The Nature of Walnut Trees
Why is it that very few plants can grow under walnut trees?
Its all in Juglones
Walnut trees are amazing, a royal pain in the ass and outstandingly beautiful all at the same time. Juglans nigra, the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in and near riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central Texas.
The trees are usually late to leaf out in the spring and among the earliest to lose their leaves in the fall with most of the energy going towards walnut production. The walnuts are lemon sized green balls made up of a fatty nut core, surrounded by a hard woody shell, covered in a dense green husky outer layer. The outer green layer turns black over time as it decomposes to expose the wooden central layer protecting the nut, hence the name “black” walnut.
At one time there were seasonal walnut purchasing depots spread across the common native range, where people could gather walnuts and exchange them for cash at the depots. The walnuts would be de-hulled and processed into raw walnuts and nut oils. The woody shells wood be ground up and used as a blasting media, for processes like sandblasting. The husky outer layers have medicinal purposes including treating athlete’s foot and worms.
Walnut products are still considered to be extremely healthy and provide a vital source of energy to the human body in the form of manganese – 55% of the daily value – which helps support metabolism as well as aid in bone structure and growth. In spite of the demand for walnuts for health and industrial use, the depots are virtually non-existant. Black Walnuts also contain a substantial amount of omega-3. This helps reduce cholesterol, which in turn reduces the risk of heart disease.
The lumber from walnut trees is among the most sought after and high dollar furniture woods produced natively in North America commanding high prices/board foot. As a timber, the material is easy to work with tools and the wood is prized for its character and beautiful color. Veins of purple and sometimes lighter tans can be found mixed into the more common dark brown tones. A side benefit is the beautiful, almost nutty aroma emitted when milling the wood.
This however is only part of the story. Walnut trees are part of the juglans family and thus produce a chemical that is toxic to many other plants and animals.