Periodicities in the Chromosome Numbers of the Angiosperms

The frequency curve for chromosome numbers in the monocotyledons, herbaceous dicotyledons, and woody dicotyledons has a zigzag shape with regularly alternating highs and lows. A numerical analysis of the peaks reveals the basic numbers that are important in monobasic polyploid series in each group. In the monocotyledons, all peaks in the frequency curve are multiples of x = 6-10 and 12; the most important basic numbers, as measured by their influence on the curve, are x = 7 and 10. In the herbaceous dicotyledons, all strong peaks in the curve are multiples of x = 6-10, 12, and 17; the most important basic numbers are x = 7-10 and 17. The strong peaks in the frequency curve for the woody dicotyledons are multiples of x = 8, 9, 12, 13, 17, 19, 23, and 41; the most important of these are x = 8, 9, 12, 13, and 19. The pattern of periodicities is complex in the woody dicotyledons due to a large number of effective basic numbers.