Foliar and pollen grain micromorphology of some species of Astragalus

The present study is focused on identifying the differences between the closely related sections Microphysa and Campylanthus in the genus Astragalus using micromorphological characteristics. For this purpose, the morphological characteristics of leaf epidermal cells and stomata as well as pollen grains have been studied. The results obtained from light- and scanning electron microscopy (LM and SEM) indicated that, stomatal type was typically anemocytic in most species, while the anisocytic type was only found in two species, viz. A. callistachys and A. microphysa. The epidermal cells in most species were observed to have a polygonal shape with straight anticlinal walls. However, in A. cephalanthus, both polygonal and irregular cell shapes as well as sinuate anticlinal walls were observed. All pollen grains shed as monad and exhibited small size, single shape, tricolporate aperture type, isopolarity and symmetry, with rounded or elongated pores. It was concluded that, the micromorphological data alone were not enough to separate these two sections and determine the limits of the species.