Comparison of centimorgan lengths of linkage groups to physically measured date palm chromosomes. Al-Salih and Al-Rawi  reported the chromosome lengths (μm) of the date palm Ashgar cultivar utilizing microscopy. We plotted their reported lengths and the centimorgan based lengths of linkage groups reported in this study for the Khalas cultivar. The scaled lengths from the two methods show very good correlation over all. Differences in lengths may be due to differences in cultivar type or incomplete extension of the linkage group from unincorporated markers.