Sesbania is an erect annual herb of the legume family which typically grows to a height of 3 to 10 feet (1 to 3 meters). Its rather large leaves are 4 to 12 inches (1 to 3 dm) long with 20 to 70 leaflets per leaf. Flowers are 1/2 to 3/4 inch (15 to 20 mm) long, yellowish in color and strongly speckled with purplish brown.
It has slender, quadrangular pods, about 6 to 8 inches (15 to 20 cm) long and 1/8 to 3/16 inch (3 to 4 mm) wide. The seeds are small and numerous, about 1/8 to 3/16 inches (3 to 4 mm) long and 1/16 inch (2 mm) wide. The seeds are more or less orange on their attachment side, with the other surface possessing a more or less olive-green background, speckled or blotched with black.
This plant of the southeastern U.S. and adjacent Mexico ranges from South Carolina to the southern tip of Florida and westward to the eastern third of Texas. From there its range extends northward to Oklahoma, Illinois and Missouri. It has also been reported as an introduced species in the northeastern U.S.
Sesbania prefers wet, highly disturbed habitats and sandy sites. It occurs in low sandy fields, sand bars of streams, alluvial ground along sloughs and borders of oxbow lakes, and along roadsides, railroads, in disturbed urban sites and agricultural areas. It may become a troublesome exotic species in wetland communities that are managed for waterfowl.
Optimum germination occurs late in the growing season when mudflats are exposed during periods of elevated temperatures. Although germination is late (best following late spring or summer drawdowns), sesbania sometimes forms dense stands that preclude germination and growth of desirable moist-soil species. Longevity of seeds is great and sporadic occurrences are common, particularly following disturbance.
In Missouri, sesbania is most common in the Mississippi Lowlands counties of southeastern Missouri, but it also occurs in other scattered counties of southern and central Missouri.
Recommended Practices in Natural Communities of High Quality
Sesbania is not likely to colonize high-quality natural communities in Missouri as it typically grows in disturbed areas. Isolated occurrences may be found on sand bars along streams or along margins of oxbows or marshes. Spot treatment may best be accomplished by mechanical removal of the stems prior to the production of fruits. Follow-up will probably be necessary for several additional growing seasons if a seed bank is present or if reinfestation occurs. Another option would be to treat local occurrences with a foliar application of Rodeo (glyphosate) herbicide prior to fruit production. Follow-up will again be necessary if a seed bank exists at the site or if reinfestation occurs.
Recommended Practices on Lands Other Than High-Quality Natural Areas
Control of sesbania is best accomplished by creating conditions favorable for the germination of beneficial plants early in the growing season. Once established, beneficial plants can outcompete newly germinated sesbania. Therefore, control strategies should be performed early in the growing season. If early control is not possible, late disk-flood often prevents reestablishment of sesbania and creates conditions favorable for fall migrating shorebirds. This can be followed by an early drawdown during the subsequent growing season. Chemical methods of control include spraying with 2,4-D at the rate of 3/4 pint per acre, applying it with a boom sprayer. One can also wick the plants with Roundup or Rodeo. A mechanical method, such as mowing, should be accomplished prior to seed set if at all possible. One should mow as high as possible to preserve and promote growth of desirable plants in the understory.
Failed or Ineffective Practices
Burning appears to stimulate germination. Soil disturbance by disking also stimulates germination when done in early to mid-summer. A late drawdown during elevated temperatures and dry weather conditions stimulates germination as well.