A premature disjunction of few to all bivalents during Meiosis-I is reported here in the genus Coix. This is a classic case of desynapsis type of mutation. The two species of Coix, Coixaquatica (2n=10) and nullisomic Coix gigantea Roxb. (2n=18) were artificially crossed. A range of interspecific hybrids from 2n=11 to 2n=26 was produced with varying numbers aquatica and gigantea chromosomes. Some hybrids were partially fertile and were selfed to study the inheritance of parental chromosomes in hybrids. Among the selfed progeny of hybrid with 2n=11 and tetrasomic C.gigantea (2n=22) two desynaptic mutants, one with 2n=11 chromosomes and another with 2n-22 chromosomes were obtained. Their detailed cytology and probable cause of this mutation is discussed.
