Common Name
Black Locust, locust, false acacia
Botanic Name
Robinia pseudoacacia
Plant Family
Prefers moist soils, along waterways and often planted as an ornamental, tolerating dry climates.
Black locust trees have become naturalized from Maine to California, and southwards.
Animals Affected
Horses, cattle, chickens and children
Black Locust - Robinia pseudoacacia
Toxic Principle
Robinin, a lectin (glycoprotein) with similar properties to ricin and abrin found in castor beans and rosary peas respectively. The bark and seeds contain the highest levels. There is considerable variation in the toxicity of the trees depending on their growing conditions. The new growth is most toxic. The toxicity of Robinia neomexicana has not been determined.
Shrub small tree up to 70 feet in height.The trunk is usually straight and the branches, smooth with sharp thorns.Leaves are alternate, pinnate with elliptical leaflets in 3-10 pairs.Drooping clusters of perfumed, white or pink (R. neomexicana) flowers are produced in early summer. The fruits are straight, flat, many seeded brown pods hanging in clusters. The pods of Robinia neomexicana (New Mexico locust) have distinctly hairy pods, and the flowers are pink in color.
Abdominal pain (colic), and constipation followed by diarrhea.
Muscle weakness and posterior ataxia. Horses may develop laminitis.
There is no specific treatment. Supportive therapy including activated charcoal via stomach tube, and intravenous fluids to combat dehydration and shock in severe cases.
Respiratory System
Rapid respirations
Ocular System
Dilated pupils
Diagnostic Tests
Diagnosis of black locust poisoning is based on the clinical signs, and evidence that the bark or new growth of the tree has been eaten. There is no readily available means of detecting robinin in the tissues of animals poisoned with black locust. Post mortem findings are not specific.
Special Notes
Black locust should not be planted as a shade tree in or around livestock enclosures. Reference Burrows GE, Tyrl RJ (Eds.)Toxic Plants of North America.Iowa State Press. 2001, 602-604.
New Mexico locust - Robinia neomexicana
Robinia neomexicana
Flowers and pinnate leaf of Black locust
Seed pods of Black locust