Cytological evolution among South IndianCyanotisD. Don (Commelinaceae)

Abstract

SUMMARYKaryotypes of 15 species of Cyanotis are reported. C. adscendens (2n = 48) is a tetraploid. The remaining species are diploids having 2n = 24 or 20 or 16 chromosomes. Adaptations for self pollination, and annual growth habit are cited as reasons for the low incidence of polyploidy in Cyanotis. C. pilosa (2n = 24; n.f. 30) is shown to be the nearest among the reported taxa to the most primitive species in the genus—C. villosa. C. wightii (2n = 24; n.f. 32) is shown to have a more symmetrical karyotype than the above two. C. arachnoidea, C. cristata, C. fasciculata, C. longifolia ssp. longifolia var. rupicola, C. nodiflora, C. obtusa and C. vaginata, all with 2n = 24; n.f., 26, have asymmetrical karyotypes. C. tuberosa, C. sarmentosa (2n = 24) both having n.f. 24 and C. adscendens (2n = 48; n.f. 48) have highly asymmetrical karyotypes. Karyotype of C. papilionacea (2n = 16; n.f. 20) is shown to be nearer to the arachnoidea type inspite of the reduction in chromosome number. The above species groups, ...