At Sweetwater Wetlands Park in Gainesville, FL, I noticed a pair of wispy trees along the boardwalk. They had orange-red blooms, but it was the draping compound leaves that caught my attention.
Other people have noticed the plant’s beauty as well, and Sesbania punicea has been widely imported from South America as an ornamental garden plant. Among gardeners it is known as Scarlet Wisteria or Chinese Rattlebox.
Mild winters across the southern United States have allowed this plant to spread. It grows in wetlands and along streams and rivers. Special cells in its bark allow it to exchange gases with the environment, and it thrives in poor soil.
In only a few years, Sesbania punicea reaches its adult height of 15 feet, and by this time is producing 100-1,000 seeds annually. The seed pods, which rattle when shaken, float in the water. This allows them to be carried to distant locations, where they embed along rivers and streams. Growing profusely, the trees form dense thickets that block water passage and choke out the native plants that prevent erosion. When conditions are unfavorable for Sesbania, the seeds can remain dormant for years.
Every part of this decorative plant is toxic. The bitter seeds are particularly dangerous, and even a small dose can be lethal to wildlife, livestock, and humans. Sesbania is sometimes unknowingly fed to horses. When the plant infiltrates hayfields, it is mown and bundled with the grasses. Symptoms of Sesbania poisoning in mammals include loss of appetite, vomiting, respiratory failure, rapid pulse, diarrhea, weakness, jaundice, ataxia (unstable gait), head pressing (the animal pushes its head against something hard), and lameness.
UF/IFAS Center for Aquatic and Invasive Species
The University of Texas at Austin
California Department of Fish and Wildlife
CarolinaNature.com (Visit this site to see excellent photos of the seeds and blossoms.)
University of California, Davis. Book excerpt: Weed Control in Natural Areas in the Western United States.
NC State Extension Gardener Plant Toolbox
Photo © Carol Fullerton-Samsel 2021