Palynological Study of Some Astragalus L. Sections Distributed in Türkiye

In this study, the morphological properties of pollen of 14 species from 9 different sections of the genus Astragalus L. (Fabaceae) distributed in Türkiye were examined, identified, and compared under light microscope (LM) and scanning electron microscope (SEM). Pollen grains of the studied taxa are radially symmetrical and isopolar. Pollen shapes were determined as prolate, subprolate, spheroidal, and prolate-spheroidal. The polar axis lengths of the pollen grains were determined to be between 24.5 and 34.4 μm, and the equatorial axis lengths were determined to be between 22.4 and 27.5 μm. The aperture type of pollen grains is mainly trizonacolporate, rarely trisyncolporate. Colpus are thin and long with acute ends. The shapes of the pores were determined as oblate, suboblate, or oblate-spheroidal. Colpus lengths were found to be between 18.2 and 28.8 μm, and widths were found to be between 2.7 and 7.1 μm. In the studied species, four types of ornamentation were determined according to the differences in the polar region and equatorial region. Type 1: perforate in polar and equatorial regions; Type 2: perforate in polar region, microreticulate in equatorial region; Type 3: microreticulate in polar and equatorial regions; Type 4: psilate-perforate in polar region, microreticulate in equatorial region. Principal component analysis (PCA) and unweighted pair group method using arithmetic average (UPGMA) analyses showed that morphological characters of pollen grains were effective in distinguishing species but could not contribute significantly to a distinction according to sections. Pollen size, colpus characteristics, and ornamentation were determined to be important characteristics that distinguish the studied taxa. This study contributes to Astragalus taxonomy and different sub-branches of palynology.