Detailed karyomorphology of four diploid species of Smilax such as S. aspera (2n=32), S. bracteata (2n=32), S. wightii (2n=32), S. zeylanica (2n=32) and of three polyploid cytotypes of S. ovalifolia (2n=64, 96, 128) from South India has been studied.
All the species are based on x=16. Their chromosomes are small sized, and karyotypes strinkingly asymmetrical (3B and with low TF% values). The diploid species are similar in gross karyomorphology; but in finer details recognisable difference is evident in a few chromosomes. In S. aspera, one chromosome (No. 7) is heteromorphic in male plants.
Systematic relationships of the genus Smilax is viewed in the light of chromsome data. The chromosome features lend support to the removal of the genus from the Liliaceous assemblage, and to the creation of a separate family (Smilacaceae) around it. The proposed affinity between Smilacaceae and Dioscoreaceae is favoured.