PLANT OF THE WEEK

Dr. T. Ombrello - UCC Biology Department

 

BLACK WALNUT

 

Common names:            Black Walnut, American Walnut  

 

Scientific name:                 Juglans nigra    

 

Explanation of scientific name:       

Juglans - From the 2 Latin words “Jovis” meaning Jupiter and “glans” meaning nut.   The word is used most likely in reference to the ancient common name for walnut fruit:  nut of Jupiter.

nigra  - Latin for dark or black.

 

A 20 year old Black Walnut tree.

Found from Massachusetts to Georgia and west to the Great Plains, the Black Walnut is an imposing tree that has a long history of use by people.  Preferring the deep, rich, moist, but well drained soils of floodplains and stream terraces, the tree rarely dominates a woodland, but is often located in association with other hardwoods such as ashes, elms, maples, and sycamores.  

American Indians utilized the tree for its nuts (eaten raw or pounded into a “butter”) and tapped the trunk for sap to make syrup in the same way sugar maples were.  

The Black Walnut fruit ripens in October and has a yellow-green husk that encloses a black, round nut 1 to 2 inches in diameter.  The nut contains a fleshy, oily, but quite edible kernel.  Unlike its European relative the “English” or more appropriately, the “Persian” Walnut, the Black Walnut’s kernel is quite difficult to extract from the fruit.  The immature husk yields an indelible yellow dye that becomes an indelible black dye as the husk begins to deteriorate.  The dye stains everything, including fingers.  American Indians and the pioneers used it to dye their homespun cloth.  The husk is quite firmly attached to the nut inside.  Very difficult to crack, suggestions for breaking the nut range from running one’s car over it to attacking it with a hammer.  

Why would one want to bother?  The nut is nutritious, stores well, and becomes available when many other foods are scarce in the fall.  So, Native Americans and early colonists (beginning with Jamestown in 1609) searched for it.  Since the kernel’s distinctive flavor and texture are not lost in cooking, it is still used today (50 million pounds each year commercially and untold amounts for home use) in cakes, candies, and that traditional American favorite, Black Walnut ice cream.  New varieties of Black Walnut have been developed.  They bear fruit earlier in their lives (2 to 3 years after planting) with easier to crack nuts yielding half or even whole kernels instead of just small pieces.

Other interesting uses for the fruits would include grinding up the nutshells for cleaning abrasives and gas mask filters.  One use, found by accident by the author, would be of interest to fishermen.  Husks and nuts allowed to sit in a bucket of water for several hours will produce a dark brown/black liquid, which if poured over soil will in minutes drive every earthworm in the area up to the surface for easy picking.  

While their nuts are of interest and of economic importance, the wood is by far the most valued part of this species.  The early colonial settlers in America soon discovered the wood to be hard, yet soft enough to work easily.  It is coarse grained, finishes well, absorbs shock, only shrinks slightly when dried, and resists decay.  The outer sapwood of the trunk is white and not highly valued, but the inner heartwood is a rich dark chocolate brown of just about unsurpassed quality.  It was valued then, and even today it is undoubtedly the most sought after native American wood.  Used primarily for furniture, antique pieces may be of solid walnut.  Today, because of its rarity and expense, Black Walnut is cut into thin (1/32 or 1/64 inch) sheets    veneers to be glued onto inferior wood for most walnut furniture.  As in the past, Black Walnut is the wood to use for gunstocks.  Black Walnut paneling is available but is quite expensive.  Until it was replaced by synthetics, the wood was used for airplane propellers.

Unfortunately, because the demand is so great, they are rare in nature, and their growing time is so long (a minimum of 60 years to get a reasonably large trunk), we cut many more Black Walnuts than are started.  Buyers search out smaller and smaller trees as their value rises.  Prices are ridiculous.  A well grown, straight trunked, 200 year old tree can sell for tens of thousands of dollars.  But, such a tree could yield enough black walnut veneer to cover nearly 3 acres.

Black Walnut thieves are becoming common.  Usually posing as tree surgeons, they appear when homeowners are away and make off with the trees in a matter of hours.  Eight trees worth over $50,000 were cut from a property in Michigan, and at least several Black Walnut thefts are reported annually in New Jersey.  While not a danger of extinction, Black Walnut trees are becoming less common in the landscape.

Defenseless against a person with a chainsaw, Black Walnut trees do, however, have the capability of defending against plant competitors.  Black Walnut roots secrete a hormone, juglone, that will retard or kill such plants as alfalfa, tomato, potato, blackberry, blueberry, and rhododendron among others.  This chemical inhibition of surrounding vegetation is termed allelopathy.  While some plants are hurt, other surrounding plants are promoted.  Beets, beans, corn, bluegrass, raspberry, grape, and even poison ivy are helped, or at least unaffected by the juglone.

An all-American tree that is exploited but certainly not unappreciated by those who recognize its beauty, the Black Walnut’s status and value are likely to continue to rise.