Wow, thank you, I had no idea. The walnut tree uses the poison to kill competitors, up to 20m away or more. Black Walnut: The Killer Tree https://www.extension

Wow, thank you, I had no idea. The walnut tree uses the poison to kill competitors, up to 20m away or more. Black Walnut: The Killer Tree https://www.extension.iastate.edu/news/2005/jul/070701.htm https://www.extension.iastate.edu/news/2005/jul/070701.htm https://en.wikipedia.org/wiki/Juglone https://en.wikipedia.org/wiki/Juglone "Juglone is occasionally used as a herbicide. Traditionally, ...has been used as a natural dye for clothing and fabrics...and as ink. ...has also found use as a coloring agent for foods and...hair dyes. ...is currently being studied for its anticancer properties"