Abstract
The complete pachytene complement of 18 bivalents from a single pollen mother cell of Hibiscus cannabinus is described. The bivalents are differentiated into short chromatic proximal regions and long achromatic distal regions which terminate without telochromomeres. Morphological relationships do not suggest that the present basic chromosome number of 18 arose by polyploidy from 9-chromosome genomes. Distal segment ratios, however, fall more or less into six groups of three, which may reflect ancient origin from 6-chromosome genomes.
