Sesbania sesban (L.) Merr.
Aeschynomene sesban L., S. aegyptiaca Poir.
Eng.: River bean, Egyptian riverhemp. Ara.: Saisaban. Tamahaq: Takawurat, takawuat, akawat, asarara.
Shrub or small tree, up to 5 m in height, hermaphrodite, deciduous, glabrous or glabrescent. Leaves alternate, paripinnate, stipulate, with rachis 4-14 cm and petiole 0.5-1.5 cm, with 16-48 leaflets, 1-2.2 × 0.5 cm, linear-oblong, glabrous, with obtuse or rounded apex. Inflorescence in axillary racemes, 2-10 cm, pedunculate, with peduncle 2-4 cm, with bracts and bracteoles often caducous, and with 2-12(18) flowers. Calyx 4-5 mm, campanulate, with 5 lobes, 0.5-1 mm, triangular-acuminate. Corolla papilionoid, yellow, glabrous, with standard 1.2-1.4 × 2 cm, with the dorsal side mottled purple and with some acute or rounded free appendages (2-5 mm) on the upper margin. Pods 10-20(25) × 0.4 cm, straight, cylindrical, with 15-40 seeds. Seeds 3-3.5 × 2 mm, subcylindrical, mottled violet.
Flowering:
March to April, although there may be flowers in other times of the year depending on rainfall.
Fruiting:
About 2 months after Flowering.
Sometimes the same plant can have flowers and mature pods at the same time.
Habitat:
It is often grown for fodder or as an ornamental; and in crop rotation for nitrogen fixation. It is naturalised in the surroundings of cultivation areas.
Distribution:
Paleotropical, African-Asiatic, widespread in Africa; it appears to have originated in Egypt, Sudan, Somalia and Ethiopia. In Egypt it reaches the Mediterranean coast.
Observations:
Another species of the genus, S. sericea (Willd.) Link (Coronilla sericea Willd., S. pubescens DC.), is quite similar, but is an annual or short lived herbaceous plant, sometimes woody at the base, that can reach more than 1 m in height. It is smaller, mostly herbaceous and completely pubescent, with the exception of the flowers and fruits, which makes it easy to separate them. With a subSaharan distribution, it is found cultivated in other parts of the planet. In North Africa it grows in the Sahel, from southern Mauritania to southern Sudan. In Egypt it is found as a ruderal species, probably naturalised in the surroundings of cultivated fields and the slopes of ditches or canals.
Conservation status:
Relatively common and widespread species, not considered threatened. Currently, they have not been assessed at a global level in the IUCN Red List of Threatened Species.