Black Walnut Tree

Botanical name: Julans nigra
Family: Juglandaceae (Walnut)

Click on images of Black Walnut to enlarge.

Black Walnut - Julans nigra - Leaf

  • Native
  • Deciduous
  • Hardwood
  • A large tree 65-95 ft. in height, sometimes reaching over 135 ft.
  • Produces large, edible walnuts with a very hard yellow-green husk, turn darker when ripe and can be used as a dye
  • Deep, dark furrowed bark that creates a diamond shaped pattern
  • Long leaves are alternate and pinnately compound with 15-23 leaflets per leaf
  • The leaflets have very fine serrations on their margins
  • Prized for it’s hardwood (to the extent that there have been accounts of stolen trees by people pretending to be tree workers) which has been used to make fine furniture, rifle stocks and flooring
  • Black walnut roots produce a hormone called juglone, which is toxic to some species of plants that may be growing nearby.
  • Unfortunately, many of the black walnut trees are now dead or are dying here in the Boulder, Colorado area due to The Thousand Cankers Disease – Geosmithia canker fungus transmitted by the walnut twig beetle (Pityophthorus juglandis).
  • Zones 4 to 9