Sesbania Scop.
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).
Literature:
Bunma S. & Balslev H. (2019) A Review of the Economic Botany of Sesbania (Leguminosae). Bot. Review 85(3): 185–251.
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]
Farruggia F.T., Lavin M. & Wojciechowski M.F. (2018) Phylogenetic Systematics and Biogeography of the Pantropical Genus Sesbania (Leguminosae). Syst. Bot. 43(2): 414-429. [available online at: http://www.bioone.org/doi/full/10.1600/036364418X697175]