Melotic anlaysis of 14 species in the genus Cuphea confirmed haploid chromosome numbers from 6 to 22. All accessions within a species were found to have the same number of chromosomes with the exception of C. leptopoda accession 264, which had n = 8, while the other three accessions were n = 10. The probability of chlasma formation between a pair of chromosome arms was calculated for each accession and values ranged from 0.565 to 0.905. An Interspecific hybrid between two diplold Cuphea species was formed and the melotic pairing data used to establish a protocol for estimating genomic affinity in Cuphea. Melotic analysis of another Interspecific hybrid between the autotetra-plold, C. caesarlata, and its diplold progenitor, C. llavea, showed that the genomes have differentiated very little and that diplodization in C. caesarlata must have occurred quite rapidly.