Studies on the South Indian Compositae. IV. Karyomorphology of eight species of Vernonia Schreb.

Abstract

Detailed karyomorphology of eight South Indian species of Vernonia falling under two basic series x=10 and x=9 has been studied namely, V. anthelmintica (2n=20), V. beddomei (2n=18), V. bourneana (2n=20), V. cinerea (2n=18), V. conyzoides (2n=18), V. divergens (2n=18), V. elaeagnifolia (2n=40) and V. malabarica (2n=18).Karyomorphological data indicate that both the basic series are moderately asymmetrical (2A and 2B). In finer details, x=9 group is seen to possess greater karyotype asymmetry.Karyotype specialization in both the series has been more through shift of centromere position which in the case of x=9 species involves more number of chromosomes.Data on the solitary polyploid species, V. elaeagnifolia appear to indicate that polyploidy and factors leading to karyotype asymmetry have been operating concomitantly in the species.