Tree Notes is about trees -- especially native trees, trees for wildlife, and trees in history.

Monday, February 26, 2007

The Durable Wood of the Black Locust Tree

Robinia pseudoacacia, famed for fenceposts


Robinia pseudoacacia, by
Pierre-Joseph Redouté (1759–1840)


The following paragraphs were published in the magazine, Scientific American (Volume 2, Issue 16), on January 9, 1847. The first part talks about the strength of black locust wood when used in wheels, and the final sentences talk about its resistance to rot.

The following notes relative to the duration of the locust wood (Robinia pseudo acacia,) have been made by M. Pepin, Jardin du Roi, Paris :

A number of trees were felled that had been planted from 40 to 50 years; but not more than one to five of those wheelwrights [makers of wheels] who came to purchase, appreciated sufficiently the locust, the others preferring elm.

Black locust fenceposts, over 60 years old.
Black locust posts. Image by Flikr user
Putneypics, who states that this fence was
probably made in the 1950s (60 years ago.)
Ultimately the locust was sold to the persons who knew its value, at one third higher price than the elm. The purchasers found that spokes made of the wood in question lasted two sets of felloes [wheel rims], and were likely to answer for a third. Under equal circumstances of wear and tear, spokes made of locust wood were perfectly sound, while those of oak required to be replaced.

M. Pepin further states that the ends of locust gate posts which had been in the soil for
upwards of forty years were still not decayed.

This sort of wood employed as feet or supports to chests made of oak, proved sound, although the oak plank in contact with them had been thrice renewed; but oak supports decayed simultaneously with the oak planks composing the chests. Vine props of locust wood are greatly esteemed.

Black locust fenceposts enjoy a reputation of unusual durability to this day. Farmers in some areas have even planted locust groves in order to sell fenceposts. Since the black locust grows 2 to 3 feet per year and sends up suckers from its roots, a small grove could supply a lot of posts.

The trees are extremely vulnerable to damage from locust borers and other insects, so their wood is not often suitable for lumber. It is primarily used for railroad ties and (yes) fenceposts. It also makes great firewood, burning nearly as hot as coal.
Young black locusts in winter
A small black locust stand grows in
a pasture near my home
Black locust blossoms
Black locust blossoms photographed
by Flikr user Rasbak

A young black locust colony, mixed with sassafras, grows in our neighbor's milk-cow pasture along our lane. In spring, the fragrance of the locust blossoms is heavenly.

2 comments -- please add yours:

Anonymous said...

I have a huue one in my fornt yard
and has the identifying seed pods
but are of a "helicopter " variety
that twirl as they drop.
Do I have the right tree? Flowers and leaves are as decribed as are thorns. I love the tree as it has a bright shade of small green all summer with many,many white small flowers that bloom right after its' leaves appear.

Genevieve said...

It is possible that you have a honey locust, not a black locust. I suspect this because:

1. You mention the size of the tree. The honey locust is generally a wide-spreading tree, but the black locust is quite narrow and spare.

2. When I compare internet photos of the seed pods of both trees, the honey locust pods often seem to have a little twist to them that might make them twirl as they drop. The black locust pods seem to be quite straight in most photos.

Honey locusts usually have much longer thorns than black locusts. Black locust thorns would usually be less than an inch long, but big honey locust thorns can be 3 or 4 inches long.

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Enrich your life with the study of trees.

"The power to recognize trees at a glance without examining their leaves or flowers or fruit as they are seen, for example, from the car-window during a railroad journey, can only be acquired by studying them as they grow under all possible conditions over wide areas of territory. Such an attainment may not have much practical value, but once acquired it gives to the possessor a good deal of pleasure which is denied to less fortunate travelers."

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Print references I frequently consult

Benvie, Sam. Encyclopedia of North American Trees. Buffalo, NY: Firefly, 2000.

Brockman, C. Frank. Trees of North America: A Guide to Field Identification. Ed. Herbert S. Zim. New York: Golden, 1986.

Cliburn, Jerry, and Ginny Clomps. A Key to Missouri Trees in Winter: An Identification Guide. Conservation Commission of the State of Missouri, 1980.

Collingwood, G. H., Warren David Brush, and Devereux Butcher. Knowing Your Trees. Washington: American Forestry Association, 1978.

Dirr, Michael. Dirr's Hardy Trees and Shrubs: an Illustrated Encyclopedia. Portland, Or.: Timber, 1997.

Elias, Thomas S. The Complete Trees of North America; Field Guide and Natural History. New York: Book Division, Times Mirror Magazines, 1980.

Grimm, William Carey. The Book of Trees;. Harrisburg, PA: Stackpole, 1962.

Hightshoe, Gary L. Native Trees, Shrubs, and Vines for Urban and Rural America: a Planting Design Manual for Environmental Designers. New York: Van Nostrand Reinhold, 1988.

Little, Elbert L. National Audubon Society Field Guide to North American Trees. New York: Chanticleer, 1996.

Martin, Alexander C., Herbert S. Zim, and Arnold L. Nelson. American Wildlife and Plants. New York: McGraw Hill, 1951.

Mitchell, Alan F., and David More. The Trees of North America. New York, NY: Facts On File Publications, 1987.

Randall, Charles E. Enjoying Our Trees. Washington: American Forestry Association, 1969.

Settergren, Carl D., and R. E. McDermott. Trees of Missouri. Columbia: University Extension, 1995.

Sternberg, Guy, and James W. Wilson. Native Trees for North American Landscapes: from the Atlantic to the Rockies. Portland: Timber, 2004.

Wharton, Mary E., and Roger W. Barbour. Trees and Shrubs of Kentucky. Lexington: University of Kentucky, 1973.

Wyman, Donald. Trees for American Gardens. New York: Macmillan, 1965.

Photos and text copyright © 2006-2010 by Genevieve L. Netz. All rights reserved. Do not republish without written permission. My e-mail address is gnetz51@gmail.com