Morphology and morphometric diversity of pollen grains of 26 Indian species of <i>Dioscorea</i> L. (Dioscoreaceae)

Abstract

Pollen morphology of 26 species of Dioscorea collected from different regions of India was examined critically under LM and SEM to explore their unique features. Pollen grains were monad, isopolar, small to medium-sized (11.3–31 µm). Peroblate, oblate, suboblate and oblate spheroidal (P/E=0.41–0.90) pollen shape, mono and bi-sulcate aperture type and psilate, reticulate, rugulose, strito-reticulate, reticulate-rugulose, punctate and striate exine ornamentation were believed to be some of the important characters for differentiation of closely related species in this studied genus. The comprehensive qualitative and quantitative characters of the pollen grains served as reliable features in taxonomical studies. The observed data were analyzed using PCA and hierarchical clustering to obtain a steady relationship and grouping of the observed species. Histograms, pie chart and bar graph were performed to enumerate the distribution of the quantitative data of various attributes (long axis, short equatorial axis, pollen shape and aperture length). Correlation scatter plot along with density graph helped to understand the interrelationship amongst the studied taxa.