Black Locust

Categories: Trees

There is an area of campus called Stewart Woods-it’s south of Stewart Hall, on the other side of the road, next to the graveyard. Our department mows underneath the trees, forming a beautiful little grove next to the road. The trees are black locust, Robinia pseudoacacia, and are in full bloom right now. A favorite of honeybees, walking over there you can just hear the air humming with the sound.

Stewart Woods in bloom

Stewart Woods in bloom

Native from Pennsylvania to Georgia, west to about Oklahoma, early settlers have since dispersed the tree far and wide. Like the lilac, old house and farm sites in Vermont can often be found by the black locust trees nearby. They had multiple uses back then, and still would, were it not for the locust borer, a destructive insect wiping out nearly all the magnificent trees in the prime of their life. The trees grow in groves, suckering up from their roots, making sharing trees with your neighbors easy. (This is like a lilac as well-popular early colonial plants were easy to propagate.) The wood was used not only for burning, with a very high BTU, matching an equal weight in coal, but also for fence posts, nearly never rotting when in contact with the ground. In fact, Donald Peattie in “A Natural History of North American Trees” quotes mark Catesby, a British naturalist who visited Jamestown a century after it’s founding. He states “they erected each of their little hovels on four only of these trees ( the locust tree of Virginia), pitched into the ground to support the four corners; many of these posts sare yet standing, and not only the parts underground, but likewise those above, perfectly sound”.

So, apparently, no “log cabins” for our early settlers, but an impressive grasp of the semi-colon.

The latin, Robinia,  honors either Jean Robin, or son Vespasien, who grew seeds of the tree sometime between 1601 and 1636, and introduced the tree to France, where it became all the rage. The wood is so strong, it is also used for nails on ships, lasting longer than the hulls they held together. The British used the superiority of our hastily built “locust fleet” as an excuse for their defeat on Lake Champlain in the war of 1812. The nails, also called Trunnels, took advantage of the nature of Locust wood, that when wet it expands and becomes leak proof.

Peattie expands the tree nails story, writing of William Cobbett, a famous English publicist and economist, who between 1917 and 1819 started a Black Locust grove on his farm on Long Island, hoping to supply the British navy with tree nails. He had to hurridly leave what he undoubtedly still called the ‘colonies’, having been chased out by popular opinion for libeling Dr. Rush for having killed George Washington by malpractice. He returned to England with some Black Locust seed, and the corpse and coffin of Thomas Paine, planning to re-intern the body in a spectacular monument to atone for his former attacks on the author. He never finished, the coffin auctioned to a furniture dealer, the corpse inside lost to history.

A special strain of Black Locust used to be described as “Shipmast Locust”, having perfectly straight and clear trunks for many feet, yielding valuable timber. It used to be described as a separate species, until botanists yelled foul, merging it back with the normal Locust, as it was probably just a cultivar asexually propagated by root suckers.

The tree itself grows fairly straight, only branching at the top. The leaves are a nice light green, aboiut 6-12″ long, with many leaflets at about 1-2″. The leaflets fold up at night and droop, making people believe the tree is conserving water, but that is a non-issue at night, so other guesses must be made.

Black Locust Bark

Black Locust Bark

 The bark is a light grey, but unmistakably furrowed and rough. The blooms are white, and hang in clusters 4-8″ long  from the branches. The scent needs to be experienced, but is spectacular.

Black Locust Flowers

Black Locust Flowers

Gardeners would recognize the bloom as similar to peas, and indeed they are in the same family. Black Locust has the ability to fix nitrogen, like all legumes, so the tree is often listed in the saddest of all plant use lists, Mine Reclamation. Micheal Dirr calls it an “Alley Cat Tree”, more as an indication of hardiness and usefulness than anything else. It is a common tree in China, and is called “yanghuai”, or Foreign Scholar Tree, as it does mimic the Scholar Tree native there.

There are many Black Locust trees on campus aside from Stewart Woods. Off the top of my head, I can think of Nichols House, below the ledge at Gifford, McKinley House, and next to Hillcrest Road. The oldest and largest are probably at the McKinley House.

P.S.- A public apology. While running a garden center and growing trees in pots, I became enamoured of a cultivar of Black Locust called “Purple Robe”.  This was a beautiful tree. Nice round shape with good branching, not like a normal locust, crisp lime green leaves, and spectacular purple flowers instead of white. We grew and sold many of them, and it was easy, for they grew fast and looked good in a pot. I even planted one in my back yard, and it would slow traffic down on our road in flower.

Purple Robe Locust Flowers

Purple Robe Locust Flowers

After several years, the trees started falling apart, literally. Some would get a couple of locust borer holes, and snap in half at a gust of wind. Others would branch poorly, and split down the middle. Still more woiuld get riddled with borer holes so bad as to just up and die. Mine did all three.

I only mention all of this because I still run into former customers in town that will not talk to me, or even nod a hello, mad at me for making them fall in love with a fast growing shade tree that died a premature death. It’s terrible to see a tree die in the prime of its life, and believe me, had I known, I wouldn’t have grown or sold them. Sometimes a plant that does well in one part of the country does poorly elsewhere, but that’s not really an excuse, is it?

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