Black Locust

Scientific name:
Robinia pseudoacacia

Other names:
Bastard locust
Black laurel
Common locust
Common robinia
False acacia
False black locus
Green locust
Honey locust
Pea flower locust
Post locust

Black locust is native to the Appalachian Mountains from Pennsylvania to northern Georgia and Alabama and to the Ozark Mountains of southern Missouri, Arkansas and eastern Oklahoma; also in southern Illinois and Indiana.

Black locust has been extensively naturalized in the United States and Canada. The trees are 40 to 60 feet tall and 1 to 2 feet in diameter. On good sites the trees may develop a clear straight bole. Other trees may be short boled with spreading branches. The largest reported specimen is over 8 feet in diameter at 4½ feet above the ground.

Weight:
Density at 15-percent moisture content is 49 pounds per cubic foot. Specific gravity 0.66; 58lb/ft³; 929 kg/m³.

Use:
Fencing, insulator pins, furniture, mine timbers, treenails for ships. The trees are used in strip mine reclamation because of their ability to survive the acid conditions and for their nitrogen-fixing roots.

General characteristic:
The sapwood of black locust is a creamy white, while the heartwood varies from a greenish yellow to dark brown. The wood turns a reddish brown when exposed to the air. The wood is often confused with osage orange (Maclura pomifera).

Working properties:
It works well with machine. However, it is difficult to nail and fasten with screws unless pilot holes are drilled.

Drying and shrinkage:
A mild kiln schedule is used when drying the wood. Since the wood does not shrink excessively, degrade is likely to be minimal. The total volumetric shrinkage for honey locust is 10.8 percent. Given the high density of locust the shrinkage is very low. It shows slight shrinkage and stays in place well Thus, the wood should be relatively stable in use.

Durability:
Black locust is very strong in bending and is one of the hardest woods in America. Its shock resistance is almost that of hickory (Carya spp.)The heartwood is rated as very resistant to decay. This resistance has resulted in specialty uses for the wood. It is important to note that only the heartwood is resistant and even the heartwood of some young, fast-growth trees may not have the resistance of older trees from which the species earned this reputation.

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