Study on the developmental stages of ovule and pollen grains of Inula aucheriana DC

In this research, developmental stages of ovule and pollen grains of Inula aucheriana were studied. The flowers and buds, in different developmental stages, were removed, fixed in FAA70, stored in 70% ethanol, embedded in paraffin and then sliced at 7-10 µm by microtome. Staining was carried out with PAS and contrasted with Hematoxylin. The results indicated that anthers were tetra-sporangiate and anther tapetum type was as secretory type one. Pollen tetrads were tetragonal. Pollen grains, when shed had three colpes and needles on the surface. Ovule was anatropous, unitegumic and tenuinucellate. Endothelium was uni-seriate. Endothelium layer was composed of monolayer cells. Embryo sac development was of monosporic and Polygonum type. The shape of megaspore tetrads was both tetrahedral and T-form. Functional megaspore was the chalazal one. Embryo sac was very small at the beginning of development, so that their nuclei were arranged as linear, but its size was increased in later of development. Antipodal nuclei were massive and exhibited polyploidy. Results of this research showed the presence of needle formed crystals in the epidermal cells of ovary that was species specific characteristic. On the outer surface of ovary long, filamentous and one-celled trichoms were visible.