Abstract

Detailed cytological studies were carried out on three species of the genus Vernonianamely Vernonia amygdalina (bitter leaf and non-bitter leaf), Vernonia cinerea andVernonia conferta to ascertain their chromosome number. The taxa studied showed diploid number of chromosome for V. cinerea (2n = 18) and V. conferta (2n = 20) and tetraploid number for V. amygdalina (2n = 36). The karyotype show nine (9) pairs of submetacentric chromosomes in V. cinerea and 10 pairs of submetacentric chromosomes in V. conferta. The karyotype of V. amygdalina (bitter leaf) varied from that of V. amygalina (non-bitter) by being larger in size and with a pair of telocentric chromosome. The studies of the pollen fertility suggest that V. amygdalina is an amphidiploid.

Key words: Chromosome numbers, karyotype, polyploidy, Vernonia.