For me, this is unusual as I am curious about everything and yet missed a great lesson in growing vegetables and flowers. This particular tree is central to a small habitat that I have and use to attract birds and other critters. It has the in-ground birdbath, (See the post on ants swimming), the hummingbird feeder, and the suet feeder for the woodpeckers and other clinging birds. Of course, squirrels also like to try to get to the suet but that is another story. But, it is an area that I have tried to grow several types of flowers including annuals and perennials. But most failed and I was perplexed to say the least. I had some success with Impatiens and Morning Glories but everything else that I tried died fairly quickly. So, I set out to find out why I was having so much difficulty with this area. And, it all started with this tree in the cover photo.
I began by identifying the seed, or in this case the drupe. (The outer fleshy part containing a seed). I determined that the tree was an Eastern Black Walnut and that it has some very interesting chemistry. Black walnut drupes contain Juglone, (Ju Glone) which is 5-hydroxy-1,4-napthoquinone, yellow quinone pigments, and tannin. The juglone is an alleochemical, a biochemically active material that has an influence on the growth of other living organisms including plants, bacteria and fungi, and even people. Alleopathy can be either positive or negative, and in the case of the flowers I was trying to grow, it was having a negative effect. But, we know that there is what is called "companion gardening" where one plant can be beneficial to another.The area that was not conducive to growth in my case extended from the expanding roots to the drip line of the tree. So, if I had identified the tree sooner I could have saved a lot of time and energy. This is a lesson well-learned.
But, that is not the end of the story of black walnuts. The liquid portion of the drupe is brown and stains everything that it comes in contact with and has been used as a dye for centuries. The tannins react with iron and can make a good quill ink. There is a post from the Ohio State University Extension Service on toxicity and some of the plants that will grow with the black walnut tree here. I have also included the following photos of black walnuts in various stages of ripeness as well as the ripe inner edible fruit: