Cytogenetics of the Indian Jasmines

II. The somatic chromosomes

Abstract

The karyotypes of four varieties of J. sambac and eight species were studied. The chromosomes in all the species show sub-median and sub-terminal constrictions besides being small and almost alike. The karyotype of the simple leaved species bears close resemblance to the trifoliolates than to those of the imparipinnately compound ones. In the sambacs, two groups of plants are recognized one with elliptic leaves and conical buds and another with ovate leaves and globose buds. The elliptic leaved group has longer set of chromosomes than the ovate leaved.
The nucleolus was found to persist throughout mitosis in all the species and its behaviour has been described. This feature appears to be a specific character.
The number of prochromosomes attached to the nucleolus at late prophase of mitosis and the number of nucleoli observed at early telophase suggest that the 26 chromosomed plants are in the nature of allotetraploids and J. angustifolium (2n: 52) an allooctoploid. J. sambac var. gunduinalli (2n: 39) and J. flexile (2n: 52) are in the nature of autopolyploids. Thus both allopolyploidy and autopolyploidy appear to have played a role in the evolution of the jasminums.