In order to find out how far karyotypic changes or undetectable gene mutations have been associated with the origin of different varieties of Lathyrus odoratus, which differ in flower colour, leaf nature, tendril character etc., a thorough analysis of the karyotype of different pure varieties of L. odoratus have been carried out in the present investigation. For this purpose a new improved method involving pre-treatment with paradichlorobenzene was employed and the procedure for all the strains had been kept constant.
It has been revealed, that in spite of a homogeneity amongst all the strains, each strain is characterised by its own karyotype. They mainly differ with respect to the number and position of constriction regions in chromosomes. All these facts suggest that the structural changes of chromosomes have always been associated with the evolution of different varieties.
Regular meiosis noticed in these strains can be explained by assuming that through extensive cultivation and selection all the structural alterations have attained a state of homozygosity.