Pollen micromorphology of some species of Gagea in Iran and its taxonomic implication

Abstract

Pollen grains of eight species of Gagea were examined using Light Microscope (LM) and Scanning Electron Microscope (SEM). Results showed that selected quantitative characters of pollen grains (polar axis, equatorial axis, P/E ratio, width of muri, lumina or pore number per 2 μm2 in the exine surface, and lumina or pore size) show significant variation providing potential diagnostic characters in discrimination of taxa in the genus. Among the pollen qualitative characters, pollen shapes varied from oblate to oblate-spheroid, and pollen size can be classified as medium (less than 50 μm) and large (more than 50 μm). Exine ornamentation in equatorial view and on sulcus margin region show also variation among the studied taxa. Cluster analysis of selected pollen morphological characters indicated two pollen groups and three types. The palynological types supported taxonomical situation of G. sect. Didymobulbos, G. sect. Plecostigma, and G. sect. Platyspermum. There is no pollen type for studied taxa of G. sect. Stipitatae. In addition, palynological issues suggest a close relationship between G. sect. Didymobulbos and G. sect. Stipitatae.