Any of about 20 species of deciduous tree s in the genus Juglans , family Juglandaceae.
Black walnut ( J. nigra ) of eastern North America and English, or Persian, walnut ( J. regia ), native to Iran, are valuable timber trees that produce edible nut s. The butternut ( J. cinerea ) of eastern North America also produces an edible nut. The walnut family contains an additional seven genera of flowering plants, found mainly in the northern temperate zone in a variety of habitats. hickory are among the many family members that are prized for both their edible nuts and their strong, attractive woods, especially noted for their grain patterns and lustre. Leaves of the walnut family are feather-like; tiny, resinous scales that look like yellow dots on the undersurface of the leaflets give Juglans species a pungent aroma.