Quantitative karyology of some species ofLuzula

The dimensions of metaphase chromosomes and nuclear DNA contents were measured in eight species ofLuzula. The 2 C DNA contents ranged from 8.51 pg inL. purpurea to 0.55 pg inL. pilosa. Total chromosome volume shows a linear relationship with DNA content; however, the total chromosome length of the complement of the different species is approximately constant. Nucleolar volume and the number of chromocentres in the different species also show a relationship with DNA content. Taken together, these data suggest that while chromosome fragmentation could have generated the present-day range of chromosome numbers in the genus, there have also been changes in the total quantity of DNA with the result that species with similar chromosome numbers have different DNA contents. The relationships of DNA content with chromosome volume inLuzula and other genera are compared and the differences discussed.