Versatile bigpod sesbania has toxic qualities

The unexpected arrival off the highway of visitors has a variety of implications and possible consequences. Some can be positive, and some negative. 

The surprise appearance in many cases leaves the host scrambling to react appropriately and recover from their lack of awareness to the potential of a stopover. The soon-to-arrive holiday season has so many opportunities for unexpected guest showing up seeking lodging and a meal or two. 

Curiously, this also happens occasionally on thoroughfare right-of-ways when unexpected species sprout from the road’s shoulders. Such has been the case currently in rural areas with a cluster of bigpod sesbania.

Sesbania herbacea, as it is scientifically known, is a native of the southeastern U.S. However, it has only been in Leon County once before, in early 2008, by the Center for Invasive Species and Ecosystem Health.

This quick growing semi-woody perennial has its good traits. This plant attracts and supports beneficial insects with its leaf margin glands which secrete sugars. 

Its seed persist through the winter and are a food source for local game birds. In other regions of the country the seed are mixed with brown top millet in game plots. 

This versatile plant has even been used as a soil improving crop. It is reputed to produce between two and three tons of biomass per acre in 75 days which contains between 90 to 130 pounds of nitrogen. 

The plant fibers have been used in a variety of homemade crafts in the region, earning it the common name Hemp Sesbania. Its stems can even be used in paper production if, for some reason, pine trees became extinct. 

Unfortunately, this surprise arrival has its problematic features too. The Sesbania species are potentially toxic, containing a compound identified as saponin. 

It has been reported that ingestion of the genus has poisoned cattle in Florida and Texas. Despite the toxicity issue, the plant is palatable to cattle and is alleged to have some nutritional value. 

Additionally, this species serves as host for several insects which also attack crops. The biggest issue with this legume is it rapidly becomes an aggressive invasive weed and pushes out other species. 

It quickly grows to ten feet tall, and while it has only a few wide reaching branches it grows in dense thickets. It produces yellow or yellowish orange flowers which are streaked or spotted with purple. 

Bigpod Sesbania produces elongated seed pods containing 30 to 40 seeds each. The seeds are mottled with orange, brown and greens. 

In warmer areas this plant can live 20 years, but is found as far north as New York where is grows as an annual. The southern range of this Sesbania species is Central America and is encountered in south Florida too.

Bigpod Sesbania grows well on disturbed sites with full sun. This can include ditches, fencerows, riverbanks and many roadsides. 

The origins initiating the local germination are uncertain. It could be environmental factors aligned and the seeds, which was lying dormant in the soil, sprouted and grew.

Another possibility is an unseen specimen had seed which were relocated to the current germination site. Lastly, seed could have come into the area in fill dirt.  

No matter, unless these unexpected species are removed along with their seed, more will be appearing next year. Guests then become residents.

To learn more about Bigpod Sesbania, contact your UF/IFAS Wakulla Extension Office at 850-926-3931 or http://wakulla.ifas.ufl.edu/

Les Harrison is the UF/IFAS Wakulla County Extension Director and Agriculture and Natural Resources Agent.