Walnut Trees

Scientific name: Juglans (genus)

Fact Box:

  • Order: Fagales
  • Family: Juglandaceae
  • Genus: Juglans


You may find this large, tall tree in a city park, where it provides ample shade, or planted in someone’s backyard. Walnut trees are famed for their longevity — for instance, English walnut trees may be 150 years old. The genus name Juglans comes from Jovis glans, meaning the nuts that Jupiter, the Roman king of gods, presumably ate.


Walnut-growers around the world most commonly cultivate the English walnut, Juglans regia, also called Persian walnut or common walnut (U.K.). This is the type of walnut that we usually buy from grocery stores.

Other common walnuts include the U.S. native Juglans nigra, or the black walnut, and the North American Juglans cinerea, the butternut.

The Southern California black walnut, Juglans californica, is a species native to California.


These uses apply to most species of walnuts, but there may be exceptions.

Medicinal: Traditional Chinese and Iranian healers, as well as others, use walnut bark in their medicine. For example, Chinese doctors use the extract of the English walnut to soothe inflammations and internal organs.

Artistic: To draw with walnut ink or dye cloth into a brown color, crush the walnut’s outer shells to obtain the nut-brown pigment. Or, in the Roman empire, you would boil walnut shells and other ingredients to produce a dark brown dye for your graying hair.

Consumable and more: People can eat shelled walnut nuts, which are high in healthy fats, oil, and protein. Chefs use walnut oil to cook; carpenters use walnut oil to polish walnut wood; cabinet-makers build cupboards out of walnut timber. And, of course, squirrels gather walnuts, in addition to other nuts, in autumn, in preparation for the winter months.

Fun fact: Out of the countries in the world, the U.S. and China export the most walnuts.