside large rivers as far north as the Canadian
border. It is a large tree
attaining heights of 30 to 40 metres. Under forest competition it develops a tall, clear bole; the open-grown form has a short bole and broad crown. The bark is grey-black and deeply furrowed. The pith of the twigs contains air spaces. The leaves are alternate, odd-pinnate, the largest leaflets located in the centre. The male flowers are in drooping catkins 8 to 10 cm long, the female flowers terminal, in clusters of two to five, ripening in the autumn into a plum-like fruit with a browish-green, semi-fleshy husk and a brown corrugated nut. The whole fruit, including the husk, falls in October
; the seed is relatively small and very hard.
The black walnut was introduced into Europe in 1629. It is cultivated there as a forest tree for its high quality wood. It is more resistant to frost than the common walnut, but thrives best in the warmer regions of Europe of fertile, lowland soils with a high water table. It is a light-demanding species. The wood is used to make furniture and rifle stocks, and oil is pressed from the seeds.