Sesbania is a pantropical genus of ca. 60 species. Several species have some economic importance and are cultivated for fiber or as ornamentals (but probably none in Belgium). Some are more or less widespread agricultural weeds in the tropics, including Sesbania herbacea.
Additional alien: Sesbania cannabina (Retz.) Pers. (Austr., Afr. As., wool alien).
Burbidge N.T. (1965) Australian species of Sesbania Scop. (Leguminosae). Austr. Journ. Bot. 13:103-141. [available online at: http://www.publish.csiro.au/BT/pdf/BT9650103]