Tough as a Black Locust

The Black Locust (Robinia pseudoacacia) long used as fence posts for its strong, rot-resistant and durable properties is the feature of today’s post. The black locust is spreading around the world’s temperate climate zones and in some places is considered invasive. The black locust has paired thorns, white flowers, 2-6 bean pods, compound leaves, 3 bud scars, and distinct barks that are deeply furrowed into long rough forking ridges. It is short lived, medium height (40’-80’), and can spread by rapidly sprouting from its stump (coppicing), a property that makes it a good candidate for firewood (but be careful, it is known to spark violently).

Toxicity, Food, and Medicine:

The locust can be poisonous to livestock and horses, but is a wildlife food source to pheasants, mourning doves, bobwhites, cottontail rabbits, snowshoe hairs, wild turkey, and deer.

The tree is reported to be toxic to humans, but the toxins break down when boiled for over 20 minutes.

According to herbs2000.com: the seeds and seed pods taste sweet after being cooked; “The peel of the fruits or berries is also used to prepare a potent, narcotizing and heady beverage;” the bark has been chewed to induce vomiting and to treat toothaches (be careful, the bark is the most toxic part of the plant); “When ingested, the leaves of the tree are able to enhance the secretion and flow of bile as well as soothe the aggravated organs. In addition to these, the juice extracted from the leaves help to combat or restrain viruses.”

The blossoms are used as vanilla flavor substitute, due to a substance called piperonal, and are used in making drinks, jams, and pancakes. Wildman Steve Brill uses the blossoms in a homemade ice cream recipe. The blossoms possess anti-spasmodic, diuretic, laxative and emollient (aptitude to soothe) properties. The flowers have also been reported to “contain an anti-tumor or tumor combating chemical called benzoaldehyde.”

History:

The black locust was the tree used in the original log cabins at Jamestown. The first cabins were built around four locusts as corner beams. In late spring its pendant spikes of honey-sweet blossoms, and the tree has been used as a honey plant (although it has a very brief blooming period-about 10 days).

The black locust has a long history in the WV coalfields. Millions of them were used as mine props, structurally supporting underground mines.

Strength:

The wood is tough! The woody cylinder is almost all heartwood, always the strongest part of a tree. It is the stiffest tree in North America, shrinks least when dried, and is the most durable hardwood (2 ½ times that of the white oak). It has the highest fuel value of any American tree, according to Peattie, “being almost the equal, per cord at 20% moisture content, of a ton of anthracite coal.”

Miscellaneous:

It has the peculiar feature of folding up its leaves during the night, a property that was once thought to conserve moisture.

It is a good pioneer species that is planted for shelter belts, and to prevent erosion, including on old strip-mines. The tree can handle rough soils because it has nitrogen-fixing properties. Flavonoids in the heartwood allow the wood to last over 100 years in soil. It is shade-intolerant, pollinated by insects and makes good bird and moth habitat.