Cytological studies of Thevetia peruviana L. and Catharanthus Roseus L.

Three varieties of Thevetia peruviana L. and Catharanthus roseus have been studied for chromosome number, chromosomal associations, chiasma frequencies, size of tetrads and pollen grains and pollen viability. In all the four plant types, the chromosome number remains more or less same (2n=16–22).Both bivalents and univalent have been observed in three varieties of T. peruviana, specially ring association. But in C. roseus, rod association is in higher frequency. Linear type of tetrads have not been found in three varies of T. peruviana but interestingly it is observed in C. roseus. The shape of viable pollen grains is quite similar in all four plant types.