Karyological Studies in Some African Species of the Genus Sesbania (Fabaceae)

Abstract

Karyological criteria of 15 African species of Sesbania, including five new records, are presented. A diploid number of 2n =12 (x=6) has been found in 12 species, 2n =14 (x=7) in one species and a tetraploid number of 2n =4x=24 was recorded in S. formosa and S. grandiflora. The karyotype in the examined species is symmetric. However, considerable variation exists in chromosome size among the species studied. The result of the present study confirm that x=6 may be considered the basic number in the genus. Our observations further indicate that Sesbania is a primitive genus in its tribe Robinieae from which other genera may have evolved through aneuploid and polyploid changes.