RELATIONSHIPS BETWEEN LATHYRUS CASSIUS, LODORATUS, AND LHIRSUTUS ASSESSED BY EXPERIMENTAL HYBRIDIZATION, ANALYSIS OF MEIOTIC PAIRING, AND DNA DNA HYBRIDIZATION

Relationships between three species of Lathyrus, including L. cassius, L. hirsutus, and L. odoratus, were studied with hybridization, cytoge netic analyses, and DNA dot blots. Broadly similar results were obtain ed with these methods, showing that L. cassius, L. hirsutus, and L. od oratus are all closely related, with L. odoratus more closely related to L. hirsutus than L. cassius. Hybrids were formed between the three species, but only those between L. odoratus and L. hirsutus show high levels of fertility and more or less regular chromosome pairing at mei osis. Despite having similar karyotypes, L. cassius had large centrome ric C-bands that are absent from L. hirsutus and L. odoratus. DNA dot blots showed that the three genomes were equally different from each o ther. Reciprocal differences in flower morphology and metaphase I chro mosome pairing were seen in hybrids between L. cassius and L. hirsutus . A modification of the most recent systematic placement of the specie s is suggested so that L. hirsutus is allied with L. cassius and L. od oratus with L. chloranthus.