Cytogenetics of Aquatic Ornamentals

VI. Evolutionary trends and relationships in the genus Nymphaea

Abstract

Cytogenetical investigations were carried out on the Indian populations, both wild and cultivated of the genus Nymphaea. The chromosome counts revealed a polyploid series ranging from diploid to octoploid levels based on x=14. In majority of the members, various abnormalities in the mitotic and meiotic systems have been noticed. Pollen sterility and seedlessness were also found to be fairly high. The present findings along with earlier published work have been taken into consideration to trace the evolutionary trends and relationships in Nymphaea. Polyploidy, weak development of isolating mechanism, structural changes of chromosomes and gene mutations appear to have involved for the evolution in this genus.