Variation in the number of rDNA sites per karyotype in a sample of 665 angiosperm (a) and 64 gymnosperm (b) karyotypes. Polyploid cytotypes and species with holokinetic chromosomes were not included. The median is underlined and the modal number is indicated by #. Sample size: 729 karyotypes.
Roa and Guerra BMC Evolutionary Biology 2012 12:225 doi:10.1186/1471-2148-12-225