A study has been made of five species of the genusAmaranthus(SectionBlitopsis) which, though cosmopolitan, are predominantly tropical.Amaranthus tricolor, A. lividusandA. graecizanshave cultivated as well as wild forms butA. viridisandA. albusare not cultivated. All are monoecious and self‐compatible and exhibit both cross‐ and self‐pollination. Cytologicallv the species are uniformly diploid with x = 16 or x = 17, the latter being more common.The complex chromosomal associations observed at meiosis in the dibasic interspecific hybrids make it difficult to unambiguously pin‐point the ancestral number. Cultivated species have a relatively lower chiasma frequency compared with the wild species. An inherent heterozygosity resulting from repeated cycles of hybridization and selection in cultivation may be responsible for this be