This study reports the chromosome number and meiotic behavior of 24 populations belonging to 16 species of Astragalus sect. Malacothrix from Iran. Thirteen populations showed the diploid chromosome number 2n = 2x = 16; consistent with the proposed base number of x = 8 from ICPN. However, tri-, tetra- and hexaploids were also observed in the rest of the taxa. Although the species displayed regular bivalent pairing and chromosome segregation at meiosis, non-oriented bivalents, laggard chromosomes, precocious migration of chromosomes to the poles, micronuclei, multipolar meiocytes, desynapsis, chromosome stickiness, bridges, asynchronism and cytomixis were also determined as meiotic abnormalities. Evolution in chromosome numbers in taxa belonging to A. sect. Malacothrix along with six other sections which have been classified under A. subgen. Hypoglottis is also discussed.
