Percentage frequency of rDNA sites along the chromosome arm in the most sampled families of angiosperms (a) and gymnosperms (b). The sites were positioned in one of four equal-sized regions of the arm or spanning the whole arm. p, proximal; ip, interstitial-proximal; it, interstitial-terminal; t, terminal; wa, whole arm. The number of karyotypes analyzed in each family appears in brackets.
Roa and Guerra BMC Evolutionary Biology 2012 12:225 doi:10.1186/1471-2148-12-225